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The Journal of Neuroscience, May 15, 2002, 22(10):3864-3872
Presynaptic Cannabinoid Sensitivity Is a Major Determinant
of Depolarization-Induced Retrograde Suppression at
Hippocampal Synapses
Takako
Ohno-Shosaku1,
Hiroshi
Tsubokawa2,
Ichiro
Mizushima1,
Norihide
Yoneda1,
Andreas
Zimmer3, and
Masanobu
Kano1
1 Department of Cellular Neurophysiology, Graduate
School of Medical Science, Kanazawa University, Kanazawa 920-8640, Japan, 2 National Institute for Physiological Sciences,
Okazaki 444-8585, Japan, and 3 Department of Psychiatry,
University of Bonn, 53105 Bonn, Germany
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ABSTRACT |
Recent studies have clarified that endogenous cannabinoids
(endocannabinoids) are released from depolarized postsynaptic neurons in a Ca2+-dependent manner and act retrogradely on
presynaptic cannabinoid receptors to suppress inhibitory or excitatory
neurotransmitter release. This type of modulation has been found in the
hippocampus and cerebellum and was called depolarization-induced
suppression of inhibition (DSI) or excitation (DSE). In this study, we
quantitatively examined the effects of postsynaptic depolarization and
a cannabinoid agonist on excitatory and inhibitory synapses in rat
hippocampal slices and cultures. We found that both DSE and DSI can be
induced, but DSE was much less prominent than DSI. For the induction of DSE, the necessary duration of depolarization was longer than for DSI.
The magnitude of DSE was much smaller than that of DSI. To explore the
reasons for these differences, we tested the sensitivity of EPSCs and
IPSCs to a cannabinoid agonist, WIN55,212-2, in hippocampal cultures.
IPSCs were dichotomized into two distinct populations, one with a high
sensitivity to WIN55,212-2 (50% block at 2 nM) and the
other with no sensitivity. In contrast, EPSCs were homogeneous and
exhibited a low sensitivity to WIN55,212-2 (50% block at 60 nM). We estimated that the 5 sec depolarization elevated
the local endocannabinoid concentration to a level equivalent to
several nanomoles of WIN55,212-2. Using CB1 knock-out mice, we verified that both DSI and DSE were mediated by the cannabinoid CB1 receptor. These results indicate that presynaptic cannabinoid sensitivity is a
major factor that determines the extent of DSI and DSE.
Key words:
excitatory transmission; inhibitory transmission; hippocampus; retrograde signal; synaptic modulation; cannabinoid
receptor
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INTRODUCTION |
Marijuana influences
various neural functions, with consequences including analgesia,
modulation of locomotor control, and impairment of cognition and memory
(Deadwyler et al., 1990 ; Heyser et al., 1993; Howlett, 1995).
These effects are thought to be mediated through the
interaction of  9-tetrahydrocannabinol, the
psychoactive component of marijuana, with specific
cannabinoid receptors. These receptors belong to the seven
transmembrane domain family of G-protein-coupled receptors and consist
of type 1 (CB1) and type 2 (CB2) receptors (Matsuda et al., 1990; Munro
et al., 1993). Cannabinoid binding sites in the CNS (Herkenham et al.,
1991) that correspond to the distribution of CB1 receptors are
heterogeneous, with high levels in some regions, including the
hippocampus (Matsuda et al., 1993; Tsou et al., 1998; Egertova and
Elphick, 2000). Thus, marijuana may act on hippocampal CB1 receptors
and interfere with actions of their endogenous ligands. This would
disrupt normal information processing in the hippocampus and thereby
cause memory impairment.
Two putative endogenous ligands for cannabinoid receptors, anandamide
(Devane et al., 1992) and 2-arachidonylglycerol (2-AG) (Mechoulam et
al., 1995; Sugiura et al., 1995, 1999), have been identified. These
molecules are produced and released from neurons in a
Ca2+-dependent manner (Di Marzo et al.,
1998; Mechoulam et al., 1998; Piomelli et al., 2000). Activation of
cannabinoid receptors exerts variable effects, including inhibition of
voltage-gated Ca2+ channels, activation of
inwardly rectifying K+ channels, and
suppression of neurotransmitter release (Di Marzo et al., 1998; Felder
and Glass, 1998). Therefore, the endogenous cannabinoid
(endocannabinoid) system is likely to play an important role in
controlling neuronal excitability and synaptic transmission.
It was revealed recently that endocannabinoids mediate a form of
activity-dependent modulation of synaptic transmission. Depolarization of a neuron induces a transient suppression of inhibitory input, a
phenomenon called depolarization-induced suppression of inhibition (DSI) (Llano et al., 1991; Pitler and Alger, 1992; Ohno-Shosaku et al.,
1998). DSI is initiated postsynaptically by an elevation of cytoplasmic
Ca2+ concentration
([Ca2+]i) and is
expressed presynaptically as a suppression of the transmitter release.
Therefore, since the discovery of DSI, it has been thought that some
retrograde signal must exist from the depolarized postsynaptic neurons
to the presynaptic terminals (Alger and Pitler, 1995). Recent studies
have demonstrated that endocannabinoids mediate such retrograde signals
at inhibitory synapses in both the hippocampus (Ohno-Shosaku et al.,
2001; Wilson and Nicoll, 2001; Wilson et al., 2001) and the cerebellum
(Kreitzer and Regehr, 2001b; Diana et al., 2002; Yoshida et al., 2002).
In addition, a phenomenon similar to DSI was found to occur at
excitatory synapses [depolarization-induced suppression of excitation
(DSE)] in the cerebellum that is also mediated by endocannabinoids
(Kreitzer and Regehr, 2001a; Maejima et al., 2001).
In the present study, we report that DSE can be induced in the
hippocampus. Although both DSE and DSI are mediated by CB1 receptors,
DSE was less prominent and required longer depolarization for the
induction compared with the DSI. Our results suggest that presynaptic
cannabinoid sensitivity is a major factor that determines the extent of
depolarization-induced retrograde suppression.
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MATERIALS AND METHODS |
Slices. All experiments were performed according to
the guidelines laid down by the animal welfare committees of Kanazawa University and the National Institute for Physiological Sciences. Hippocampal slices were prepared as described previously (Tsubokawa and
Ross, 1997; Tsubokawa et al., 2000). Young (10- to 12-d-old) rats were
deeply anesthetized with ether and decapitated. The brains were quickly
removed and hemisected on filter paper moistened with cutting solution
of the following composition (in mM): 120 choline-Cl, 3 KCl, 8 MgCl2, 1.25 NaH2PO4, 26 NaHCO3, and 20 glucose, equilibrated with 95%
O2-5% CO2. Brain tissues
containing the hippocampi on each side were dissected out and put into
a cutting chamber filled with ice-cold cutting solution. These two
blocks were sliced into 300 µm sections transversely to their
longitudinal axis with a microtome (Vibroslicer; Campden Instruments,
Lafayette, IN). The slices were immediately placed into a
reservoir chamber filled with normal solution, incubated at 35°C for
~30 min, and then maintained at room temperature. In some
experiments, hippocampal slices were prepared from the CB1 knock-out
mice and wild-type mice by the same procedure as described above. The
normal solution was composed of (in mM): 125 NaCl, 2.5 KCl, 2 CaCl2, 2 MgCl2, 1.25 NaH2PO4, 26 NaHCO3, and 20 glucose, bubbled with a mixture of
95% O2 and 5% CO2, with a
final pH of 7.4. For recording, a single slice was transferred to a
submerged chamber mounted on the stage of an upright microscope
(BX50WI; Olympus Optical, Tokyo, Japan). The slice was superfused
continuously with the normal solution at room temperature (for
experiments shown in Figs. 2 and 3) or regulated at 30-32°C (Fig.
1).
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Figure 1.
Transient suppression of EPSCs induced by
depolarization of a CA1 pyramidal neuron in the hippocampal slice.
A, Example of EPSC traces acquired at the time points
indicated in B. Each trace is the average of three
consecutive EPSCs. B, Time course of the change in EPSC
amplitudes. EPSCs were evoked at 1 Hz. The pyramidal neuron was
depolarized to  30 mV or to 0 mV for 7 sec at the times indicated by
arrows.
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Electrical recordings were made from CA1 pyramidal cell somata in
slices using patch pipettes pulled from 1.5-mm-outer diameter (o.d.), thick-walled glass tubing (1511-M; Friedrich & Dimmock, Melville, NJ). The pipette solution contained (in mM): 115 K-gluconate, 10 KCl, 10 NaCl, 10 HEPES, 2 Mg-ATP, and 0.3 GTP, pH
adjusted to 7.3 with KOH. The open resistance of the pipettes was 5-7
M . Whole-cell tight seals (>5 G) were made on the soma under
visual control with a 40× water-immersion lens (Edwards et al., 1989). Capacitance was fully compensated by a patch-clamp amplifier (Axopatch 1D; Axon Instruments, Foster City, CA). The range of series resistance we accepted was 10-15 M. Bipolar stimulation electrodes constructed from Teflon-coated thin tungsten wire (50 µm o.d.) were placed on the
stratum radiatum to generate EPSCs and IPSCs. The membrane potential of
neurons was held at 70 mV. The bath solution was supplemented with 10 µM SR95531 or 10 µM bicuculline methiodide for recording EPSCs and with 10 µM
6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) and 50 µM
DL-2-amino-5-phosphonovaleric acid (APV) for recording
IPSCs. Cells were identified as pyramidal neurons according to both
electrical and anatomic criteria.
Cultures. Hippocampal cells were enzymatically (with
trypsin) or mechanically dissociated from the hippocampus of newborn rats (1-2 d of age) and were plated onto culture dishes pretreated with poly-L-ornithine (0.01%). The cells were
incubated in DMEM/F-12 medium (Invitrogen, San Diego, CA)
supplemented with putrescine (0.1 mM), sodium
selenite (30 nM),
L-glutamine (1.4 mM),
gentamycin (10 µg/ml), insulin (5 µg/ml), and fetal calf serum
(10%). Cultures were maintained at 36°C in 5%
CO2 for 10-14 d. For the experiments shown in
Figure 8, hippocampal neurons were cultured from the CB1 knock-out mice
and wild-type mice by the same procedure. All experiments were
performed at room temperature. The external solution contained (in
mM): 140 NaCl, 2.5 KCl, 1 MgCl2, 2 CaCl2, 10 HEPES, and 10 glucose, pH 7.3 adjusted with NaOH. The bath was perfused with
the external solution with or without drugs at a flow rate of 1-3
ml/min. The internal solution contained (in mM):
120 K-gluconate, 15 KCl, 6 MgCl2, 0.2 EGTA, 10 HEPES, 10 KOH, and 5 Na2ATP, pH 7.3 adjusted with
KOH. In some of the experiments in which the sensitivity of synaptic
currents to a cannabinoid agonist, WIN55,212-2, was examined, the
internal solution containing 5 mM EGTA was used. Because the sensitivity to WIN55,212-2 was not different between 0.2 and 5 mM EGTA in the internal solution, data
acquired with the two internal solutions were pooled. The internal
solution with 5 mM EGTA was also used for the
experiments on mouse cultured neurons (see Fig. 8). The electrode
resistance ranged from 3 to 5 M when the pipette was filled
with the solution.
A pair of neurons were whole-cell clamped with two different patch
pipettes, and membrane potentials of both cells were held at 80 mV.
The presynaptic neuron was stimulated by applying positive-voltage pulses (80 mV, 2 msec) at 0.2-1 Hz, and EPSCs or IPSCs were measured from the postsynaptic neuron with a patch-clamp amplifier (EPC-9/2; Heka Elektronik, Lambrecht/Pfalz, Germany). EPSCs were usually measured
in the presence of 5-10 nM TTX to suppress spontaneous firing. IPSCs were measured in the presence of 1 mM
kynurenic acid.
Induction of DSE and DSI. To induce DSE and DSI, the
postsynaptic neuron was depolarized to 0 mV for the indicated duration (0.5-10 sec) unless otherwise noted. The magnitudes of
depolarization-induced suppression were measured as the percentage of
the mean amplitude of synaptic currents acquired between 4 and 18 sec
after the end of depolarization relative to that acquired for 30 sec
before the depolarization. The depression caused by drugs was estimated as the percentage of the mean amplitudes of 5-12 consecutive synaptic currents during drug application relative to that before application. Averaged data from different experiments are presented as mean ± SEM.
CB1 receptor knock-out mouse. CB1 receptor knock-out mice
were generated as described previously (Zimmer et al., 1999). Briefly, the coding region of the CB1 gene was replaced
between amino acids 32 and 448 with phosphoglycerate kinase-neo in
embryonic stem cells. Chimeric mice derived from these cells were bred
with C57BL/6J animals. Homozygous mutant (CB1/) and
wild-type (CB1+/+) mice were produced with heterozygous
intermatings. In the present investigation, neonatal [postnatal day 1 (P1)] and juvenile (P9-P12) mice of both sexes were used to prepare
cultures and slices, respectively. Animals were housed in groups under
standard laboratory conditions (12 hr light/dark cycle) with food and
water available ad libitum.
Materials. WIN55,212-2, AM281, SR95531, CNQX, and APV were
purchased from Tocris Cookson (Ballwin, MO). Other chemicals were purchased from Sigma (St. Louis, MO). SR141716A was a generous gift
from Sanofi Recherche (Montpellier, France). For the perfusion of
solutions containing WIN55,212-2, AM281, or SR141716A, different tubes
were used to avoid contamination.
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RESULTS |
Endocannabinoid-mediated DSE in the hippocampus
We first examined whether depolarization of the postsynaptic
neuron can induce DSE in hippocampal slices from the rat. When a CA1
pyramidal neuron was depolarized for several seconds under the
voltage-clamp mode, the subsequent EPSCs from the depolarized neuron
were transiently suppressed. In a CA1 pyramidal neuron shown in Figure
1, depolarization from 70 to 30 mV (Fig. 1Aa,b) or 0 mV (Fig. 1Ac,d) for 7 sec was effective at
inducing DSE (Fig. 1B). Because the DSE in the
cerebellum is shown to be mediated by endocannabinoids (Kreitzer and
Regehr, 2001a; Maejima et al., 2001), we subsequently examined whether
a CB1 antagonist, SR141716A, could block DSE. In five neurons, a
depolarizing voltage pulse (from 70 to 0 mV; 10 sec) was applied
before and after addition of 5 µM SR141716A.
The depolarization induced a clear suppression of EPSCs in the normal
external solution (Fig.
2A), whereas the same
depolarization caused no significant change in the presence of
SR141716A (Fig. 2B). These results clearly indicate
that DSE in the hippocampus is also mediated by endocannabinoids that
are released from depolarized postsynaptic neurons and suppress the excitatory transmission through activation of cannabinoid receptors, presumably CB1 receptors.
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Figure 2.
Blockade of DSE by a cannabinoid antagonist,
SR141716A. Averaged time courses of the changes in EPSC amplitudes
induced by depolarization to 0 mV for 10 sec before
(A) and after (B) treatment
with 5 µM SR141716A are shown. The data shown in
B were acquired at least 30 min after the bath
application of the antagonist. EPSCs were evoked at 1 Hz. In each
experiment, mean amplitudes of five consecutive EPSCs were calculated.
Each point is the average of the mean EPSC amplitudes
for the 5 sec period from five different cells. EPSC traces acquired
before and after depolarization (Depo) were superimposed
(right). Each trace is the average of eight consecutive
EPSCs.
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Excitatory transmission is less sensitive to
postsynaptic depolarization
We then compared DSE and DSI in the slices from the same animals.
As shown in Figure 3, depolarization for
5 sec induced a marked suppression of IPSCs (DSI) (Fig. 3A),
whereas the same depolarization induced no significant DSE (Fig.
3B). Although subsequent depolarization of a longer duration
(10 sec) induced clear DSE (Fig. 3B), it was still less
prominent than the DSI induced by the 5 sec depolarization (Fig.
3A). These results indicate that excitatory transmission is
less sensitive to postsynaptic depolarization than inhibitory
transmission.
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Figure 3.
DSE is less prominent than DSI in CA1 pyramidal
cells. Averaged time courses of the changes in amplitude of IPSCs
(A) and EPSCs (B) are
shown. IPSCs and EPSCs were evoked at 0.33 and 1 Hz, respectively.
Pyramidal neurons were depolarized to 0 mV for 5 or 10 sec at the times
indicated by arrows. In each experiment, mean amplitudes
of five consecutive IPSCs or EPSCs were calculated. Each
point is the average of the mean amplitudes from five
different cells.
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One possible explanation for these quantitative differences is that the
inhibitory presynaptic terminals might be more sensitive to
endocannabinoids than the excitatory terminals. In the following experiments, we tested this possibility in cultured hippocampal neurons.
Excitatory presynaptic terminals are less sensitive
to cannabinoids
We determined the cannabinoid sensitivities of excitatory and
inhibitory synapses using neuron pairs with excitatory or inhibitory synaptic connections. In each pair, the effects of different
concentrations of a cannabinoid agonist, WIN55,212-2, on EPSCs or
IPSCs were examined. When WIN55,212-2 was applied at 1-1000
nM, the EPSC amplitude was decreased in a dose-dependent
manner (Fig. 4A). The
suppressing effect was reversed by a cannabinoid receptor antagonist,
0.3 µM AM281 (n = 8) or 0.3 µM SR141716A (n = 3), confirming that WIN55,212-2 acted on cannabinoid receptors. The concentration of WIN55,212-2 that reduced the EPSC amplitude by 50%
was between 10 and 100 nM (Fig.
4A). Excitatory synapses were relatively homogeneous
in terms of sensitivity to WIN55,212-2, and similar results were
obtained in another seven pairs. In contrast, inhibitory synapses were
heterogeneous and divided into two populations, those sensitive and
those insensitive to WIN55,212-2, as reported previously (Ohno-Shosaku
et al., 2001). In one population, IPSCs were suppressed by nanomolar
concentrations of WIN55,212-2 (Fig. 4B). The
concentration of WIN55,212-2 that caused 50% inhibition was
between 1 and 10 nM (Fig. 4B).
In the other population, IPSCs were totally insensitive to WIN55,212-2,
even at concentrations as high as 1000 nM (Fig.
4C).
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Figure 4.
Effects of a cannabinoid agonist, WIN55,212-2
(WIN), on EPSCs (A) and
IPSCs (B, C). Amplitudes of EPSCs
(A) and IPSCs (B, C) are plotted
as a function of time. The bath was perfused with a solution containing
1-1000 nM WIN55,212-2 or a cannabinoid antagonist, AM281
(0.3 µM), for the periods indicated by the
horizontal lines. The traces of EPSCs
(A) and IPSCs (B, C) acquired
before and during application of WIN55,212-2 are superimposed
(right).
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Figure 5 summarizes data for the
sensitivity to WIN55,212-2 of excitatory synapses and the two
populations of inhibitory synapses. The WIN55,212-2 concentrations for
50% inhibition were ~60 nM for EPSCs and 2 nM for the WIN55,212-2-sensitive IPSCs, indicating that
EPSCs are ~30-fold less sensitive than the WIN55,212-2-sensitive IPSCs (Fig. 5A). In the presence of 100 nM WIN55,212-2, the EPSC amplitude was decreased
to 23-60% of controls (38.7 ± 5.3%; n = 8)
(Fig. 5B, closed circles). In contrast, values
for the WIN55,212-2-sensitive IPSCs were all <10% (1.7 ± 0.8%;
n = 16) (Fig. 5B, open circles), and those of the WIN55,212-2-insensitive IPSCs were all >90%
(99.3 ± 2.8%; n = 8) (Fig. 5B,
open triangles). There was no overlap of individual data
among these three populations.
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Figure 5.
Summary of the dose-dependent suppressions of
EPSCs and IPSCs by WIN55,212-2 (WIN).
A, Amplitudes of WIN55,212-2-sensitive IPSCs
(open circles), WIN55,212-2-insensitive IPSCs
(triangles), and EPSCs (closed
circles) plotted against the concentration of WIN55,212-2. In
each cell, current amplitudes in the presence of WIN55,212-2 were
expressed as the percentages of the control values (dotted
line) obtained before application of WIN55,212-2. Each
symbol represents the average value from the indicated
number of neuron pairs. B,
Individual values of current amplitudes in the presence of 100 nM WIN55,212-2 for WIN55,212-2-sensitive IPSCs (open
circles), WIN55,212-2-insensitive IPSCs
(triangles), and EPSCs (closed
circles).
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To test whether WIN55,212-2 causes presynaptic or postsynaptic change
in excitatory transmission, we examined paired-pulse plasticity. The
paired-pulse ratio of EPSC amplitudes was significantly increased by
WIN55,212-2 (Fig. 6A).
In the presence of 0.1 and 1 µM WIN55,212-2,
the EPSC amplitude decreased by 57 and 77% of controls, and the
paired-pulse ratio increased by 34 and 44%, respectively (Fig. 6,
closed circles). A decrease in the probability of vesicular
transmitter release from presynaptic terminals is generally accompanied
by an increase in the paired-pulse ratio (Zucker, 1989). Therefore, the
present results indicate that WIN55,212-2 acts on cannabinoid receptors
on excitatory presynaptic terminals and causes the suppression of
transmitter release, which is in agreement with the previous study
(Shen et al., 1996). This mechanism is essentially identical to that
for the action of WIN55,212-2 on inhibitory synapses (Katona et al.,
1999; Hoffman and Lupica, 2000; Ohno-Shosaku et al., 2001, 2002; Wilson
and Nicoll, 2001). We also found that DSE is accompanied by clear
increases in the paired-pulse ratio (Fig. 6B,
open circles), indicating that DSE is expressed
presynaptically as a decrease in excitatory transmitter release.
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Figure 6.
Changes in paired-pulse ratio during suppression
of EPSCs by WIN55,212-2 (WIN) (A;
B, closed circles) and DSE
(B, open circles). A,
Examples of EPSCs evoked by paired stimuli with an interpulse interval
of 50 msec. Each trace is the average of 10-12 consecutive EPSCs.
Traces scaled to the amplitude of the first EPSC are shown at the
bottom. The traces acquired before and during bath
application of WIN55,212-2 are superimposed. B, The
relationships between the reduction in the first EPSC amplitude and the
increase in paired-pulse ratio induced by applications of 100 and 1000 nM WIN55,212-2 (closed circles) and the 5 sec and 10 sec depolarizing pulses (DSE). Each symbol
represents the averaged value from the indicated number
of neuron pairs.
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Estimation of local cannabinoid levels during DSE and DSI
Subsequently, we attempted to estimate the local level of
endocannabinoids during DSE and DSI as an equivalent concentration of
WIN55,212-2. For this purpose, we measured magnitudes of DSI and DSE
(Fig. 7) and compared them with those of
suppressions induced by WIN55,212-2 (Fig. 5A).
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Figure 7.
Induction of DSI and DSE depends on the duration
of depolarization. A, B, Example of DSI
(A) and DSE (B) induced by
various depolarizing pulses with durations of 0.5-10 sec. The
postsynaptic neuron was depolarized at the times indicated by
arrows. Traces of IPSCs (A) or
EPSCs (B) acquired before and 7 sec after
depolarization with a duration of 3 sec (A) or 10 sec (B) are superimposed on the
right. C, The relationships between the
depolarizing pulse duration and the relative amplitude of IPSCs
(open circles) and EPSCs (closed circles)
obtained 6-16 sec after the end of depolarization. The
amplitude was normalized to the averaged value (dotted line)
before depolarization. Each symbol represents the
averaged value obtained from the indicated number of
neuron pairs.
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DSI was induced by depolarizations with pulse durations of 0.5, 1, 3, and 5 sec at WIN55,212-2-sensitive inhibitory synapses (Fig.
7A,C). In a pair shown in Figure 7A, a 0.5 sec
depolarization induced significant DSI, and a depolarization of a
longer duration induced more prominent DSI. The averaged data show a
clear dependence of the DSI magnitude on the depolarizing pulse
duration (Fig. 7C, open circles). DSE was induced
by depolarizations with pulse durations of 1, 3, 5, and 10 sec in 14 pairs with excitatory connections (Fig. 7B,C). In a pair
exemplified in Figure 7B, depolarizing pulses with a
duration of >3 sec induced a slight but significant decrease in EPSC
amplitudes. The averaged data in Figure 7C show that the 5 sec depolarization of postsynaptic neurons suppressed the IPSC
amplitude by 81% (Fig. 7C, open circles) and the
EPSC amplitude by 10% (Fig. 7C, closed circles)
of control values. These magnitudes of suppression correspond to those
for IPSCs and for EPSCs induced by ~5 nM
WIN55,212-2 (Fig. 5A). These results indicate that the local
concentration of endocannabinoids around excitatory and inhibitory
presynaptic terminals is estimated to reach a level equivalent to
several nanomoles of WIN55,212-2 after postsynaptic depolarization for
5 sec. Thus, the quantitative difference between DSE and DSI can be
explained by the difference in the cannabinoid sensitivity between
excitatory and inhibitory synaptic terminals.
CB1 receptors are responsible for both DSI and DSE in
the hippocampus
It was reported recently that both DSI and the WIN55,212-2-induced
suppression of IPSCs are absent in hippocampal slices from CB1
knock-out (CB1/) mice (Varma et al., 2001; Wilson et
al., 2001). We therefore examined whether CB1 receptors mediate the effects of cannabinoids on IPSCs in cultured mouse hippocampal neurons.
In neurons prepared from wild-type mice (CB1+/+), DSI (>20% suppression after 5 sec depolarization) was observed in 11 of
25 neuron pairs. In such DSI-positive pairs, WIN55,212-2 (100 nM) was always effective and decreased the IPSC amplitude to 5.2 ± 8.9% of controls (n = 9). In contrast,
neither DSI nor WIN55,212-2-induced suppression was observed in
cultured neurons from CB1/ mice. The IPSC amplitude
after depolarization was 96.2 ± 3.4% of controls
(n = 17), and the amplitude in the presence of 100 nM WIN55,212-2 was 108.4 ± 7.5%
(n = 10). These results confirmed that CB1 receptors
mediate DSI as well as effects of cannabinoids on inhibitory synapses
in cultured hippocampal neurons.
We then examined whether CB1 receptors are also responsible for
hippocampal DSE. In cultured neurons from CB1+/+ mice, DSE was clearly induced by a 5 sec depolarization and was completely abolished after treatment with the cannabinoid antagonist AM281 (Fig.
8A,C). The EPSC
amplitude was strongly suppressed after application of 100 nM WIN55,212-2 (Fig. 8B,C). In
neurons from CB1/ mice, however, neither depolarization
nor WIN55,212-2 affected EPSCs (Fig. 8). In some experiments, a longer
depolarization (10 sec) and a higher dose of WIN55,212-2 (1 µM) were tested. However, we could not detect
any significant effects on EPSCs (n = 5; data not
shown). The GABAB agonist baclofen (10 µM) effectively suppressed EPSCs of
CB1/ neurons (Fig. 8C), indicating that other
components required for G-protein-mediated presynaptic inhibition are
intact. The involvement of CB1 receptors in DSE was also confirmed in slice preparations. The magnitudes of DSE after a 10 sec depolarization were 6.8 ± 2.3% for CB1/ (n = 7)
and 20.3 ± 5.4% for CB1+/+ (n = 7)
mice (p < 0.05). These results indicate that
DSE is mediated by CB1 receptors in the hippocampus.
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Figure 8.
DSE and WIN55,212-2
(WIN)-induced suppression of EPSCs in
CB1+/+ and CB1/ mice. A,
Examples of DSE induced by 5 sec depolarization (Depo)
in cultured neurons prepared from CB1+/+ and
CB1/ mice. Two EPSC traces acquired before and 6 sec
after depolarization are superimposed. B, Examples of
WIN55,212-2-induced suppression of EPSCs in cultured neurons prepared
from CB1+/+ and CB1/ mice. Two EPSC traces
acquired before and after application of 100 nM WIN55,212-2
are superimposed. C, The averaged data for DSE before
(DSE) and after (DSE/AM281) treatment
with 0.3 µM AM281 and suppression of EPSCs by 100 nM WIN55,212-2 or 10 µM baclofen in cultured
neurons prepared from CB1+/+ and CB1/ mice.
Each bar represents the averaged value obtained from the
indicated number of neuron pairs.
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DISCUSSION |
In the present study, we report for the first time that DSE can be
induced in the hippocampus. Both DSI and DSE were mediated by CB1
receptors, but DSE was less prominent and required longer depolarizations for induction than DSI. This quantitative difference can be explained by the difference in sensitivities to cannabinoids between excitatory and inhibitory synapses. Excitatory transmission was
estimated to be ~30-fold less sensitive to cannabinoids than inhibitory transmission in cultured hippocampal neurons.
Cannabinoid sensitivities of excitatory and
inhibitory synapses
Several previous studies show that WIN55,212-2 induces suppression
of EPSCs in hippocampal cultures (Shen et al., 1996; Sullivan, 1999)
and slices (Misner and Sullivan, 1999). Conversely, other studies show
that excitatory transmission in the hippocampus is not suppressed by
WIN55,212-2 (Paton et al., 1998) or 2-AG (Stella et al., 1997). One
possible explanation for this discrepancy might be the difference in
age of the animals used. Most of the studies showing no effect of
cannabinoid agonists have been done with older animals. It is possible
that cannabinoid modulation of excitatory transmission would be
developmentally regulated, as reported recently (Al-Hayani and Davies,
2000). In our preliminary experiments, however, excitatory transmission
was still sensitive to WIN55,212-2 in hippocampal slices from
5-week-old rats. Another possibility is that the discrepancy might
derive from the difference in recording techniques. The groups
reporting the positive effects of WIN55,212-2 applied the patch-clamp
technique to cultured neurons (Shen et al., 1996; Sullivan, 1999) or to
neurons in slices that were presumably close to the surface (Misner and
Sullivan, 1999). Conversely, the groups reporting no effect of
cannabinoid agonists measured field potentials (Stella et al., 1997;
Paton et al., 1998) that primarily reflected the responses of neurons
located in the depth of the slices. Because WIN55,212-2 and 2-AG are
lipid in nature, they may not easily diffuse into slices. Thus, it is
possible that their local levels around the synapses deep in the slices may have been too low to affect excitatory transmission.
A previous study on hippocampal DSI demonstrated that postsynaptic
depolarization affected inhibitory but not excitatory transmission (Wagner and Alger, 1996). The apparent discrepancy between the findings
of Wagner and Alger (1996) and the present data may be attributable to
the difference in the induction protocol. They used depolarization for
1 sec, which has now turned out to be too short. We found that
depolarization with a duration of >7 sec was necessary to induce
detectable DSE in slice preparations.
The reasons for the difference in sensitivity to cannabinoids between
excitatory and inhibitory transmissions remain elusive. One possibility
is that cannabinoid receptor subtypes on presynaptic terminals are
different between excitatory and inhibitory synapses. A recent article
reports that WIN55,212-2 still suppresses EPSCs in adult
CB1/ mice (Hajos et al., 2001), suggesting an
involvement of a novel subtype of cannabinoid receptors. In the present
study, however, we could not detect any effects of WIN55,212-2 on
either IPSCs or EPSCs in CB1/ mice. Importantly, neither
DSI nor DSE was induced in CB1/ mice. We therefore
conclude that the CB1 receptor mediates both DSI and DSE, at least in
the juvenile animals used in the present study. It is possible,
however, that the expression of the novel cannabinoid receptor subtype
may be developmentally regulated and become functional in older
animals. It is also possible that the CB1/ mouse lines
used by Hajos et al. (2001) and in the present study were constructed
differently and might be on different backgrounds.
Another possibility for the difference in cannabinoid
sensitivity between excitatory and inhibitory synapses is that CB1
receptors are expressed more densely at inhibitory presynaptic
terminals than at excitatory ones. Anatomic studies support this
possibility. In situ hybridization studies on rats (Matsuda
et al., 1993) and mice (Marsicano and Lutz, 1999) suggest that large
and moderate amounts of CB1 mRNA are distributed in GABAergic and
pyramidal cells, respectively. An immunocytochemical study shows an
expression of CB1 receptors in hippocampal pyramidal cells (Pettit et
al., 1998). However, other immunocytochemical studies (Katona et al., 1999; Hajos et al., 2000) with a different antibody demonstrate that
CB1 receptors are densely localized at subpopulations of GABAergic
presynaptic terminals but are absent on glutamatergic neurons. These
results suggest that the difference in cannabinoid sensitivity between
excitatory and inhibitory transmissions is at least partly attributable
to the difference in the amount of CB1 proteins at presynaptic terminals.
Possible physiological significance of DSI and DSE
What could be a functional role of DSI and DSE in the hippocampus?
Previous studies show that endocannabinoids are synthesized "on
demand" in stimulated neurons and released from them in a Ca2+-dependent manner (Di Marzo et al.,
1998; Mechoulam et al., 1998; Piomelli et al., 2000). We have shown
that the postsynaptic elevations of
[Ca2+]i and DSI
had similar time courses in cultured hippocampal neurons (Ohno-Shosaku
et al., 2001). Therefore, the amount of released endocannabinoids can
directly reflect the activity of postsynaptic neurons and the resultant
elevation of
[Ca2+]i. If
endocannabinoids suppress excitatory and inhibitory inputs to the same
extent, they will cause no change in the excitability of postsynaptic
neurons. The present study, however, has revealed that excitatory and
inhibitory synapses of the hippocampus have different sensitivities to
cannabinoids. Whereas excitatory synapses were homogeneous and had
moderate sensitivities to WIN55,212-2, inhibitory synapses were
dichotomized into two distinct populations, one with a high sensitivity
to WIN55,212-2 and the other with no sensitivity. Thus,
endocannabinoids can control the balance between excitatory and
inhibitory inputs, depending on the local concentration around synapses.
DSI can occur only at CB1-expressing synapses. One of the
CB1-expressing neurons is a cholecystokinin (CCK)-containing basket cell (Katona et al., 1999). In contrast, the other type of basket cell,
which contains palvalbumin (PV) but not CCK, is devoid of CB1 receptors
(Katona et al., 1999). Both types of basket cells form perisomatic
synapses on pyramidal neurons. These anatomic data suggest that DSI
occurs selectively at CCK-containing but not PV-containing perisomatic
synapses on pyramidal cells. In addition to these two types, a third
type of inhibitory synapse has been characterized
electrophysiologically (Wilson et al., 2001). This type is insensitive
to cannabinoids, exhibits no DSI, and presumably originates in distal
dendrites because of their slow rise and decay kinetics. This is
essentially in agreement with the finding by Martin et al. (2001) that
IPSCs can be classified into at least three types: DSI-susceptible IPSC
with fast kinetics, DSI-resistant IPSC with fast kinetics, and
DSI-resistant IPSC with slow kinetics. To understand the physiological
roles of DSI, the heterogeneity of synapses has to be considered
carefully in terms of their CB1 expression and locations on pyramidal
cells. In addition, it should be noted that the release of
cotransmitters might also be modulated by endocannabinoids. The
activation of CB1 receptors was found to suppress CCK release in the
hippocampus (Beinfeld and Connolly, 2001). If DSI also reduces the
release of cotransmitters, DSI can influence neural activity by
modulating both fast and slow synaptic events.
We have estimated the local cannabinoid concentration during DSI and
DSE in cultured neurons. The magnitudes of DSI and DSE induced by a 5 sec depolarization corresponded to the suppressions induced by ~5
nM WIN55,212-2 for both IPSCs and EPSCs. These results suggest that at least in our culture system, the difference in the
magnitudes of DSI and DSE is determined primarily by presynaptic cannabinoid sensitivities and not by the difference in the local cannabinoid level around presynaptic terminals. However, it should be
noted that inputs, synaptic organization, and geometry of neurons may
be altered in cultures from the nervous tissue in vivo.
Regulation of DSI and DSE may be more complex in the brain. For
example, postsynaptic depolarization may induce heterogeneous
elevations of
[Ca2+]i within
single neurons because of heterogeneous distributions of voltage-gated
Ca2+ channels and
Ca2+ stores along the soma and dendrites.
This may cause a heterogeneity of endocannabinoid concentration after
depolarization. It is likely that relative contributions of DSE and DSI
to neuronal excitability may depend on the geometry of the neuron and
distribution of synapses. In addition, recent studies suggest that the
activation of postsynaptic metabotropic glutamate receptors (mGluRs)
enhances the depolarization-induced release of endocannabinoids (Varma
et al., 2001; Ohno-Shosaku et al., 2002). This finding suggests that
cannabinoid-mediated modulation may also be influenced by the
distribution of mGluRs in neurons.
In addition to the modulation of synaptic transmission, cannabinoid
agonists have been reported to exert variable effects on neurons (Di
Marzo et al., 1998; Felder and Glass, 1998). These include inhibition
of adenylate cyclase (Howlett and Fleming, 1984), inhibition of
voltage-gated Ca2+ channels (Mackie and
Hille, 1992; Mackie et al., 1995; Twitchell et al., 1997), and
activation of inwardly rectifying K+
channels (Mackie et al., 1995). These effects can be produced by 1-100
nM WIN55,212-2. It is therefore likely that these effects can work in concert with DSI and DSE to regulate the net excitability of the postsynaptic neuron in vivo.
| |
FOOTNOTES |
Received Dec. 26, 2001; revised Feb. 20, 2002; accepted Feb. 27, 2002.
This work was supported in part by grants-in-aid for scientific
research (T.O., M.K.) and special coordination funds for promoting science and technology (M.K.) from the Ministry of Education, Culture,
Sports, Science, and Technology of Japan and by grants from the
Novartis Foundation (M.K.), the Cell Science Research Foundation
(M.K.), and the Sumitomo Foundation (T.O.).
Correspondence should be addressed to Masanobu Kano, Department of
Cellular Neurophysiology, Graduate School of Medical Science, Kanazawa
University, 13-1 Takara-machi, Kanazawa 920-8640, Japan. E-mail:
mkano{at}med.kanazawa-u.ac.jp.
| |
REFERENCES |
-
Alger BE,
Pitler TA
(1995)
Retrograde signaling at GABAA-receptor synapses in the mammalian CNS.
Trends Neurosci
18:333-340[Web of Science][Medline].
-
Al-Hayani A,
Davies SN
(2000)
Cannabinoid receptor mediated inhibition of excitatory synaptic transmission in the rat hippocampal slice is developmentally regulated.
Br J Pharmacol
131:663-665[Web of Science][Medline].
-
Beinfeld MC,
Connolly K
(2001)
Activation of CB1 cannabinoid receptors in rat hippocampal slices inhibits potassium-evoked cholecystokinin release, a possible mechanism contributing to the spatial memory defects produced by cannabinoids.
Neurosci Lett
301:69-71[Web of Science][Medline].
-
Deadwyler SA,
Heyser CJ,
Michaelis RC,
Hampson RE
(1990)
The effects of delta-9-THC on mechanisms of learning and memory.
NIDA Res Monogr
97:79-93[Medline].
-
Devane WA,
Hanus L,
Breuer A,
Pertwee RG,
Stevenson LA,
Griffin G,
Gibson D,
Mandelbaum D,
Etinger A,
Mechoulam R
(1992)
Isolation and structure of a brain constituent that binds to the cannabinoid receptor.
Science
258:1946-1949[Abstract/Free Full Text].
-
Diana MA,
Levenes C,
Mackie K,
Marty A
(2002)
Short-term retrograde inhibition of GABAergic synaptic currents in rat Purkinje cells is mediated by endogenous cannabinoids.
J Neurosci
22:200-208[Abstract/Free Full Text].
-
Di Marzo V,
Melck D,
Bisogno T,
De Petrocellis L
(1998)
Endocannabinoids: endogenous cannabinoid receptor ligands with neuromodulatory action.
Trends Neurosci
21:521-528[Web of Science][Medline].
-
Edwards FA,
Konnerth A,
Sakmann B,
Takahashi T
(1989)
A thin slice preparation for patch-clamp recordings from neurons of the mammalian central nervous system.
Pflügers Arch
414:600-612[Web of Science][Medline].
-
Egertova M,
Elphick MR
(2000)
Localisation of cannabinoid receptors in the rat brain using antibodies to the intracellular C-terminal tail of CB1.
J Comp Neurol
422:159-171[Web of Science][Medline].
-
Felder CC,
Glass M
(1998)
Cannabinoid receptors and their endogenous agonists.
Annu Rev Pharmacol Toxicol
38:179-200[Web of Science][Medline].
-
Hajos N,
Katona I,
Naiem SS,
Mackie K,
Ledent C,
Mody I,
Freund TF
(2000)
Cannabinoids inhibit hippocampal GABAergic transmission and network oscillations.
Eur J Neurosci
12:3239-3249[Web of Science][Medline].
-
Hajos N,
Ledent C,
Freund TF
(2001)
Novel cannabinoid-sensitive receptor mediates inhibition of glutamatergic synaptic transmission in the hippocampus.
Neuroscience
106:1-4[Web of Science][Medline].
-
Herkenham M,
Lynn AB,
Johnson MR,
Melvin LS,
de Costa BR,
Rice KC
(1991)
Characterization and localization of cannabinoid receptors in rat brain: a quantitative in vitro autoradiographic study.
J Neurosci
11:563-583[Abstract].
-
Heyser CJ,
Hampson RE,
Deadwyler SA
(1993)
Effects of delta-9-tetrahydrocannabinol on delayed match to sample performance in rats: alterations in short-term memory associated with changes in task specific firing of hippocampal cells.
J Pharmacol Exp Ther
264:294-307[Abstract/Free Full Text].
-
Hoffman AF,
Lupica CR
(2000)
Mechanisms of cannabinoid inhibition of GABAA synaptic transmission in the hippocampus.
J Neurosci
20:2470-2479[Abstract/Free Full Text].
-
Howlett AC
(1995)
Pharmacology of cannabinoid receptors.
Annu Rev Pharmacol Toxicol
35:607-634[Web of Science][Medline].
-
Howlett AC,
Fleming RM
(1984)
Cannabinoid inhibition of adenylate cyclase: pharmacology of the response in neuroblastoma cell membranes.
Mol Pharmacol
26:532-538[Abstract].
-
Katona I,
Sperlágh B,
Sík A,
Käfalvi A,
Vizi ES,
Mackie K,
Freund TF
(1999)
Presynaptically located CB1 cannabinoid receptors regulate GABA release from axon terminals of specific hippocampal interneurons.
J Neurosci
19:4544-4558[Abstract/Free Full Text].
-
Kreitzer AC,
Regehr WG
(2001a)
Retrograde inhibition of presynaptic calcium influx by endogenous cannabinoids at excitatory synapses onto Purkinje cells.
Neuron
29:717-727[Web of Science][Medline].
-
Kreitzer AC,
Regehr WG
(2001b)
Cerebellar depolarization-induced suppression of inhibition is mediated by endogenous cannabinoids.
J Neurosci
21:RC174[Abstract/Free Full Text]:1-5.
-
Llano I,
Leresche N,
Marty A
(1991)
Calcium entry increases the sensitivity of cerebellar Purkinje cells to applied GABA and decreases inhibitory synaptic currents.
Neuron
6:565-574[Web of Science][Medline].
-
Mackie K,
Hille B
(1992)
Cannabinoids inhibit N-type calcium channels in neuroblastoma-glioma cells.
Proc Natl Acad Sci USA
89:3825-3829[Abstract/Free Full Text].
-
Mackie K,
Lai Y,
Westenbroek R,
Mitchell R
(1995)
Cannabinoids activate an inwardly rectifying potassium conductance and inhibit Q-type calcium currents in ATT20 cells transfected with rat brain cannabinoid receptors.
J Neurosci
15:6552-6561[Abstract/Free Full Text].
-
Maejima T,
Hashimoto K,
Yoshida T,
Aiba A,
Kano M
(2001)
Presynaptic inhibition caused by retrograde signal from metabotropic glutamate to cannabinoid receptors.
Neuron
31:463-475[Web of Science][Medline].
-
Marsicano G,
Lutz B
(1999)
Expression of the cannabinoid receptor CB1 in distinct neuronal subpopulations in the adult mouse forebrain.
Eur J Neurosci
11:4213-4224[Web of Science][Medline].
-
Martin LA,
Wei DS,
Alger BE
(2001)
Heterogeneous susceptibility of GABA(A) receptor-mediated IPSCs to depolarization-induced suppression of inhibition in rat hippocampus.
J Physiol (Lond)
532:685-700[Abstract/Free Full Text].
-
Matsuda LA,
Lolait SJ,
Brownstein MJ,
Young AC,
Bonner TI
(1990)
Structure of a cannabinoid receptor and functional expression of the cloned cDNA.
Nature
346:561-564[Medline].
-
Matsuda LA,
Bonner TI,
Lolait SJ
(1993)
Localization of cannabinoid receptor mRNA in rat brain.
J Comp Neurol
327:535-550[Web of Science][Medline].
-
Mechoulam R,
Ben-Shabat S,
Hanus L,
Ligumsky M,
Kaminsky NE,
Schatz AR,
Gopher A,
Almog S,
Martin BR,
Compton DR,
Pertwee RG,
Griffin G,
Bayewitch M,
Barg J,
Vogel Z
(1995)
Identification of an endogenous 2-monoglyceride, present in canine gut, that binds to cannabinoid receptors.
Biochem Pharmacol
50:83-90[Web of Science][Medline].
-
Mechoulam R,
Fride E,
Di Marzo V
(1998)
Endocannabinoids.
Eur J Pharmacol
359:1-18[Web of Science][Medline].
-
Misner DL,
Sullivan JM
(1999)
Mechanism of cannabinoid effects on long-term potentiation and depression in hippocampal CA1 neurons.
J Neurosci
19:6795-6805[Abstract/Free Full Text].
-
Munro S,
Thomas KL,
Abu-Shaar M
(1993)
Molecular characterization of a peripheral receptor for cannabinoids.
Nature
365:61-65[Medline].
-
Ohno-Shosaku T,
Sawada S,
Yamamoto C
(1998)
Properties of depolarization-induced suppression of inhibitory transmission in cultured rat hippocampal neurons.
Pflügers Arch
435:273-279[Web of Science][Medline].
-
Ohno-Shosaku T,
Maejima T,
Kano M
(2001)
Endogenous cannabinoids mediate retrograde signals from depolarized postsynaptic neurons to presynaptic terminals.
Neuron
29:729-738[Web of Science][Medline].
-
Ohno-Shosaku T,
Shosaku J,
Tsubokawa H,
Kano M
(2002)
Cooperative endocannabinoid production by neuronal depolarization and group I metabotropic glutamate receptor activation.
Eur J Neurosci
15:953-961[Web of Science][Medline].
-
Paton GS,
Pertwee RG,
Davies SN
(1998)
Correlation between cannabinoid mediated effects on paired pulse depression and induction of long term potentiation in the rat hippocampal slice.
Neuropharmacology
37:1123-1130[Web of Science][Medline].
-
Pettit DA,
Harrison MP,
Olson JM,
Spencer RF,
Cabral GA
(1998)
Immunohistochemical localization of the neural cannabinoid receptor in rat brain.
J Neurosci Res
51:391-402[Web of Science][Medline].
-
Piomelli D,
Giuffrida A,
Calignano A,
Rodriguez de Fonseca F
(2000)
The endocannabinoid system as a target for therapeutic drugs.
Trends Pharmacol Sci
21:218-224[Medline].
-
Pitler TA,
Alger BE
(1992)
Postsynaptic spike firing reduces synaptic GABAA responses in hippocampal pyramidal cells.
J Neurosci
12:4122-4132[Abstract].
-
Shen M,
Piser TM,
Seybold VS,
Thayer SA
(1996)
Cannabinoid receptor agonists inhibit glutamatergic synaptic transmission in rat hippocampal cultures.
J Neurosci
16:4322-4334[Abstract/Free Full Text].
-
Stella N,
Schweitzer P,
Piomelli D
(1997)
A second endogenous cannabinoid that modulates long-term potentiation.
Nature
388:773-778[Medline].
-
Sugiura T,
Kondo S,
Sukagawa A,
Nakane S,
Shinoda A,
Itoh K,
Yamashita A,
Waku K
(1995)
2-Arachidonoylglycerol: a possible endogenous cannabinoid receptor ligand in brain.
Biochem Biophys Res Commun
215:89-97[Web of Science][Medline].
-
Sugiura T,
Kodaka T,
Nakane S,
Miyashita T,
Kondo S,
Suhara Y,
Takayama H,
Waku K,
Seki C,
Baba N,
Ishima Y
(1999)
Evidence that the cannabinoid CB1 receptor is a 2-arachidonoylglycerol receptor.
J Biol Chem
274:2794-2801[Abstract/Free Full Text].
-
Sullivan JM
(1999)
Mechanisms of cannabinoid-receptor-mediated inhibition of synaptic transmission in cultured hippocampal pyramidal neurons.
J Neurophysiol
82:1286-1294[Abstract/Free Full Text].
-
Tsou K,
Brown S,
Sañudo-Reña JC,
Mackie K,
Walker JM
(1998)
Immunohistochemical distribution of cannabinoid CB1 receptors in the rat central nervous system.
Neuroscience
83:393-411[Web of Science][Medline].
-
Tsubokawa H,
Ross WN
(1997)
Muscarinic modulation of spike backpropagation in the apical dendrites of hippocampal CA1 pyramidal neurons.
J Neurosci
17:5782-5791[Abstract/Free Full Text].
-
Tsubokawa H,
Offermanns S,
Simon MI,
Kano M
(2000)
Calcium-dependent persistent facilitation of spike backpropagation in the CA1 pyramidal neurons.
J Neurosci
20:4878-4884[Abstract/Free Full Text].
-
Twitchell W,
Brown S,
Mackie K
(1997)
Cannabinoids inhibit N- and P/Q-type calcium channels in cultured rat hippocampal neurons.
J Neurophysiol
78:43-50[Abstract/Free Full Text].
-
Varma N,
Carlson GC,
Ledent C,
Alger BE
(2001)
Metabotropic glutamate receptors drive the endocannabinoid system in hippocampus.
J Neurosci
21:RC188[Abstract/Free Full Text]:1-5.
-
Wagner JJ,
Alger BE
(1996)
Increased neuronal excitability during depolarization-induced suppression of inhibition in rat hippocampus.
J Physiol (Lond)
495:107-112[Abstract/Free Full Text].
-
Wilson RI,
Nicoll RA
(2001)
Endogenous cannabinoids mediate retrograde signalling at hippocampal synapses.
Nature
410:588-592[Medline].
-
Wilson RI,
Kunos G,
Nicoll RA
(2001)
Presynaptic specificity of endocannabinoid signaling in the hippocampus.
Neuron
31:453-462[Web of Science][Medline].
-
Yoshida T,
Hashimoto K,
Maejima T,
Araishi K,
Kano M
(2002)
The cannabinoid CB1 receptor mediates retrograde signals for depolarization-induced suppression of inhibition in cerebellar Purkinje cells.
J Neurosci
22:1690-1697[Abstract/Free Full Text].
-
Zimmer A,
Zimmer AM,
Hohmann AG,
Herkenham M,
Bonner TM
(1999)
Increased mortality, hypoactivity, and hypoalgesia in cannabinoid CB1 receptor knockout mice.
Proc Natl Acad Sci USA
96:5780-5785[Abstract/Free Full Text].
-
Zucker RS
(1989)
Short-term synaptic plasticity.
Annu Rev Neurosci
12:13-31[Web of Science][Medline].
Copyright © 2002 Society for Neuroscience 0270-6474/02/22103864-09$05.00/0
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|
A. F. Hoffman, M. Oz, R. Yang, A. H. Lichtman, and C. R. Lupica
Opposing actions of chronic {Delta}9-tetrahydrocannabinol and cannabinoid antagonists on hippocampal long-term potentiation
Learn. Mem.,
January 1, 2007;
14(1-2):
63 - 74.
[Abstract]
[Full Text]
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B. Szabo, M. J. Urbanski, T. Bisogno, V. D. Marzo, A. Mendiguren, W. U. Baer, and I. Freiman
Depolarization-induced retrograde synaptic inhibition in the mouse cerebellar cortex is mediated by 2-arachidonoylglycerol
J. Physiol.,
November 15, 2006;
577(1):
263 - 280.
[Abstract]
[Full Text]
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N. Wettschureck, M. van der Stelt, H. Tsubokawa, H. Krestel, A. Moers, S. Petrosino, G. Schutz, V. Di Marzo, and S. Offermanns
Forebrain-Specific Inactivation of Gq/G11 Family G Proteins Results in Age-Dependent Epilepsy and Impaired Endocannabinoid Formation
Mol. Cell. Biol.,
August 1, 2006;
26(15):
5888 - 5894.
[Abstract]
[Full Text]
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S. D. Brenowitz, A. R. Best, and W. G. Regehr
Sustained elevation of dendritic calcium evokes widespread endocannabinoid release and suppression of synapses onto cerebellar Purkinje cells.
J. Neurosci.,
June 21, 2006;
26(25):
6841 - 6850.
[Abstract]
[Full Text]
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R. E. Blair, L. S. Deshpande, S. Sombati, K. W. Falenski, B. R. Martin, and R. J. DeLorenzo
Activation of the Cannabinoid Type-1 Receptor Mediates the Anticonvulsant Properties of Cannabinoids in the Hippocampal Neuronal Culture Models of Acquired Epilepsy and Status Epilepticus
J. Pharmacol. Exp. Ther.,
June 1, 2006;
317(3):
1072 - 1078.
[Abstract]
[Full Text]
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I. Katona, G. M. Urban, M. Wallace, C. Ledent, K.-M. Jung, D. Piomelli, K. Mackie, and T. F. Freund
Molecular Composition of the Endocannabinoid System at Glutamatergic Synapses
J. Neurosci.,
May 24, 2006;
26(21):
5628 - 5637.
[Abstract]
[Full Text]
[PDF]
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T. Yoshida, M. Fukaya, M. Uchigashima, E. Miura, H. Kamiya, M. Kano, and M. Watanabe
Localization of diacylglycerol lipase-alpha around postsynaptic spine suggests close proximity between production site of an endocannabinoid, 2-arachidonoyl-glycerol, and presynaptic cannabinoid CB1 receptor.
J. Neurosci.,
May 3, 2006;
26(18):
4740 - 4751.
[Abstract]
[Full Text]
[PDF]
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Y. Kawamura, M. Fukaya, T. Maejima, T. Yoshida, E. Miura, M. Watanabe, T. Ohno-Shosaku, and M. Kano
The CB1 cannabinoid receptor is the major cannabinoid receptor at excitatory presynaptic sites in the hippocampus and cerebellum.
J. Neurosci.,
March 15, 2006;
26(11):
2991 - 3001.
[Abstract]
[Full Text]
[PDF]
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M. Ivenshitz and M. Segal
Simultaneous NMDA-Dependent Long-Term Potentiation of EPSCs and Long-Term Depression of IPSCs in Cultured Rat Hippocampal Neurons
J. Neurosci.,
January 25, 2006;
26(4):
1199 - 1210.
[Abstract]
[Full Text]
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S. Di, C. Boudaba, I. R. Popescu, F.-J. Weng, C. Harris, V. L. Marcheselli, N. G. Bazan, and J. G. Tasker
Activity-dependent release and actions of endocannabinoids in the rat hypothalamic supraoptic nucleus
J. Physiol.,
December 15, 2005;
569(3):
751 - 760.
[Abstract]
[Full Text]
[PDF]
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A. Straiker and K. Mackie
Depolarization-induced suppression of excitation in murine autaptic hippocampal neurones
J. Physiol.,
December 1, 2005;
569(2):
501 - 517.
[Abstract]
[Full Text]
[PDF]
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A. C. Kreitzer and R. C. Malenka
Dopamine Modulation of State-Dependent Endocannabinoid Release and Long-Term Depression in the Striatum
J. Neurosci.,
November 9, 2005;
25(45):
10537 - 10545.
[Abstract]
[Full Text]
[PDF]
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B. E. Alger
Endocannabinoid Identification in the Brain: Studies of Breakdown Lead to Breakthrough, and There May Be NO Hope
Sci. Signal.,
November 8, 2005;
2005(309):
pe51 - pe51.
[Abstract]
[Full Text]
[PDF]
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C. Bernard, M. Milh, Y. M. Morozov, Y. Ben-Ari, T. F. Freund, and H. Gozlan
Altering cannabinoid signaling during development disrupts neuronal activity
PNAS,
June 28, 2005;
102(26):
9388 - 9393.
[Abstract]
[Full Text]
[PDF]
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D. A. Rusakov, F. Saitow, K. P. Lehre, and S. Konishi
Modulation of Presynaptic Ca2+ Entry by AMPA Receptors at Individual GABAergic Synapses in the Cerebellum
J. Neurosci.,
May 18, 2005;
25(20):
4930 - 4940.
[Abstract]
[Full Text]
[PDF]
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E. D. Nosyreva and K. M. Huber
Developmental Switch in Synaptic Mechanisms of Hippocampal Metabotropic Glutamate Receptor-Dependent Long-Term Depression
J. Neurosci.,
March 16, 2005;
25(11):
2992 - 3001.
[Abstract]
[Full Text]
[PDF]
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S. Ohba, T. Ikeda, Y. Ikegaya, N. Nishiyama, N. Matsuki, and M. K. Yamada
BDNF Locally Potentiates GABAergic Presynaptic Machineries: Target-selective Circuit Inhibition
Cereb Cortex,
March 1, 2005;
15(3):
291 - 298.
[Abstract]
[Full Text]
[PDF]
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D. A. Fortin, J. Trettel, and E. S. Levine
Brief Trains of Action Potentials Enhance Pyramidal Neuron Excitability Via Endocannabinoid-Mediated Suppression of Inhibition
J Neurophysiol,
October 1, 2004;
92(4):
2105 - 2112.
[Abstract]
[Full Text]
[PDF]
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N. Kang, L. Jiang, W. He, J. Xu, M. Nedergaard, and J. Kang
Presynaptic Inactivation of Action Potentials and Postsynaptic Inhibition of GABAA Currents Contribute to KA-Induced Disinhibition in CA1 Pyramidal Neurons
J Neurophysiol,
August 1, 2004;
92(2):
873 - 882.
[Abstract]
[Full Text]
[PDF]
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M. Galante and M. A. Diana
Group I Metabotropic Glutamate Receptors Inhibit GABA Release at Interneuron-Purkinje Cell Synapses through Endocannabinoid Production
J. Neurosci.,
May 19, 2004;
24(20):
4865 - 4874.
[Abstract]
[Full Text]
[PDF]
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J. Guo and S. R. Ikeda
Endocannabinoids Modulate N-Type Calcium Channels and G-Protein-Coupled Inwardly Rectifying Potassium Channels via CB1 Cannabinoid Receptors Heterologously Expressed in Mammalian Neurons
Mol. Pharmacol.,
March 1, 2004;
65(3):
665 - 674.
[Abstract]
[Full Text]
[PDF]
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M. Melis, M. Pistis, S. Perra, A. L. Muntoni, G. Pillolla, and G. L. Gessa
Endocannabinoids Mediate Presynaptic Inhibition of Glutamatergic Transmission in Rat Ventral Tegmental Area Dopamine Neurons through Activation of CB1 Receptors
J. Neurosci.,
January 7, 2004;
24(1):
53 - 62.
[Abstract]
[Full Text]
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E. T. Tzavara, M. Wade, and G. G. Nomikos
Biphasic Effects of Cannabinoids on Acetylcholine Release in the Hippocampus: Site and Mechanism of Action
J. Neurosci.,
October 15, 2003;
23(28):
9374 - 9384.
[Abstract]
[Full Text]
[PDF]
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M. J. Wallace, R. E. Blair, K. W. Falenski, B. R. Martin, and R. J. DeLorenzo
The Endogenous Cannabinoid System Regulates Seizure Frequency and Duration in a Model of Temporal Lobe Epilepsy
J. Pharmacol. Exp. Ther.,
October 1, 2003;
307(1):
129 - 137.
[Abstract]
[Full Text]
[PDF]
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R. E. Hampson, S.-y. Zhuang, J. L. Weiner, and S. A. Deadwyler
Functional Significance of Cannabinoid-Mediated, Depolarization-Induced Suppression of Inhibition (DSI) in the Hippocampus
J Neurophysiol,
July 1, 2003;
90(1):
55 - 64.
[Abstract]
[Full Text]
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T. F. FREUND, I. KATONA, and D. PIOMELLI
Role of Endogenous Cannabinoids in Synaptic Signaling
Physiol Rev,
July 1, 2003;
83(3):
1017 - 1066.
[Abstract]
[Full Text]
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TOP
ABSTRACT
INTRODUCTION
Compound via MeSH
