RT Journal Article
SR Electronic
T1 Endogenous Adenosine Mediates the Presynaptic Inhibition Induced by Aglycemia at Corticostriatal Synapses
JF The Journal of Neuroscience
JO J. Neurosci.
FD Society for Neuroscience
SP 4509
OP 4516
DO 10.1523/JNEUROSCI.17-12-04509.1997
VO 17
IS 12
A1 Paolo Calabresi
A1 Diego Centonze
A1 Antonio Pisani
A1 Giorgio Bernardi
YR 1997
UL http://www.jneurosci.org/content/17/12/4509.abstract
AB Energy deprivation, as a result of aglycemia, leads to depression of the central synaptic transmission. Endogenous adenosine has been implicated in this depressant effect. We have studied the possible involvement of endogenous adenosine in the depression of corticostriatal excitatory transmission induced by glucose deprivation by using intracellular recordings in brain slices. After stimulation of corticostriatal fibers, EPSPs were recorded from striatal spiny neurons. Adenosine (3–300 μm) or brief periods (5–10 min) of aglycemia reduced the EPSP amplitude but did not alter the membrane potential and the resistance of the recorded cells. These inhibitory effects were not associated with an alteration of the postsynaptic sensitivity to exogenous glutamate but were coupled with an increased paired-pulse facilitation, suggesting the involvement of presynaptic mechanisms. A delayed postsynaptic membrane depolarization/inward current was detected after 15–20 min of glucose deprivation. The presynaptic inhibitory effects induced by adenosine and aglycemia were both antagonized either by the nonselective adenosine receptor antagonist caffeine (2.5 mm) or by the A1 receptor antagonists 8-cyclopentyl-1,3-dimethylxanthine (CPT, 1 μm) and 1,3-dipropyl-8-cyclopentylxanthine (CPX, 300 nm). Conversely, these antagonists affected neither the delayed membrane depolarization/inward current nor the underlying conductance increase produced by glucose deprivation. The ATP-sensitive potassium channel blockers tolbutamide (1 mm) and glipizide (100 nm) had no effect on the aglycemia-induced decrease of EPSP amplitude. Our data demonstrate that endogenous adenosine acting on A1 receptors mediates the presynaptic inhibition induced by aglycemia at corticostriatal synapses, whereas ATP-dependent potassium channels do not play a significant role in this presynaptic inhibition.