Mitral cell presynaptic Ca2+ influx and synaptic transmission in frog amygdala
Section snippets
In vivo filling of mitral cell terminals with Ca2+ indicators
Adult male Rana pipiens (N=38; Sullivan Co., Nashville, TN, USA) were used in this study. All experimental procedures were in accordance with Simon Fraser University Animal Care Use Regulations, which are in turn in line with national guidelines on the ethical use of animals. All efforts were made to minimize the number of animals used and their suffering. Frogs were anesthetized by immersion in a pH neutral 60 mg/100 ml solution of tricaine methanesulfonate (Sigma).60 Frogs were removed from
Loading terminals with Ca2+ indicator and quantitative measurements of Ca2+ influx and transmitter release
The anatomy of the frog AOB is similar to the main olfactory bulb, but is less organized and laminar.26 Unlike the main olfactory bulb, which has diffuse mitral cell axonal projections to the telencephalon, the mitral cells of the AOB project exclusively to the amygdala.48., 49. The well-defined AOT emerges from the posterior face of the AOB and courses posteriorly for 2–3 mm along the ventromedial wall of the lateral cortex to terminate in the amygdala. Neuronal somata in the amygdala
A model system for studying synaptic transmission
The small size of most presynaptic terminals in the vertebrate brain prevents the use of electrodes to directly record presynaptic currents, except in the special case of the calyx of Held.22 Therefore, selective loading of Ca2+ indicators into nerve terminals has become an important tool for the study of Ca2+ in synaptic transmission.21., 35., 43., 63., 66. In this study, we selectively loaded mitral cell presynaptic terminals in the frog amygdala with dextran-conjugated fluorescent Ca2+
Acknowledgements
Fluo-4–dextran was kindly supplied by Ian Johnson and Kyle Gee of Molecular Probes, who are also thanked for their helpful discussions of its properties. This work was supported by an NSERC Operating Grant and the Ida Steel Fund for Addiction Research to K.D.
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The Nanophysiology of Fast Transmitter Release
2016, Trends in NeurosciencesCitation Excerpt :The argument for single domain secretion at some synapses was reiterated in a review [9] and supportive evidence was obtained in a series of new reports. A study exploring the comparative role of CaV2.1 or CaV2.2 in release gating at the frog mitral cell/amygdala neuron synapse reported a linear, not a cooperative, drop in transmitter release, implying single domain release [50]. Another report noted that action potentials triggered discrete and discernible single-channel activity at the frog NMJ (Figure 2D, lower-right panel) [25], a finding that was incompatible with extensive multichannel microdomains as predicted at the nCoH.
PresyNaptic calcium channels: Why is P selected before N?
2015, Biophysical JournalCitation Excerpt :It is interesting to speculate on how the difference in CaV2.1 and CaV2.2 kinetics might affect transmitter release gating. There is a growing consensus (6–10) that, at fast transmitting synapses, SV discharge can be triggered by one or a very few local calcium channels (11). Virtually instantaneously after the calcium channel opens, a high concentration domain of Ca2+ forms, which is centered on the pore.
High convergence of olfactory and vomeronasal influence in the telencephalon of the terrestrial salamander Plethodon shermani
2011, NeuroscienceCitation Excerpt :The results suggest a great variety of olfactory cell types in the SPTA, lateral pallium and amygdala region. Despite the fact that natural stimulation of the olfactory organs will almost certainly produce different neural activity patterns compared to those induced by artificial nerve stimulation, the excitatory nature of projection neurons in both olfactory bulbs (Jung et al., 1990; Mulligan et al., 2001) should result in information convergence in natural situations. Investigations of convergence using natural odors are now needed.
In Vivo Simultaneous Tracing and Ca<sup>2+</sup> Imaging of Local Neuronal Circuits
2007, NeuronCitation Excerpt :Similarly, for in vivo local electroporation, even though our results showed no sign of disrupting circuit function, a cocktail of glutamate receptor antagonists can be introduced before electroporation, either by bath perfusing the exposed brain or being included in the dye-loading pipette. It is also reported that dextran-bound Ca2+ dye can be successfully loaded into neurons of the frog olfactory bulb, just by inserting several glass pipettes that are dry-coated with Ca2+ dye dextran conjugate (Mulligan et al., 2001). It is not clear whether this is due to active dye uptake or to membrane damage caused mechanically by pipette penetration.
Consequences of molecular-level Ca<sup>2+</sup> channel and synaptic vesicle colocalization for the Ca<sup>2+</sup> microdomain and neurotransmitter exocytosis: A Monte Carlo study
2004, Biophysical JournalCitation Excerpt :We also do not know if they have a flexible geometry, if they are highly constrained, or to what extent their relative structure can be modulated (Stanley et al., 2003). Although release seems to arise from the cooperative action of several Ca2+ channels in some synapses (Borst and Sakmann, 1996), there is good evidence for release evoked by one or a few channels opening in other synapses (Augustine et al., 1991; Stanley, 1993; Mulligan et al., 2001; Wachman et al., 2004). This wide range of Ca2+ channel cooperativity might be attributed to, or influenced by, the particular active zone organization found at various central and peripheral synapses (Stanley, 1997).