Neuroscience 2004 Abstract
| Presentation Number: | 597.9 |
|---|---|
| Abstract Title: | Electrical coupling among irregular-spiking GABAergic interneurons expressing CB1 receptors in the neocortex. |
| Authors: |
Galarreta, M.*1
; Erdelyi, F.
; Szabo, G.
; Hestrin, S.1
1Dept of Comparative Med., Stanford Univ Sch Med, Stanford, CA |
| Primary Theme and Topics |
Synaptic Transmission and Excitability - Synaptic Transmission -- Postsynaptic mechanisms: Inhibitory |
| Session: |
597. Postsynaptic Mechanisms II Slide |
| Presentation Time: | Tuesday, October 26, 2004 10:00 AM-10:15 AM |
| Location: | San Diego Convention Center - Room 11B |
| Keywords: | CANNABINOIDS, GAP JUNCTION, SYNCHRONIZATION, IPSP |
Marijuana and endogenous cannabinoids affect brain function primarily by activating the G-protein-coupled cannabionoid receptor-1 (CB1). In the neocortex, CB1 receptors are selectively expressed by a subset of GABAergic interneurons. It has been proposed that these cells regulate rhythmic activity and play a key role in mediating cannabinoid cognitive actions. The physiology, anatomy and synaptic connectivity of neocortical CB1-expressing (CB1+) interneurons remain, however, poorly studied. Electrical coupling among other classes of cortical interneurons have been recently shown to contribute to the generation of rhythmic synchronous activity. It is therefore important to establish whether CB1+ interneurons are also interconnected via electrical synapses. We addressed these issues using paired-recordings in acute slices of mouse neocortex and identified a population of CB1+ interneurons in layer II/III. These cells were multipolar or bitufted in appearance with a widely extending axon, and exhibited a characteristic irregular spiking (IS) in response to current injection. CB1+-IS cells were inhibitory, establishing GABAA receptor-mediated synapses onto pyramidal cells and other CB1-IS cells (4 out of 21 pairs). Furthermore, we found that 19 out of 21 pairs (90 %) of simultaneously recorded pairs of CB1-IS cells were electrically coupled. The average coupling coefficient was ~ 6 %. Signaling through electrical synapses promoted synchronous firing among CB1-IS cells. These results identify in the neocortex a population of electrically coupled CB1+ GABAergic interneurons that are characterized by an irregular pattern of firing. The synaptic interactions of these cells may play an important role mediating the cognitive actions of cannabinoids and regulating coherent neocortical activity.
Supported by EY-09120 and EY12114 grants
Sample Citation:
[Authors]. [Abstract Title]. Program No. XXX.XX. 2004 Neuroscience Meeting Planner. San Diego, CA: Society for Neuroscience, 2004. Online.
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