Cannabinoid receptor-mediated regulation of neuronal activity and signaling in glomeruli of the main olfactory bulb.
Cannabinoid receptors (CB1Rs) are present in glomeruli of the main olfactory bulb. The functions of CB1Rs and their endogenous activators, endocannabinoids, for glomerular signaling are unknown. Glomeruli contain at least three types of neurons: periglomerular (PG), external tufted (ET), and short-axon (SA) cells. PG cells form inhibitory GABAergic dendrodendritic synapses with ET cells. ET cells form excitatory glutamatergic dendrodendritic synapses with PG and SA cells. In mouse brain slices, we used whole-cell patch-clamp recordings to study the role of CB1Rs in regulating PG and ET cells. Cannabinoids displayed strong, direct inhibitory effects on PG cells and weak effects on ET cells. Single pulses or a train of pulses of depolarizing current injected into an ET cell evoked suppression of IPSCs. This suggests retrograde endocannabinoid signaling, namely, depolarization-induced suppression of inhibition (DSI) in ET cells. Our results support the hypothesis that burst firing of ET cells triggers the release of endocannabinoids which in turn directly inhibit PG cells and reduce GABA release from PG cells. This, in turn, can result in a transient reduction of PG cell inhibitory input to ET cells.
Department of Anatomy, Howard University College of Medicine, Washington, DC 20059, USA.
Ze-Jun
ZJ
Wang
Liqin
L
Sun
Thomas
T
Heinbockel
D018750:6-Cyano-7-nitroquinoxaline-2,3-dione / Q000494:pharmacology; D000818:Animals; D001095:Arachidonic Acids / Q000494:pharmacology; D048588:Benzoxazines / Q000494:pharmacology; D063386:Cannabinoid Receptor Agonists; D063387:Cannabinoid Receptor Antagonists; D002186:Cannabinoids / Q000494:pharmacology; D003627:Data Interpretation, Statistical; D063388:Endocannabinoids; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D005260:Female; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009025:Morpholines / Q000494:pharmacology; D009281:Naphthalenes / Q000494:pharmacology; D009415:Nerve Net / Q000502:physiology; D009474:Neurons / Q000502:physiology*; D009830:Olfactory Bulb / Q000166:cytology / Q000502:physiology*; D018408:Patch-Clamp Techniques; D010880:Piperidines / Q000494:pharmacology; D053284:Polyunsaturated Alkamides / Q000494:pharmacology; D011720:Pyrazoles / Q000494:pharmacology; D043884:Receptor, Cannabinoid, CB1 / Q000819:agonists / Q000037:antagonists & inhibitors; D043882:Receptors, Cannabinoid / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology*; D013569:Synapses / Q000502:physiology; D009435:Synaptic Transmission / Q000187:drug effects
D001095:Arachidonic Acids; D048588:Benzoxazines; D063386:Cannabinoid Receptor Agonists; D063387:Cannabinoid Receptor Antagonists; D002186:Cannabinoids; D063388:Endocannabinoids; D018691:Excitatory Amino Acid Antagonists; D009025:Morpholines; D009281:Naphthalenes; D010880:Piperidines; D053284:Polyunsaturated Alkamides; D011720:Pyrazoles; D043884:Receptor, Cannabinoid, CB1; D043882:Receptors, Cannabinoid; C103505:AM 251; C070417:(3R)-((2,3-dihydro-5-methyl-3-((4-morpholinyl)methyl)pyrrolo-(1,2,3-de)-1,4-benzoxazin-6-yl)(1-naphthalenyl))methanone; D018750:6-Cyano-7-nitroquinoxaline-2,3-dione; C078814:anandamide