title: Anandamide inhibits excitatory transmission to rat substantia gelatinosa neurones in a manner different from that of capsaicin.
abstract: Actions of anandamide (10 microM) were examined on monosynaptic glutamatergic transmission from the periphery to substantia gelatinosa (SG) neurones in adult rat spinal cord slices using the whole-cell patch-clamp technique. In 64% of neurones examined, Adelta-fibre-evoked excitatory postsynaptic currents (EPSCs) were depressed (in amplitude; by 32 +/- 4%, n=21) by anandamide. On the contrary, an inhibitory action on C-fibre-evoked EPSCs was observed in only 31% of neurones tested; this magnitude (17 +/- 3%, n=4) was less than that of Adelta-fibre EPSCs (P<0.05). A cannabinoid-receptor agonist, WIN 55,212-2 (5 microM), exhibited similar actions on the EPSCs. In a neurone with minimal effects of anandamide on C-fibre EPSCs, capsaicin (1 microM) largely depressed the EPSCs (n=3); Adelta-fibre EPSCs were little affected by capsaicin. It is concluded that unlike capsaicin, anandamide inhibits more effectively Adelta-fibre than C-fibre-mediated excitatory transmission in the SG, possibly through the activation of the cannabinoid receptor.
authors.affiliation: Department of Physiology, Saga Medical School, 5-1-1 Nabeshima, Saga 849-8501, Japan.
authors.forename: Ceng
authors.initials: C
authors.lastname: Luo
authors.forename: Eiichi
authors.initials: E
authors.lastname: Kumamoto
authors.forename: Hidemasa
authors.initials: H
authors.lastname: Furue
authors.forename: Jun
authors.initials: J
authors.lastname: Chen
authors.forename: Megumu
authors.initials: M
authors.lastname: Yoshimura
mesh_terms: D000818:Animals; D001095:Arachidonic Acids / Q000378:metabolism / Q000494:pharmacology*; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D002211:Capsaicin / Q000494:pharmacology; D004558:Electric Stimulation; D063388:Endocannabinoids; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects* / Q000502:physiology; D018698:Glutamic Acid / Q000378:metabolism; D009412:Nerve Fibers / Q000187:drug effects* / Q000378:metabolism; D009413:Nerve Fibers, Myelinated / Q000187:drug effects* / Q000378:metabolism; D009431:Neural Conduction / Q000187:drug effects / Q000502:physiology; D009619:Nociceptors / Q000187:drug effects* / Q000378:metabolism; D010146:Pain / Q000188:drug therapy / Q000378:metabolism / Q000503:physiopathology; D053284:Polyunsaturated Alkamides; D051381:Rats; D013376:Substantia Gelatinosa / Q000187:drug effects* / Q000378:metabolism; D009435:Synaptic Transmission / Q000187:drug effects* / Q000502:physiology
chemical_list: D001095:Arachidonic Acids; D002121:Calcium Channel Blockers; D063388:Endocannabinoids; D053284:Polyunsaturated Alkamides; D018698:Glutamic Acid; D002211:Capsaicin; C078814:anandamide