title: L-type calcium channels mediate dynorphin neuropeptide release from dendrites but not axons of hippocampal granule cells.
abstract: Granule cells in the guinea pig dentate gyrus release kappa opioid neuropeptides, dynorphins, from dendrites as well as from axon terminals. We have found that both L- and N-type calcium channel antagonists inhibited dendritic dynorphin release. In contrast, N-type but not L-type calcium channel antagonists inhibited axonal dynorphin release. Neither L- nor N-type channel antagonists directly altered the effects of kappa opioid receptor activation. By inhibiting dynorphin release, L-type channel antagonists also facilitated the induction of long-term potentiation of the perforant path-granule cell synapse. These studies establish that a single cell type can release a transmitter from two different cellular domains and provide new distinction between axonal and dendritic transmitter release mechanisms.
authors.affiliation: Department of Pharmacology, University of Washington, Seattle 98195, USA.
authors.forename: M L
authors.initials: ML
authors.lastname: Simmons
authors.forename: G W
authors.initials: GW
authors.lastname: Terman
authors.forename: S M
authors.initials: SM
authors.lastname: Gibbs
authors.forename: C
authors.initials: C
authors.lastname: Chavkin
mesh_terms: D000818:Animals; D001369:Axons / Q000187:drug effects / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000502:physiology*; D003712:Dendrites / Q000187:drug effects / Q000378:metabolism*; D004399:Dynorphins / Q000378:metabolism*; D006168:Guinea Pigs; D006624:Hippocampus / Q000502:physiology / Q000648:ultrastructure*; D017275:Isradipine / Q000494:pharmacology; D017774:Long-Term Potentiation; D009271:Naltrexone / Q000031:analogs & derivatives / Q000494:pharmacology; D009543:Nifedipine / Q000494:pharmacology; D010455:Peptides / Q000494:pharmacology; D017473:Receptors, Opioid, kappa / Q000187:drug effects / Q000502:physiology; D020866:omega-Conotoxin GVIA
chemical_list: D002121:Calcium Channel Blockers; D015220:Calcium Channels; D010455:Peptides; D017473:Receptors, Opioid, kappa; C051844:norbinaltorphimine; D009271:Naltrexone; D004399:Dynorphins; D020866:omega-Conotoxin GVIA; D009543:Nifedipine; D017275:Isradipine