Regulation of transmitter release by presynaptic receptors at a cholinergic neuro-neuronal synapse.
The modulation of evoked transmitter release by presynaptic receptors was studied at an identified cholinergic synapse in the buccal ganglion of Aplysia. Two auto-receptors affecting acetylcholine release in opposite ways were identified. Additionally acetylcholine (ACh) release was found to be facilitated by the peptide FLRFamide and inhibited by histamine. Ca2+ channels appeared as the final effectors controlled by these non-cholinergic presynaptic receptors whereas the activation of cholinergic presynaptic receptors did not affect the Ca2+ influx. The intracellular pathway activated by FLRFamide receptors was investigated in detail. The facilitation of transmitter release induced by this peptide was prevented by bath application of H-7, a protein kinase C inhibitor. Moreover, a diacylglycerol analog mimicked the action of FLRFamide. These results suggest that activation of protein kinase C leading to the phosphorylation of Ca2+ channels could be the mechanism through which presynaptic FLRFamide receptors increase evoked quantal release of acetylcholine at this synapse.
Tauc
L
L
Laboratoire de Neurobiologie Cellulaire et Moléculaire, C.N.R.S., Gif-sur-Yvette, France.
Fossier
P
P
Baux
G
G
D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D000109:Acetylcholine / Q000378:metabolism*; D000818:Animals; D001048:Aplysia / Q000502:physiology*; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism; D019835:FMRFamide; D006632:Histamine / Q000494:pharmacology; D007447:Invertebrate Hormones / Q000494:pharmacology; D007546:Isoquinolines / Q000494:pharmacology; D009479:Neuropeptides / Q000494:pharmacology; D010879:Piperazines / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism; D013569:Synapses / Q000187:drug effects / Q000378:metabolism*
D015220:Calcium Channels; D007447:Invertebrate Hormones; D007546:Isoquinolines; D009479:Neuropeptides; D010879:Piperazines; D019835:FMRFamide; D006632:Histamine; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D011493:Protein Kinase C; D000109:Acetylcholine