Arachidonic acid may mediate the galanin-induced hyperpolarization in parasympathetic neurons from Necturus maculosus.
The effects of arachidonic acid (AA) and compounds that inhibit intracellular signalling pathways on membrane potential and galanin-induced hyperpolarizations were investigated in parasympathetic neurons from Necturus maculosus. Treatment for 10-90 min with 10-20 microM 4-bromophenacylbromide or 10 microM cyclosporin A caused a progressive decrease in the amplitude of galanin-induced hyperpolarizations without any change in resting membrane potential. The galanin-induced hyperpolarization was not altered following a 10-120 min treatment with the protein kinase inhibitor H-7. These results indicated that phospholipase A2 activation, but not protein kinase activation, may be required for the galanin-induced hyperpolarization. Arachidonic acid (20-100 microM) caused a concentration-dependent membrane hyperpolarization of the parasympathetic neurons and a decrease in the amplitude of the galanin-induced hyperpolarization. These data indicate that phospholipase A2-catalyzed liberation of AA may be involved in the galanin-induced membrane hyperpolarization observed in mudpuppy parasympathetic neurons.
Mulvaney
J M
JM
Department of Anatomy and Neurobiology, University of Vermont, College of Medicine, Burlington 05405, USA.
Parsons
R L
RL
D000098:Acetophenones / Q000494:pharmacology; D000818:Animals; D016718:Arachidonic Acid / Q000502:physiology*; D016572:Cyclosporine / Q000494:pharmacology; D004594:Electrophysiology; D019004:Galanin; D009337:Necturus; D009474:Neurons / Q000502:physiology*; D009479:Neuropeptides / Q000494:pharmacology; D010275:Parasympathetic Nervous System / Q000166:cytology / Q000502:physiology*; D010455:Peptides / Q000494:pharmacology*; D010741:Phospholipases A / Q000037:antagonists & inhibitors; D054467:Phospholipases A2
D000098:Acetophenones; D009479:Neuropeptides; D010455:Peptides; D016718:Arachidonic Acid; D016572:Cyclosporine; D019004:Galanin; D010741:Phospholipases A; D054467:Phospholipases A2; C006821:4-bromophenacyl bromide