Vasoactive intestinal polypeptide presynaptically enhances the synaptic transmission in cultured sympathetic neurons.
We studied the effects of vasoactive intestinal polypeptide (VIP) on the cholinergic synaptic transmission that was developed between rat sympathetic neurons in culture. Electrophysiological examinations revealed that the amplitude of fast excitatory postsynaptic potential (fast EPSP) was increased by VIP (0.2-0.8 microM) reversibly and dose-dependently, whereas transient nicotinic depolarization evoked by pressure application of acetylcholine (ACh) was not affected by VIP. In most of the cells examined, VIP depolarized membrane potential by a few millivolts with concomitant increases in membrane conductance. Furthermore, the VIP-induced depolarization was suppressed by Co2+ but not by hexamethonium or atropine. Hence it is highly likely that the peptide augmented the amplitude of fast EPSPs by increasing ACh release from the presynaptic cell. These results demonstrate that VIP influences the presynaptic phase of cholinergic synaptic transmission between sympathetic neurons.
Takahashi
M
M
Department of Neuropsychiatry, Kochi Medical School, Japan.
Ogawa
M
M
Ohta
H
H
Ikeda
H
H
D000109:Acetylcholine / Q000494:pharmacology / Q000502:physiology; D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D000831:Animals, Newborn / Q000502:physiology; D002478:Cells, Cultured; D004594:Electrophysiology; D005728:Ganglia, Sympathetic / Q000166:cytology / Q000187:drug effects; D008564:Membrane Potentials / Q000187:drug effects; D009474:Neurons / Q000187:drug effects*; D051381:Rats; D011919:Rats, Inbred Strains; D013268:Stimulation, Chemical; D013564:Sympathetic Nervous System / Q000166:cytology / Q000187:drug effects*; D013569:Synapses / Q000187:drug effects*; D009435:Synaptic Transmission / Q000187:drug effects*; D014660:Vasoactive Intestinal Peptide / Q000494:pharmacology*
D014660:Vasoactive Intestinal Peptide; D000109:Acetylcholine