Facilitation of [3H]acetylcholine and [3H]5-hydroxytryptamine release from rat cerebral cortex synaptosomes by a factor extracted from the skin of the Australian frog Pseudophryne coriacea.
A partly purified extract of the skin of the Australian frog Pseudophryne coriacea (PsC) evoked the release of [3H]acetylcholine [( 3H]ACh) and of [3H]5-hydroxytryptamine [( 3H]5-HT) from superfused rat cerebral cortex synaptosomes prelabeled with [3H]choline or [3H]5-HT, respectively. The PsC-evoked release of both transmitters was sensitive to tetrodotoxin and was strictly Ca2+-dependent. The release of [3H]5-HT caused by PsC was unaffected by the 5-HT uptake inhibitor citalopram. Activation of muscarinic autoreceptors by ACh or of serotonin autoreceptors by 5-HT depressed the PsC-evoked release of [3H]ACh or of [3H]5-HT, respectively. It is concluded that PsC elicits a Ca2+-dependent exocytotic-like transmitter release, possibly by opening Na+ channels in the presynaptic membrane.
Istituto di Farmacologia e Farmacognosia, Università degli Studi di Genova, Italy.
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Raiteri
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Marchi
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Bonanno
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Melchiorri
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Erspamer
D000109:Acetylcholine / Q000378:metabolism*; D000818:Animals; D001001:Anura / Q000502:physiology; D002118:Calcium / Q000172:deficiency; D002540:Cerebral Cortex / Q000187:drug effects / Q000378:metabolism*; D066298:In Vitro Techniques; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D011950:Receptors, Cholinergic / Q000378:metabolism; D012701:Serotonin / Q000378:metabolism*; D012879:Skin Physiological Phenomena; D013574:Synaptosomes / Q000187:drug effects / Q000378:metabolism*; D013779:Tetrodotoxin / Q000494:pharmacology; D014020:Tissue Extracts / Q000494:pharmacology*
D011950:Receptors, Cholinergic; D014020:Tissue Extracts; D012701:Serotonin; D013779:Tetrodotoxin; D000109:Acetylcholine; D002118:Calcium