Choline increases endogenous GABA release in rat hippocampus by a mechanism sensitive to hemicholinium-3.
The effects of choline (Ch) on the spontaneous release of endogenous gamma-aminobutyric acid (GABA) and of 3H-GABA were studied in superfused rat hippocampal synaptosomes. Choline enhanced in a concentration-dependent way the release of endogenous GABA but did not affect that of the radioactive aminoacid. The effect of Ch was not antagonized by atropine or mecamylamine; moreover, it was not mimicked by acetylcholine, oxotremorine or carbachol. The Ch-induced GABA release was counteracted by hemicholinium-3. Thus the release of endogenously synthesized GABA (but not that of the aminoacid taken up) may be regulated by Ch through a mechanism involving penetration into the releasing terminal through a Ch uptake system.
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Istituto di Farmacologia e Farmacognosia, Universitá di Genova, Italy.
Raiteri
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D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D002217:Carbachol / Q000494:pharmacology; D002794:Choline / Q000494:pharmacology*; D006426:Hemicholinium 3 / Q000494:pharmacology*; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism*; D066298:In Vitro Techniques; D008297:Male; D008464:Mecamylamine / Q000494:pharmacology; D010095:Oxotremorine / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D013574:Synaptosomes / Q000187:drug effects; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
D006426:Hemicholinium 3; D005680:gamma-Aminobutyric Acid; D010095:Oxotremorine; D008464:Mecamylamine; D001285:Atropine; D002217:Carbachol; D002794:Choline; D000109:Acetylcholine