title: Nicotinic effect of acetylcholine on the release of newly synthesized (3H)dopamine in rat striatal slices and cat caudate nucleus.
abstract: The effect of acetylcholine (ACh), carbachol and nicotinic blocking agents on the release of newly synthesized [3H]dopamine ([3H]DA) was studied in vitro on rat striatal slices and in vivo on the cat caudate nucleus. In the latter case, the animals were anaesthetized with halothane; in some experimetns an 'encéphale isolé' preparation was used to eliminate anaesthesia. Rat striatal slices placed in a superfusion chamber were continuously superfused with L-[3,5-3H]tyrosine. A cup placed on the ventricular surface of the cat caudate nucleus similarly allowed a continuous superfusion of the structure with the 3H amino acid. In both cases the quantities of [3H]DA contained in serial superfusate fractions were estimated; the drugs were always added in superfusing medium. In vitro ACh (10(-5) M) and carbachol (10(-5) M) enhanced the release of [3H]DA (90%). Similar results were obtained in vivo in anaesthetized cats. The effect of ACh (10(-5) M) was more pronounced (125%) in presence of eserine (10(-4) M) than with ACh alone (65%). ACh was also effective in unanaesthetized cats. The ACh effect on [3H]DA release was reproducible within the same experiment both in vitro and in vivo. This allowed to test the effect of anticholinergic agents on the ACh induced release of [3H]DA. In vivo hexamethonium (10(-4) M, 10(-5) M) partially blocked the release of [3H]DA induced by ACh (10(-5) M) alone; the effect was not seen when ACh was added in the presence of eserine (10(-4) M). Both in vivo and in vitro the prior introduction of mecamylamine into the superfusing medium antagonized the stimulating effect of ACh (10(-5) M) on [3H]DA release. The effects of this nicotinic blocking agent were seen with various concentrations (10(-6); (10(-5) 10(-4) in the in vitro experiments.
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology*; D000818:Animals; D002217:Carbachol / Q000494:pharmacology; D002415:Cats; D002421:Caudate Nucleus / Q000187:drug effects* / Q000378:metabolism; D003342:Corpus Striatum / Q000187:drug effects* / Q000378:metabolism; D003655:Decerebrate State; D004298:Dopamine / Q000096:biosynthesis / Q000378:metabolism*; D005260:Female; D006584:Hexamethonium Compounds / Q000494:pharmacology; D008297:Male; D008464:Mecamylamine / Q000494:pharmacology; D010830:Physostigmine / Q000494:pharmacology; D051381:Rats; D014443:Tyrosine / Q000378:metabolism
chemical_list: D006584:Hexamethonium Compounds; D014443:Tyrosine; D008464:Mecamylamine; D002217:Carbachol; D010830:Physostigmine; D000109:Acetylcholine; D004298:Dopamine