title: Muscarinic receptor activation inhibits both release and synthesis of noradrenaline in rat hippocampal synaptosomes.
abstract: Rat hippocampal synaptosomes were used to investigate the effects of muscarinic cholinergic drugs on the release of [(3)H]noradrenaline and the rate of noradrenaline synthesis. Oxotremorine and acetylcholine caused depression of K(+)-evoked release of [(3)H]noradrenaline; these effects were reversed by atropine and pirenzepine. Muscarinic agonists depressed 2-chloroadenosine- and isoprenaline-stimulated noradrenaline synthesis but had no effect on 8-Br-cyclic AMP-stimulated synthesis. Oxotremorine also depressed the K(+)-acceleration of noradrenaline synthesis. The action of pirenzepine suggests that the inhibition of release and synthesis are mediated by separate muscarinic receptor subtypes.
authors.affiliation: University Laboratory of Physiology, Parks Road, Oxford OX1 3PT, U.K.
authors.forename: P J
authors.initials: PJ
authors.lastname: Birch
authors.forename: M
authors.initials: M
authors.lastname: Fillenz