Studies on the indirect feedback inhibition of cholinergic neurons triggered by oxotremorine in striatum

Oxotremorine produced 30–75% increases in rat striatal acetylcholine content and 10–15% decreases in choline content at the subtremorogenic doses of 0.34–1.34 μmol/kg, without affecting choline acetyltransferase and acetylcholinesterase activities and the sodium-dependent high affinity uptake of choline. The increases in acetylcholine was blocked by atropine and by reserpine indicating that oxotremorine indirectly influences the intrinsic striatal cholinergic neurons through a monoamine-mediated negative feedback loop. Experiments designed to interfere with neurotransmitter function indicated that noradrenaline and not dopamine or serotonin, mediated the response to oxotremorine.