Heterogeneity of presynaptic muscarinic receptors regulating neurotransmitter release in the rat brain.

摘要: The existence of multiple muscarinic receptors in the brain was investigated by using neurotransmitter release as a functional parameter and comparing effects agonists antagonists on three systems regulation mediated presynaptic receptors. selected models for our experiments were: 1) autoreceptors mediating inhibition acetylcholine cortex; 2) present nerve endings hippocampus; 3) potentiation striatal dopamine (heteroreceptors). were performed rat synaptosomes superfusion. Acetylcholine, oxotremorine carbachol inhibited [3H]acetylcholine evoked 15 mM KCI cortex hippocampus potentiated K+-evoked [3H]dopamine striatum. concentration-response curves similar systems, rank potency being: greater than carbachol. counteracted several with different potencies ratios. In particular, drugs tested was: atropine secoverine stercuronium pirenzepine at autoreceptors, both but it = stercuronium, heteroreceptors Pirenzepine 100 times more potent autoreceptors. Our results suggest possibility differential activation or blockade central selective drugs.