Interaction acetylcholine-glutamate in rat hippocampus: involvement of two subtypes of M-2 muscarinic receptors.

摘要: The effects of acetylcholine (ACh) on the release endogenous glutamic acid (GLU) and [3H]ACh have been investigated comparatively in superfused rat hippocampal synaptosomes. Exogenous ACh added to superfusion fluid inhibited Ca++-dependent K+ (15 mM)-evoked GLU a concentration-dependent manner (the maximal inhibition was about 50%). Carbachol oxotremorine mimicked, although less potently, action ACh. caused by 10 microM antagonized 0.1 atropine but not mecamylamine. It also insensitive M-1 receptor antagonists pirenzepine or dicyclomine (both at 1 microM). In contrast, novel M-2 muscarinic antagonist AF-DX 116 [(11-[(2-[diethylamino]methyl)-1-piperidinyl]acetyl)-5-11-dihydro-6 H-pyrido-[2-3-b][1,4]benzo-diazepine-6-one] as potent blocking brought autoreceptor-mediated observed presence (10 microM) totally (0.1 mecamylamine microM), (1 However, it much sensitive (80-100 times) than cholinergic release. is concluded that 1) hippocampus can be through 2) this belongs subtype seems differ pharmacologically from autoreceptor.