To ascertain the role played by adenosine 3´, 5´-cyclic monophosphate(cAMP) in neuronal acetylcholine(Ach) release from the rabbit hippocampus and to delineate its physiological role, the effects of forskolin and related drugs on electrically evoked release of 3H-acetylcholine were investigated.
1). The responses to forskolin, a specific adenylate cyclase activator, were characterized by elevation of Ach release, in a dose related fashion in doses ranging from 0.1 to 30 pM. The effects of forskolin were not influenced by 10 pM rolipram, a phosphodiesterase inhibitor.
2). Oxotremorine, a specific muscarinic receptor agonist, elicited dose-dependent decrease in Ach release, and these results were not affected by 10 and/or 30 pM forskolin pretreated.
3). Atropine(2 pM), a specific muscarinic receptor antagonist, produced significant increment of Ach rlease. The effects of combine treatment with atropine and forskolin were mcre less additive than those by ones.
It is concluded from these results that the cAMP might play in the release of acetylcholine release from the rabbit hippocampus as well as in adrenergic neurons.
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