5-fluoronicotine, noranhydroecgonine, and pyridyl-methylpyrrolidine release acetylcholine and biogenic amines in rat cortex in vivo.

The effects of nicotinic receptor agonists 5-fluoronicotine, noranhydroecgonine and pyridyl-methylpyrrolidine on the cortical release of acetylcholine (ACh), norepinephrine (NE), dopamine (DA) and serotonin (5-HT) were investigated with microdialysis in rat. 5-Fluoronicotine significantly elevated ACh to 76% above basal values and DA to 69% above baseline. Pyridyl-methylpyrrolidine significantly increased the release of ACh to 39% above basal values and NE to 63% above baseline. Noranhydroecgonine significantly elevated NE to 64% above basal values and DA to 147% above baseline. 5-Fluoronicotine did not affect NE release; pyridylmethylpyrrolidine did not alter DA release; and noranhydroecgonine did not significantly elevate ACh release. None of these agonists increased the release of 5-HT. All responses were blocked by prior administration of mecamylamine, a nicotinic receptor antagonist. The distinctive neurotransmitter-related profiles for the three agonists are suggestive of activity at subtypes of nicotinic receptors, an effect that may be related to the structural diversity of these compounds.