The effect of 4-(1-naphthylvinyl)-pyridine on the acetylcholine system and on the number of synaptic vesicles in the central nervous system of the rat.

The in vivo effects of 4-(1-naphthylvinyl)-pyridine on the activities of choline acetyltransferase and acetylcholinesterase, the levels of acetylcholine and choline, the sodium-dependent high affinity choline uptake and the number of synaptic vesicles were investigated in the rat brain. Our results indicate that 4-(naphthylvinyl)-pyridine (200 mg/kg, i.p.) reduced the acetylcholine level by 60% (P < 0.001), and the sodium-dependent high-affinity choline uptake in the CNS of rat. The combination of in vivo 4-(1-naphthylvinyl)-pyridine with a 15-min swimming stress induced an 87% (P < 0.001) reduction of acetylcholine in brain. The number of synaptic vesicles was reduced. We suggest that in vivo 4-(1-naphthylvinyl)-pyridine does reduce the steady-state level of acetylcholine, but that the reduction is due to a general effect of the drug on the acetylcholine system and membranes, rather than to a specific inhibitory action on the choline acetyltransferase activity.