Effect of d-nicotine on the l-nicotine-induced increase in gastric acid secretion in rats

d-Nicotine (1000 micrograms) applied into the cerebral ventricle of urethane anesthetized rats increased gastric acid secretion. When 50 micrograms of d-nicotine was concomitantly administered with 5 micrograms of 1-nicotine, the 1-nicotine-induced increases in gastric secretion was blocked. The appearance of convulsion induced by I-nicotine in mice was also inhibited by pretreatment with d-nicotine. These results suggest that d-nicotine has agonistic and antagonistic actions to I-nicotine in the central nervous system and that its agonistic potency varies with preparations.