Systemic nicotine administration suppresses food intake via reduced meal sizes in both male and female rats.

The appetite suppressing effect of tobacco products, via the main pharmacological agent nicotine, is a major reason for its usage both by woman and man. Food intake (FI) could be changed by altering either meal size (MZ) or meal number (MN), which are regulated dependently in a reciprocal manner. The present study investigated the effect of systemic nicotine administration on the rat feeding pattern. Because of gender differences in the effects of nicotine, both male and female rats were studied. Alzet mini-osmotic pumps (Model 2001) and the automated rat eatometer were used to evaluate the feeding pattern of male and female Fischer 344 rats during seven days of systemic nicotine infusion (6 mg/kg b.w. s.c.). The main findings are: 1) systemic nicotine infusion decreased food intake in both sexes; 2) the decreased food intake was due to significantly reduced meal sizes while meal numbers were not altered significantly in either males or females; 3) the cyclical pattern of vaginal smears, food intake, meal number and meal size of female rats was not affected by nicotine administration. We conclude that the feeding suppressive effect of nicotine, which is due to reduced meal sizes and thus satiation, is not sex-hormones related.