Nicotine-induced weight loss in rats without an effect on appetite

Rats were administered 0.8 mg/kg nicotine (as base) i.p. 2 or 3 times a day for 5 weeks, and their mean body weights were observed to be significantly lower than those of control groups administered 0.9% saline on a similar regimen. The reduction in body weight after chronic nicotine administration proved highly replicable and was produced in the absence of a significant decrease in food consumption. Upon cessation of nicotine administration, the mean body weights of the rats returned to control group levels. Administration of phenylbenzoquinone, an agent that stimulated sensory pain receptors, failed to produce a similar decrease in body weight. Likewise, pretreatment with cholinergic blocking drugs, mecamylamine and hexamethonium did not antagonize the nicotine-induced decrease in body weight. Application of these results to the human smoking habit and possible mechanisms of actions are discussed.