Effects of nicotine on body weight, food intake and brown adipose tissue thermogenesis.

Chronic treatment with nicotine results in reduced body weight gain without a change in food intake. To evaluate the role of brown adipose tissue (BAT) thermogenesis in this effect of nicotine, male Sprague-Dawley rats were chronically treated (3X daily, IP) over a 14 day period with either saline, 0.8 mg/kg nicotine, 10 mg/kg caffeine or a combination of 0.8 mg/kg nicotine and 10 mg/kg caffeine and were pretreated (once daily) with either saline or 20 mg/kg nadolol, a long-acting beta-adrenergic receptor blocker. Nicotine significantly reduced body weight gain but not food intake and nadolol did not reverse the effect of nicotine on body weight gain. To evaluate whether nicotine induces BAT thermogenesis, rats were injected IP with either saline or 0.8, 1.2 or 1.6 mg/kg nicotine hydrogen tartrate, with 5 mg/kg dl-phenylpropanolamine (dl-PPA) or with a combination of 0.8 mg/kg nicotine and 10 mg/kg caffeine with interscapular BAT (IBAT) temperatures recorded for 30 minutes after injection. No dose of nicotine produced a change in IBAT temperature whereas a combination of caffeine and nicotine produced a temperature increase in IBAT (0.95 degree C) 63% of that induced by 5 mg/kg dl-PPA. These data suggest that changes in body weight gain induced by nicotine treatment are not the result of an action of nicotine on BAT thermogenesis.