Acute effects of nicotine on plasma free fatty acid concentrations and on the response to cold stress, in lean and obese (genotype ob/ob) mice.

Lean and genetically obese (ob/ob) male and female mice were given nicotine by subcutaneous injection. Nicotine treatment was found to raise plasma free fatty acids by similar amounts in both lean and obese mice. In lean mice, nicotine caused depression of rectal temperature at ambient temperatures 22-25 degrees C and partially prevented the hypothermia in these mice when exposed to cold (o-3 degrees C). In obese mice, nicotine treatment did not alter either rectal temperature at 22-25 degrees C or the severe hypothermia on cold exposure. It is proposed that the effect of nicotine on free fatty acids is due to release of adrenal catecholamines and that this mechanism operates in both lean and obese animals. It is also proposed that, in obese mice under normal circumstances, there is a defect in the central nervous control of this adrenergic mechanism which may contribute to the observed fall in body temperature at low ambient temperatures.