Leptin administration to cold-acclimated rats reduces both food intake and brown adipose tissue thermogenesis

Acute (24h) and chronic (3 weeks) cold-exposure causes an increase in energy utilization to maintain body temperature. As a result, there is a decrease in body fat, a reduced plasma leptin concentration and a concomitant hyperphagia. When cold-acclimated rats were subjected to a chronic administration of leptin, a reduction in food intake was observed. This finding demonstrates that leptin can display its satiating role even in animals with a physiological hyperphagia as that taking place in cold-exposed rats. Nevertheless, cold-acclimated leptin-treated rats did not reach a fasting-like state since their plasma glucose, free fatty acids and beta-hydroxybutyrate levels were unchanged. Simultaneously, a reduction in brown adipose tissue thermogenesis took place in the cold-acclimated leptin-treated rats. These results show that in cold-acclimated rats the fall in energy gains induced by the anorectic effect of leptin is compensated by a decreased energy expenditure. (C) 2003 Elsevier Ltd. All rights reserved.