Centrally administered resistin enhances sympathetic nerve activity to the hindlimb but attenuates the activity to brown adipose tissue

Resistin, an adipokine, is believed to act in the brain to influence energy homeostasis. Plasma resistin levels are elevated in obesity and are associated with metabolic and cardiovascular disease. Increased muscle sympathetic nerve activity (SNA) is a characteristic of obesity, a risk factor for diabetes and cardiovascular disease. We hypothesized that resistin affects SNA, which contributes to metabolic and cardiovascular dysfunction. Here we investigated the effects of centrally administered resistin on SNA to muscle (lumbar) and brown adipose tissue (BAT), outputs that influence cardiovascular and energy homeostasis. Overnight-fasted rats were anesthetized, and resistin (7 mu g) was administered into the lateral cerebral ventricle (intracerebroventricular). The lumbar sympathetic nerve trunk or sympathetic nerves supplying BAT were dissected free, and nerve activity was recorded. Arterial blood pressure, heart rate, body core temperature, and BAT temperature were also recorded. Responses to resistin or vehicle were monitored for 4 h after intracerebroventricular administration. Acutely administered resistin increased lumbar SNA but decreased BAT SNA. Mean arterial pressure and heart rate, however, were not significantly affected by resistin. BAT temperature was significantly reduced by resistin, and there was a concomitant fall in body temperature. The findings indicate that resistin has differential effects on SNA to tissues involved in metabolic and cardiovascular regulation. The decreased BAT SNA and the increased lumbar SNA elicited by resistin suggest that it may contribute to the increased muscle SNA and reduced energy expenditure observed in obesity and diabetes.