Hypothalamic Arcuate Nucleus Mediates the Sympathetic and Arterial Pressure Responses to Leptin

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Abstract
Leptin is an adipocyte-derived hormone that plays an important role in the regulation of energy homeostasis through its action in the central nervous system. Leptin decreases body weight by promoting satiety and increasing thermogenesis via increasing sympathetic nerve activity (SNA) to brown adipose tissue. Leptin also increases renal SNA and arterial pressure. The arcuate nucleus is considered as a major nucleus for leptin action on energy homeostasis. We tested whether leptin action in the arcuate nucleus simultaneously activates SNA to brown adipose tissue and the kidney. The sympathetic and cardiovascular responses to intra-arcuate injection of leptin were compared with those evoked by intracerebroventricular administration of leptin in rat. Intracerebroventricular administration of leptin (10 μg) caused a significant increase in SNA to brown adipose tissue and the kidney. Intracerebroventricular leptin also increased mean arterial pressure. Direct injection of leptin (500 ng) into the arcuate nucleus increased both brown adipose tissue (254±49%; P P P =0.02). These data demonstrate that leptin action in the arcuate nucleus of the hypothalamus is important for the control of sympathetic outflow to both brown adipose tissue and the kidney. These results also suggest that the cardiovascular effects of leptin might be evoked by the action of this hormone in the arcuate nucleus of the hypothalamus.