Leptin expression in hypothalamic PVN reverses dietary obesity and hyperinsulinemia but stimulates ghrelin

Objective: In order to circumvent the multiple peripheral effects of hyperleptinemia and leptin resistance, the efficacy of leptin transgene expression in the hypothalamic paraventricular nucleus (PVN) to reinstate the central energy homeostasis in obesity was examined. Research Methods and Procedures: A recombinant adeno-associated viral vector encoding either leptin (rAAV-lep) or green fluorescent protein (rAAV-GFP) was microinjected into the PVN of obesity-prone rats consuming a high-fat diet (HFD). Results: rAAV-lep, and not rAAV-GFP, microinjection significantly reduced energy intake and enhanced energy expenditure, thereby resulting in normalization of weight and blood levels of leptin, insulin, free fatty acids, and glucose concomitant with enhanced ghrelin secretion during the extended period of observation. Discussion: Thus, we show, for the first time, that amelioration of leptin insufficiency with enhanced localized leptin availability in the PVN alone can reverse dietary obesity and the attendant hyperinsulinemia and concurrently block the central stimulatory effects of elevated endogenous ghrelin on food intake and adiposity.