SerpinA3N in leptin-sensitive neurons is required for energy and glucose homeostasis and autonomic regulation.

AIMS: SerpinA3N (Serpin peptidase inhibitor clade A member 3) is a serine protease inhibitor upregulated in the hypothalamus by leptin and obesity, yet its role in physiological regulation remains poorly understood. This study aims to elucidate the role of hypothalamic SerpinA3N in regulation of energy balance, glucose homeostasis, and autonomic and cardiovascular functions. METHODS AND RESULTS: Immunostaining revealed that SerpinA3N is primarily expressed in neurons, including those expressing the leptin receptor (LepRb). Targeted deletion of SerpinA3N in LepRb neurons reduced body weight and adiposity and improved insulin sensitivity in female mice. SerpinA3N deficiency also enhanced leptin sensitivity, evidenced by amplified leptin-induced anorexia, weight loss, and LepRb signaling in the hypothalamic arcuate nucleus. Upon exposure to an obesogenic diet, mice lacking SerpinA3N in LepRb neurons exhibited attenuated weight gain, hepatic lipid accumulation and microgliosis. Notably, SerpinA3N deletion in LepRb neurons impaired baroreflex sensitivity and elevated renal sympathetic nerve activity, with dietary obesity further exacerbating sympathetic tone. CONCLUSIONS: These findings identify neuronal SerpinA3N as a key regulator of energy balance, leptin and insulin sensitivity, and autonomic function.