STAT5 ablation in AgRP neurons increases female adiposity and blunts food restriction adaptations.

AgRP neurons are important players in the control of energy homeostasis and are responsive to several hormones. In addition, STAT5 signalling in the brain, that is activated by metabolic hormones and growth factors, modulates food intake, body fat and glucose homeostasis. Given that, and the absence of studies that describe STAT5 function in AgRP cells, the present study investigated the metabolic effects of Stat5a/b gene ablation in these neurons. We observed that STAT5 signalling in AgRP neurons regulates body fat in female mice. However, male and female STAT5 knockout mice did not exhibit altered food intake, energy expenditure or glucose homeostasis compared to control mice. The counter-regulatory response or glucoprivic hyperphagia induced by 2-deoxi-D-glucose treatment were also not affected by AgRP-specific STAT5 ablation. However, under 60% food restriction, AgRP STAT5 knockout mice had a blunted upregulation of hypothalamic Agrp mRNA expression and corticosterone serum levels compared to control mice, suggesting a possible role for STAT5 in AgRP neurons for neuroendocrine adaptations to food restriction. Interestingly, ad libitum fed knockout male mice had reduced Pomc and Ucp-1 mRNA expression compared to control group. Taken together, these results suggest that STAT5 signalling in AgRP neurons regulates body adiposity in female mice, as well as some neuroendocrine adaptations to food restriction.