Brain mechanism to survive starvation

Abstract

Energy homeostasis is balanced by regulating energy intake (food intake) and energy expenditure. Mammals including humans consume a large amount of energy to maintain body temperature. In starved conditions, neuropeptide Y (NPY) is secreted in the hypothalamus, resulting in lowered energy expenditure and increased appetite. However the central neural mechanism by which NPY lowers metabolism and stimulates appetite was unknown. We revealed that NPY action in the hypothalamus leads to activation of GABAergic neurons in the intermediate and parvicellular reticular nuclei (IRt/PCRt) in the medulla oblongata, which then inhibit brown adipose tissue thermogenesis and promote food intake. The NPY-elicited reduction of energy expenditure and promotion of food intake are representative hunger responses for animals to effectively survive starvation.