Stress prompts brown fat into combustion

Abstract

Activation of dorsomedial hypothalamic-rostral medullary raphe neural signaling promotes brown fat thermogenesis, leading to elevated body temperature. In this issue, Kataoka et al. (2014) establish an important role for this brain-brown fat thermogenic action in psychological stress-induced hyperthermia in rats, implying a potential mechanism behind human psychogenic fever.

Figure 1. The hypothalamic-rostral medullary raphe (RMR) pathway in the regulation of brown adipose tissue (BAT) thermogenesis and body temperature

The hypothalamic preoptic area (POA) contains temperature-sensitive neurons that are primarily GABAergic and elicit inhibitory effects on neurons in the dorsomedial hypothalamus (DMH). DMH neurons innervate sympathetic premotor neurons glutamatergically in the RMR that modulate sympathetic nervous system (SNS) stimulation of BAT thermogenesis. Cold exposure or pyrogenic infection causes decreased GABAergic signaling from the POA to the DMH. The resulting disinhibition (excitation) of neurons in the DMH promotes RMR neuronal activity, which increases sympathetic nervous activity to BAT, leading to increased BAT thermogenesis and body temperature. Psychological stress causes neuronal activation in the DMH via a yet to be identified neural signaling pathway(s), and such activation promotes BAT thermogenesis though increasing the RMR-SNS-BAT activity.