Effect of intrahypothalamic hydroxybutyrate on sympathetic firing rate.

Following the microinjection of 3-hydroxybutyrate into either the paraventricular or ventomedial nucleus of the hypothalamus, there was a significant increase in firing rate of the sympathetic nerves to brown adipose tissue, with a peak increase in activity occurring three minutes following the injection. The response in both hypothalamic regions was dose-dependent. When injected into both regions at the same time, the increase in firing rate was additive. These studies suggest that ketone bodies in the central nervous system may activate the sympathetic nervous system.