Brown adipose tissue thermogenesis induced by low level electrical stimulation of hypothalamus in rats

Brown adipose tissue (BAT) is an energy dissipating form of adipose tissue implicated in non-shivering thermogenesis as well as diet-induced thermogenesis. In the present study, in vivo interscapular BAT (IBAT) temperature was recorded prior to and following low level electrical stimulation (a 30 sec train of 60 Hz, 100 microA 0.5 msec isolated pulses) of various hypothalamic regions in rats. Significant increases in IBAT temperature were observed after stimulation of the anterior, medial preoptic, paraventricular and dorsomedial hypothalamus but not after stimulation of either ventromedial or caudal hypothalamus. For positive sites, IBAT temperature typically increased at 3-4 minutes following stimulation, peaked at 7-8 minutes after stimulation and declined at 20 minutes after stimulation. Although alterations in diet-induced thermogenesis have been reported after ventromedial hypothalamic lesions, the increases in BAT temperature noted in the present study suggest that inhibitory fibers that course through the paraventricular hypothalamus may form part of the central nervous system control of brown adipose tissue thermogenesis induced by overfeeding.