Functional disconnection of brown adipose tissue in hypothalamic obesity in rats

The metabolic responses to electrical nerve stimulation, norepinephrine or octanoate additions were studied using continuous monitoring of NAD(P)H/NADP redox state by reflexion spectrophotometry of interscapular brown adipose tissues from control and ventromedial hypothalamic (VMH) lesioned rats. The responses to these stimuli were all greatly decreased already 3 days after VMH lesions, indicating a reduced cell capacity to oxidize free fatty acids. Measurements of interscapular brown adipose tissue composition 4-5 weeks after VMH lesions showed a decrease of both DNA concentration and total content, indicating some tissue involution. It is concluded that the involvement of the ventromedial hypothalamus in the activation of brown adipose tissue provided a possible anatomical clue concerning pathways connecting thermal and weight regulations.