Pontine and basal forebrain transections disinhibit brown fat thermogenesis in neonatal rats

Bignall, Heggeness and Palmer (1975) were the first to demonstrate increases in metabolic heat production following midpontine transection in neonatal rats. Subsequent work in adult rats has shown that this procedure disinhibits thermogenesis by brown adipose tissue (BAT). Bignall and his colleagues also found that hypothalamic ablation did not result in increased thermogenesis in 5-day-olds, leading them to conclude that thermoregulation depends on more caudal structures at that age. We have also found that midpontine transection disinhibits BAT thermogenesis and, furthermore, have extended that finding to newborn pups. When transections were made in the basal forebrain, however, we also found profound and rapid increases in brown fat thermogenesis. These results suggest the presence of at least two sources of inhibition of BAT thermogenesis in newborn rats: one located in the rostral pons-caudal midbrain and one located in the basal forebrain.