PONTINE AND BASAL FOREBRAIN TRANSECTIONS DISINHIBIT BROWN FAT THERMOGENESIS IN NEONATAL RATS

Bignall, Heggeness and Palmer (1975) were the first to demonstrate inc reases in metabolic heat production following midpontine transection i n neonatal rats. Subsequent work in adult rats has shown that this pro cedure disinhibits thermogenesis by brown adipose tissue (BAT). Bignal l and his colleagues also found that hypothalamic ablation did not res ult 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 thermog enesis and, furthermore, have extended that finding to newborn pups. W hen transections were made in the basal forebrain, however, we also fo und profound and rapid increases in brown fat thermogenesis. These res ults 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.