Effect of Growth Hormone and Dexamethasone on Lipolysis and Metabolism in Isolated Fat Cells of the Rat

Abstract

The available evidence suggests that growth hormone and glucocorticoids are involved in the mobilization of lipid in animals deprived of food or insulin (l-7). In a study with adrenalectomized rats it was found that fatty acid release measured in vitro was much higher in tissues taken from rats treated with growth hormone and dexamethasonel (a potent synthetic glucocorticoid) than in tissue from rats given a single hormone (8). Dexamethasone given alone produced a small increase in fret fatty acid release whereas growth hormone had no effect (8). Dexamethasone added in &o also increased release of fatty acids in incubated adipose tissue from fasted normal rats (9). Growth hormone added in &o stimulated free fatty acid release in adipose tissue from normal rats (IO-13), but the amount of hormone needed, 200 to 1000 pg per ml, was so large that the effect was attributed to thyroid-stimulating hormone contamination in the growth hormone preparat,ions (14). The present experiments were designed to examint t,he effect of growth hormone and dexamethasone, added in. vitro, on free fatty acid release in incubated adipose tissue and isolated fat cells. The effects of insulin, puromycin, and actinomycin D on the response to growth hormone and dexamethasone were also examined. The lipolytic effect of adrenocorticotrophic: and thyroid-stimulat,ing hormones was (bornpared with that of growth hormone and dexamethasone.