Hormonal control of net glucose-stimulated lipogenesis during transition from brown to white adipose tissue in the goat

Perinatal (1-2 days of age) and one-month-old (24-32 days of age) male goat s were used to investigate the effect of age and long-term culture (24 h) o f perirenal and omental adipose explants in the presence of insulin, cortis ol and bovine somatotropin (alone or in different combinations) on net gluc ose-stimulated lipogenesis (NGSL, i.e. the rate of lipogenesis in the prese nce of glucose minus the rate of lipogenesis in the absence of glucose) in the absence and in the presence of catecholamines in acute incubations (2 h ). Mean values of NGSL in both freshly prepared and cultured explants were consistently lower in perinatal than in one-month-old goats. Cortisol alone decreased and combinations of insulin plus cortisol increased NGSL in peri renal explants of one-month-old animals. When perirenal explants from these one-month-old goats were cultured in the presence of insulin plus cortisol plus bovine somatotropin, the rates of lipogenesis were lower than those i n cultures with insulin plus cortisol. No such effects of these hormones we re noted in omental explants of both perinatal and one-month-old animals. I n freshly prepared perirenal and omental explants, the rates of NGSL were i nhibited by isoprenaline in tissues of both groups of animals and by noradr enaline in omental tissues of animals of the older group only. The mean val ues of NGSL in cultured explants of perinatal animals were not affected by noradrenaline. Isoprenaline inhibited NGSL, in omental but not in perirenal tissue. In older animals the rates of NGSL were decreased by both noradren aline and isoprenaline in perirenal and omental adipose tissues. Isoprenali ne was more effective than noradrenaline in perirenal adipose tissue.