Influence of the Pituitary on Lipolysis and Lipogenesis in Fetal Pig Adipose Tissue

Abstract

This study was performed to verify and further characterize the role of neuroendocrine factors in the regulation of fetal adipose metabolism. On day 72 to 74 of gestation, pig fetuses in one uterine horn were hypophysectomized (hypoxed) by micro-cauterization, fetuses in the other horn served as sham controls. Fetuses were removed by laparotomy on day 110 of gestation. Slices of subcutaneous adipose tissue from control fetuses responded to lipolytic stimulation by norepinephrine alone (NE; 1 microgram/ml), NE plus adenosine deaminase (160 mUnits/ml) or dibutyryl cyclic AMP (5 mM). Adipose tissue from hypoxed fetuses, however, responded to lipolytic stimulation by only dibutyryl cyclic AMP, not NE. Lipogenesis in adipose tissue slices, as quantitated by 3H2O incorporation into triglyceride fatty acids, was increased 2.6 fold by hypophysectomy. These results demonstrate the necessity of a functioning pituitary in the normal regulation of fatty acid synthesis and receptor-mediated lipolytic response in developing fetal adipose tissue.