The influence of human growth hormone on preadipocyte development in serum-supplemented and serum-free cultures of stromal-vascular cells from pig adipose tissue.

The influence of human growth hormone (hGH) on the differentiation of preadipocytes was examined in primary cultures of stromal-vascular (s-v) cells from porcine adipose tissue. In these experiments, cells were exposed to test media for 7-8 days after seeding and plating for two days in fetal bovine serum. In serum-free (insulin, transferrin and selenium) cultures hGH (1 and 10 nM) reduced the number and size of fat cell clusters (P less than .05) by 50% relative to controls (no hGH). Differentiation of preadipocytes was assayed by labelling dividing cells with tritiated thymidine under identical conditions and then exposing cultures to test media for seven days. Fat cells were then separated from the other cells and radioactivity was determined in each fraction. In serum containing (2% pig serum) cultures hGH (10 nM) inhibited (P less than .05) the differentiation of labelled preadipocytes. In cultures with serum and with 1 microM insulin and in serum-free cultures, 1 and 10 nM hGH reduced (P less than .05) the levels of glycerol phosphate dehydrogenase (GPDH) specific activity by approximately 50%. However, hGH (1 and 10 nM) had no affect on GPDH activity in cultures with serum but without insulin. These studies indicate that hGH significantly impedes porcine preadipocyte development in vitro. Therefore, the decreased rate of adipose tissue growth observed in pigs chronically treated with GH could be due in part to impaired preadipocyte growth.