Adipocyte insensitivity to insulin in growth hormone-transgenic mice

Growth hormone (GH) has an inhibitory effect on adipogenesis, and its effec t is associated with insulin action in obesity. In this study, the relation ship between GH effect on insulin sensitivity and adipocyte differentiation in vivo was investigated. Transgenic (TG) female mice expressing porcine G H had reduced body weights and weights of retroperitoneal and parametrial f at depots. Insulin treatment increased PPAR gamma and GLUT4 expression in a dipose tissue of WT mice but had no effect in TG mice. Content of transcrip tion factors, PPAR gamma and C/EBP alpha and beta, was higher in adipose ti ssue of WT mice, and for C/EBP alpha and PPAR gamma, the difference occurre d primarily in 24-, compared to la-week-old, mice. Expression of preadipocy te factor-1 was higher in adipose tissue of TG mice, and expression of TNF- alpha and leptin was reduced in adipose tissue of 24-week-old TG mice. Our results suggest that increased expression of GH reduces adipogenesis by ind ucing adipocyte resistance to the adipogenic effect of insulin. (C) 2001 Ac ademic Press.