Porcine growth hormone: a central metabolic hormone involved in the regulation of adipose tissue growth.

During the past 20 y, much has been learned about how porcine growth hormone (pGH) affects growth and nutrient partitioning in growing pigs. Our contemporary understanding of the biology of pGH has as its roots the seminal studies conducted by Larry Machlin. His studies and many subsequent reports by other investigators have established that treatment of growing pigs with pGH markedly stimulates muscle growth and, concurrently, reduces fat deposition. In growing pigs, maximally effective doses of pGH increase average daily gain as much as 10% to 20%, improve feed efficiency 15% to 30%, decrease adipose tissue mass and lipid accretion rates by as much as 50% to 80%, and concurrently increase protein deposition by 50%. These effects are associated with a decrease in feed intake of approximately 10% to 15%. These responses occur because pGH has a wide array of biological effects that modulate nutrient partitioning between adipose tissue and skeletal muscle. The decrease in adipose tissue growth is due to a reduction in lipogenesis that is the consequence of pGH blunting the effects of many insulin-dependent events. This article provides an overview of some of the biological effects pGH has in adipose tissue and discusses what is known about the underlying mechanisms that account for these effects.