THE PORCINE INSULIN-LIKE-GROWTH-FACTOR SYSTEM - AT THE INTERFACE OF NUTRITION, GROWTH AND REPRODUCTION

The IGF system is implicated in the regulation of cellular response to protein-and energy-restriction, Although it is clear that the IGF and their binding proteins are profoundly influenced by dietary factors, a number of important questions remain about this relationship. In par ticular, although studies to date have focused on nutritional modulati on of hepatic IGF gene expression, the molecular mechanisms underlying metabolic regulation of liver IGF and IGF binding protein genes remai n relatively unknown, Moreover, the potential effects of altered nutri tion on the expression and/or actions of IGF system components in tiss ues other than the liver have been examined only in cursory fashion. M any of these studies have used rats, an admittedly important model, bu t one which differs from the human in a potentially significant way: r ats lack circulating IGF-II and IGFBP-2 during post-weaning and adult life. Here, we summarize current research on the porcine IGF system an d highlight the particular usefulness this system may offer for unrave ling the complex relationships of nutrition and systemic/local IGF exp ression and actions that are relevant to human nutritional physiology.