EFFECTS OF EXOGENOUS RECOMBINANT HUMAN GROWTH-HORMONE ON AN ANIMAL-MODEL OF SUBOPTIMAL NUTRITION

Background: Nutritional dwarfing, a form of suboptimal nutrition, has been identified as a frequent cause of short stature and delayed sexua l development in children. Retarded growth is an adaptive response to suboptimal nutrition. Objective: To assess whether recombinant human g rowth hormone (rhGH) may promote growth during various levels of subop timal nutrition. Methods: Using a previously developed rat model of su boptimal nutrition, six groups of rats (six rats/group) were fed a bal anced 1:1 carbohydrate:fat ratio diet for 4 weeks. Three of the groups were administered daily injections of rhGH (0.1 mg/100 g BW) subcutan eously in the back while the other three groups were kept as controls and were given similar dosages of normal saline solution (NSS), Restri cted rats within each treatment group were pair fed 80 and 60% of the ad-libitum rats intake. Daily intake of the 80 and 60% fed groups were determined based on the intake of the ad-libitum fed groups. Serum IG F-I and insulin were determined after 4 weeks of dietary treatment by radioimmunoassay while IGFBP-3 was determined by an immunoradiometric assay. Body composition was assessed in all rats by carcass analysis. Results: After 4 weeks, total weight gain and tail growth were higher (p<0.05) in the rhGH treated group at 80 and 60% of-libitum energy int ake. Serum levels of IGF-I and IGFBP-3 were higher (p<0.05) in rhGH tr eated rats fed at 60% of ad-libitum. In comparison to the NSS groups, administration of rhGH in rats fed ad-libitum increased total body wat er. Energy restriction caused decreased fat percentage (p<0.05) in bot h rhGH and NSS groups without differences among treated groups. Conclu sion: These results suggest that the anabolic effects of rhGH may over come mild to moderate energy restriction.