Low dosages of exogenous growth hormone and its effect on growth in an animal model of suboptimal nutrition

In a previous study, weight gain, insulin growth factor-1 (IGF-1) and insul in growth factor binding protein-3 (IGFBP-3) were increased in rats fed sub optimal levels of energy and administered 0.1 mg/100 g of body weight of re combinant human grow th hormone (rhGH). Our objective was to determine whet her these anabolic effects were still obtained with lower dosages of rhGH i n similarly fed rats. Three groups of male, prepubertal Sprague-Dawley rats were administered rhGH and three groups of similar rats were given normal saline solution daily (0.05 mg/100 g of body weight subcutaneously). All ra ts were fed a balanced 1:1 carbohydrate:fat ratio diet for 4 wk. Restricted rats within each treatment were pair fed 80% and 60% ad libitum. Daily bod y weight, food intake, and efficiency were recorded. After 4 wk, serum IGF- 1 and IGFBP-3, body fat,fat-free mass, and total body water were determined . Total weight gain and serum IGFBP-3 were significantly higher, with a ten dency for increased,body fat, in rats treated with rhGH and fed at 60% ad L ibitum. However, within each treatment, energy restriction caused decreased body fat and total body water. These results suggest that lower dosages of rhGH provide anabolic effects during suboptimal energy intake. (C) Elsevie r Science Inc. 2000.