Growth hormone promotes somatic and skeletal muscle growth recovery in rats following chronic protein-energy malnutrition

The efficacy of recombinant human growth hormone (GH) and/or a diet enriche d in protein and energy to improve growth recovery following prolonged maln utrition was examined in male rats food-restricted from birth until 120 d o f age. At d 121, restricted rats were randomly assigned to recovery groups receiving either a control or enriched diet with or without daily subcutane ous injections of GH. Rats were killed after 16 or 47 d of recovery. At d 1 6, GH treatment stimulated liver, heart, plantaris, soleus, carcass and bod y weight gain and inhibited fat gain when compared to recovery controls. Ra ts receiving GH also exhibited the highest serum insulin-like growth factor -I (IGF-I) concentrations and total muscle protein. At d 47, GH effects on body and muscle recovery were minimal, and differences among recovery group s in serum IGF-I concentration and total muscle protein were no longer pres ent. Consumption of an enriched diet increased fat pad and liver mass, but did not promote muscle recovery. There were no differences among treatment groups in skeletal muscle IGF-I mRNA levels at d 16 or 47. In summary, GH h ad positive effects on somatic and skeletal muscle growth early in the reco very process, possibly via endocrine IGF-I-stimulated protein accretion, In contrast, the enriched diet promoted fat deposition with no impact on skel etal muscle growth recovery.