Combined growth hormone (GH) and insulin-like growth factor-I (IGF-I) treatment is more effective than GH or IGF-I alone at enhancing recovery from neonatal malnutrition in rats

Abstract

The effect of hormonal therapy on enhancing recovery from neonatal malnutrition was assessed in rats. Malnutrition was induced by maternal food restriction (60% control intake) during lactation. On d 16 postpartum, restricted pups were refed by cross-fostering to control dams and were subcutaneously administered growth hormone (GH), insulin-like growth factor-I (IGF-I), GH + IGF-I or saline. At d 21, pups were weaned and continued hormonal treatments until d 39 postpartum. By d 39, body weight of GH (96% control) and GH + IGF-I- (98%) treated animals were normal, whereas IGF-I (88%) and saline- (85%) treated animals were still stunted. Hormone effectiveness was age dependent, with growth rates of GH + IGF-I-, IGF-I- and GH-treated pups being greatest between d 16 and 30, d 16 and 21 and after d 30, respectively. Protein accretion by d 39 was higher (P < 0.01) in GH and GH + IGF-I groups than saline- or IGF-I-treated groups. On d 39, serum IGF-I concentrations were as follows: GH + IGF-I > IGF-I > GH = saline (placebo), indicating that an elevated serum IGF-I was not required for GH-stimulated growth. Of the three hormonal treatments, GH + IGF-I therapy was most efficacious at promoting rapid and complete body weight recovery and supporting lean body mass accretion.