Growth hormone therapy during neonatal hypoxia in rats: body composition, bone mineral density, and insulin-like growth factor-1 expression

Abstract

Hypoxia from birth results in a decrease in body weight gain, body size, and bone mineral density (BMD). The purpose of the present study was to determine whether short-term administration of growth hormone (GH) (rat GH; 100 microg/d) could attenuate some of these effects of neonatal hypoxia. Rat pups (with their lactating dams) were exposed to hypoxia (vs normoxic control) from birth. Hypoxia was continued until 14 d of age, with rat GH (vs vehicle control) administered daily. Hypoxia significantly inhibited body weight gain; GH therapy did not reverse this effect. GH therapy did reverse the inhibitory effect of hypoxia on tail length but not on body length. Hypoxia decreased BMD analyzed by dual X-ray absorptiometry (DXA); this effect was not reversed by GH therapy. Both GH therapy and hypoxia decreased the percentage of body fat analyzed by DXA, the effects of which were additive when combined. There were minimal effects of hypoxia and GH therapy on plasma insulin-like growth factor-1 (IGF-1), IGF-binding protein-3, and hepatic IGF-1 mRNA expression. We conclude that some of the effects of hypoxia on body habitus are reversed by GH therapy, but that short-term GH therapy did not prevent a loss of BMD. GH therapy for more than 14 days may be necessary to appreciate fully its potential in the treatment of the sequelae of neonatal hypoxia.