Treatment with growth hormone (GH) alone or combined with insulin-like growth factor-I (IGF-I) attenuates dexamethasone (dex)-induced delays in growth and bone metabolism in piglets

Treatment with DEX improves pulmonary compliance in premature infants with chronic lung disease but can impair normal growth and bone development. We investigated whether adjunctive therapy with GH or GH+IGF-I during DEX could attenuate the detrimental effects of DEX. Seven day old male piglets (n=32) were randomized to placebo control, DEX (oral dose 0.5, 0.3 and 0.2 mg/kg/d for 5 d each), DEX+GH (0.1 mg/kg/d) or DEX+GH+IGF-I (0.1 mg/kg/d). Weight was measured daily. Blood samples and length were taken at each change in DEX dose. Whole body and femoral bone mineral density (HMD) were measured at d 15 using dual energy x-ray absorptiometry (Hologic QDR1000W). At d 15, the DEX+GH and DEX+GH+IGF-I groups were significantly (p<0.05) heavier and longer than DEX alone. Plasma GH was not altered by any treatment. Plasma IGF-I was lowest in DEX piglets but infusion of IGF-I resulted in significantly (p<0.05) higher IGF-I compared to all other groups at d 15. DEX reduced (p<0.05) circulating IGFBP-3 on d 11, and IGFBP-2 on d 6, 11 and 15 compared to control. Plasma osteocalcin was reduced (p<0.05) by DEX alone at d 6 and d 11 compared to control but by d 11 there was a rise to higher (p<0.05) values in DEX+GH and DEX+GH+IGF-I vs DEX alone. The lower (p<0.05) whole body and femoral BMD in DEX vs control was not observed in piglets treated with DEX+GH or DEX+GH+IGF-I. The results indicate that GH promotes normalization of growth and bone metabolism during DEX therapy; no synergistic effect of IGFI with GH was observed.