There is emerging evidence suggesting that the administration of recombinant human growth hormone (rhGH) to critically ill adults in order to reduce catabolism is related to increased morbidity and mortality. The underlying methods responsible included inhibition of glutamine release from skeletal muscle and subsequent inhibition of splanchnic glutamine supply. The current study evaluated the effects of rhGH on plasma glutamine levels and on muscle and liver glutamine concentrations and protein synthesis rates in sepsis. The authors, in addition, examined whether the administration of supplemental glutamine can improve any adverse effects of rhGH.

The trial enrolled a total of 78 male experimental animals which were categorized in six groups. These animals received 6-hr tail vein infusions, beginning 18 hrs after cecal ligation and puncture, of either (a) 0.9% sodium chloride, (b) a standard parenteral nutrition (PN) solution without glutamine, or (c) an isocaloric, isonitrogenous PN solution with glutamine. Moreover, PN groups were administered with 400 microg rhGH or equivolume 0.9% sodium chloride vehicle in a divided subcutaneous and intravenous dose at its initiation. They were killed at the end of the infusion period. Another group considered as controls were unoperated, uninfused and killed at 24 hrs. Glutamine concentrations were investigated by fluorometry and protein synthesis in muscle and liver was assessed by a "flooding-dose" technique using L-[4-H]phenylalanine.

The results demonstrated that plasma glutamine was elevated after cecal ligation and puncture, except in the saline and glutamine with rhGH animals. Muscle glutamine was decreased after cecal ligation and puncture, and was remarkably lower in animals receiving standard PN with rhGH in contrast to saline alone. Liver glutamine got elevated in animals receiving saline and those administered with standard PN with rhGH. Furthermore, PN, with or without glutamine, increased muscle protein synthesis, and the administration of rhGH subsequently increased this effect. It was also reported that PN, glutamine, or rhGH did not exhibit any impact on the increased liver protein synthesis, suggestive of the presence of sepsis.

Thus, it can be concluded that elevated muscle protein synthesis with PN and rhGH administration in sepsis is not correlated with increased muscle glutamine levels. Moreover, no reduction in liver glutamine levels or rates of hepatic protein synthesis can occur after the administration of rhGH. PN containing glutamine is comparable to standard PN in effectively increasing muscle protein synthesis.

Source: OLeary MJ, Ferguson CN, Rennie M, Hinds CJ, Coakley JH, Preedy VR. Effect of growth hormone on muscle and liver protein synthesis in septic rats receiving glutamine-enriched parenteral nutrition. Crit Care Med. 2002 May;30(5):1099-105.