Effect of recombinant human growth hormone on age-related hepatocyte changes in old male and female Wistar rats

Aging induces changes in several organs, such as the liver, and this process might be due to damage caused by free radicals and inflammatory mediators. The growth hormone (GH)/insulin-like growth factor-1 (IGF-1) axis shows a reduction with age, and this fact could be associated with some age-related changes. The aim of this study was to investigate the effect of GH administration on age-induced alterations in hepatocytes. Two and twenty two month-old male and female Wistar rats were used. Old rats were treated with human recombinant GH for 10 wk. At the end of the treatment, hepatocytes were isolated from the liver and cultured, and different parameters were measured in cells and medium. Plasma IGF-1 was also measured. Aging significantly decreased plasma IGF-1 in males. In females, plasma IGF-1 was also reduced, but not significantly. GH treatment restored plasma IGF-1 levels to values similar to young males. Aging was associated with a significant increase in lipid peroxidation (LPO), nitric oxide (NO), carbon monoxide (CO) and cyclic guanosyl-monophosphate (cGMP), as well as a reduction in adenosyl triphosphate (ATP) and phosphatidylcholine (PC) synthesis. GH administration partially prevented all these changes in males. In females, some of the parameters were significantly improved by GH (ATP, CO, cGMP), while others showed a tendency to improvement, although differences did not reach significance. In conclusion, GH administration could exert beneficial effects against age-related changes in hepatocytes, mainly in males.