The aim of our study was to elucidate the role of growth hormone (GH) replacement therapy in three of the main mechanisms involved in sarcopenia: alterations in mitochondrial biogenesis, increase in oxidative stress, and alterations in protein balance. We used young and old Wistar rats that received either placebo or low doses of GH to reach normal insulin-like growth factor-1 values observed in the young group. We found an increase in lean body mass and plasma and hepatic insulin-like growth factor-1 levels in the old animals treated with GH. We also found a lowering of age-associated oxidative damage and an induction of antioxidant enzymes in the skeletal muscle of the treated animals. GH replacement therapy resulted in an increase in the skeletal muscle protein synthesis and mitochondrial biogenesis pathways. This was paralleled by a lowering of inhibitory factors in skeletal muscle regeneration and in protein degradation. GH replacement therapy prevents sarcopenia by acting as a double-edged sword, antioxidant and hypertrophic.

The effect of a chronic combined treatment with growth hormone (GH) plus melatonin (Mel) on different age-related processes in cytosolic and nuclear fractions of hearts from SAMP8 mice (2 and 10 months) has been investigated. The parameters studied have been messenger RNA expressions of IL-1, IL-10, NFkBp50, NFkBp52, TNFα, eNOS, iNOS, HO-1, HO-2, BAD, BAX, and Bcl2 and protein expressions of iNOS, eNOS, TNFα, IL-1, IL-10, NFkBp50, NFKbp52, and caspase activity (3 and 9). Our results supported the existence of a proapoptotic and oxidative status together with inflammatory processes in the heart of old mice, with increases of inflammatory cytokines, caspase activity, HO-1, BAX, NFkBp50, and NFkBp52 and decreases of eNOS and Bcl2. Also, we were able to observe the translocation of NFkB to nuclei. The combined treatment was able to partially reduce the incidence of these deleterious changes, showing differences with the separated treatments with GH and Mel as were investigated in previous articles from our group.