GH as antiaging factor in old bones.

Aging induces changes in bone. Growth Hormone is reduced by aging, and age-related changes observed in old bones might be due to a decrease in the Growth Hormone/Insulin-like Growth Factor-I axis. Growth Hormone administration on aged individuals is controversial. This study aimed to assess the effect of systemic Growth Hormone treatment on bone properties, bone metabolism, and bone mineral density in long bone of old rats. METHODS Aged Wistar rats were treated with Growth Hormone at a dose of 2 mg/kg/day during 10 weeks. Plasma osteocalcin, Insulin-like Growth Factor-I, and Carboxy-terminal telopeptide of type I collagen levels were measured. Cross-sectional bone areas and bone mineral density were measured by morphometric and densitometric analysis, respectively. Femora were analyzed by three point-bending testing. T-test was used for statistical evaluation. p<0.05 was considered to be significant. RESULTS Significantly enhanced bone area, at the expense of the cortical area, was found in treated rats. The densitometric analysis showed 11% higher bone mineral density in the experimental group. Significantly higher bone flexural modulus, stiffness, and ultimate load were observed in the treated rats. Plasma osteocalcin and Insulin-like Growth Factor-I levels were significantly increased in the treated group, while the resorption marker concentration remained unchanged. CONCLUSION Within the limitations of this experimental study, systemic Growth Hormone administration has shown to enhance biomechanical properties, bone mineral density, cortical mass and plasma IGF-I and osteocalcin in old treated rats, when compared to the control group; consequently, Growth Hormone could be considered as an alternative therapy against age-related changes in the bone.