Mechanism of melatonin combined with calcium carbonate on improving osteoporosis in aged rats

The effects of melatonin and calcium carbonate on aged rats with osteoporosis (OP) were assessed. Forty female Sprague-Dawley (SD) rats aged 15 months were randomly divided into a model group (group OP), melatonin group (group M), calcium carbonate group (group Ca) and melatonin combined with calcium carbonate group (group M+Ca), while 10 rats aged 3 months were set as the control group (group NC). The changes of bone density and bone mineral level of lumbar vertebra and bilateral femur in rats of each group were observed. The levels of serum calcium, phosphorus, superoxide dismutase (SOD), malondialdehyde (MDA) and glutathione peroxidase (GSH-Px) in rats of each group were determined. Compared with those in group NC, bone density of lumbar vertebra and bilateral femur and bone mineral level were distinctly reduced, serum calcium and activities of SOD and GSH-Px were obviously decreased, and MDA content was remarkably increased in rats of groups OP, M and Ca; the differences were statistically significant (P<0.05 or P<0.01); compared with that in group OP, bone density of lumbar vertebra and bilateral femur and bone mineral level were remarkably increased, serum calcium and activities of SOD and GSH-Px were obviously increased, and MDA content was remarkably decreased in rats of groups M, Ca and M+Ca; the differences were statistically significant (P<0.05 or P<0.01); compared with those in groups M and Ca, bone density of lumbar vertebra and bilateral femur and bone mineral level were obviously elevated, serum calcium and activities of SOD and GSH-Px were evidently elevated, and MDA content was remarkably decreased in rats of group M+Ca; the differences were statistically significant (P<0.05). Melatonin and calcium carbonate can significantly improve antioxidative ability in rats with osteoporosis, increase bone density, elevate serum calcium level and reduce bone mineral loss, thus preventing and treating osteoporosis, and the combination displays more remarkable effects.