Melatonin is more effective on bone metabolism when given at early night than during the day in ovariectomized rats

Melatonin has diverse effects, and been reported to promote bone formation in addition regulating the sleep–wake cycle. In present study, we investigated effects of melatonin on metabolism using ovariectomized (OVX) rats; a model postmenopausal osteoporosis. Here, focused differences when was subcutaneous injected at day or early night. The OVX rats were with once daily (0.8 8 mg/head) between 11:00 14:00 18:00 19:30 for night, respectively, six weeks. After completion injection, femur tibia dissected under general anesthesia examined by quantitative computed tomography (pQCT) histological analysis, respectively. Interestingly, trabecular mineral density metaphysis receiving mg/head night higher than those during they recovered similar level as sham treatment. diaphysis, pQCT analysis results indicated that there no significant difference melatonin-injected rats. Histological secondary rats, revealed matrix area group compared had treatment Taken together, injection found better day. timing is crucial factor examining influence metabolism.