Cold stress facilitates calcium mobilization from bone in an ovariectomized rat model of osteoporosis

In an ovariectomized rat model of osteoporosis, the effects of cold stress on intestinal Ca2+ transference and rate of bone turnover were evaluated. In the ovariectomized rats, a significant reduction in intestinal transference of Ca2+ was associated with decreased activities of intestinal mucosal enzymes, alkaline phosphatase (AP), and calcium ATPase (Ca2+-ATPase) in all the different segments of small intestine in a descending gradient. The development of a high rate of bone turnover and osteoporosis in these animals was confirmed by significant alteration in plasma AP activity and calcium (Ca) level, urinary excretion of Ca and phosphate, and Ca : creatinine ratio. Cold stress in this model, apart from its unique influence in elevating plasma corticosterone and thyroid hormone level, enhanced all the above referred parameters studied in connection with intestinal transference of Ca2+, bone turnover rate, and osteoporosis. The results of this study emphasize that cold stress may have a positive influence on bone loss for an early development of hypogonadal osteoporosis in rats.