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 st ress on intestinal Ca2+ transference and rate of bone turnover were ev aluated. In the ovariectomized rats, a significant reduction in intest inal transference of Ca2+ was associated with decreased activities of intestinal mucosal enzymes, alkaline phosphatase (AP), and calcium ATP ase (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 altera tion in plasma AP activity and calcium (Ca) level, urinary excretion o f Ca and phosphate, and Ca:creatinine ratio. Cold stress in this model , apart from its unique influence in elevating plasma corticosterone a nd thyroid hormone level, enhanced all the above referred parameters s tudied in connection with intestinal transference of Ca2+, bone turnov er rate, and osteoporosis. The results of this study emphasize that co ld stress may have a positive influence on bone loss for an early deve lopment of hypogonadal osteoporosis in rats.