Effects of different intensities of cold stress on certain physiological phenomena related to skeletal health in a hypogonadal rat model

Intestinal transference pattern of calcium and associated changes in the ac tivities of intestinal mucosal enzymes, rate of bone turnover and bone meta bolism were evaluated in ovariectomized rats exposed to cold stress of vari ous intensities i.e., mild (15 degreesC) or stronger (8 degreesC and 4 degr eesC) for 5 min everyday for 7 consecutive days. Except mild cold stress-in duced group (15 degreesC), rats of other two groups (8 degreesC and 4 degre esC) showed considerable decrease in the rate of in situ intestinal transfe rence of calcium. Likewise, in these groups, the activities of intestinal m ucosal enzymes, alkaline phosphatase (AP) and calcium ATPase (Ca2+-ATPase) were decreased significantly in all the segments of small intestine in a de scending gradient. Also significant changes in bone turnover and bone resor ption were confirmed in these animals by marked alterations in plasma AP ac tivity, urinary calcium and phosphate excretion and urinary calcium to crea tinine ratio (Ca: Cr). The skeletal changes were further ascertained by exa mining other and biochemical parameters of bone metabolism viz., body mass, bone ratio of mineral to matrix and mineral content of bone ash (calcium a nd phosphate) in the ovariectomized rat model. All these results suggest th at stronger cold stress (8 degreesC and 4 degreesC) may be an important eco logical factor in the development of earlier bone loss in hypogonadal rats.