Effects of mixed subchronic lead acetate and cadmium chloride on bone metabolism in rats

Abstract

This study aimed to determine the effects of administering a mixture of subchronic lead acetate (Pb (NO3)2) and cadmium chloride (CdCl2·2.5H2O) on the bone metabolism of rats. A control group and three experimental groups consisted of randomly selected rats. Rats in each experimental group were orally administered with a mixture of Pb (NO3)2 and CdCl2·2.5H2O with the following respective doses for 90 consecutive days: 0 mg/kg body weight b.w. (Group I, to serve as a control), 29.96 mg/kg b.w. (Group II, 29.25 + 0.71), 89.88 mg/kg b.w. (Group III, 87.74 + 2.14), and 269.65 mg/kg b.w. (Group IV, 263.23 + 6.42). Serum osteocalcin (OC) and bone-specific alkaline phosphates (BALP) were considered as bone-formation markers, whereas carboxy-terminal cross-linking telopeptides of type I collagen (CTX) in serum acted as bone resorption markers. Calcitonin (CT) and parathormone (PTH) were tested as calciotropic hormones markers. The (Ca) and phosphorus (Pi) concentrations in the serum and urine were determined. These results were indicated by a significant (P < 0.05 - P < 0.01) increase in BALP, CTX, and PTH concentrations and decrease in CT and OC concentrations. Moreover, the concentrations of Ca and Pi in the serum were decreased, whereas those in urine increased. Results indicated that the administration of Pb and Cd induced bone metabolism disorders by decreasing bone formation and increasing bone resorption to destroy the hormonal regulation of mineral metabolism as a result of Ca and Pi imbalance.

Keywords: Lead and cadmium; bone metabolism; calciotropic hormones; calcium and phosphorus; rats.

Figure 1

The concentrations of Pb (A) and Cd (B) in the blood and urine. Group I: control group; Group II: low dose group; Group III: intermediate dose group; Group IV: high dose group. Data are shown as means ± SE (n = 6). Three asterisks indicate statistically significant difference (P < 0.001) vs. control.