THE STUDY ON THE EFFECT OF ARTIFICIAL OSTEOPOROSIS CREATED BY COMBINED OVARIECTOMY AND CALCIUM-RESTRICTED DIETS IN A PORCINE MODEL

Abstract

This study design is to evaluate the mid-term changes in bone mineral density (BMD) with combined calcium-restricted and ovariectomized miniature porcine models as a large animal model in osteoporosis. The combined old practice hangs on for almost 30 years. Four 6-month-old (T0) female miniature pigs were enrolled in this study. The pigs were fed a normal diet prior to the ovariectomy at the age of 1 year and 3 months (T1) but switched to a diet with restricted calcium content afterwards. Each of the pigs received dual-energy X-ray absorptiometry (DXA) once before ovariectomy, and once every three months (T2, T3, T4) after the ovariectomy to evaluate the changes in BMD. The body weight of all four subject pigs increased significantly during this study (p < 0.05). The initial changes in both the BMD levels (T1/T2) were found to be statistically insignificant (p = 0.325 and p = 0.137, respectively). However, upon comparison of later BMD changes (T3/T4, T1/T3 and T1/T4), statistically significant elevations were found (p < 0.05 for all three comparisons). Ovariectomy and calcium-restricted diets are ineffective in achieving an osteoporotic porcine model based on BMD assessments. BMD levels of the subject pigs continued to rise until the point at which body growth had stopped because the ideal pigs for surgical experiments were far from maturity. This finding is not unexpected; after all, the subject pigs are not senile. Without violations of the physiology and Institutional Animal Care and Use Committee (IACUC) regulations, moreover, pigs could be fed by strictly calcium-restricted diets or deprived of soybean component feed. Furthermore, the alternative protocols in osteoporotic porcine model shall perform experiments as soon as possible after ovariectomy. We should take other studies about artificial osteoporotic pigs more into consideration whether it is based on a rational method.