【Animal modeling】-Effect of different intervention programs of simvastatin on bone mass in osteoporotic rats

  Objective: To explore and compare the intervention effects of simvastatin on bone loss and bone quality decline in ovariectomized rats under different intervention programs.

  Methods: Thirty-two 3-month-old female SD rats were randomly divided into 4 groups with 8 rats in each group: sham operation (A) group, ovariectomy (B) group, and ovariectomy plus simvastatin first half-course intervention group (C) and the second half of the intervention group (D). Except for group A, which received sham operation, the other groups underwent bilateral oophorectomy. Group C was given simvastatin (5 mg/kg/d) after 10 weeks of intervention, and then the drug was stopped. Group D was given 10 weeks after operation. Zhou began to receive simvastatin intervention. All rats were sacrificed 20 weeks after operation, and the serum levels of type I procollagen amino-terminal propeptide (PINP) and type I collagen carboxy-terminal cross-linked telopeptide (ICTP) were detected by enzyme-linked immunosorbent assay (ELISA). , 4 and 5 lumbar vertebrae, the bone mineral density of the third lumbar vertebra was detected by dual energy X-ray, the biomechanical indexes such as the maximum load and elastic modulus of the fourth lumbar vertebra were detected by compression test, and the micro-computed tomography (micro-CT) was used to detect the first 5. Cancellous bone mass and microstructure of the lumbar spine.

  Results: (1) Serological test results: PINP and ICTP in groups B, C and D were significantly higher than those in group A; (2) BMD: group B was significantly lower than the other groups, and groups C and D were significantly lower than group A (P<0.05); (3) Biomechanics: the maximum load and elastic modulus of group B were significantly lower than those of the other three groups (P<0.05), and groups C and D were significantly lower than those of group A (P<0.05); 4. Micro -CT: The bone volume ratio (BV/TV) and trabecular bone number (Tb.N) of group A were significantly higher than those of the other three groups, and the degree of trabecular bone separation (Tb.Sp) was significantly lower than those of the other three groups (P<0.05). ), Tb.Sp in groups C and D were significantly lower than those in group B (P<0.05).

  CONCLUSION: Obvious bone mass loss and bone quality decline occurred 20 weeks after ovariectomy in rats. Both the first and second half interventions could partially prevent the bone loss, microstructure degeneration and mechanical properties decline in this model, but the bone mineral density decreased. were not able to return to normal levels.