[Skeletal biomechanical properties improvement in ovariectomized osteoporotic rats of teriparatide was retarded by alendronate].

ABSTRACT

OBJECTIVE: To implore the effects of teriparatide (PTH) and alendronate (Alen) on skeletal biomechanical properties of ovariectomized (OVX) osteoporotic rats. METHODS: 70 female Wistar rats of 6 months were randomly divided into 7 groups (1) Baseline sacrificed at baseline; (2) OVXb sacrificed in 6 weeks after OVX; (3) Sham operation; (4) OVXe sacrificed 14 weeks after OVX; (5) PTH 40 microg.kg(-1).d(-1); (6) Alen 100 microg.kg(-1).d(-1); (7) A + P PTH 40 microg.kg(-1).d(-1) and Alen 100 microg.kg(-1).d(-1). In group (5)-(7), different medicines were injected 5 times per week from 6th to 14th week after OVX. The cancellous biomechanical properties were measured with indentation test and the cortical properties were investigated with three-point bending test. RESULTS: (1) The can load and can stiff of distal femur of OVXb were significantly lower than those of baseline (P < 0.01). It is indicated that osteoporotic rat models with impaired bone strength were established. (2) The can load and can stiff of distal femur of PTH [(36.3 +/- 9.2) N, (160.7 +/- 48.0) N/mm(2)], Alen [(42.7 +/- 13.0) N, (122.9 +/- 35.6) N/mm(2)] and A + P [(44.3 +/- 18.2) N, (105.2 +/- 58.4) N/mm(2)] groups were all higher than those of OVXe [(19.5 +/- 8.5) N, (83.2 +/- 37.7) N/mm(2), P < 0.001 or P < 0.01]. In femoral shaft, maximal load and elastic load in PTH, Alen and A + P groups were higher than those of OVXe (P < 0.001, P < 0.01 or P < 0.05). (3) Can stiff in distal femur was higher in PTH than that in Alen and A + P groups (P < 0.05). Elastic load, maximal load and energy absorption in femoral shaft were higher in PTH and A + P groups than those in Alen group (P < 0.05), and maximal stress was higher in PTH than that in A + P and Alen group (P < 0.05). CONCLUSION: PTH and Alen were effective in improving the skeletal mechanical properties of OVX rats, but improvement in Alen and A + P was not so good as that in PTH group. It is indicated that anabolic effects of PTH was retarded by Alen's significant inhibition of bone turnover, therefore, PTH and Alen should not be utilized simultaneously.