Background Osteoporosis may cause not only fractures but also chronic back pain in elderly women. Bente et al reported that postmenopausal women with severe osteoporosis who were prescribed teriparatide (TPTD) in standard clinical practice had a reduction in back pain. However, there have been no reports regarding the effect of TPTD on pain in animal models of osteoporosis.
Objectives In this study, we investigated the effect of TPTD on pain-related behavior in ovariectomized mice.
Methods 8-week-old female ddY mice were ovariectomized (OVX) and assigned to 3groups; SHAM-operated mice treated with vehicle (SHAM), OVX mice treated with vehicle (OVX-V), OVX mice treated with TPTD (OVX-TPTD). Starting immediately after surgery, vehicle or 40μg/kg TPTD was injected subcutaneously 5 times a week for 4 weeks. The bilateral proximal tibial metaphyses were analyzed three-dimensionally by μCT 4 weeks after surgery (each group; 4 mice). Mechanical sensitivity was tested using von Frey filaments 4 weeks after surgery. To evaluate the 50% withdrawal threshold, nine von Frey filaments with forces of 0.02, 0.04, 0.07, 0.16, 0.4, 0.6, 1.0, 1.4 and 2.0 g were applied to the middle of the plantar surface. Testing was initiated with the 0.6 g filament. In the absence of a clear paw withdrawal response, increasingly stronger filaments were presented consecutively, until one of them was found to elicit such a response. If the 0.6 g filament elicited a response, filaments with decreasing strength were presented until determination of the first one which failed to cause paw withdrawal. Data was collected using the up-down method to calculate the 50% mechanical paw withdrawal threshold
Results μCT analysis of the proximal tibial metaphysis (Fig. 1) showed that bone volume/tissue volume (BV/TV) and trabecular number (Tb.N) were significantly less in the OVX-V group than in the SHAM group, whereas trabecular separation (Tb.Sp) was significantly greater in the OVX-V group than in the SHAM group. In the OVX-TPTD group, BV/TV and Tb.N were significantly greater than in the OVX-V group, whereas Tb.Sp was significantly less than in the OVX-V group. The 50% withdrawal threshold was significantly lower in the OVX group than in the SHAM group, whereas it was higher in the OVX-TPTD group than in the OVX-V group,but there was not significant.
Conclusions In this study,TPTD prevented ovariectomy-induced bone loss. Mechanical hyperalgesia in hindlimbs tended to be decreased in OVX group compered with OVX-TPTD group.TPTD may be usefull for treatment of the postmenopausal osteoporotic pain.
Disclosure of Interest None declared