LONG-TERM TREATMENT OF INDOMETHACIN REDUCES VERTEBRAL BONE MASS AND STRENGTH IN OVARIECTOMIZED RATS

We investigated the effect of the long-term treatment of indomethacin, on lumbar spinal bone mineral density (LSBMD), cancellous bone mass, structure, and strength of vertebral body in old ovariectomized (OVX) rats, Ten-month-old female Wistar rats were divided into five groups: the sham operated + vehicle (sham+VEH) group, the OVX + vehicle (OVX+V EH) group, the OVX + indomethacin (IN) 1.5 mg/kg/week (OVX+IN1.5) grou p, the OVX + IN 6.0 mg/kg/week (OVX+IN6.0) group, and the OVX + IN 15. 0 mg/kg/week (OVX+IN15.0) group, LN or vehicle were given by subcutane ous injection (sc) three times per week The treatments were started at 1 week after operation and continued for 24 weeks, LSBMD(L2-L5) was m easured at 0, 12, and 24 weeks after the beginning of treatment, At th e end of the experimental period, the animals were sacrificed, and bon e histomorphometrical and biomechanical analysis of lumbar vertebral b ody were done, LSBMD, trabecular bone volume (BV/TV), and trabecular t hickness (Tb.Th) decreased significantly in a dose-related manner with IN, In the OVX+IN15.0 group, LSBMD decreased by 12.7%, BV/TV decrease d by 65.5%, and Tb.Th decreased by 32.8%, compared with the OVX+VEH gr oup, In addition, the maximum stress in a compressive mechanical test of LA vertebral body in OVX groups was also decreased in a dose-relate d manner with IN, and this value in the OVX+IN15.0 group mas 31.3% low er than in the OVX+VEH group, We conclude that long-term treatment wit h LN accentuated the 0VX-related decrease in trabecular bone mass and the compressive strength of lumbar vertebrae.