Endocrine Abstracts

Objective: Estrogen or raloxifen prevent estrogen deficiency-induced bone loss animals and humans. There is a medical need for agent with the positive effects of estrogen on bone and the cardiovascular system, but without the negative effects tissue. So, we investigated the effects of raloxifen on bone strength and cholesterol levels in osteoporotic rats and compared them with estrogen treatment.

Methods: Thirty-one ovariectomized (OVX) Sprague-Dawney rats were divided into three groups for treatment with raloxifen (1 mg/kg SC for 8 weeks), ethynyl estradiol (EE, 0.1 mg/kg), or vehicle. A fourth group of ten rats that underwent sham operated and received vehicle was use for comparison. Treatment was initiated 12 weeks after ovariectomy and continued for 8 weeks. The effects of ovx, raloxifen and estrogen were measured at femur and lumbal vertebras (L4). Bone strength was assessed with compression test in vertebras and with three-point bending test in femurs by using Shimadzu AG-50 kNG as newton (N). Statistical analyses made by Mann-Whitney U nonparametric test, correlation analysis and Kruskal Wallis test.

Results: It was shown that raloxifen increases femoral and vertebral bone strength significantly in osteoporotic rats. These effects on bone strength of raloxifen is lower than that of estrogen (p=0.04). Bone strength was found to be 87,8±8,09 N in femurs of OVX plus estrogen (p=0.001) and 80.8± 11,6 N in femurs of OVX plus raloxifen (p=0.01) and 70.7±13,4 N in femur of OVX group. Bone strength of sham operated groups was assessed to be 74.02±14.9 N. Raloxifen treatment resulted in lower cholesterol levels (103.9±13.8mg/dl, p= 0.01)) when compared with vehicle treated OVX rats ( 125.2±18.6mg/dl).

Conclution: In this study, raloxifen has promise as a agent with beneficial bone and cardiovascular effects in the absence of negative effects in tissue. Effects of raloxifen on bone and cholesterol levels are beneficial and equivalent to those of estrogen treatment.