The effect of clomiphene citrate on osteoporosis in ovariectomized rats

The aim of this study was to investigate whether clomiphene citrate (CC) administration could be a new therapeutic agent in case of contraindication of estrogen therapy for hormone-dependent osteoporosis and to show the changes in bone structure by histomorphometric analysis in ovariectomized rats administered CC.

This study was carried out in the Experimental Surgery Laboratory of the Brain Research Centre of the Medical Faculty of Ege University. Four-month-old Sprague-Dawley rats were used for the experiment. The study was carried out on six groups of animals each consisted of eight rats. Four groups of rats were ovariectomized and 2 groups of rats were used as control group. For 6 weeks every day, rats were injected physiological saline solution (1 ml/kg), clomiphene citrate (1 or 10 mg/1 ml/kg, Organon), 17beta-estradiol (50 microg/1 ml/kg, within susame oil, Sigma) or susame oil (1 ml/kg, Sigma). Drug administrations were carried out according to the weekly weight measurements. Group 1(PSS), n = 8, non-ovariectomized, were injected with physiological saline solution. Group 2(CC-1), n = 7, non-ovariectomized, were injected with CC (1 mg/1 ml/kg). Group 3(OVX + CC-1), n = 7, ovariectomized, were injected with CC (1 mg/1 ml/kg). Group 4(OVX + CC-10), n = 6, ovariectomized, were injected with CC (10 mg/1 ml/kg). Group 5(OVX + E), n = 8, ovariectomized, were injected with 17beta-estradiol (50 microg/1 ml/kg). Group 6(OVX), n = 8, ovariectomized, were injected with susame oil (1 ml/kg) Bone-specific serum alkaline phosphatase (ALP) levels were measured and statistical analyses were made by Kruskal Wallis test. Left femur bone histomorphometric studies were done. The uteri were dissected out to measure their weight and ANOVA was used to show the intergroup differences.

The level of ALP in group 3 was significantly higher than the other five groups. Bone histomorphometric examination showed that total bone volume in group 3, 4, and 5 was higher than group 6, and group 4 had the highest level of bone volume compared to the rest of the groups. Uterus weights in group 1 were significantly higher than group 3 and 6 (P = 0.02, P = 0.01) and uterus weights in group 5 were significantly higher than group 3 and 4 (P = 0.00, P = 0.01)

In ovariectomized rats, treatment with CC is seen as effective as estrogen treatment in preventing osteoporosis, without causing uterin hyperstimulation. Nevertheless, further investigations on more rats are needed to assess whether it is an alternative treatment method to estrogen.