Influence of estrogen deficiency and tibolone therapy on trabecular and cortical bone evaluated by computed radiography system in rats

To verify the effects of tibolone administration on trabecular and cortical bone of ovariectomized female rats by computed radiography system (CRS). The experiment was performed on two groups of rats previously ovariectomized, one received tibolone (OVX+T) while the other did not (OVX), those groups were compared to a control group (C) not ovariectomized. Tibolone administration (1mg/day) began thirty days after the ovariectomy and the treatment remained for five months. At last, the animals were euthanized and femurs and tibias collected. Computed radiographies of the bones were obtained and the digital images were used to determine the bone optical density and cortical thickness on every group. All results were statistically evaluated with significance set at P<0.05%. Tibolone administration was shown to be beneficial only in the densitometric analysis of the femoral head, performing higher optical density compared to OVX. No difference was found in cortical bone thickness. Ovariectomy caused bone loss in the analyzed regions and tibolone administered in high doses over a long period showed not to be fully beneficial, but preserved bone mass in the femoral head.