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

Abstract

PURPOSE: To verify the effects of tibolone administration on trabecular and cortical bone of ovariectomized female rats by computed radiography system (CRS). METHODS: 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%. RESULTS: 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. CONCLUSION: 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.

The influence of estrogen deficiency on the structural and mechanical properties of rat cortical bone

“…Previous studies investigating the effects of ovariectomy on the stiffness of the bone material of rat cortical bone have reported inconsistent results. Some studies found decreased stiffness (Peng et al, 1997), while others found no change (Miyagawa et al, 2011) or even increased bone material stiffness following ovariectomy (De Carvalho et al, 2012). Other studies found a site specific or time-dependent effect, with initially superior mechanical properties of cortical bone in control rats, which disappears with time (12-28 weeks post OVH) (Peng et al, 1997).…”

“…Nevertheless the majority of studies of osteoporosis are conducted on cancellous (trabecular) bone, while there are fewer studies investigating cortical bone. Furthermore, previous studies examining the effects of ovariectomy on cortical bone in rats reported conflicting results (De Carvalho et al, 2012;Miyagawa et al, 2011;Peng et al, 1997).…”

Matriz de recomendações para farmacoterapia da osteoporose e da osteoartrite: recurso para subsidiar a adaptação de guias de prática clínica

“…Outra recomendação, parte da terapia hormonal, é o uso de tibolona, um hormônio sintético que apresenta atividade estrogênica, progestagênica e androgênica. Vários ensaios clínicos tem demonstrado que a tibolona mantém a integridade dos ossos e previne perda de massa óssea em mulheres na pós menopausa (168,169). Quatro GPC mencionam o uso de tibolona, sendo que o GPC da Malásia 2012e o GPC de Taiwan (2011) mencionam a ressalva de que o uso de tibolona pode aumentar a incidência de derrame em mulheres acima de 60 anos (59,122).…”