ESTUDIO DEL EFECTO DE LA TIBOLONA SOBRE EL DAÑO INDUCIDO POR LA OVARIECTOMIA EN EL HIPOCAMPO DE LA RATA ADULTA

Abstract

To prevent symptoms of menopause, hormone replace therapy (HRT) is prescribed. This may have estrogenic and/or progestin components. HRT increases the incidence of endometrial and breast cancer. A strategy to reduce this impact is the use of tibolone, which also has estrogen and progestin components. However, the role of tibolone in the process of learning and memory is unknown. The aim of this study was to evaluate the long term effect of different dosis of tibolone (0 mg/Kg, 0.01 mg/Kg, 0.1 mg/Kg 1.0 mg/Kg and 10 mg/Kg orally daily for 18 weeks) on the memory and learning of ovariectomized rats. For this purpose, two behavioral animal models (autoshaping and T maze) were employed, as well as a direct measurement of the content of acetyl choline transferase (ChAT) and tryptophan hydroxylase (TPH) by Western blot in the hippocampus. In the autoshaping model and in the spontaneous activity test, no significant changes were observed. In the T maze there was an increased latency with the doses of 1 and 10 mg/Kg. Whereas the ChAT content decreased with increasing doses of tibolone, the TPH content increased with the doses of 1 and 10 mg/Kg of tibolone. These data suggest that high doses of tibolone improve the results of an emotional learning task, an effect that depends on the modular effect in cholinergic and serotonin systems.