Effects of droloxifene on apoptosis and Bax, Bcl-2 protein expression of luteal cells in pseudopregnant rats

AIM: To study the effects of droloxifene on apoptosis and the expression of Bax and Bcl-2 protein in corpus luteum of pseudopregnant rats. METHODS: HE staining was used to examine the histological changes of ovaries. Apoptosis detection in situ was performed with TUNEL method. Expression of Bax and Bcl-2 protein was observed by immunohistochemistry analysis. RESULTS: Apoptosis of luteal cells during the spontaneous regression of corpus luteum of pseudopregnant rats appeared on d 13 of pseudopregnancy, and the marked increase of apoptotic luteal cells could be observed on d 15. When pseudopregnant rats were treated with droloxifene 20 mg.Kg(-1) on d 2, apoptosis of luteal cells could be observed on d 8, and the duration of pseudopregnancy could be shortened from (15.5 +/- 1.1) d to (12.8 +/- 1.6) d. In pseudopregnant rats, the expression of Ear and Bcl-2 protein was found in the cytoplasm of luteal cells. However, no obvious differences in the intensity or localization could be found during various days of the pseudopregnancy, while an increase in Fax and a decrease in Bcl-2 protein expression could be induced by droloxifene treatment. CONCLUSION: Droloxifene could facilitate apoptosis of luteal cells in pseudopregnant rats and shorten the period of pseudopregnancy. An increased Bax/Bcl-2 ratio might be involved in the facilitation of apoptosis induced by droloxifene in corpus luteum of pseudopregnant rats.