Connexin 43 expression in rat aortic smooth muscle after ovariectomy and hormonal replacement

The purpose of this study was to determine the effects of ovariectomy and l ong-term combined sexual hormone replacement on the gap junctional protein, connexin 43 (Cx43) of aortic medial smooth muscle cells in rats. Twenty non-pregnant mature Wistar female rats were divided into five groups (four animals in each group). Group A underwent ovariectomy, Group B under went ovariectomy and received estradiol propionate, Group C underwent ovari ectomy and received medroxyprogesterone acetate and Group D underwent ovari ectomy and received both hormones. Group E was sham-operated and used as co ntrol. After 15 weeks of treatment, thoracic aortas were removed and immuno histochemistry was carried out using a specific fluorescent antibody agains t Cx43. Tissue sections were examined by confocal laser scanning microscopy and analysed by the Scion Image program. All five different groups had the same distribution and extent of Cx43 in t he aorta. Neither the ovariectomy nor the hormone replacement had any effec t on the Cx43 expression of aortic smooth muscle cells in rats as compared to control animals. These results indicate that sexual steroids do not influence the gap juncti onal protein Cx43 of the medial layer of aorta in rats. They may suggest th at the beneficial effects of estrogen are not mediated via gap junctions in the human aorta either.