Expression Of Aromatase Cytochrome P450 Gene And Cyclooxygenase-2 Gene In Tissues Of Endometriosis And Effects Of Their Inhibitors On Rat Models

Endometriosis is an estrogen-dependent disorder. It is shown that high local concentrations of Estradiol(E2) and prostaglandin (PGs, especially PGE2) in endometriotic lesions contribute to the progression of endometriosis. Aromatase is a cytochrome P450 enzyme which catalyzes the rate-limiting step in estrogen biosynthesis. Cyclooxygenase-2 catalyzes the biosynthesis of PGE2 which is found to be the most potent known inducer of aromatase activity .Thus these two kinds of enzymes are of paramount importance in the pathophysiology of endometriosis due to their activities, their genetic expression and their effects on each other . Aromatase inhibitor is found to inhibit the activity and expression of aromatase and further lead to the regressing of the ectopic endometria by decreasing the level of E2 in local lesions. Cyclooxygenase-2 inhibitor is a novel agent which decreases the level of PGE2 in endometriotic lesions by inhibiting the expression of cyclooxygenase-2 in a more selective and effective manner. The objective of this study is to investigate the relationship between the expression of the two genes and endometriosis and to observe further the effect of their inhibitors on rat model of endometriosis.Materials and methods1. Reverse transcript-polymerase chain reaction(RT-PCR) was used to detect P450 arom mRNA and COX-2 mRNA expression in the ectopic and eutopic endometrium of women with endometriosis and that in the normal endometrium. 2. Surgically transplanted autologous uterine tissues to ectopic sites beside the uterines in rats were used as animal models to study endometriosis. The models were then divided into five groups: 1) rats oralled with Arimidex 0.1mg/kg daily for 4 weeks; 2) rats oralled with Celecoxib 5mg/kg daily for 4 weeks; 3) rats oralled with Arimidex 0.1mg/kg and combined with Celecoxib 5mg/kg daily for 4 weeks; 4) rats ovariectomized for 4 weeks;5) The controls oralled with saline solution daily for 4 weeks. Radioimmunoassay was used to detect the serum levels of E2,FSH and LH in each group after one-week and four-week therapy; RT-PCR method was utilized to detect the expression of P450arm mRNA and COX-2 mRNA in endometriotic explants; Macroscopic changes of endometriotic explants were observed and histologic and image analysis were also done.Results1.Expression of COX-2 mRNA and P450arom mRNA in the ectopic and eutopic endometrium of women with endometriosis was strongly positive, and the relative levels were remarkly higher than that of controls (P<0.05). The levels of the expression of COX-2 mRNA in the secretory phase were slightly higher than that in the proliferative phase in eutopic endometria of women with and without endometriosis but were of no significance. However, they remained significantly high in the ectopic endometria of women with endometriosis regardless of the menstrual phase; No variation of expression of P450 arom mRNA in the ectopic endometrium of women with endometriosis was found in all menstrual phases. There was no statistically significant difference between the expression of both mRNA and rAFS stage of endometriosis (P>0.05).2.The serum levels of E2 were decrease remarkly when rat models were treated with Arimidex alone or combined with Celecoxib after 1 week (P<0.05),And they were restored to the same levels as the control's when the models had been administrated for 4 weeks (P>0.05).The serum levels of FSH and LH increased slightly when rats exposed to the conditions mentioned above after one week or four weeks but were no statistically significant difference as compared with that of the controls (P>0.05). There were statistically significant differences as to serum values of E2 ,FSH and LH between the ovariectomized group and the control group. Celecoxib alone showed little effect on the serum levels of E2 ,FSH and LH. The explant sizes in Arimidex-treated or combination-treated or ovariectomized group were found smaller than that in the control (P<0.01), And they showed no changes in Celecoxib-treated group. The percentage...