Abstract

UTERINE PEROXIDASE ACTIVITY DURING PREIMPLANTATION PERIOD IN RAT: EFFECTS OF CENTCHROMAN, A NONSTEROIDAL ANTIESTROGEN

F. W. Bansode*

Abstract

Peroxidase enzyme is a major estrogen–regulated glycoprotein in uterus. It catalyzes conversion of estrogen to catechol estrogens and associated with uterine receptivity. Present study was conducted to determine the uterine peroxidase activity in adult rats ( B. Wt. 180-200 g) administered centchroman (CCN; 1.25 mg/Kg; p. o.) or a vehicle on day 1 post-coitum (p.c.) and autopsied between 10:00-11:00h from days 2-6 p.c. Results on cellular localization of uterine peroxidase activity showed strong staining intensity in endometrial exogenous eosinophilic leucocytes and blood vessels on day 2 p.c., which increased further from days 3-5 p.c., with maximal enzyme activity on day 5 p.c. in entire endometrium (including uterine exogenous/endogenous cells and blood vessels). Biochemical estimations of uterine (soluble/Ca2+-extracted) peroxidase activity revealed an increasing trend from days 3-5 p.c., with its maximum on day 5(10:00 h) p.c. in control rats. In contrast, enzyme activity (in uterine frozen sections/Ca2+-extracted fraction) declined following postsensitivity period (on day 6 p.c.). Post-coital treatment of CCN (1.25 mg/kg) produced a localized strong staining reaction in endometrial eosinophilic leucocytes on day 2. But, caused significant decrease in uterine (sections/tissue extracts) peroxidase activity on days 3, 4 and 6 as compared to corresponding controls. Uterine peroxidase activity did not show any significant change on days 5 and 6 (in soluble fraction) except its insignificant increase on day 5 coinciding with eosinophilic leucocytes activity and plasma peroxidase level in treatedrats. In contrast, uterine ligation (on day 1 p.c.) caused significant inhibition in Ca2+- extracted peroxidase activity on days 5 and 6. In immature ovariectomized (OVX) rats. CCN treatment (0.25 or 1.25 mg/kg for 3 days) in combination with E2 (1 or 10μg), caused significant decrease in uterine Ca2+-extracted peroxidase activity as compared to E2 treated rats. Findings indicate- (1) Highest peroxidase activity in relation to maximal endometrial sensitivity, (2) Correlation between uterine soluble peroxidase activity and localized staining intensity in endometrial eosinophilic leucocytes related to non-genomic estrogen action, whereas, Ca2+-extracted peroxidase activity of endogenous (stromal/epithelial) cells related to genomic response, (3) Inhibition of uterine (fractions/ sections) peroxidase activity on days 3, 4 (pre-sensitivity) and 6 (post-sensitivity) by CCN treatment may be due to inhibition of estrogen action. Its insignificant increase on day 5 (10:00 h) coinciding with increased plasma peroxidase level in treated-rat, may be due to weak inherent estrogenicity of this compound, (4) Inhibition of enzyme activity by uterine ligation may suggest the role for local embryonic estrogen/peroxidase activity in uterine sensitivity.

Keywords: Peroxidase activity, endometrial sensitivity, centchroman, Rat.