Abstract

HORMONAL REGULATION OF UTERINE LUCINEAMINOPEPTIDASE ACTIVITY IN RAT: EFFECT OF A TRIPHENYLETHYLENE ANTIESTROGEN, CENTCHROMAN

F. W. Bansode*

Abstract

Lysosomal enzyme-system has been well documented during preimplantation uterine growth/proliferation and decidualization. Present study was conducted to determine the effects of a single antiimplantation dose (1.25mg/Kg, p.o., on day 1 post-coitum) of centchroman (CCN) on uterine localization of lucine-aminopeptidase (LAP) activity in Sprague-Dawley rats autopsied between 10:00- 11:00h from day’s 2-6 post-coitum (p.c.). In addition, localization of this enzyme activity was also carried out in ligated rat uterus (on days 4, 5 and 6 p.c.), and in immature ovariectomized (OVX) rats administered CCN (0.25 or 1.25 mg/kg, i.m. for 3 or 5 days). Parallel control groups of rats maintained were given vehicle only. Results revealed an increase in uterine LAP activity from days 2-4 p.c., with its maximal staining intensity on day 4 (11:00 h) in control rats. Period of maximal endometrial sensitivity (day 5, 10:00 h p.c.) was marked by decreased LAP activity in antimesometrial stroma. In contrast, increased enzyme activity was observed in early deciduas immediate to post-sensitivity period (day 6, 10:00h p.c.). Post-coital CCN (1.25 mg/Kg) treatment caused marked inhibition in uterine LAP enzyme activity during pre- (day 4, 10:00h) - and postsensitivity (day 6)-periods in CCN-treated or in ligated rats as compared to corresponding controls. But, it did not show any significant change in its staining reaction on day 2, except for increased mesometrial LAP activity on day 3 in treated-rats. Inhibition of endometrial sensitivity (day 5, 10:00h) by CCN caused localized increase in antimesometrial (stroma/epithelium) LAP activity. Uterine ligation too, caused an increase in uterine LAP activity on day 5. In immature OVX-rats, CCN treatment (0.25 and 1.25 mg/Kg) alone or in conjunction with estradiol (1 or 10μg) caused an increase in uterine LAP activity as compared to estradiol treatment. Results of the study, (1) confirm the role of LAP enzyme during uterine growth and proliferation, and differentiation into deciduas as evidenced by its increased activity just prior (day 4) to- and post (day 6)–implantation periods. (2) Inhibition of uterine LAP enzyme activity during pre (day 4, 10:00 h) - and post (day 6; 10:00 h) - sensitivity periods by CCN treatment may be due to inhibition of estrogen action. While, increased LAP activity in antimesometrial endometrium on day 5(10:00 h) in CCN-treated or in ligated rats might be due to inhibition of blastocyst-implantation.

Keywords: LAP – uterus – centchroman - rat.