Search

Mifepristone is a potent agent used in emergency contraception (EC). In the present study, we examined the contraceptive efficacy of mifepristone used in EC and then, using the model of mifepristone-based EC, we investigated its mechanism of action in the rhesus monkey. Sexually mature females were allowed to cohabitate with male animals from 1600 to 900 h of any one day of days 8-17 of cycle without (Group I; n = 6) and with a single dose of mifepristone (Group II, n = 31, 25 mg per animal, subcutaneous) 72 h postcoitus. Blood samples from all animals of Groups I and II were used to determine the concentrations of estradiol (E), progesterone (P) and chorionic gonadotrophin in peripheral circulation for retrospective analysis of the days of ovulation and blastocyst implantation. Four out of six animals (66.6%) in Group I became pregnant, while all 31 monkeys in Group II failed to establish pregnancy along with marginal changes in serum concentrations of E and P. In the second part of the study, animals were subjected to the same experimental protocol followed by collection of endometrial tissue samples on cycle day 22 from animals of both Group I (n = 6) and Group II (n = 24). Endometrial samples were subjected to morphological analysis including mitotic index, immunohistochemistry for vascular endothelial growth factor (VEGF), leukemia inhibitory factor (LIF), transforming growth factor beta1, estradiol receptor (ER), progesterone receptor (PR), proliferating cell nuclear antigen, placental protein 14 (PP 14) and detection of apoptosis by terminal nick end labeling method followed by histometric analysis. The results were retrospectively analyzed between the two groups on the basis of the day of treatment after ovulation: early luteal phase (days 0-3 postovulation) and mid-luteal phase (days 4-7 after ovulation). Mifepristone used in EC in the present study resulted in general loss of functional integrity of epithelial compartment characterized by loss of secretory maturation, increased apoptosis and higher degree of degeneration along with decreased expression of VEGF, LIF, PP14 and ER, while PR level increased as compared to control samples. The vascular compartment appeared to be compromised along with affected morphological features and decreased expression of VEGF, LIF, ER and PR following the administration of mifepristone. It appears that mifepristone used in EC alters the physiological homeostasis in epithelial and vascular compartments of implantation stage endometrium rendering it hostile to blastocyst implantation. Furthermore, the degree to which the endometrial function is affected largely depends on the day of mifepristone treatment in a parameter-specific manner resulting in a higher degree of degenerative changes in samples obtained from animals who received mifepristone during mid-luteal phase of cycles.

In the present study, fumagillin, which is an antibiotic with potent angiostatic activity secreted from Aspergillus fumigatus was administered intravaginally during peri-implantation stage in the rhesus monkey and its effects on ovarian function, blastocyst implantation and pregnancy outcome in the rhesus monkey were investigated. Female monkeys (n = 18) showing normal menstrual cycles were vaginally inserted with tampons containing fumagillin (0 mg/animal in group 1; 1 mg/animal in group 2; 2 mg/animal in group 3; 4 mg/animal in group 4) on cycle day 20 of the mated treatment cycle, and these were removed on day 26 of the treatment cycle. Pregnancy was found to occur in animals treated with 1 mg and 2 mg fumagillin. However, animals treated with 4 mg fumagillin remained non-pregnant along with decreased (p

Intravaginal administration of an anti-microbial agent, (Ala 8,13,18 )-magainin II amide, during blastocyst implantation inhibits pregnancy establishment in a dose-related manner in the rhesus monkey ( Macaca mulatta ). In the present study, mated female rhesus monkeys were vaginally inserted with tampons containing vehicle (Group 1; n = 5) and test agent (magainin, 0.5 mg/animal; Group 2; n = 6) on cycle day 20. Endometrial tissue samples were collected on Cycle Day 24 from all monkeys and processed for morphometric and ultrastructural analysis. Concentrations of estradiol-17β, progesterone, and chorionic gonadotrophin in peripheral circulation were determined, which revealed that two monkeys in Group 1 were pregnant while no animals were pregnant in Group 2. Endometrial morphology, however, revealed histologic evidence of pregnancy in three out of the six magainin-treated animals. It appears that intra-vaginal administration of magainin II amide had a marginal effect on the implantation stage endometrium and the initiation of the implantation process in the rhesus monkey.

The hypothesis that timed application of a potent anti-microbial, anti-tumor agent like magainin peptides can inhibit blastocyst implantation was examined in the present study using the rhesus monkey as the primate model. Incidence of pregnancy, vaginal bleeding patterns, serum levels of progesterone, estrogen and monkey chorionic gonadotropin were examined following vaginal administration of (Ala8,13,18)-magainin II amide, a synthetic analogue of magainin 2, via tampon during days 20 to 26 of mated cycles. Implantation occurred in two out of three animals following administration of 0.25 mg magainin, while administration of 0.5 mg (Ala8,13,18)-magainin II amide resulted in inhibition of implantation in all females with no change in lengths of treatment cycles, and subsequent cycles. It appears from the present study that, besides being a local microbicidal agent, intravaginal administration of (Ala(8,13,18))-magainin II amide is a potential anti-implantation strategy for intercepting pregnancy.