No abstract

Uterine cytosolic and nuclear receptors for estradiol (E2) and progesterone (P), were simultaneously determined in pseudopregnant rats subjected to a traumatic decidualizing stimulus (knife-scratch). The entire decidualizing endometrium, myometrium, and metrial gland were separated, homogenized, and studied on alternate days beginning with day 1 post trauma (pt) and extending to day 13 pt when even the metrial gland is regressing. The rise and fall in E2 and P receptors during the earlier stages of deciduoma differentiation confirmed the work of others. Splitting of the deciduoma on day 5 pt into antimesometrial and mesometrial segments showed a higher concentration of cytosolic P receptor in the well differentiated antimesometrial segment, whereas there was a higher concentration of E2 cytosolic receptor in the still differentiating mesometrial segment. The differences, measured as femtomoles per microgram DNA or per mg protein were statistically significant. The receptor changes in the myometrium were not as pronounced as in the endometrium especially with regard to the low myometrial levels of nuclear E2 and P. The metrial gland which comes into prominence while the deciduoma is regressing, showed sustained high concentrations of cytosolic P receptor. It is suggested that although initiated by the same decidualizing stimulus, the hormonal and receptor interplay in the metrial gland may be somewhat different from that of the deciduoma. The metrial gland merits further study because of an implied immunological role.

Cycling adult female hamsters can be induced to mate and ovulate 24 h early by the injection of 20 IU human chorionic gonadotropin (hCG) at 1500 h on Day 3 (day before proestrus), but pregnancy is not established. Although there is evidence of decreased sperm transport in precociously ovulated females, this does not appear to be the primary cause of infertility. Reduced size and vascularity of corpora lutea (CL) in treated females suggests incomplete or failed CL activation. Control and hCG-treated females were killed by exsanguination under ether anesthesia at intervals for the first 5 days after mating. Serum luteinizing hormone (LH), follicle-stimulating hormone (FSH), prolactin, estradiol, and progesterone were measured by radioimmunoassay. Luteinizing hormone in treated animals was very high at 2200 h on Day 1 after mating (31 h after the hCG injection), due to endogenous release, and dropped below control levels thereafter. Follicle-stimulating hormone, by contrast, was significantly lower than controls at 2200 h on Day 1 and remained low until 2200 h on Day 3 after mating. Prolactin in treated animals was not different from that in controls, except for 1000 h on Day 4, when it showed a significant dip. Estradiol in treated animals was significantly higher than in controls at 2200 h on Day 1 (when LH was also high and FSH was low), and remained high at 1000 h and 2200 h on Day 2, dropping thereafter to control levels. Progesterone was initially at control levels but had dropped significantly by 1000 h on Day 2 and remained low for the next 24 h. These results suggest that pregnancy failure is due to inadequate activation of corpora lutea. This may be due to: 1) immaturity of follicles at the time of ovulation; 2) inappropriate timing of preovulatory events; 3) the luteolytic effects of high levels of LH or estradiol or both; 4) the low level of FSH in the early stages of corpus luteum development; or 5) a combination of the above. Abnormalities of prolactin secretion were not investigated in detail but cannot be ruled out at this time.