Early changes of affinity and binding sites of progesterone and oestrogen receptors in decidua exposed to RU 486

Expression in promoter variant of the ERα gene in bos taurus liver

Due to the variant functions that estrogens play in the regulation of reproduction, development of the mammary gland, growth and differentiation of cells, estrogen receptors and their genes are considered as a candidates for the markers of production and functional traits in farm animals, including cattle. In the earliest study, a 2853-bp bovine ER gene 5'-region was PCR amplified and sequenced. Moreover, for the first time, a polymorphism was described within 5' region of the bovine ERalpha gene--A/G transition lying upstream at position 2591 from acceptor splice site +85, possibly within its promoter--which could be recognized with RFLP-BglI. In other study we are found second polymorphism-A/G transition at position 1213 from acceptor splice site +85, located in promoter for exon B. We have examined the specific mRNA expression of ERalpha in various genotypes using real-time RT-PCR. We used four animals from each genotype group--AG, GG for BglI and AA, AG for SnaBI--to analyse liver ERalpha expression at the level of Real-time PCR. Liver samples were taken from the 16 young Friesian bulls of the different ERalpha genotypes, slaughtered at the local abattoir. As shown by Real-Time PCR, on the livers of animals with different genotype ERalpha mRNA for BglI polymorphism we didn't found variability, but for SnaBI we have found variability between AG and AA genotypes.

Tissue and serum levels of steroid hormones and RU 486 after administration of mifepristone

The present study was designed to examine the effect RU 486 administration on steroid hormone levels in serum and decidua. Sixty women at 6-7 weeks gestation were divided into three groups. The first group took a placebo 24 hours before interruption of pregnancy. The other two groups took 200 mg mifepristone 12 and 24 hours before the surgical procedure, respectively. The concentrations of steroids and mifepristone were measured by radioimmunoassay or high performance liquid chromatography. Mifepristone treatment increased the levels of estradiol, cortisol and testosterone in serum and decidual cytosol (p < 0.05 or p < 0.01). A minor elevation in progesterone level was observed but was not statistically significant. The tissue levels of progesterone, estradiol and testosterone were much higher than the serum levels, whereas RU 486 concentration in the tissue was only one-third of the serum level. In addition, the RU 486 level in decidual cytosol was of the same order as that of progesterone. This competitive concentration was not achieved in chorionic villi in our previous observation, explaining why mifepristone exerts its predominant effect on decidua rather than villi. It is concluded that RU 486 reached an effective inhibitory concentration in decidua and had significant effects on the endocrine milieu.

Estrogen and progesterone receptors in human decidua after RU486 treatment

OBJECTIVE

To examine RU486 action on decidua at the level of cellular estrogen receptor (ER) and P receptor (PR).

DESIGN

Controlled basic study for contragestion mechanism of mifepristone.

SETTING

Normal human volunteers in an academic research environment.

PATIENTS

Sixty women with 6 to 7 weeks of gestation who voluntarily requested termination of pregnancy were recruited and randomly divided into three groups.

INTERVENTION

A single dose of 200 mg RU486 was orally administered to the two treatment groups 12 and 24 hours, respectively, before surgical interruption of pregnancies. Placebo was used for control group. Decidual tissues were collected right after operation.

MAIN OUTCOME MEASURE

Immunocytochemical reactions of PR and ER in decidua after RU486 treatment were compared with the control subjects. The differences of the reaction in decidual area with or without trophoblast invasion were noted.

RESULTS

RU486 treatment increased PR and ER staining in vessel and stroma of decidua without trophoblast invasion (decidua parietalis) but not in decidua with trophoblast invasion (decidua capsularis or basalis). Chi-squared analysis indicated a significant increase in the number of ER-positive samples after RU486 treatment.

CONCLUSION

The decidua parietalis was the primary target site of RU486. The lack of RU486 effect on decidua capsularis implied that trophoblast invasion prevented against antiprogestin impact.