Estrogen and Progesterone Receptors in the Endometrium, Myometrium, and Metrial Gland of the Rat during the Decidualization Process*

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.

Tenascin in Pregnant and Non-Pregnant Rat Uterus: Unique Spatio-Temporal Expression during Decidualization1

“…Some evidence to support this can be derived from the present study. Tenascin expression apparently followed the path of differentiation of the endometrial stroma, which has been shown to be reflected in the levels of progesterone receptors expressed as decidualization occurs [42]-indeed, maintenance of the metrial gland relies on progesterone [43]. However, regulation of ECM proteins may not reside solely at the hormonal level.…”

Histopathological and Immunohistochemical Characterization of Spontaneously Occurring Uterine Deciduomas in Young Adult Rats

“…In our cases, PgR and ER were expressed strongly in the mesometrial region; however, ER was not expressed in the antimesometrial region. According to a previous report 27 , the involvement of both receptors may suggest that as the decidual cells become differentiated, they become enriched in PgR and impoverished in ER.…”

Estrogen Receptors α and β in Rat Decidua Cells: Cell-Specific Expression and Differential Regulation by Steroid Hormones and Prolactin1

“…The antimesometrial and mesometrial regions were separated as described by Martel et al (16). The day a vaginal plug was found was designated day 1 of pseudopregnancy.…”