PARENT SESSION
SLIDE SESSION 18: HORMONE RECEPTORS, STEROID HORMONE ACTION
Chairs: Terry Nett, Leslie Heckert, Dustin Vale-Cruz (Trainee)
Univ Ottawa-Arts Hall 257
1:30 PM-3:30 PM

EXPRESSION OF ANDROGEN RECEPTORS IN THE PERI-ATTACHMENT PORCINE UTERUS.

Vale-Cruz, Dustin¹, Kowalski, Andres¹, Simmen, Frank¹, Simmen, Rosalia ¹, ¹

ABSTRACT- Among the many signaling molecules within the pig uterine micro-environment during early pregnancy (Px), estrogen (E) synthesized by the peri-attachment embryo is presumed to play major paracrine and autocrine roles. The recent report that the embryo-specific type III cytochrome P450 aromatase isoform catalyzes the conversion of testosterone (T) to 19-nortestosterone (NT), and the presence of androgens in uterine fluids during this period suggest, however, that T and NT can similarly modulate Px-associated events. To begin to evaluate the physiological relevance of uterine androgens, the expression of androgen receptors (AR) in distinct cell types of the uterine endometrium at different Px days (d) was examined. Northern analysis demonstrated pig endometrial AR gene expression during Px, with high levels observed between d10 to 18 and undetectable levels at later stages. Immunoblot analysis of endometrial nuclear proteins using anti-AR antibody (PG21-39; Dr. Gail Prins, Univ Illinois), showed that the AR protein (110 kDa) had an expression pattern similar to that of its mRNA. Immunocytochemical analysis of paraffin sections of Px endometrium displayed nuclear localization of AR in glandular epithelial (GE) and stromal (ST) cells and its absence in luminal epithelial (LE) cells. The AR-positive GE and ST cells were responsive to added T (50 and 500 nM), as measured by their diminished incorporation of labeled thymidine in T-treated compared to untreated, cells in vitro. Interestingly, primary cultures of LE cells, which do not express AR in vivo, had increased expression of the T-responsive gene ornithine decarboxylase with added T, relative to control cells. Results show that the Px-associated endometrial expression of AR is coincident with presence of its ligands in uterine fluids and suggest that ligand-bound AR, possibly in concert with conceptus-derived E acting through its specific receptors, modulates endometrial function during early Px. Supported by NIH grant HD-21961 and USDA grant 98-35205-6739.

KEY WORDS: androgen receptor, pregnancy, Sus scrofa, endometrium