GAP JUNCTION REGULATION IN THE UTERUS AND OVARIES OF IMMATURE RATS BYESTROGEN AND PROGESTERONE

The effects of estrogen (E2) and progesterone (P) were examined on the expression levels of multiple gap junction (GJ) gene products (alpha( 1)=Cx43, beta(1)=Cx32, beta(2)=Cx26) in the uterus and ovaries of imma ture rats by immunohistochemistry, electron microscopy and northern bl ot analysis, E2 induced the expression of alpha(1) connexin in the ute rus (specifically in the myometrium and in endometrial stroma proximal to luminal epithelium) and ovaries, The E2-induced alpha(1) expressio n was completely suppressed by P in the uterus, but only partly in ova ries, Steroid hormones also modulated the quantity, size, and distribu tion of beta(1) and beta(2) containing junctional plaques along latera l cell borders in polarized luminal and glandular uterine epithelia. S mall GJs were detected at basolateral regions in proliferative luminal epithelium following administration of E2. In contrast, large GJs wer e localized at subapical-lateral cell borders of the secretory epithel ium following P-treatment. The co-administration of E2+P had a synergi stic effect on beta(1) and beta(2) expression in the luminal epitheliu m, but an inhibitory effect on beta(2) expression in glandular epithel ium. Myometrial GJs were detected in freeze-fracture replicas as aggre gates containing regularly arranged particles with particle free zones , In contrast, GJs in secretory epithelium contained particles which w ere arranged in a non-crystalline fashion, These GJs contained domains of mixed and segregated beta(1) and beta(2) antigens within a single plaque as revealed by laser scanning confocal microscopy analysis of i mmuno-double-labeled secretory epithelium, The demonstration of segreg ated antigens within a single GJ plaque indicates the possibility of m ultiple channel populations formed by homo-oligomeric connexons. These results suggest that different connexins can be differentially regula ted by steroid hormones in different cell types, and that the same ste roid hormone can have different effects on the same connexin in differ ent cell types.