Abstract. The expression of three different gap junction transcripts, or, (Cx43), B~ (Cx39, and B2 (Cx26) was examined in several organs during pregnancy in the rat. In all of the organs that were examined-uterus, ovary, heart, and liver-there was a strong correlation between levels of gap junction mRNA and gap junction antigens that were detected at different stages of pregnancy. A striking change in o~ transcript levels (a 5.5-fold increase) was detected in the uterine myometrium on the day before parturition. This elevation of the c~, transcript is thought to be associated with the formation of gap junctions that are required for synchronizing the contractility of the myometrial cells during parturition. 2 d before parturition, there was a detectable elevation of/32 transcripts and protein in the endometrial epithelium, which was then followed by a dramatic decrease in j52 gap junctional protein on the day before parturition. There was also a substantial elevation of tx~ transcripts (a 6.7-fold increase) in the stromal regions of the ovary on the day before parturition that was identical to the temporal pattern of ott expression in the myometrium. In all three instances-the c~, transcripts in the myometrium, ~2 transcripts in the endometrium, and at transcripts in the ovary-the transcript modulation appeared to be cell specific, because the changes in transcript levels of these three gene products occurred independently of the poly(A)+RNA concentrations at the same pregnancy stages in the respective organs. There were no specific changes detected in gap junction transcript levels in the heart and liver during pregnancy. These observations indicate that a cell-specific modulation of gap junction expression occurs in two regions of the uterus and the ovary during pregnancy. Further, it appears that the same gap junction gene in different organs, such as the ct~ gene in the uterine myometrium and the heart, can be differentially regulated.

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A series of 5-benylidene-1,2-dihydrochromeno[3,4-f]quinolines (4) were synthesized and tested in bioassays to evaluate their progestational activities, receptor- and tissue-selectivity profiles as selective progesterone receptor modulators (SPRMs). Most of the new analogues exhibited as highly potent progestins with more than 100-fold receptor selectivity over other steroid hormone receptors and LG120920 (7b) demonstrated tissue selectivity toward uterus and vagina versus breasts in a rodent model after oral administration.