The distribution of immunocytes in the rat uterus undergoes profound changes during early pregnancy. This study was designed to evaluate the respective contributions of hormonal and local factors to regulation of the distribution and number of MCA341+ monocyte-macrophage antigen-bearing cells and T-lymphocyte-polymorphonuclear leukocyte (PMN) antigen-bearing cells before and during implantation of the fertilized ovum. Immunohistological data in normal rat pregnancy were compared to those found in cycling rats, ovariectomized rats, pseudopregnant rats (the oviducts of which had been sectioned on Day 0.5 of pregnancy), and pregnant rats injected with the antiprogesterone RU-486 on Day 0.5 of pregnancy. Four major events were observed: (1) transient accumulation of T-lymphocyte-PMN antigen-bearing cells in the endometrium close to the lumen and occurring only in the pregnant state 12 h after mating; (2) accumulation of an MCA341+ antigen-bearing monocyte-macrophage subset in the uterus, especially the luminal endometrium, 12 h after ovulation in pregnant as well as cycling rats; (3) progressive disappearance of these labeled cells starting 1 day after ovulation in the pregnant and nonpregnant states and influenced by RU-486 injection; (4) relative persistence of labeled cells in the deep endometrium before the implantation of the conceptus--which requires the presence of fertilized ovum in the genital tract. In conclusion, a complex multifactorial and sequential control of the distribution and number of cells bearing MCA341+ monocyte-macrophage or T-lymphocyte antigens appears to be at work before and during implantation of the rat conceptus, and may involve hormonal factors as well as local factors produced by the embryo or trophoblastic cells.
Human breast cancer cell lines have been shown to possess high affinity receptors for 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) and their growth is inhibited by this steroid. The present study examines the effect of 1,25(OH)2D3 on the activity of glucose-6-phosphate dehydrogenase (G6PD) in cells of a human breast cancer cell line MCF-7. G6PD, an enzyme which controls the hexose monophosphate shunt, is elevated and sensitive to 17 beta-estradiol in breast tumors. G6PD activity was stimulated by 1,25(OH)2D3 in a dose-dependent manner at very low concentrations of steroid (10(-10)-10(-12) M). 1,25(OH)2D3 increased maximum velocity without modifying the affinity constant of the enzyme for glucose-6-phosphate.
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