title: Timing of anti-uterotrophic effects of a single injection of progesterone in the oestrogen-stimulated uterus: comparison of the sheep and mouse.
abstract: Progesterone (P) is anti-uterotrophic in the oestradiol (E2)-stimulated uterus of the mouse but not the sheep. To further understand this species difference, the time course of some early effects of a single injection of P on the E2-stimulated uterus has been examined. In the mouse, P caused a prompt (2-4 h) decline in uterine wet weight and in vitro rate of RNA synthesis, and a more gradual decrease (4-12 h) in RNA: DNA and protein: DNA ratios and in vitro rate of protein synthesis in whole uterus. In the sheep, P had no effect at any time on either whole uterus or caruncular endometrium. The results support the concepts that (1) anti-uterotrophic effects of P in E2-stimulated mice are mediated by a direct P effect on nuclear E2 receptor level, and (2) in the sheep P is not anti-uterotrophic because it does not regulate nuclear E2 receptor level.
mesh_terms: D000818:Animals; D004247:DNA / Q000096:biosynthesis; D004334:Drug Administration Schedule; D004717:Endometrium / Q000033:anatomy & histology; D004958:Estradiol / Q000494:pharmacology; D005260:Female; D051379:Mice; D009929:Organ Size / Q000187:drug effects; D011374:Progesterone / Q000008:administration & dosage*; D014176:Protein Biosynthesis; D012313:RNA / Q000096:biosynthesis; D011987:Receptors, Steroid / Q000187:drug effects* / Q000378:metabolism; D012756:Sheep; D014599:Uterus / Q000187:drug effects*
chemical_list: D011987:Receptors, Steroid; D011374:Progesterone; D004958:Estradiol; D012313:RNA; D004247:DNA