Progesterone-regulated Changes in Oestradiol-stimulated Guinea Pig Uterus: Steroid Hormone Receptor Levels and RNA and Protein Metabolism

Abstract

By 24 h after its administration progesterone (P) is markedly anti-uterotrophic in the oestradiol (E2)-stimulated uterus of several species, including the mouse, but less so in the E2 -stimulated uterus of the guinea pig. The time course of some early responses to a single injection of P in the E2-stimulated uterus has been further examined in the guinea pig. E2 caused early, marked increases in uterine wet weight and in vitro rates of protein and RNA synthesis, which were maximal at 4 h, but relatively little tissue growth or increase in RNA: DNA and protein: DNA ratios at 12-24 h. P uniformly abolished all of these various uterine responses to E2.