Comparative effects of naturally occurring, synthetic and plant estrogens on uterine metabolism

Various estrogens biologically equivalent to 1.0 μg estradiol-17β were administered intraperitoneally to immature female rats to monitor the relative dose and time course effects on water imbibition. Estradiol-17β, estriol and diethystil-bestrol (DES) were the strongest estrogens in inducing tissue edema. Plant estrogens, genistein and coumestrol, in pure crystalline form were approximately 10⁻³ times as potent in stimulating water imbibition as estradiol-17β. The administration of estradiol-17β, genistein and coumestrol was shown to enhance the permeability of uterine vasculature as indicated by the diffusion of intravenously infused India ink. Large doses (5.0 μg) of estradiol-17β were administered to immature female rats to measure the rate of synthesis of RNA and DNA in the uterus. It was observed that the uterine cell cycle was significantly (P < 0.025) reduced after the administration of estradiol-17β. Net accumulation of RNA and DNA was shown to occur after 12 and 24 hours respectively. The incorporation of [5,6-³H] uridine into the uterine tissue was studied by administering natural, synthetic and plant estrogens intraperitoneally to immature female rats. After a six hour period there was a decreased uterine specific activity 3 of [5,6-³H] uridine in estrogen treated rats when compared to control animals. Estradiol-17β produced the greatest reduction in the specific activity of the hydrolyzed RNA while DES, estriol and estradiol-17α produced relatively smaller reductions. The reduction of specific activity six hours after in vivo pulsing with estradiol-17β was probably due to a dilution effect associated with changes occurring in cell permeability. Genistein and coumestrol also reduced the specific activity of C5,6-³H] uridine similar to that observed with estriol. Extracts of alfalfa hay and soybean meal were analyzed quantitatively and qualitatively for plant estrogens. Short in vivo pulsing of 30 minutes of various estrogens was employed to determine the uptake of [5,6-³H] uridine by the uterine tissue. Estradiol-17β, purified genistein, alfalfa and soybean extracts were found to incorporate [5,6-³H] uridine at greater rates than control groups.Land and Food Systems, Faculty ofGraduat