A comparison of the effects of estradiol and 2- and 4-hydroxyestradiol on uterine ornithine decarboxylase activity in immature rats

Effects of estradiol (E2) and catechol-estrogens (CEs: 2-OHE2 and 4-OHE2) on uterine ornithine decarboxylase (ODC) activity have been compared in immature rats. The intensity of their actions by s.c. (1 μg) and intrauterine right-horn (i.u., 25 ng) injection was in the order of: 4-OHE2 ≧E2>2-OHE2. Although i.u.-injection of E2 caused an increase in ODC activity in the left (intact)-horn, which was about 60% that of the right-horn, the effects by CEs were limited only to the right-horn. The results are consistent with the previous view about the order of the potency of 4-OHE2 and 2-OHE2 and also suggest that locally produced CEs may play a role in the physiological functions of the production site.