Proportions of Nucleic Acids in the Uteri of Ewes with Clover Disease and the Effect of Oestrogen after Ovariectomy

Abstract

In entire ewes, the ratio of RNA to DNA in the uterus was higher at oestrus than at dioestrus but did not differ between control and clover-affected ewes at either stage of the oestrous cycle.After ovariectomy the ratio of RNA to DNA in the uteri decreased in both control and cloveraffected ewes, but the decrease was greater in the control ewes (P < 0·01). Subsequently when ewes received a single injection of oestradiol-17 p, a similar rise in uterine RNA/DNA ratio occun:ed in the two groups. However, following injection of the ewes with oestradiol-17 p for 3 days, the ratio of uterine RNA to DNA was higher in control than in clover-affected ewes (P < 0·05). Thus, the uteri from clover-affected ewes undergo less regression after ovariectomy and yet show less response to repeated oestrogenic stimulation than do those of control ewes. This pattern of response is consistent with the hypothesis that the permanent changes caused by phyto-oestrogens in ewes are analogous to the differentiation which normally occurs during organogenesis.

Apparently normal oestrogen receptor system in ovariectomized ewes with impaired response to oestrogen after prolonged grazing on oestrogenic pasture

“…In the absence of oestrogenic stimulation, ovari¬ ectomized ewes with clover infertility have a higher ratio of RNA : DNA in the uterus than non-affected ewes (Tang & Adams, 1982), and greater rates of pro¬ tein and glycoprotein synthesis in the cervix (Tang & Adams, 1981). The response to oestrogenic stimu¬ lation, however, is reduced in affected ewes when measured by the RNA : DNA ratio in the uterus (Tang & Adams, 1982), or by cervical mucus produc¬ tion and keratinization of vaginal epithelium (Adams, 1979). Similarly, there is a reduced response to oestrogen as judged by both the surge of luteinizing hormone (Adams & Martin, 1983) and the degree of female sexual behaviour (Adams, 1978).…”