S. Kimmins et La. Maclaren, Oestrous cycle and pregnancy effects on the distribution of oestrogen and progesterone receptors in bovine endometrium, PLACENTA, 22(8-9), 2001, pp. 742-748
Reproductive cyclicity and Pregnancy require cell and tissue specific expre
ssion of oestrogen (OR) and progesterone receptors (PR). To determine the e
ffects of cycle day and early Pregnancy (days 16-30) on the distribution of
OR and PR, uteri were collected from cycling (n = 39), pregnant (n = 14),
and steroid-treated ovariectomized cattle (n = 10). Immunohistochemistry wa
s used to localize OR and PR, and staining intensity was scored. Moderate s
taining for the PR was detected in the stroma at proestrus (days 17-20). Ex
pression increased through oestrous, reaching maximal levels by metestrus (
days 1-6) (P <0.05). During diestrus (days 7-16), PR expression was downreg
ulated (P <0.05). Progesterone receptor expression was detected in the lumi
nal epithelium in one of three animals each at days 3 and 6 of the oestrous
cycle. In pregnant animals only, caruncular stroma showed reduced PR stain
ing compared to intercaruncular stroma (P <0.05). Reactivity to the OR anti
body in cycling animals was detected in the stroma and glandular epithelium
. Levels increased through proestrus and oestrous, were maximal during mete
strus (P <0.05), and decreased during diestrus (P <0.05). Interestingly, th
ere was transient upregulation in the luminal epithelium on day 16 or day 1
4 (P <0.05). This was not evident at day 16 of pregnancy, although some OR
reactivity was present in stroma. and glands. BN day 18 of pregnancy OR A e
re undetectable (P <0.05). Oestrogen-treated ovariectomized animals had inc
reased OR and PR expression in comparison to progesterone treated cows (P <
0.05). Untreated ovariectomized cows showed constitutive steroid receptor e
xpression. These results support the widely accepted role for sex steroids
in the regulation of their receptors and indicate that there is paracrine r
egulation of steroid receptor expression in the bovine uterus. (C) 2001 Har
court Publishers Ltd.