Characterization of cystic endometrial hyperplasia (CEH) in swine leukocyte antigen (SLA) miniature swine: Serum hormone and endometrial estrogen receptor concentrations

Abstract

Swine leukocyte antigen (SLA) female miniature swine often exhibit a pathological condition classified as cystic endometrial hyperplasia (CEH). Based on direct examination of the uteri by mid-ventral laparotomy five and four pigs were assigned to CEH and non-CEH groups, respectively. The serum concentrations of estrone (E 1), estradiol (E 2), progesterone (P), testosterone (T) and luteinizing hormone (LH) were determined during a synchronized estrous cycle for both groups of animals. There were no significant differences ( P > 0.05) in the serum concentrations of E 1, E 2 and T during the estrous cycles of CEH and non-CEH groups. Peak (mean ± s.e.m.) level of LH of the CEH group was found to be significantly lower ( P < 0.05) than that of the non-CEH group (4.7 ±0.9 and 7.9 ±1.5 μg/l, respectively). Mean serum P concentration (32.1 ±6.4 nmol/l) in CEH pigs was, however, significantly lower ( P < 0.01) than that of non-CEH pigs (67.1 ± 8.9 nmol/l). Additionally, luteolysis occurred 2 days earlier in CEH pigs, compared to normal animals. The concentrations of cytosolic estrogen receptors in the endometria of CEH and non-CEH animals were not significantly different ( P > 0.05) during the luteal phase. The concentration of unoccupied nuclear estrogen receptors in the endometrium of CEH pigs was, however, significantly lower ( P < 0.05) than that of non-CEH animals (32.5 ±4.5 vs. 105.8 ±11.8 fmol/mg protein, respectively). The dissociation constants of cytosolic and nuclear estrogen receptors in the endometria of CEH and non-CEH groups were similar. These studies indicate that CEH in SLA miniature swine was associated with lower serum progesterone concentration and reduced concentration of unoccupied endometrial nuclear estrogen receptors.