IMMUNOHISTOCHEMICAL ANALYSIS OF ESTROGEN-RECEPTORS IN CYSTIC-ENDOMETRITIS-PYOMETRA COMPLEX IN THE BITCH

Monoclonal antibodies to human estrogen receptor were used with an ind irect immunohistochemical technique to localize in formalin-fixed, par affin-embedded sections of the genital tract of the bitch. The presenc e of estrogen receptors in the uterus of dogs with cystic hyperplasia endometritis complex (CHE) was compared with normal uteri from dogs at the same stage of estrous cycle. Lower estrogen receptor expression w as found in the squamous metaplastic epithelium covering the luminal s urface of the endometrium from dogs with CHE than in the columnar epit helium from normal dogs. In contrast, the basal glands from uteri of C HE group dogs contained more estrogen receptor than glands from normal dogs at the same stage of estrous cycle. This was most pronounced and statistically significant in the late secretary stage of the estrous cycle. When the glands presented cystic degeneration, the estrogen rec eptor labeling was less pronounced. The highest estrogen receptor scor e was present in normal glands from dogs treated with progestins. In t his group even cystic degenerated glands contained high estrogen recep tor concentrations compared with those of the other groups. From this study it was concluded that the down regulation of estrogen receptor e xpression in the endometrial glands under the influence of rising prog esterone concentrations is defective in dogs with CHE. Therefore it is suggested that the regulation of estrogen receptor expression in endo metrial glands may play an important role in the pathogenesis of CHE i n the bitch. (C) 1997 by Elsevier Science Inc.