CORRELATION BETWEEN NUCLEAR-BODIES AND ESTROGEN-RECEPTORS IN ENDOMETRIAL EPITHELIAL-CELLS OF OLD RATS

Nuclear bodies (NB) are prominent round structures in interchromatin r egions of interphase nuclei, regarded as markers of stimulated I RNA s ynthesis, Their frequency was found to be estrogen-dependent and corre lated with estrogen receptor (ER) content in endometrial epithelial ce lls of prepubertal and cyclic rats. The present study was designed to simultaneously examine the frequency of simple and complex NE and the status of ER in endometrial epithelia of old mts in relation to age an d vaginal cytology. The vaginal cycles of old Wistar mts (n degrees = 24) at 24, 28, 32, and 36 months of age, which were longitudinally mon itored for at least 180 days by daily vaginal smears, were extremely i rregular with a predominance of either persistent estrus or persistent diestrus over many days, weeks and even months. In all age groups ER- immunoexpression was very high (+++ = > 75%) in persistent-estrus mts and coincided with particularly frequent NE (2-3 simple NE out of 4-5 total NE per nuclear profile) in the tall epithelial cells with ultras tructural signs of intense protein synthesis. In persistent-diestrus r ats isolated simple and complex NE (1 per nuclear profile) and an almo st absent ER expression were distinctive of the nuclei in low, ultrast ructurally ''inactive'' endometrial luminal and glandular epithelial c ells. ThuS, ER immunoexpression and NE frequency are also estrogen-dep endent in old mts. Our findings show, for the first time, that ER immu noexpression in endometrial epithelial cells is down-regulated only in old mrs in persistent diestrus, whereas in persistent-estrus mts inte nse ER expression harmonizes with high NB frequency, irrespective of a nimal age. (C) 1998 by Elsevier Science inc.