AGNORS IN ESTROGEN-INDUCED AND LISURIDE-INHIBITED AND THYREOIDIN-INHIBITED RAT ANTERIOR-PITUITARY HYPERPLASIA - COMPUTER IMAGE-ANALYSIS ANDNONAUTOMATED AGNOR TYPING

OBJECTIVE: A model of estrogen (E)-induced mt anterior pituitary hyper plasia blocked partly by thyroid hormones (estradiol plus thyreoidin [ ET]) and nearly completely by lisuride (estradiol plus lisuride [EL]) and thyreoidin plus lisuride combination (estradiol plus thyreoidin pl us lisuride [ETL]) was used to test a computer image analysis program, LUCIA, for argyrophilic nucleolar organizer region (AgNOR) evaluation . STUDY DESIGN: Nuclear and AgNOR area were measured in more than 700 cells in each experimental group. The nucleoli were also typed without the automated procedure. RESULTS: Mean nuclear area teas significantl y higher in E and lower in T. In all groups with blocked hyperplasia ( ET, EL, ETL) the mean nuclear area was lower than in T. Mean AgNOR are a was significantly higher in E but also, to a lesser extent, in T. Th e ET combination produced a partly diminished mean AgNOX area as compa red to E; a severe reduction was observed in the EL and ETL groups. In nucleolar typing, thyreoidin, lisuride and their combination inhibite d the increase in large nucleoli with finely dispersed AgNORs induced by estradiol. CONCLUSION: The LUCIA image analysis program for AgNOR e valuation proved able to monitor the slight changes in AgNORs in thyro id hormones- and lisuride-inhibited, estradiol-induced rat anterior pi tutary hyperplasia.