EXPRESSION OF PROGESTERONE-RECEPTOR MESSENGER-RNA IN THE ENDOMETRIUM DURING THE NORMAL MENSTRUAL-CYCLE AND IN NORPLANT(R) USERS

The expression of endometrial progesterone receptor mRNA during the hu man menstrual cycle and in Norplant users was studied using digoxigeni n-labelled ribonucleic probes for in-situ hybridization on 6 mu m para ffin embedded endometrial sections. The staining intensity was scored blind semi-quantitatively. Blood ovarian steroid concentrations were m easured in Norplant users. All data were analysed by analysis of varia nce. Glandular progesterone receptor mRNA concentrations were low duri ng the menstrual-to-early proliferative stage but increased during the early-to-mid to late-proliferative stage then declined nonsignificant ly over the secretory stage. No such variation was observed in stromal cells. Progesterone receptor mRNA concentrations were lower in Norpla nt than controls during early-to-mid to late-proliferative stages (in glandular epithelium and stroma) and during secretory stage (in stroma only). Norplant subjects with amenorrhoea had higher concentrations o f stromal progesterone receptor mRNA but lower plasma oestrogen concen trations than subjects with breakthrough bleeding. The pattern of vari ation in progesterone receptor mRNA concentrations during the normal m enstrual cycle resembles the published pattern for the receptor protei n. The results demonstrate: (i) a differential sensitivity of glandula r and stromal progesterone receptors to steroid regulation; (ii) in co ntrast to previous findings of an increase in immunoreactive progester one receptor protein in Norplant endometrium, progesterone receptor mR NA concentrations in these tissues were reduced; and (iii) there was s ignificantly more progesterone receptor mRNA in subjects with amenorrh oea than in those with breakthrough bleeding.