EFFECT OF ESTRADIOL BENZOATE, TAMOXIFEN AND MONOHYDROXYTAMOXIFEN ON IMMATURE RAT UTERINE PROGESTERONE RECEPTOR SYNTHESIS AND ENDOMETRIAL CELL-DIVISION

The non-steroidal antioestrogens tamoxifen and monohydroxytamoxifen are partial agonists in the immature rat uterine wet weight test. Tamoxifen and monohydroxytamoxifen can both stimulate progesterone receptor synthesis in the immature rat uterus but neither tamoxifen nor monohydroxytamoxifen can stimulate a consistent increase in rat uterine DNA content or endometrial cell division. It is suggested that antioestrogens produce a subtle change in the oestrogen receptor which can provoke progesterone receptor synthesis but cannot initiate endometrial cell division. © 1979.