HORMONAL STIMULATION OF PROTEASE INHIBITOR ACTIVITY IN ENDOMETRIAL SECRETION DURING EARLY PREGNANCY

Abstract

The influence of oestrogen and gestagen on the protease inhibitor activity in endometrial secretion during early pregnancy in the rabbit was studied by means of fibrin agar electrophoresis and trypsin diffusion. Secretion specimens were obtained by flushing uterine cornua from 24 animals, sacrificed on day 6 post coitum (p. c.). Administration of 17β-oestradiol, progesterone, and both hormones combined enhanced the protease inhibitor activity of endometrial secretion. Uterine specific protease inhibitors have been called uterus-antitrypsins (U-AT₁ and U-AT₂). Hormonal stimulation of these inhibitors is discussed in relation to their possible involvement in general sterility, retardation of blastocyst development, and failure of the normal implantation mechanisms.