Interrelationships of proteins secreted by the ovine conceptus and endometrium during the periattachment period

Abstract

Relationships between secretory proteins from the ovine conceptus and endometrium were investigated by in vitro culture of conceptus and endometrial tissues, either together or separately. This approach permitted investigation of the effect of one tissue upon the secretory protein profile of the other. There was no difference between secretory protein profiles from the ipsilateral and contralateral uterine horns, when the tissues were cultured either alone or with conceptus tissue. Of 12 endometrial proteins studied, the level of one was decreased and four were increased in the presence of conceptus tissue. Concentrations of ovine trophoblast protein one (oTP-1) in culture medium were higher ( P < 0.05) when conceptus and endometrial tissues were cultured together. The presence of endometrial tissue did not quantitatively affect the secretion of seven other conceptus proteins studied. In a second experiment, conceptus or endometrial tissues were cultured in conditioned medium containing radiolabelled endometrial or conceptus proteins, respectively. There was no evidence of uptake of radiolabelled conceptus proteins by endometrium, although levels of oTP-1 in culture medium decreased in the presence of endometrial tissue. An endometrial protein with a molecular weight of approximately 70 000 D (hereafter referred to as the 70k protein) became associated with conceptus tissue in vitro.