LOCATIONS AND MOLECULAR-FORMS OF GASTRIN-RELEASING PEPTIDE-LIKE IMMUNOREACTIVE ENTITIES IN OVINE PREGNANCY

Large quantities of gastrin-releasing peptide-like immunoreactivity (G RP-LI) are present in ovine pregnancy fluids (allantoic fluid > fetal plasma > esophageal fluid = amniotic fluid = urine > maternal plasma) and in term endometrium (60 +/- 29 pmol . g(-1)) and myometrium (4.5 /- 1.2 pmol . g(-1)). The larger molecular size [greater than GRP(1-27 )] of this GRP-LI entity is not due to a GRP binding protein nor to a C-terminal extension of GRP. In contrast, ovine fetal colon extracts a ppear to contain the usual GRP(1-27) and GRP(18-27) forms. Hence, the uterus, not the fetus, is the probable source of this novel GRP-like p eptide. It apparently acts as a hormone in ovine pregnancy and may pla y an important role in fetal-placental development.