AJP - Endocrinology and Metabolism, Vol 265, Issue 6 E866-E873, Copyright © 1993 by American Physiological Society
Mammalian bombesin as a hormone in ovine pregnancy: ontogeny, origin, and molecular forms
A. Giraud, L. Parker, D. Taupin, K. Hardy and A. Shulkes
Department of Medicine, Western Hospital, Footscray, Victoria, Australia.
Mammalian gastrin-releasing peptides (GRP) are present in female
reproductive tissues and stimulate uterine contraction and DNA synthesis in
the endometrium. We set out to establish whether the GRP were likely to
play a role in fetal development by measuring the fetal and maternal plasma
concentrations in chronically cannulated fetal sheep from 115 days
gestation to term (145 days) and for 18 days after parturition. Placental
fluids and fetal urine were also obtained. In a separate series of animals,
uterine, placental, and fetal gut and lung tissues were collected. Samples
were extracted in acid and assayed by radioimmunoassay, and molecular forms
were characterized by high-performance liquid chromatography. GRP were
present in the decidua (> 10 pmol/g), as well as placental, uterine,
lung, and gastrointestinal tissues (all < 6 pmol/g). Fetal and maternal
plasma GRP were elevated compared with nonpregnant ewes, falling sharply
after parturition. Placental fluids and urine also contained GRP (80-410
fmol/ml). The main molecular form in all tissues and fluids examined
coeluted with porcine GRP-(18-27). GRP immunoreactivity was primarily
localized to epithelial cells of the decidua. These data suggest that
plasma GRP is probably derived from the decidua and may play a role as a
circulating hormone in ovine fetal and uterine development.
