This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by CHALLIS, J. R. G. Articles by POYSER, N. L. Search for Related Content PubMed PubMed Citation Articles by CHALLIS, J. R. G. Articles by POYSER, N. L.

A POSSIBLE RÔLE OF OESTROGENS IN THE STIMULATION OF PROSTAGLANDIN F₂ OUTPUT AT THE TIME OF PARTURITION IN A SHEEP

We have reported elsewhere that the concentration of progesterone in the uterine venous blood of sheep decreases before the onset of parturition, whereas the concentration of total unconjugated oestrogens (predominantly oestrone) increases sharply within 48 hr before delivery (Challis, 1971a, b; Bedford, Challis, Harrison & Heap, 1972). In one of these ewes, concentrations of prostaglandin F₂ (PGF₂) in uterine venous blood have been measured, as well as those of progesterone and oestrogens, to define the temporal relations of these compounds in the same animal immediately before term. Recent work in the sheep has shown that the concentration of PGF₂ in the uterine venous blood and the maternal caruncles increases at parturition which has been induced experimentally by infusion of dexamethasone into the fetus (Liggins & Grieves, 1971; Thorburn, Nicol, Bassett, Shutt & Cox, 1972) and it has been suggested that an elevated fetal cortisol level (Bassett & Thorburn, 1969) may provide a stimulus for PGF₂ synthesis (Liggins, Grieves, Kendal & Knox,