Endocrine changes, with emphasis on 13, 14–dihydro–15–keto–prostaglandin F2α and corticosteroids, before and during parturition in dromedary camels (Camelus dromedarius)

Abstract

SUMMARYA study was conducted on eight preparturient camels which were kept in individual stalls adjacent to the Cairo abattoir during 1989. Four novel phenomena are described in this paper: (i) a significant (P < O·05) prepartum decrease in plasma concentrations of progesterone evident over the 48 h preceding parturition; (ii) a remarkably consistent increase in total plasma unconjugated oestrogens, commencing 2–4 days prior to parturition and peaking in excess of 200 pg/ml for c. 2 h before delivery; (iii) a tenfold increase to 5·4±0·19 ng/ml (mean±S.E.) in plasma concentrations of 13, 14-dihydro-15-keto-prostaglandin F2α (PGFM) between days –10 and – 1, showing a sudden and large increase during the 5 h prior to delivery; and (iv) three peaks of total plasma corticosteroids during the 4 h preceding delivery, with the third peak showing the greatest magnitude (24·0±3·11 ng/ml). These results suggest that the dromedary camel is an example of a species in which luteal secretion of progesterone, especially 3α-dihydroprogesterone, is required throughout pregnancy and in which cessation of luteal function, associated with a rapid increase in the oestrogen: progesterone ratio and the secretion of prostaglandin F2α (PGF2α), is a requirement for parturition.