11-Ketotetranor PGF metabolites, a suitable indicator for measuring prostaglandin release during the normal oestrous cycle and early pregnancy in the goat

Abstract

Peripheral plasma levels of 15-ketodihydro-PGF 2α, 11-ketotetranor PGF metabolites and progesterone were measured during normal oestrous cycle and early pregnancy in six goats. The does were synchronized before the start of the study by means of 10 mg of PGF 2α. Blood samples were collected twice daily until day 12 of the oestrous cycle and subsequently every 3 h until the onset of oestrus, at which time the does were mated. The blood sampling protocol was repeated until day 28 of pregnancy. High pulsatile peaks of 15-ketodihydro-PGF 2α and 11-ketotetranor PGF metabolites were observed during the last days of the oestrous cycle, indicating PGF 2α releases. This coincided with a fall in progesterone levels. During early pregnancy no such peaks of prostaglandin metabolites were recorded and high levels of progesterone were maintained. In the goat, analysis of the 11-ketotetranor PGF metabolites seems to be a better indicator of PGF 2α release than the analysis of 15-ketodihydro-PGF 2α. The former metabolites are more long-lived in the circulation and are thus easier to detect.