G. Fredriksson

Endotoxin-induced prostaglandin release and corpus luteum function in goats☆

Abstract Endotoxin (lipopolysaccharide) from Salmonella typhimurium was administered to non-pregnant and pregnant goats to investigate its capacity to induce synthesis and release of prostaglandin with subsequent alteration of reproductive functions. Prostaglandin release was determined by measurement of 15-keto-13,14-dihydro-PGF 2α and the corpus luteum function was monitored by measurement of progesterone. Endotoxin administered into the lumen of the uterus did not alter the hormonal patterns. However, when 1.8 μg/kg of the endotoxin was given i.v., a rapid increase of 15-keto-13,14-dihydro-PGF 2α and a subsequent decline in progesterone levels were seen. Both non-pregnant and hysterectomized animals shortened their lengths of oestrous cycles. In two out of three pregnant animals the i.v. administration of the endotoxin (0.1 μg/kg) resulted in abortions. When comparing the prostaglandin metabolite response of intact vs. hysterectomized animals, the response was somewhat less in the latter group. When endotoxin was administered in smaller amounts (0.5 μg/kg) to non-pregnant goats it created an immediate increase in prostaglandin metabolite levels, but the subsequent decline in progesterone levels was less pronounced and the length of the oestrous cycle was not altered. From the present study it is obvious that i.v. administered endotoxin can influence the life-span of the corpus luteum, which is probably mediated by induction of synthesis and release of PGF 2α .

Utero-ovarian relationships during the bovine postpartum period

Abstract During the postpartum period in the cow a massive PGF 2α release occurs. This release is negatively correlated to uterine involution in normal cows and positively correlated in cows with uterine infections. The PG release seems to inhibit ovulation/corpus luteum formation. By treatment with PGF 2α the uterine involution can be promoted. No effect, or a slight positive effect, is seen after treatment with prostaglandin synthesis inhibitors on the speed of uterine involution. Resumption of ovarian activity is positively correlated to uterine involution. Prostaglandin F 2α can also stimulate onset of ovarian cyclicity.

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-PGF2α, 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 PGF2α. 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-PGF2α and 11-ketotetranor PGF metabolites were observed during the last days of the oestrous cycle, indicating PGF2α 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 PGF2α release than the analysis of 15-ketodihydro-PGF2α. The former metabolites are more long-lived in the circulation and are thus easier to detect.