Effect of Salmonella typhimurium endotoxin on PGF-2 alpha release and fetal death in the mare.

The research investigates how infusing the endotoxin from Salmonella typhimurium affects the release of PGF-2 alpha, a type of prostaglandin, in pregnant mares and its potential to cause fetal death.

Release Pattern of PGF-2 alpha

• Upon infusion of Salmonella typhimurium endotoxin into pregnant mares, a two-phase release pattern of PGF-2 alpha was observed.
• The first phase lasted for about an hour, followed by an intensified release two hours after the infusion, as measured by concentrations of 15-keto-13,14-dihydro-PGF-2 alpha.
• Six hours after the infusion, these concentrations returned to their base levels.

Fetal Death Post Infusion

• The study involved mares at different days of gestation. In 7 mares that were at 23, 26, 29, 33, 36, 53 and 55 days of gestation, fetal death was noted between 36 and 120 hours post-infusion.
• However, in the case of 12 mares at 46, 51, 56, 59, 65, 71, 73, 85, 103, 138, 283 and 318 days of gestation, the endotoxin infusion did not lead to an abortion.

Luteal Activity and Progesterone Levels

• In all mares, luteal activity – which refers to the functioning of the corpus luteum, an endocrine structure involved in pregnancy – was adversely impacted within 9 hours of the endotoxin infusion.
• Progesterone, a hormone crucial for maintaining pregnancy, had consistently lower concentrations in the mares that had abortions post-infusion (1-2 ng/ml) when compared to those that did not abort.

Susceptibility to Fetal Loss

• According to the study, mares might be susceptible to a risk of fetal loss due to a clinical syndrome activated by Salmonella typhimurium endotoxin until approximately 50-60 days of gestation.