Oxytocin release and its relationship to dihydro-15-keto PGF2alpha and arginine vasopressin release during parturition and to suckling in postpartum mares.

The study investigates the patterns of oxytocin release in mares during childbirth and early lactation, and its relationship with the release of prostaglandin and arginine vasopressin hormones. It finds that an increase in oxytocin follows an increase in prostaglandin before the delivery of the foal, and that there is no significant relationship between suckling and oxytocin release in mares.

Objective and Testing Methodology

• The aim of this research was to understand how the hormone oxytocin behaves during horse parturition (the process of giving birth) and early lactation. It also aimed to discern the relationship between the release of oxytocin, prostaglandin (involved in inducing labor) and arginine vasopressin (a hormone that can crucially affect blood pressure) during the birthing process.
• The blood was collected from the pituitary body of five mares before and during childbirth, and from nine mares immediately after childbirth to examine oxytocin patterns.
• In four mares, sample collection began 6 hours before the rupture of the chorioallantois (a membrane surrounding the fetus).
• Cross-correlation analysis was applied on the log-transformed oxytocin and PGF(2alpha) concentrations to establish their relationship.
• The effect of suckling on oxytocin release was also evaluated.

Major Findings

• The research established a significant increase in the concentration of PGF(2alpha) before a significant rise in oxytocin levels.
• The study also identified a significant correlation between prostaglandin and oxytocin levels, where an increase in prostaglandin was followed 6 minutes later by an increase in oxytocin within 2 hours before the foal’s delivery.
• The results also showed that suckling doesn’t have any significant impact on the release of oxytocin in mares.
• The research concludes two major points: firstly, oxytocin secretion from the maternal posterior pituitary gland starts before or in association with the second stage of labor, starting after an increase in prostaglandin in the circulatory system. Secondly, suckling doesn’t significantly contribute to oxytocin release in mares.