Tissue Oxytocinase Activity in Diestrus Mares

Oxytocin is important in the regulation of key physiologic processes in mares such as: uterine clearance, luteal maintenance, milk ejection, passage of the fetal membranes, and maternal foal bonding, however while it is known that oxytocin has a short half-life, there is a lack of understanding of how oxytocin is metabolized. In most species the metabolism of oxytocin occurs through serum and tissue oxytocinase (OTase) often referred to as insulin regulated aminopeptidase (IRAP) or leucyl-cystinyl aminopeptidase (LNPEP). We hypothesized that OTase in mares would be similar to other species and would be found widely distributed in tissues and serum. The objective of this study was to characterize OTase activity in serum and in various tissues in diestrous mares. [...]