Changes of Plasma Cystine Aminopeptidase Activities in Pregnant Horses

Abstract

Plasma Cystine aminopeptidase (CAP) activities were examined in 40 pregnant and 10 nonpregnant Thoroughbred horses by spectrophotometric analysis using S-benzyl-L-Cystine-p dimethylaminoanilide as a substrate. Plasma CAP activities were remarkably low and no difference was observed between pregnant and non-pregnant horses. No changes of plasma CAP activities related with pregnant conditions, such as placental growth, functions and fetal growth, were observed. These results suggested that the plasma CAP activities seemed to be unavailable for the marker of maternal gestational conditions in horses.

Characterization of serum and tissue oxytocinase and tissue oxytocin in the pregnant and non-pregnant mare

“…We compared the serum LNPEP concentrations of early pregnant mares (D0–22) 67.5 (65.4, 74.1) to the pre-partum mare 43.7 (19.7, 63.2), the latter has significantly decreased concentrations of LNPEP ( P = 0.0001). This finding is in agreement with previous study that evaluated monthly blood samples from both non-pregnant and pregnant animals and found similar LNPEP levels 36 . Placental LNPEP is unlikely to contribute to serum LNPEP as LNPEP concentration does not increase as placental mass increased nor did it decrease dramatically post-partum.…”

“…We investigated the association between serum progesterone in LNPEP concentrations. Serum progesterone concentration started to diverge between pregnant mares and non-pregnant from D14–16, which corresponds with luteolysis 36 . A statistically significant difference in progesterone was noted from D18 on, where pregnant mares maintained an elevated progesterone concentration and the non-pregnant groups had undergone luteolysis.…”