Arginine vasotocin level in plasma and prostaglandin concentrations in the uterine tissue before and after premature oviposition induced by orthophosphate solution in the hen.

Abstract

We measured arginine vasotocin (AVT) level in plasma and concentrations of prostaglandins (PGs) in the uterine (shell gland) tissue before and after premature oviposition induced by intrauterine injection of orthophosphate solution in the laying hens. The administration of phosphate solution 15-17 h before the expected time of oviposition led to premature oviposition which was coincided with a significant (P<0.01) increase in plasma AVT. A signifiant (P<0.01) increase of PGE2 concentration in the uterine tissue was also observed immediately after oviposition, decreasing to basal level 30min after oviposition. The changing pattern of PGF2α concentration in the uterine tissue was almost similar to that of PGE2, though no significant difference was found between before and immediately after oviposition. Pretreatment of the hen with indomethacin blocked premature oviposition, and a noticeable change in plasma AVT level was not observed after phosphate injection into indomethacin-treated hens. The results obtained in this study suggest that the increase in plasma AVT level may result from increment in uterine contractility caused by PGs produced in the uterine tissue during oviposition.