Effects of arginine vasotocin and prostaglandin E1 on the hen uterus

In the domestic hen, the uterine portion of the oviduct responded in vitro to arginine vasotocin (AVT) and prostaglandin E1 (PGE1) at all investigated stages of the egg-laying cycle. However, the uterus was less responsive to both hormones during oviposition. The injections of these hormones provoked premature oviposition and a significant pressure increase in the uterus. In vitro and in vivo AVT was a more potent uterine stimulant than PGE1. Indomethacin, an inhibitor of prostaglandin biosynthesis, antagonized in vitro the contractor activity of AVT but not that of PGE1. Prostaglandin-like activity was demonstrated in the hen uterine tissue at the time of oviposition. It is concluded that AVT may cause uterine contractions via a prostaglandin activated mechanism.