Changes in prostaglandin F2α receptor bindings in the hen oviduct uterus before and after oviposition

The specific binding component for prostaglandin F(2α) (PGF(2α)) that exists in the plasma membrane fraction of the oviduct uterus myometrium of laying hens was shown to possess receptor properties for PGF(2α), such as binding specificity to PGF(2α), binding saturation, high affinity, and limited capacity. The value of the equilibrium dissociation constant (K(d)) for the receptor was not different between laying hens and nonlaying hens, but the value of the maximum binding capacity (B(max)) was smaller in laying hens than in nonlaying hens. During an oviposition cycle, the K(d) value did not show a significant change, but the B(max) value decreased at 3 and 0.5 h before oviposition and 2 h after oviposition. Neither the K(d) nor B(max) value changed in nonlaying hens during a 24-h period. An intravenous injection of PGF(2α) (5 μg/hen) decreased the B(max) value, but not the K(d) value, of the PGF(2α) receptor. It is thought from the results that PGF(2α) may act directly on the oviduct uterus myometrium at a fixed time before and after oviposition in laying hens.