Effects of Progesterone, Estradiol and Testosterone on Cytoplasmic Progesterone Receptor Concentrations in the Hen Hypothalamus and Pituitary

The cytoplasmic progesterone receptor concentrations in the hypothalamus and pituitary were measured in immature pullets and in nonlaying hens at various hours after a single injection of progesterone, estradiol or testosterone. The hypothalamic and pituitary concentrations, expressed as the amount of specific [3H]-progesterone binding/mg cytosol protein, showed a decrease 1 h after the injection of progesterone. When estradiol was injected, the hypothalamic concentration showed an increase 8 h (immature pullets) or 4 and 8 h (nonlaying hens) after the injection and the pituitary concentration also showed an increase at 1 h. The injection of testosterone did not cause any appreciable change in the hypothalamic concentration up to 12 h, but caused an increase in the pituitary concentration at 4 h. The results suggest that the cytoplasmic progesterone receptor concentrations in the hen hypothalamus and pituitary are controlled by the sex steroid hormones.