Prolactin receptors in rat liver: possible induction by prolactin.

A prolactin receptor, present in adult female rat liver, can be induced in males by estrogen. Hypophysectomy diminished receptor levels in the female and rendered males unresponsive to estrogen. A renal pituitary implant blunted the decrease in hypophysectomized females and induced the receptor in hyophysectomized males. The increased receptor level in hypophysectomized males with a renal pituitary implant was preceded by a sustained elevation of circulating prolactin. Our observations suggest that prolactin induces its own receptor.