Prolactin receptors in Rana catesbeiana during development and metamorphosis

Specific binding of ovine prolactin was found in microsomal preparations of tail, gill, and kidney of the bullfrog Ran catesbeiana. Binding by larval and adult liver and by kidney before larval stage XVII was low or nondetectable. Renal binding increased during metamorphic climax and in response to treatment with thyroid hormone. The emergence of renal binding of prolactin may signify a shift in the hormone's participation in the control of hydromineral homeostasis from the gill, which is resorbed, to the kidney. A renal action of prolactin during climax may facilitate metamorphosis.