Control of rat mammary-gland pyruvate dehydrogenase by insulin and prolactin

Abstract

Withdrawal of prolactin or of insulin from the circulation of lactating rats leads, within 3 h, to increased inactivation by phosphorylation of mammary-gland pyruvate dehydrogenase. Prolactin may act by priming the tissue to respond directly to normal concentrations of circulating insulin and by this means be responsible for the increased activation of the enzyme during the course of normal lactation.