Feed Back Inhibition of Lactation: An Autocrine Regulator of Milk Secretion

Abstract

Frequency of milking or complete evacuation of udder regulates the rate of milk secretion by a mechanism which is local, chemical and inhibitory in nature. The active whey protein, which we term as FIL (Feedback Inhibitor of Lactation), decreases milk secretion temporarily when introduced into a mammary gland of lactating animals. FIL is synthesized by mammary epithelial cells, and secreted vectorially together with other milk proteins. N-terminal amino acid sequencing indicated that it is a hitherto unknown protein. Local control of mammary secretion during weaning, and after peak lactation in dairy animals, may be due to the actions of this inhibitor, and can be manipulated by frequency of milk removal.