Reprod. Nutr. Dev. 42 (2002) 399-413
DOI: 10.1051/rnd:2002034

Mammary leptin synthesis, milk leptin and their putative physiological roles

Muriel Bonnet^a, Carole Delavaud^a, Karine Laud^b, Isabelle Gourdou^b, Christine Leroux^a, Jean Djiane^b and Yves Chilliard<sup>a

a</sup>  Unité de Recherche sur les Herbivores, Équipe Tissu Adipeux et Lipides du Lait, INRA, 63122 Saint-Genès-Champanelle, France
^b  Unité de Biologie Cellulaire et Moléculaire, INRA, 78352 Jouy-en-Josas Cedex, France

Abstract
This paper reviews data on mammary leptin and leptin receptor gene expression as well as on blood and milk leptin levels during the pregnancy-lactation cycle in humans, rodents and ruminants, with the aim of better understanding milk leptin origin and functions. The few published papers report that leptin may be produced by different cell types in the mammary tissue, and may act as a paracrine factor on mammary epithelial cell proliferation, differentiation and/or apoptosis via adipose-epithelial and/or myoepithelial-epithelial cellular interactions. In addition to leptin synthesis, epithelial cells may transfer leptin from the blood, and these two mechanisms may account for the presence of leptin in the milk. The respective parts of these two processes remain to be determined, as well as the true milk leptin levels. Indeed, reported concentrations for milk leptin vary strongly according to species and mainly according to the milk fractions and the assay methods used. If leptin levels in milk (and specially colostrum) are found to be significant, this hormone could be involved in neonate physiology.

Key words: leptin / mammary tissue / milk

Correspondence and reprints: Yves Chilliard
    e-mail: chilliar@clermont.inra.fr

© INRA, EDP Sciences 2002