Leptin mRNA Expression in the Mammary Gland of Holstein Dairy Cows

Leptin is secreted mainly from adipocytes, regulates energy metabolism and influences obesity and many other mechanisms. Milk contains higher concentrations of leptin than blood and mammary epithelial cells produce leptin. The present study examines leptin gene expression in the mammary glands of lactating and non-lactating cows using RT-PCR. The amplified PCR products were sequenced. Researchers found that unlike the mouse, the leptin mRNA is not expressed at all in the non-lactating mammary gland and is sometimes not expressed in the lactating mammary gland of cows. Sequencing analysis confirmed two leptin precursors like those of human and mouse. One precursor consisted of 167 amino acids and the other consisted of 166 amino acids with a deletion at glutamine 49. This study suggests that leptin may be associated with proliferation of mammary epithelial cells to prepare subsequent lactation during pregnancy.