Plasma leptin levels in rat mother and offspring during pregnancy and lactation

The profiles of plasma leptin levels in pregnant and lactating rats and the ir offspring were determined. The plasma leptin levels increased on days 12 and 20 of gestation and declined on day 21 of gestation, remaining at this level during lactation. These changes were similar for lumbar adipose tiss ue weight, and a significant correlation was found when both variables were plotted with individual values. During the last 2 days of intrauterine lif e, the plasma leptin levels in the fetuses were in the same range as in the ir mothers, declining from day 20 to day 21. On the 1st day of life, the le ptin levels increased to decline in suckling newborns after 4 days, remaini ng stable until day 20 of rife. The enhancement in maternal white adipose t issue mass that takes place during pregnancy and its decline around parturi tion and lactation are proposed to contribute actively to the changes in th e plasma leptin profile detected at these stages. Besides the contribution of placental leptin for the fetus and milk leptin for the suckling newborn, it is proposed that brown adipose tissue, which is the first form of adipo se tissue that appears during development in the rat, is responsible for mo st of the changes in plasma leptin levels seen around birth, whereas its la ter decline could be mediated by the hormonal changes occurring after birth . Copyright (C) 2000 S. Karger AG, Basel.