Leptin levels and gene expression during the perinatal phase in the rat

The role of leptin in controlling food intake and adiposity has been the aim of many different investigations in the last 3 years. Pregnancy and lactation are two physiological situations associated with a clear hyperphagia (together with important changes in metabolism and adipose mass) to sustain the different and varying demands for foetal growth and milk production respectively. We therefore focused on the role of leptin in perinatal hyperphagia. The circulating leptin levels and leptin gene expression in adipose tissue of both pregnant and lactating rats were examined. Pregnant rats showed unchanged adipose tissue leptin mRNA levels but increased circulating leptin; this probably reflects the high fat carcass content characteristic of pregnancy. Conversely, lactating rats did not show any change either in circulating leptin or adipose tissue mRNA levels. Litter-removal caused a significant increase in both circulating leptin levels and gene expression. The results obtained permit us to suggest that leptin does not seem to have a role in controlling food intake during the perinatal phase.