Potential role of high serum leptin concentration in age-related decrease of fatty acid synthase gene expression in rat white adipose tissue

Ageing in rats is associated with significant reduction of lipogenic enzymes genes expression and the rate of fatty acids synthesis in white adipose tissue. Since resistance to insulin and/or triiodothyronine is not directly related to reduction in lipogenic enzymes activity in white adipose tissue of old rats, we have proposed recently that the age-related increase in leptin gene expression and high serum leptin concentration could, at least partly, account for the down regulation of lipogenic enzymes gene expression. To test this hypothesis, in this paper we experimentally (by single intraperitoneal injection of recombinant leptin) increased plasma leptin concentration in young rats to the level observed in old animals, and we examined its effect on fatty acids synthase (FAS) gene expression in white adipose tissue. The results presented in this paper indicate that leptin administration to young rats, in amount that cause the increase in serum leptin concentration to that found in old rats, significantly decreased the white adipose tissue FAS gene expression. We propose, therefore, that leptin could play a causative role in the down-regulation of lipogenic enzyme gene expression observed with ageing.