Regulation of appetite: role of leptin in signalling systems for drive andsatiety

BACKGROUND: The healthy regulation of appetite involves a balance between e xcitatory (drive) and inhibitory (satiety) processes. For many years resear ch has concentrated on the identification of signalling systems that mediat e satiety to the relative exclusion of drive-inducing biological events. Ho wever, the so-called long-term regulation of body weight has recently been given substance by the identification of a chemical signal believed to link the brain with adipose tissue stores. ANALYSIS: This signal, leptin, is in position to modulate the expression of a drive to eat. Studies on the relationship between leptin and perceived h unger, and on the eating behaviour of leptin-deficient individuals, are con sistent with the intervention of leptin in a drive system. The contrast bet ween the roles of leptin and serotonin in appetite regulation reflects the difference between drive-signalling and satiety signalling processes. CONCLUSION: It is proposed that leptin modulates the drive signals arising from the metabolic demand for energy but also shows some properties of a po st-prandial satiety signal.