ORECTIC AND ANORECTIC PEPTIDES AND THEIR IMPLICATION IN OBESITY AND THE METABOLIC SYNDROME
Background and aims: Cardiovascular diseases, diabetes mellitus, the metabolic syndrome and obesity are now globally widespread clinical conditions, addressing different ages, lately extending to young and children. The causes are multiple, involving an interaction between individual genetic risk factors and environmental factors. Many studies showed the importance of the hypothalamic neuropeptides and other neuropeptides in the regulation of the balance between food intake and energy consumption. We reviewed 25 recent research studies describing the physiological and physiopathological mechanisms of the orectic and anorectic peptides and their interaction to adjust the balance between food intake and energy expenditure. Conclusions: The hypothalamus, through its nuclei (arcuate and paraventricular) controls the balance between food intake and energy expenditure. The proopiomelanocortin (POMC) / Cocaine and amphetamine-related transcript (CART) neurons represent the anorectic centre. The neurons that release neuropeptide Y (NPY) and agouti-related protein (AgRP) by stimulation form the orectic centre. The neuropeptide Y (NPY) is the main hypothalamic orectic neuropeptide. Its action, besides stimulating the orectic effect, is to modulate the release of other hypothalamic orectic and anorectic neuropeptides. In addition, the energy balance is regulated by adipokines released by the adipose cells, hormones and neurotransmitters, blood glucose level and other metabolites.