Neuropeptides and Control of Food Intake

In all vertebrates, food intake is a sophisticated complex of neurohumoral networks that convey signals between the brain and periphery, to modulate energy status. Gut hormones , such as peptide YY, pancreatic polypeptide, glucagon-like peptide-1, oxyntomodulin, and ghrelin, are modulated by acute food ingestion. In contrast, adiposity signals such as leptin and insulin are implicated in both short-and long-term energy homeostases. The mechanisms of action of these substances are similar among vertebrates. Their regulation might vary with the feeding and reproductive state, and between different tissues and organs, and it might also be affected by environmental parameters. The control of food intake is carried out by short-term and long-term regulation mechanisms. The short-term signals act primarily as determinants of satiety to limit the size of individual meals. Long-term signals communicate total energy stores, integrate over time, and interact with other systems that rely upon the energy status of the organism (e.g., growth, immune function, and reproduction). Both long-and short-term signals interact to influence the behavior and energy balance of the organism. We know that disrupted signaling in many of these systems leads to dramatic changes in feeding behavior and weight gain (or loss). However, fully understanding control of food intake will require knowledge of: (a) which peptides are involved; (b) areas of the central nervous system where this peptides are expressed and (c) assessment of the biological effects of the different neu-ropeptides in the integrated control of energy and metabolic homeostasis. In this special issue we selected several papers that carry out a systematic and critical review of some of the topics that following recent developments are currently at the forefront of obesity research. This special issue is particularly timely since it becomes available 20 years after the seminal discovery of leptin in Friedman's lab. H. M. Zerón et al. provide a deep and comprehensive review of the different gut hormones involved in energy homeostasis; they give an update on the available evidence regarding the interaction between macronutrients and gas-trointestinal hormone secretion. Furthermore, they review the available data regarding the evidences postulating a yet uncharacterized production of a putative hormone produced in the foregut of diabetic patients that should act decreasing insulin-sensitivity at peripheral tissues. This topic is of particular clinical relevance since it provides a rationale for the so-called metabolic surgery that has been advocated by some as possible therapy in diabetic patients. Most of the data gleaned over …