Abstract
Regulation of food intake and nutritional status is a complex process which takes place in several organ systems. Hypothalamus is the central regulator that integrates signals from the nervous system and peripheral hormones and monitors serum levels of glucose and lipids.
In the hypothalamus, there are neurons producing both orexigenic hormones that increase food intake (neuropeptide Y, agouti-related protein, orexins), and anorexigenic hormones, that act in antagonistic way (proopiomelanocortin, cocaine- and amphetamine-regulated transcript). Gastrointestinal tract is mainly the source of anorexigenic regulatory hormones (cholecystokinin, oxyntomodulin, bombesin), that influence hypothalamic centres by both circulation and vagal nerves.
The only orexigenic peptide produced by gastrointestinal tract is ghrelin. Pancreatic hormones (insulin, pancreatic polypeptide, amylin), that influence glucose metabolism, regulate also food intake and nutritional status of the organism both by direct action on CNS and indirectly through changes of glycaemia.
Adipose tissue is not considered a passive place of energy stores anymore. Adipocytes produce quite a number of hormonally active substances that participate in the regulation of body weight (leptin), and insulin sensitivity (adiponectin, resistin).
Serum levels of above-mentioned regulatory hormones are dynamically influenced both by food intake, and general nutritional status of the organism. Peripheral or central administration leads to changes in food intake and for some of them synthetic analogues are being developed with potential future use in treatment of nutritional disorders.
Thus, these hormones are suitable for studies in the field of clinical biochemistry as potential biomarkers.