Gut-central nervous system axis is a target for nutritional therapies

The energy balance is determined by the relationship between the acquisition and expenditure of energy. This perfect interaction occurs among physiological signals in peripheral organs and the central nervous system (CNS). Apart from the obvious digestive and absorptive functions of the gastrointestinal tract, gut and adipose tissue hormones play an important role in controlling the energy balance, particularly via the regulation of food intake in both the short- and long-term, respectively. Therefore, the enteric nervous system (ENS), gut hormones, and nutrients act in the control process at the beginning and termination of meals [1,2].The CNS-gut axis is controlled by the ENS and its importance in the health and disease has been recognised by several studies [3,4]. According to health professionals, advances in the physiological and molecular mechanisms involving the ENS are responsible for the control of the energy balance, and for the nutritional therapies used in patients with obesity, type 2 diabetes mellitus, inflammatory bowel diseases (IBDs), bariatric surgery and cancer-associated anorexia [5-9].In the 1950s, the chemist Linus Pauling established a relationship between decreased longevity and obesity [10]. At this time, with the advent of studies involving the mechanisms that modulate appetite control, it was recognised that the hypothalamus is the "appetite centre". In rats, some researchers observed that lesions in the lateral hypothalamus produced anorexia (hunger centre) and lesions in the ventromedial nuclei of the hypothalamus produced obesity (satiety centre) [11-14].More recently, the discovery of cloned leptin in 1994, which is produced and secreted by adipose tissue, provided some evidence that appetite control could also be modulated by peripheral tissues [15].In relation to the mechanisms of intestinal hormonal action, the beginning of the food intake process results in the release of anorexigenic hormones, such as peptide YY (PYY), the glucago