The role of ghrelin and serotonin in the control of eating behavior in patients with obesity and diabetes mellitus type 2

In recent years, the incidence of obesity and type 2 diabetes mellitus (DM) has been increasing steadily; therefore, the search for hormonal and metabolic substances the correction of which can normalize human eating behavior is required. The main system for controlling hunger and appetite — the melanocortin pathway — is located in the hypothalamus. Activation of this signa­ling system by melanocortins leads to appetite decrease and causes a feeling of satiety. Neuropeptide Y and agouti-related protein act antagonistically and enhance hunger. There are different types of eating disorders, such as binge eating and night ­eating syndrome, which are most common among obese patients and those with type 2 DM. They are characterized by excessive intake of food and, consequently, complication of the course of underlying disease due to its negative impact on carbohydrate and lipid metabolism. There are various hormonal and metabolic substances that are responsible for suppressing and stimulating the center of hunger in the hypothalamus. This article examines the effect of ghrelin and serotonin on the mechanism of eating habits formation and the control of eating behavior in patients with obesity and type 2 DM. This article highlights the role of ghrelin and serotonin in eating behavior. Ghrelin is an orexigenic hormone and is capable of activating the center of hunger. The concentration of this hormone in patients with obesity and/or type 2 DM is reduced compared to healthy individuals that indicates the adaptation of the body to positive energy balance and excess calorie intake by humans. In turn, serotonin, whose receptors are also present in the hypothalamus, upon bin­ding to 5-HT2C receptor causes inhibition of neuropeptide Y secretion that leads to feeling of satiety and normalization of appetite and weight, thus exhibiting anorexigenic properties. Lorcaserin is currently the only serotonin receptor agonist approved by the Food and Drug Administration for the treatment of obesity. That is why studies of hormonal and metabolic substances that are involved in the signaling pathways of the hypothalamus hunger center will help find effective ways to treat obesity and type 2 DM.