Neuroendocrinology of Adipose Tissue and Gut–Brain Axis

Abstract

Food intake and energy expenditure are closely regulated by several mechanisms which involve peripheral organs and nervous system, in order to maintain energy homeostasis.Short-term and long-term signals express the size and composition of ingested nutrients and the amount of body fat, respectively. Ingested nutrients trigger mechanical forces and gastrointestinal peptide secretion which provide signals to the brain through neuronal and endocrine pathways. Pancreatic hormones also play a role in energy balance exerting a short-acting control regulating the start, end, and composition of a meal. In addition, insulin and leptin derived from adipose tissue are involved in long-acting adiposity signals and regulate body weigh as well as the amount of energy stored as fat over time.This chapter focuses on the gastrointestinal-, pancreatic-, and adipose tissue-derived signals which are integrated in selective orexigenic and anorexigenic brain areas that, in turn, regulate food intake, energy expenditure, and peripheral metabolism.

Adipose Tissue-Derived Biomarkers of Intestinal Barrier Functions for the Characterization of Diarrhoea-Predominant IBS

“…An interplay between visceral adipose tissue, located close to the GI tract, and intestinal permeability has been demonstrated [13]. Adipose tissue is the most extensive endocrine organ, being the source of active molecules able to affect both physiological and pathological processes and a source of neurological mediators involved in the cross-talk between the ENS and central nervous system (CNS) [14].…”

Roles of Adipokines in Digestive Diseases: Markers of Inflammation, Metabolic Alteration and Disease Progression

“…Adipokines preferentially affect islet vasculature [147]. Pancreatic hormones play a role in energy balance, exerting short-acting control, while insulin and leptin derived from adipose tissue are involved in long-acting adiposity signaling and regulate body weight [148]. Leptin receptors are widely expressed in peripheral tissues, including the beta (β) cells of the endocrine pancreas [149], and their activation directly inhibits insulin secretion from these endocrine cells.…”

The Role of Glucagon-Like Peptide-1 in Energy Homeostasis

“…25 This positioning is potentially advantageous in that it allows ready access for peripheral hormones that regulate food intake without having to first penetrate the blood-brain barrier. Similarly, the area postrema, another important brain area involved in energy regulation and juxtaposed to the NTS in the brainstem, 7 also possesses an incomplete blood-brain barrier. 26 Hence, meal-related circulating gut hormones can readily cross from the bloodstream and bind directly to their receptors in this region of the brainstem.…”

“…5 Energy homeostasis is coordinated by the brain and involves the integration of chemical, hormonal, and neuronal signals from peripheral organs such as adipose tissue, pancreas, liver, and the gut, constituting the gut-brain axis. 6,7 Peripheral signals, such as leptin and insulin, reflect the body's level of energy stores and various gut factors convey the types and availability of nutrients signifying the timing, frequency, caloric amount, and macronutrient content of ingested meals. Disruption of the signals constituting this axis is thought to be a common pathophysiological pathway that leads not only to unwanted weight gain and the development of obesity, but is now also recognized to be a key mediator in the development of metabolic disorders such as dyslipidemia, prediabetes, and type 2 diabetes.…”

“…However, outside of their glucoregulatory role, GLP-1 receptor agonists (GLP-1RAs) have also demonstrated effects on appetite and energy metabolism, likely by acting directly on specific areas of the brainstem and hypothalamus. 7 In this review, we explore the role of GLP-1 as a component of the gut-brain axis involved in the regulation of energy homeostasis, and the implications of this role for the development of therapeutic treatment options for obesity.…”