Risk of postprandial insulin resistance: The liver/vagus rapport

Abstract

Ingestion of a meal is the greatest challenge faced by glucose homeostasis. The surge of nutrients has to be disposed quickly, as high concentrations in the bloodstream may have pathophysiological effects, and also properly, as misplaced reserves may induce problems in affected tissues. Thus, loss of the ability to adequately dispose of ingested nutrients can be expected to lead to glucose intolerance, and favor the development of pathologies. Achieving interplay of several organs is of upmost importance to maintain effectively postprandial glucose clearance, with the liver being responsible of orchestrating global glycemic control. This dogmatic role of the liver in postprandial insulin sensitivity is tightly associated with the vagus nerve. Herein, we uncover the behaviour of metabolic pathways determined by hepatic parasympathetic function status, in physiology and in pathophysiology. Likewise, the inquiry expands to address the impact of a modern lifestyle, especially one’s feeding habits, on the hepatic parasympathetic nerve control of glucose metabolism.

Central Insulin Administration Improves Whole-Body Insulin Sensitivity via Hypothalamus and Parasympathetic Outputs in Men

“…We detected an increased high-frequency band, that is, parasympathetic activity to be associated with brain-derived peripheral insulin sensitization, indicating that vagal outputs are involved. This interpretation is well in line with animal data, where brain outputs regulating peripheral insulin sensitivity depend on the vagus nerve, the major parasympathetic nerve (2,3).…”

“…Sixteen axial slices with slice thickness of 5 mm were acquired. Each measurement consisted of 79 alternating tag and control images with the following imaging parameters: TI 1 = 700 ms, TI 2 = 1,800 ms, resonance time = 3,000 ms, echo time = 19 ms, inplane resolution = 3 3 3 mm 2 , field of view = 192 mm, and flip angle = 90°. The same sequence was used to estimate equilibrium magnetization of the blood (M0) for absolute CBF quantification.…”

“…Experiments in animals suggest that the brain can rapidly influence insulin sensitivity of the body through the autonomic nervous system (1-5). Particularly, the action of insulin in the brain modulates insulin sensitivity in other organs such as liver (2,3,6,7), muscle (8), and adipose (1,9,10) tissue. However, at least for the liver, the relevance of this mechanism is still under debate (11,12).…”

Vagotomy diminishes obesity in cafeteria rats by decreasing cholinergic potentiation of insulin release

“…The ANS regulates several aspects of energy homeostasis through both parasympathetic and sympathetic branches [21]. The parasympathetic nervous system (PNS) transmits peripheral signals to the central nervous system (CNS), regulating food intake, through the afferent fibers in the vagus nerves [25].…”

“…The parasympathetic nervous system (PNS) transmits peripheral signals to the central nervous system (CNS), regulating food intake, through the afferent fibers in the vagus nerves [25]. Efferent vagal fibers, which comprise less than 20 % of the vagus nerve fibers, indirectly control energy homeostasis by regulating gastric emptying and accommodation, hepatic glucose and lipid metabolism, and insulin secretion [15,18,21,22].…”