Vagus Nerve Stimulation and Gastric Acid Secretion
Stimulation of the vagus nerve increases gastric acid secretion. [1]
Vagal efferent signaling increases acid secretion through cholinergic pathways that act on muscarinic (M3) receptors on parietal cells and through stimulation of gastrin and histamine release. [1] [2]
Mechanisms of Increased Acid Secretion
Vagal stimulation promotes acetylcholine-mediated activation of parietal cells via muscarinic M3 receptors. [1] [2]
Vagal stimulation also increases acid secretion indirectly by stimulating gastrin release from gastric G cells and histamine release from enterochromaffin-like cells, which then further potentiate parietal cell secretion. [1] [3]
Directionality: Stimulation vs Inhibition
Electrical vagal stimulation increases acid secretion in experimental physiology. [4]
Vagotomy reduces maximal gastric acid secretion in vivo in humans. [5]
Clinical Corollaries
Because vagal stimulation increases acid output, acid-suppressive therapies that block downstream signaling (eg, muscarinic antagonism, H2 receptor antagonism, proton pump inhibition) counteract vagally driven acid secretion. [1] [2]
Neuroanatomic Pathways Involved
Vagal efferent pathways regulate acid secretion via enteric and gastric reflex circuits that coordinate neurotransmitter release to parietal cells and enteroendocrine cells. [2] [3]
Evidence Summary
Reviews of gastric acid physiology identify acetylcholine (vagal/intramucosal reflex stimulation), gastrin, and histamine as the major physiological stimulants of parietal cell acid secretion. [1] [3]
Human data show substantial reduction in maximal acid secretion after proximal gastric vagotomy. [5]
Takeaway Answer
Vagus nerve stimulation increases gastric acid secretion. [1] [4]