The nervous system plays an important role in the regulation of epithelial homeostasis and has also been postulated to play a role in tumorigenesis. We provide evidence that proper innervation is critical at all stages of gastric tumorigenesis. In three separate mouse models of gastric cancer, surgical or pharmacological denervation of the stomach (bilateral or unilateral truncal vagotomy, or local injection of botulinum toxin type A) markedly reduced tumor incidence and progression, but only in the denervated portion of the stomach. Vagotomy or botulinum toxin type A treatment also enhanced the therapeutic effects of systemic chemotherapy and prolonged survival. Denervation-induced suppression of tumorigenesis was associated with inhibition of Wnt signaling and suppression of stem cell expansion. In gastric organoid cultures, neurons stimulated growth in a Wnt-mediated fashion through cholinergic signaling. Furthermore, pharmacological inhibition or genetic knockout of the muscarinic acetylcholine M₃ receptor suppressed gastric tumorigenesis. In gastric cancer patients, tumor stage correlated with neural density and activated Wnt signaling, whereas vagotomy reduced the risk of gastric cancer. Together, our findings suggest that vagal innervation contributes to gastric tumorigenesis via M₃ receptor–mediated Wnt signaling in the stem cells, and that denervation might represent a feasible strategy for the control of gastric cancer.

A recent study reported that a special weekly scheduled time-restricted feeding regimen (TRF), i.e., no food consumption for 15h during the light (inactive) phase per day for 5 weekdays, attenuated the outcome of diverse nutritional challenges in response to high-fat diet in mice. In the present study, we wanted to further test whether this TRF could restrict body weight gain in both juvenile and adult animals when fed a high-fat diet. Fifty male Sprague-Dawley rats at ages from 5 to 27weeks were used. First, we found that freely fed rats with 60% fat diet gained weight significantly, which was associated with more calorie intake (particularly during light phase) than those fed standard food (7% fat). Secondly, we found that TRF restricted high-fat diet-induced weight gain in both groups of juvenile rats (5 and 13weeks of age) compared to freely fed rats with high-fat diet, despite the same levels of 24h-calorie intake during either weekdays or the weekend. Thirdly, we found that TRF did not restrict high-fat diet-induce weight gain in adult rats (27weeks of age). Thus, we suggest that this special TRF regimen could be further tested in humans (particularly young adults) for the purpose of obesity prevention.

Vagotomy reduces gastric acid secretion and was therefore introduced as a surgical treatment for peptic ulcers in the 1970s. Later, it was replaced by acid reducing medication, such as histamine type 2 (H2) receptor antagonists and proton pump inhibitors (PPIs). A large body of evidence has indicated that drug-induced hypochlorhydria per se does not increase the risk of gastric cancer. Early studies on the effects of vagotomy in chemically-induced rodent models of gastric cancer reported an increased risk of developing gastric cancer. This was most likely due to a delayed gastric emptying, which later has been accounted for by including an additional drainage procedure, e.g. pyloroplasty. In a recent study using three different mouse models of gastric cancer (including genetically engineered, chemically-induced and Helicobacter pylori-infected mice), either unilateral vagotomy or bilateral truncal vagotomy with pyloroplasty was found to significantly attenuate tumorigenesis in the denervated side of the stomach at early preneoplastic stages as well as at later stages of tumorigenesis. Consistently, pharmacological denervation using botulinum toxin A or muscarinic acetylcholine receptor 3 (M3R) blockade inhibited tumorigenesis. Moreover, it was found that recurrence of gastric cancer was reduced in patients following vagotomy. Thus, these new findings suggest the potential treatment strategies to target the nerve, neurotransmitters, corresponding receptors and their down-stream signaling pathways for the malignancy.

Many physiological functions of the stomach depend on an intact mucosal integrity; function reflects structure and vice versa. Histamine in the stomach is synthesized by histidine decarboxylase (HDC), stored in enterochromaffin-like (ECL) cells, and released in response to gastrin, acting on CCK₂ receptors on the ECL cells. Mobilized ECL cell histamine stimulates histamine H₂ receptors on the parietal cells, resulting in acid secretion. The parietal cells express H₂, M₃, and CCK₂ receptors and somatostatin sst₂ receptors. This review discusses the consequences of disrupting genes that are important for ECL cell histamine release and synthesis (HDC, gastrin, and CCK₂ receptor genes) and genes that are important for “cross-talk” between H₂ receptors and other receptors on the parietal cell (CCK₂, M₃, and sst₂ receptors). Such analysis may provide insight into the functional significance of gastric histamine.