Helene Johannessen

Denervation suppresses gastric tumorigenesis.

Surgical or pharmacologic interruption of muscarinic innervation to the stomach suppresses gastric tumor growth in mice and humans. Treating Cancer by Getting on Its Nerves The nervous system plays a role in the regulation of many different organs, including the gut. Now, Zhao et al. have shown that the vagal nerve, which signals to the stomach through muscarinic receptors, contributes to the growth of gastric tumors. The authors demonstrated that vagotomy (surgical interruption of the vagal nerve) can prevent gastric cancer in mice and reduce the recurrence of gastric tumors in human patients. Moreover, the same result can be achieved in mice treated with Botox or anticholinergic drugs to inhibit vagal nerve signaling, raising the hope of a safer treatment for gastric cancer without irreversible side effects. 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.

PYY-Dependent Restoration of Impaired Insulin and Glucagon Secretion in Type 2 Diabetes following Roux-En-Y Gastric Bypass Surgery

Summary Roux-en-Y gastric bypass (RYGB) is a weight-reduction procedure resulting in rapid resolution of type 2 diabetes (T2D). The role of pancreatic islet function in this restoration of normoglycemia has not been fully elucidated. Using the diabetic Goto-Kakizaki (GK) rat model, we demonstrate that RYGB restores normal glucose regulation of glucagon and insulin secretion and normalizes islet morphology. Culture of isolated islets with serum from RYGB animals mimicked these effects, implicating a humoral factor. These latter effects were reversed following neutralization of the gut hormone peptide tyrosine tyrosine (PYY) but persisted in the presence of a glucagon-like peptide-1 (GLP-1) receptor antagonist. The effects of RYGB on secretion were replicated by chronic exposure of diabetic rat islets to PYY in vitro. These findings indicate that the mechanism underlying T2D remission may be mediated by PYY and suggest that drugs promoting PYY release or action may restore pancreatic islet function in T2D.

Mechanistic Comparison between Gastric Bypass vs. Duodenal Switch with Sleeve Gastrectomy in Rat Models

Background Both gastric bypass (GB) and duodenal switch with sleeve gastrectomy (DS) have been widely used as bariatric surgeries, and DS appears to be superior to GB. The aim of this study was to better understand the mechanisms leading to body weight loss by comparing these two procedures in experimental models of rats. Methods Animals were subjected to GB, DS or laparotomy (controls), and monitored by an open-circuit indirect calorimeter composed of comprehensive laboratory animal monitoring system and adiabatic bomb calorimeter. Results Body weight loss was greater after DS than GB. Food intake was reduced after DS but not GB. Energy expenditure was increased after either GB or DS. Fecal energy content was increased after DS but not GB. Conclusion GB induced body weight loss by increasing energy expenditure, whereas DS induced greater body weight loss by reducing food intake, increasing energy expenditure and causing malabsorption in rat models.

Vagal Blocking for Obesity Control: a Possible Mechanism-Of-Action

BackgroundRecently, the US FDA has approved “vagal blocking therapy or vBLoc® therapy” as a new treatment for obesity. The aim of the present study was to study the mechanism-of-action of “VBLOC” in rat models.MethodsRats were implanted with VBLOC, an intra-abdominal electrical device with leads placed around gastric vagal trunks through an abdominal incision and controlled by wireless device. Body weight, food intake, hunger/satiety, and metabolic parameters were monitored by a comprehensive laboratory animal monitoring system. Brain-gut responses were analyzed physiologically.ResultsVBLOC reduced body weight and food intake, which was associated with increased satiety but not with decreased hunger. Brain activities in response to VBLOC included increased gene expression of leptin and CCKb receptors, interleukin-1β, tumor necrosis factor, and transforming growth factor β1 in the brainstem; increased CCK, somatostatin, and tyrosine hydroxylase in the hippocampus; increased NPY, AgRP, and Foxa2 in the hypothalamus; and reduced CCKb receptor, melanocortin 4 receptor, and insulin receptor in the hypothalamus. Plasma concentrations of CCK, gastrin, glucagon, GLP-1, and PYY and gastric acid secretion were unchanged in response to VBLOC.ConclusionsBased on the present study, we may suggest that VBLOC induces satiety through vagal signaling, leading to reduced food intake and loss of body weight.

Steady-state energy balance in animal models of obesity and weight loss

Abstract Objective: We wanted to exam the steady-state energy balance by using high-fat diet-induced obese (DIO) rats and mice as models for positive energy balance, and gastric bypassed (GB) rats and gene knockout of muscarinic acetylcholine M3 receptor (M3KO) mice as models for negative energy balance. Methods: One hundred and thirty-two rats and mice were used. Energy balance was measured by a comprehensive laboratory animal monitoring system. Gene expression was analysed by in situ hybridisation in M3KO mice. Results: DIO rats reached the plateau of body weight 28 weeks after starting high-fat diet (25% heavier than controls), whereas DIO mice reached the plateau after 6 weeks (23% heavier than controls). At the plateau, DIO rats had higher calorie intake during the light phase but not during the dark phase, while mice had the same calorie intake per day as controls. DIO rats and mice had lower energy expenditure (EE) and respiratory exchange ratio (RER) than controls. GB-rats reached the plateau (15% weight loss) 2 weeks after surgery and had the same calorie intake as sham-operated controls. EE, but not RER, was higher in GB rats than controls during the dark phase. The lean M3KO mice (25% lighter than wild-type (WT) mice at the plateau between 6 and 15 months of age) had the same calorie intake but higher EE, RER and hypothalamic mRNA expression of NPY, AgRP and leptin receptor than WT mice. Conclusion: When body weight gain or loss reached a plateau, the steady-state energy balance was mainly maintained by EE and/or RER rather than calorie intake.

Effects of duodenal switch alone or in combination with sleeve gastrectomy on body weight and lipid metabolism in rats

Background:A combined procedure of sleeve gastrectomy and duodenal switch (SG+DS) has been applied to the treatment of super obesity. The aim of the present study was to test whether duodenal switch alone (DS) leads to similar weight loss and changes in lipid metabolism as SG+DS.Methods:Male Sprague–Dawley rats underwent sham surgery (Sham, N=7), duodenal switch alone (DS, N=5) or sleeve gastrectomy followed by duodenal switch (SG+DS, N=5). Body weight, feed and water intakes, and ambulatory activity were recorded 2 months post surgery. Tissue and faecal lipids, faecal bile acids, plasma cytokines and lipid metabolism-related gene expression in adipose tissue and liver were analysed.Results:Daily energy intake, relative feed uptake, ambulatory activity and body weight reduction were similar between DS and SG+DS rats. The hepatic triacylglycerol content was higher and faecal secretion of triacylglycerol was lower after SG+DS compared to DS (P<0.05). Faecal bile acid secretion was higher in SG+DS than in DS rats (P<0.05) despite similar hepatic CYP7A1mRNA level. Plasma levels of proinflammatory cytokines interleukin (IL)-1b, IL-2, IL-4, IL-5, IL-6, IL-12, granulocyte-macrophage colony stimulating factor and tumour necrosis factor alpha were higher in SG+DS than in DS rats (P<0.05).Conclusions:Although DS and SG+DS had similar efficacy in terms of body weight loss, SG+DS resulted in a poorer regulation of lipid metabolism than DS.

Mo2054 Preclinical Trial of Gastric Injection of Botulinum Toxin Type a As Weight-Loss-Surgery

Background/aim: Recently, a clinical trial enrolling 60 obese patients failed to show that gastric injection of botulinum neurotoxin type -A (Botox) promotes body weight (BW) loss. The aim of this study was to verify the effectiveness and the underlying mechanism of gastric injection of Botox as weight-loss-surgery (WLS). Methods: 102 male rats (42 normal rats at 500 g BW and 60 high-fat-diet-induced obese rats at 700-800 g BW) were subjected to Botox injection, vehicle injection, or sleeve gastrectomy (SG) followed by Botox injection. Rats on high-fat-diet were continuously fed the high-fat-diet after Botox injection or surgery. Botox was injected at a dose of 20 U/rat into the subserosa layer of pyloric antrum or the remaining antrum post SG, and Botox injection was repeated when rats regained BW. Measurements included BW development, food intake, eating behavior and metabolic parameters (monitored by Comprehensive Laboratory Animal Monitoring System, CLAMS), fasting blood glucose levels, gastric emptying rate (acetaminophen absorption test), gut hormones (RIA), and expression of genes encoding orexigenic and anorexigenic neuropeptides in the hypothalamus (in situ hybridization). Results: There were no mortality, adverse effects and pathological changes in rats subjected to Botox injection. Botox injection reduced BW by 14% in normal rats and 25% in obese rats compared to values before Botox injection (p 0.05). Additional Botox injection led to BW loss of 22% (p<0.01). Botox injection increased satiety ratio (min/g), leading to reduced food intake (g/day), and increased energy expenditure (kcal/h/100g BW). Botox injection reduced fasting blood glucose levels, while gastric emptying rate was unchanged (measured at 3 days, 1, 2 or 3 weeks after Botox injection) in either normal or obese rats. Gene expression in hypothalamus and plasma levels of gut hormones were unchanged at 48 hours after Botox injection. However, 8 weeks after Botox injection, the gene expression for neuropeptide Y and agouti-related peptide was increased, while pro-opiomelanocortin was decreased in arcuate nucleus in hypothalamus, and plasma levels of cholecystokinin, gastrin, and peptide YY, but not glucagon, glucagon-like peptide-1, were reduced, suggesting compensatory changes in the gut hormones-hypothalamus pathway. Conclusions: This preclinical trial demonstrates the safety and efficacy of gastric injection of Botox as WLS when it is performed alone or in combination with SG. Botox reduced food intake and increased energy expenditure, independently of the gastric emptying rate and of the hypothalamusgut hormone pathway.

Mo1917 Preclinical Trial of Botulinum Toxin Type a Injection in the Treatment of Gastric Cancer

Background/aim: Innervation plays an important role in the regulation of epithelial homeostasis as well as tumorigenesis. Botulinum neurotoxin type A (Botox) is known to block both afferent and efferent nerve fibers by binding to SNARE proteins. The aim of this trial was to evaluate the effectiveness and underlying mechanism of local injection of Botox in the treatment of gastric cancer. Methods: 268 genetically-manipulated INS-GAS male and female mice with spontaneous gastric cancer were subjected to Botox injection or subdiaphragmatic unilateral vagotomy (UVT), with or without chemotherapy (5-FU, oxaliplatin, or 5-FU + oxaliplatin). Botox was injected subserosally along the greater curvature on the anterior side of the stomach and the injection was repeated every 2nd month. Chemotherapy was given by intraperitoneal injection once per week for 4 weeks in a two-cycle course with a 1-week rest. Clinical endpoints included tumor size, histopathological score, and survival. Gastric organoid cultures with or without Botox, neurons, or a muscarinic receptor agonist or antagonist were used. Results: Botox treatment was given to INS-GAS mice at 6 months of age when gastric cancer started to develop. Six months later, tumor size, cell proliferation rate, scores of inflammation, epithelial defects, atrophy, hyperplasia, dysplasia and metaplasia were markedly reduced in comparison with the uninjected posterior area of the stomach. When Botox treatment was given at 14 months of age in combination with 5-FU+oxaliplatin, tumor size was significantly reduced as early as 2 months after starting treatment, particularly in the area of Botox injection or in the surgically denervated stomach following UVT. The combination of either Botox or UVT with chemotherapy led to a significant increase in survival compared to chemotherapy alone. In vitro studies showed that neurons stimulated gastric organoid growth when compared to gastric organoids cultured in the absence of neurons, and that the addition of either Botox or scopolamine inhibited this stimulatory effect, whereas pilocarpine increased organoid growth. Furthermore, pilocarpine upregulated expression of stem cell markers and Wnt target genes, such as Lgr5, CD44, and Sox9, and both pilocarpine and neurons could substitute for Wnt3a in gastric organoid cultures that were otherwise strictly dependent on the addition of Wnt ligands. Conclusions: This preclinical trial demonstrates the efficacy of local Botox injection with or without chemotherapy in the treatment of gastric cancer. The therapeutic effect is likely mediated by acetylcholinemediated Wnt signaling in gastric stem cells. We may further suggest that greater consideration should be given to novel denervation approaches in combination with other therapies for gastric cancer and likely other solid malignancies.

New Approaches for Weight Loss: Experiments in Animal Model

The number of people who are overweight and obese are continuously increasing both in the adult and adolescent populations. Coinciding with this is the increased prevalence of health problems such as type 2 diabetes (T2D). Bariatric surgery is the only proven long-term treatment of obesity and may induce remission of T2D, although the underlying mechanisms are unknown. The translational studies presented here might provide insight on the mechanism of steady-state energy balance of the obese phenotype using a special time-restricted feeding regimen for weight loss during the steady-state energy balance; mechanism by vagal blocking therapy (vBLoc® therapy) as a new treatment for obesity; and possible mechanism behind the remission of T2D following gastric bypass surgery.

Erratum to: Vagal Blocking for Obesity Control: a Possible Mechanism-Of-Action

1 Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, Trondheim, Norway 2 Department of Clinical Neuroscience and Rehabilitation, The Sahlgrenska Academy at Gothenburg University, Gothenburg, Sweden 3 Rowett Institute of Nutrition and Health, University of Aberdeen, Aberdeen, Scotland 4 Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden 5 Department of Biomedical Sciences, the Panum Institute, University of Copenhagen, Copenhagen, Denmark 6 Department of Clinical Biochemistry, Rigshospitalet, Copenhagen, Denmark 7 Department of Translational Neuroscience, Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht, Netherlands 8 Center for Obesity Research, Department of Surgery, St. Olavs Hospital, Trondheim University Hospital, Trondheim, Norway OBES SURG (2017) 27:186 DOI 10.1007/s11695-016-2370-2