Vagotomy accelerates the onset of symptoms during early disease progression and worsens joint-level pathogenesis in a male rat model of chronic knee osteoarthritis

Objective

Low vagal tone is common in osteoarthritis (OA) comorbidities and results in greater peripheral inflammation. Characterizing vagal tone's role in OA pathogenesis may offer insights into OA's influences beyond the articular joint. We hypothesized that low vagal tone would accelerate onset of OA-related gait changes and worsen joint damage in a rat knee OA model.

Methods

Knee OA was induced in male Sprague Dawley rats by transecting the medial collateral ligament and medial meniscus. Then, left cervical vagus nerve transection (VGX, n ​= ​9) or sham VGX (non-VGX, n ​= ​6) was performed. Gait and tactile sensitivity were assessed at baseline and across 12 weeks, with histology and systemic inflammation evaluated at endpoint.

Results

At week 4, VGX animals showed limping gait characteristics through shifted stance times from their OA to non-OA limb (p ​= ​0.055; stance time imbalance ​= ​1.6 ​± ​1.6%) and shifted foot strike locations (p ​< ​0.001; spatial symmetry ​= ​48.4 ​± ​0.835%), while non-VGX animals walked with a balanced and symmetric gait. Also at week 4, while VGX animals had a mechanical sensitivity (50% withdrawal threshold) of 13.97 ​± ​7.70 compared to the non-VGX animal sensitivity of 29.74 ​± ​9.43, this difference was not statistically significant. Histologically, VGX animals showed thinner tibial cartilage and greater subchondral bone area than non-VGX animals (p ​= ​0.076; VGX: 0.80 ​± ​0.036 ​mm2; non-VGX: 0.736 ​± ​0.066 ​mm2). No group differences in systemic inflammation were observed at endpoint.

Conclusions

VGX resulted in quicker onset of OA-related symptoms but remained unchanged at later timepoints. VGX also had thinner cartilage and abnormal bone remodeling than non-VGX. Overall, low vagal tone had mild effects on OA symptoms and joint remodeling, and not at the level seen in common OA comorbidities.

Lipopolysaccharide-producing Veillonella infantium and Escherichia fergusonii cause vagus nerve-mediated cognitive impairment in mice

Gut microbiota communicates bidirectionally with the brain through the nervous, immune, and endocrine systems of the gut. In our preliminary study, the fecal microbiota of volunteers with mild cognitive impairment (Fmci) exhibited a higher abundance of Escherichia fergusonii (NK2001), Veillonella infantium (NK2002), and Enterococcus faecium (NK2003) populations compared with those of healthy volunteers. Therefore, we examined the effects of Fmci, NK2001 (gram-negative), NK2002 (gram-negative-like), and NK2003 (gram-positive) on cognitive impairment-like behavior, neuroinflammation, and colitis in mice with or without antibiotics. Fmci transplantation increased cognitive impairment-like behavior, hippocampal tumor necrosis factor (TNF)-α expression, and the size of toll-like receptor (TLR)4+Iba1+, TLR2+Iba1+, and NF-κB+Iba1+ cell populations independent of antibiotic treatment. Oral gavage of NK2001, NK2002, or NK2003, which induced TNF-α expression in Caco-2 cells, significantly increased cognitive impairment-like behavior and hippocampal TNF-α expression and Iba1-positive cell populations and decreased brain-derived neurotrophic factor (BDNF) expression in mice. Celiac vagotomy significantly decreased NK2001- or NK2002-induced cognitive impairment-like behavior and hippocampal Iba1+ cell population and TNF-α expression and increased NK2001- or NK2002-suppressed hippocampal BDNF expression. However, NK2003-induced cognitive impairment-like behavior and hippocampal Iba1+ cell population and TNF-α expression were partially, but not significantly, attenuated by celiac vagotomy. Furthermore, celiac vagotomy did not affect NK2001-, NK2002-, or NK2003-induced lipopolysaccharide (LPS) levels in the blood and feces and TNF-α expression and NF-κB-positive cell population in the colon. In conclusion, LPS-producing NK2001 and NK2002 and LPS-nonproducing NK2003 may induce NF-κB-mediated neuroinflammation through the translocation of byproducts such as LPS and peptidoglycan into the brain through gut-blood/vagus nerve-brain and gut-blood-brain pathways, respectively, resulting in cognitive impairment.

Surgical Management of Upper Gastrointestinal Bleeding

The use of surgery in managing upper gastrointestinal (GI) bleeding has rapidly diminished secondary to advances in our understanding of the pathologies that underlie upper GI bleeding, pharmaceutical treatments for peptic ulcer disease, and endoscopic procedures used to gain hemostasis. A surgeon must work collaboratively with gastroenterologist and interventional radiologist to determine when, and what kind of, surgery is appropriate for the patient with upper GI bleeding.

Hepatic Vagotomy in Patients With Obesity Leads to Improvement of the Cholesterol to High-Density Lipoprotein Ratio

INTRODUCTION/PURPOSE

The obesity epidemic is rapidly growing, and visceral adiposity is associated with metabolic consequences secondary to peroxisome proliferator-activated receptor (PPAR)-induced inter-organ signaling pathways. PPARs are ligand-activated transcription factors that modulate vagal pathways which can improve blood pressure, arterial remodeling, cholesterol levels, and insulin sensitivity. However, an obesity-induced inflammatory milieu can interfere with the beneficial effects of PPAR activity, suggesting that a dysregulated PPAR-vagus pathway may play a role in the pathogenesis of obesity-related hypertension. Therefore, we hypothesized that hepatic vagotomy (HV) in patients with obesity would result in a significant reduction in blood pressure and/or the number of hypertension medications compared to control.

METHODS

We conducted a retrospective chart review of 160 patients undergoing laparoscopic sleeve gastrectomy. Patients were divided into HV and control groups, and information was collected at each clinic visit.

RESULTS

At six-months post-operation, the HV group was found to have significantly lower total cholesterol (TC)/high-density lipoprotein (HDL) ratios than the control group. The HV group also had a numerically better blood profile for TC, HDL, low-density lipoprotein (LDL), triglycerides, C-reactive protein, and LDL/HDL ratio. Hypertensive patients in the HV group showed numerically lower hypertension medication counts after six weeks when compared to control.

CONCLUSION

We present the first study to report clinically significant changes related to HV in human subjects. Our results did not support our initial hypothesis but did demonstrate an improvement of the TC/HDL ratio with HV in patients with obesity. Future studies should confirm these findings in a randomized control trial.

Is vagotomy necessary in palliative surgery for incurable advanced gastric cancer?: a retrospective case-control study

BACKGROUND

The interplay between the nervous system and cancer plays an important role in the initiation and progression of gastric cancer. Few studies have presented evidence that the sympathetic nervous system inhibits the occurrence and development of gastric cancer while the parasympathetic nervous system promotes the growth of gastric cancer. To investigate the effect of vagotomy, which is the resection of a parasympathetic nerve innervating the stomach, on the progression of gastric cancer, a retrospective study was conducted comparing the prognosis of simple palliative gastrojejunostomy (PGJ) and palliative gastrojejunostomy with vagotomy (PGJV).

METHODS

From January 01, 2000, to December 31, 2021, the medical records of patients who underwent PGJ or PGJV because of gastric outlet obstruction due to incurable advanced gastric cancer at the Yeungnam University Medical Center were retrospectively reviewed. Patients were divided into two groups: locally unresectable gastric cancer (LUGC) or gastric cancer with distant metastasis (GCDM), according to the reason for gastrojejunostomy, and factors affecting overall survival (OS) were analyzed.

RESULTS

There was no significant difference in surgical outcomes and postoperative complications between the patients with PGJV and patients with PGJ. In univariate analysis, vagotomy was not a significant factor for OS in the GCDM group (HR 1.14, CI 0.67-1.94, p value 0.642), while vagotomy was a significant factor for OS in the LUGC group (HR 0.38, CI 0.15-0.98, p value 0.045). In multivariate analysis, when vagotomy is performed together with PGJ for LUGC, the OS can be significantly extended (HR 0.25, CI 0.09-0.068, p value 0.007).

CONCLUSIONS

When PGJ for LUGC was performed with vagotomy, additional survival benefits could be achieved with low complication risk. However, to confirm the effect of vagotomy on the growth of gastric cancer, further prospective studies using large sample sizes are essential.

The effects of gallic acid and vagotomy on motor function, intestinal transit, brain electrophysiology and oxidative stress alterations in a rat model of Parkinson's disease induced by rotenone

INTRODUCTION

The neuropathology of Parkinson's disease (PD) is complex and affects multiple systems of the body beyond the central nervous system. This study examined the effects of gallic acid (GA) and gastrointestinal vagotomy (VG) on motor, cognitive, intestinal transit time, and thalamic nuclei electrical power in an animal model of PD induced by rotenone.

MATERIALS AND METHODS

Male Wistar rats were divided into 4 groups: Sham, ROT, ROT+GA, VG + ROT. Sham rats received vehicle, those in ROT received rotenone (5 mg/kg/2 ml, ig), PD rats in ROT+GA were treated with GA (100 mg/kg, gavage/once daily, for 28 days), and in VG + ROT, the vagal nerve was dissected. Stride length, motor coordination and locomotion, intestinal transit time, cognitive and pain threshold, and thalamic local EEG were evaluated. Oxidative stress indexes in striatal tissue were also measured.

RESULTS

Rotenone diminished significantly the stride length (p < 0.001), motor coordination (p < 0.001), power of thalamic EEG (p < 0.01) and pain (p < 0.001). MDA increased significantly (p < 0.001) while GPx activity decreased (p < 0.001). Intestinal transit time rose significantly (p < 0.01). PD rats treated with GA improved all above disorders (p < 0.001, p < 0.01). Vagotomy prevented significant alterations of motor and non-motor parameters by rotenone.

CONCLUSION

According to current findings, rotenone acts as a toxin in GI and plays a role in the pathogenesis of PD through gastric vagal nerve. Thus, vagotomy could prevent the severity of toxicity by rotenone. In addition, GA improved symptoms of PD induced by rotenone. Therefore, GA can be regarded as a promising therapeutic candidate for PD patients.

Metabolic effects of truncal vagotomy when combined with bariatric-metabolic surgery

Bariatric-metabolic surgery (BMS) in patients with obesity frequently leads to remission of concurrent type 2 diabetes mellitus (T2DM), even before body weight loss takes place. This is probably based on the correction of a dysmetabolic cycle in the gastrointestinal physiology of T2DM that includes increased vagus-dependent exocrine pancreatic secretion (EPS) and, hence, amplified digestion and nutrient absorption. The resultant chronic exposure of tissues to high plasma levels of glucose, fatty acids and amino acids causes tissue resistance to the actions of insulin and, at a later stage, β-cell dysfunction and reduction of insulin release. We hypothesize that the addition of a surgical truncal vagotomy (TV) may improve and solidify the beneficial results of BMS on T2DM by stably decreasing EPS, - hence reducing the digestion and absorption of nutrients -, and increasing incretin secretion as a result of increased delivery of unabsorbed nutrients to the distal intestine. This hypothesis is supported by surgical data from gastrointestinal malignancies and peptic ulcer operations that include TV, as well as by vagal blockade studies. We suggest that TV may result in a stable reduction of EPS, and that its combination with the appropriate type of BΜS, may enhance and sustain the salutary effects of the latter on T2DM.

Impact of Vagotomy on Postoperative Weight Loss, Alimentary Intake, and Enterohormone Secretion After Bariatric Surgery in Experimental Translational Models

Obesity may be treated by bariatric procedures and is related to enterohormone release modulation. Nevertheless, a majority of commonly used surgical procedures have a significant impact on vagus nerve function by breaking the connections with its gastric branches. In the case of an intragastric balloon (BAL), this interaction is unclear. However, BAL-induced weight reduction is not long-lasting. Interestingly, this method has not been used in combination with vagotomy (VAG). Thus, we evaluated, for the first time, the short- and long-term effects of combined BAL and VAG using the animal-based translational model and compared these effects with sleeve gastrectomy (SG) and Roux-en-Y gastric bypass (RYGB). Wistar rats were fed a high-calorie diet for 8 weeks to induce obesity before SG, RYGB, BAL + / - VAG. Animals' weight and eating behaviors were monitored weekly. After 90 days, serum samples were collected to evaluate postprandial and fasting GLP-1, GIP, PYY, ghrelin, glucagon, insulin, leptin, and pancreatic polypeptide concentrations by fluorescent assay. VAG, SG, RYGB, and BAL + VAG significantly reduced body weight 30 and 90 days after surgery. BAL alone induced temporal weight reduction observed after 30 days, reversed after 90 days. Calories intake was reduced at the first half of the observation period in all groups. Fluid intake was reduced in all groups except SG and BAL. Enterohormone profile for BAL + VAG was comparable to SG and RYGB but not BAL. VAG and BAL + VAG but not BAL alone maintain weight reduction, alimentary intake changes, and enterohormone release after long-term observation. VAG may improve the effectiveness of bariatric procedures for obesity treatment in clinical practice.

Predominant role of gut-vagus-brain neuronal pathway in postoperative nausea and vomiting: evidence from an observational cohort study

BACKGROUND

Postoperative nausea and vomiting (PONV) as a clinically most common postoperative complication requires multimodal antiemetic medications targeting at a wide range of neurotransmitter pathways. Lacking of neurobiological mechanism makes this 'big little problem' still unresolved. We aim to investigate whether gut-vagus-brain reflex generally considered as one of four typical emetic neuronal pathways might be the primary mediator of PONV.

METHODS

Three thousand two hundred twenty-three patients who underwent vagus nerve trunk resection (esophagectomy and gastrectomy) and non-vagotomy surgery (hepatectomy, pulmonary lobectomy and colorectomy) from December 2016 to January 2019 were enrolled. Thirty cases of gastrectomy with selective resection on the gastric branch of vagus nerve were also recruited. Nausea and intensity of vomiting was recorded within 24 h after the operation.

RESULTS

PONV occurred in 11.9% of 1187 patients who underwent vagus nerve trunk resection and 28.7% of 2036 non-vagotomy patients respectively. Propensity score matching showed that vagotomy surgeries accounted for 19.9% of the whole PONV incidence, much less than that observed in the non-PONV group (35.1%, P <  0.01). Multivariate logistic regression result revealed that vagotomy was one of underlying factor that significantly involved in PONV (OR = 0.302, 95% CI, 0.237-0.386). Nausea was reported in 5.9% ~ 8.6% vagotomy and 12 ~ 17% non-vagotomy patients. Most vomiting were mild, being approximately 3% in vagotomy and 8 ~ 13% in non-vagotomy patients, while sever vomiting was much less experienced. Furthermore, lower PONV occurrence (10%) was also observed in gastrectomy undergoing selective vagotomy.

CONCLUSION

Patients undergoing surgeries with vagotomy developed less PONV, suggesting that vagus nerve dependent gut-brain signaling might mainly contribute to PONV.

Reduced acetylcholine and elevated muscarinic receptor 2 in duodenal mucosa contribute to the impairment of mucus secretion in 6-hydroxydopamine-induced Parkinson's disease rats

Patients with Parkinson's disease (PD) have a higher incidence rate of duodenal ulcers. The mucus barrier provides the first line of defense for duodenal mucosal protection. However, it is unknown whether duodenal mucus secretion is affected in PD. In the present study, we used the rats microinjected 6-hydroxydopamine (6-OHDA) into the bilateral substantia nigra to investigate duodenal mucus secretion and potential therapeutic targets in duodenal ulcer in PD. Alcian blue-periodic acid-Schiff, transmission electron microscopy, immunofluorescence, duodenal mucosal incubation, and enzyme-linked immunosorbent assays were used. The 6-OHDA rats exhibited mucin accumulation and retention in duodenal goblet cells. Mucin granules were unable to fuse with the apical membranes of goblet cells, and the exocytosis ratio of goblet cells was significantly reduced. Moreover, decreased acetylcholine and increased muscarinic receptor 2 (M₂R) levels were detected in the duodenal mucosa of 6-OHDA rats. Bilateral vagotomy rats were also characterized by defective duodenal mucus secretion and decreased acetylcholine with increased M₂R levels in the duodenal mucosa. Application of the cholinomimetic drug carbachol or blocking M₂R with methoctramine significantly promoted mucus secretion by goblet cells and increased MUC2 content in duodenal mucosa-incubated solutions from 6-OHDA and vagotomy rats. We conclude that the reduced acetylcholine and increased M₂R contribute to the impaired duodenal mucus secretion of 6-OHDA rats. The study provides new insights into the mechanism of duodenal mucus secretion and potential therapeutic targets for the treatment of duodenal ulcers in PD patients.

Recording and manipulation of vagus nerve electrical activity in chronically instrumented unanesthetized near term fetal sheep

BACKGROUND

The chronically instrumented pregnant sheep has been used as a model of human fetal development and responses to pathophysiologic stimuli. This is due to the unique amenability of the unanesthetized fetal sheep to the surgical placement and maintenance of catheters and electrodes, allowing repetitive blood sampling, substance injection, recording of bioelectrical activity, application of electric stimulation, and in vivo organ imaging. Recently, there has been growing interest in the pleiotropic effects of vagus nerve stimulation (VNS) on various organ systems such as innate immunity and inflammation, and metabolism. There is no approach to study this in utero and corresponding physiological understanding is scarce.

NEW METHOD

Based on our previous presentation of a stable chronically instrumented unanesthetized fetal sheep model, here we describe the surgical instrumentation procedure allowing successful implantation of a cervical uni- or bilateral VNS probe with or without vagotomy.

RESULTS

In a cohort of 68 animals, we present the changes in blood gas, metabolic, and inflammatory markers during the postoperative period. We detail the design of a VNS probe which also allows recording from the fetal nerve. We also present an example of fetal vagus electroneurogram (VENG) recorded from the VNS probe and an analytical approach to the data.

COMPARISON WITH EXISTING METHODS

This method represents the first implementation of fetal VENG/VNS in a large pregnant mammalian organism.

CONCLUSIONS

This study describes a new surgical procedure allowing to record and manipulate chronically fetal vagus nerve activity in an animal model of human pregnancy.

Intraperitoneal injection of lithium chloride induces lateralized activation of the insular cortex in adult mice

Insular cortex is a critical brain region that participates in the interoceptive sensations. Here, we combined the iDISCO + method and Fos immunostaining to confirm that the middle part of the right-side, but not the left-side, insular cortex in adult male mice is activated by intraperitoneal injection of lithium chloride. Lateralized activation of the insular cortex is also observed in adult female mice, but not in young or aged male mice. Furthermore, asymmetrical activation of the insular cortex was completely blocked when both sides of the vagal nerve are transected, whereas intravenous injection of lithium chloride has no effect on the insular activation. Combined together, these results indicate that the insular cortex unilaterally responds to aversive visceral stimuli in an age-dependent way and this process depends on the vagal afferent pathways.

Effects of microbiota transplantation and the role of the vagus nerve in gut-brain axis in animals subjected to chronic mild stress

INTRODUCTION

Currently, there is a growing emphasis on the study of intestinal signaling as an influencer in the pathophysiology of neuropsychiatric diseases, and the gut-brain axis is recognized as a communication route through endocrine, immune, and neural pathways (vagus nerve). Studies have shown that diets that modify the microbiota can reduce stress-related behavior and hypothalamic-pituitary-adrenal axis activation. Investigators have used fecal microbiota transplantation (FMT) approaches to demonstrate that stress-related microbiota composition plays a causal role in behavioral changes.

AIM

We hypothesized that FMT may present immunomodulatory, biochemical, endocrine, cognitive, and behavioral benefits in stress situations and that these changes can be mediated via the vagus nerve.

METHODS

Animals were subjected to a chronic mild stress (CMS) protocol. In one experiment, animals were divided into five groups: control, control + FMT, control + FMT + CMS, CMS + saline, and CMS + FMT. The animals received FMT, and behavioral tests were performed; cytokine and carbonyl levels were measured. In a second experiment, animals were submitted to vagotomy and divided into two groups: CMS + FMT and CMS + vagotomy + FMT.

RESULTS

Animals submitted to the CMS protocol or that received FMT from stressed animals showed behavioral changes and changes in neuroactive substances (increased IL-6 and TNF-α levels and carbonyl proteins). The FMT of healthy donors improved the analyzed parameters. In addition, vagotomy influenced beneficial FMT results, confirmed by behavioral testing and protein carbonyl in the hippocampus.

CONCLUSION

Manipulation of the microbiota reversed the behavioral and biochemical changes induced by the CMS protocol, and the vagus nerve influenced the gut-brain axis response.

A Population-Based Cohort Study Examining the Long-term Risk of Repeated Surgery in Non-Helicobacter pylori-Infected PPU Patients Who Underwent Simple Closure

OBJECTIVES

The management of perforated peptic ulcer (PPU) has shifted from vagotomy/drainage to simple closure, followed by postoperative proton pump inhibitors (PPIs) and Helicobacter pylori (HP) eradication. Few studies have focused on the long-term impacts of this trend shift. We hypothesize that simple closure with PPIs is sufficient and does not carry an elevated rate of repeated surgery in non-HP-infected PPU patients.

METHODS

Hospitalized PPU patients who underwent simple closure or truncal vagotomy/pyloroplasty (TVP) in the National Health Insurance Research Database (NHIRD) from 2000 to 2008 were collected. The index date was defined as the date of ulcer admission. Patients who underwent other ulcer surgeries (e.g., gastrectomy, highly or selective vagotomy), who had a history of HP infection, or who were < 18 or > 100 years old were excluded. Additionally, the distributions of postoperative nonsteroidal anti-inflammatory drug (NSAID) and PPI use were calculated using the Longitudinal Health Insurance Database (LHID).

RESULTS

After exclusion, a total of 66,413 patients were enrolled. There were 7232 (10.9%) patients who underwent TVP and 59,181 (89.1%) patients who underwent simple closure. The incidences of repeated ulcer-associated surgery were 5.10 and 23.05 versus 5.11 and 15.77 per 1000 person-years in the TVP cohort vs. the simple closure cohort before and after propensity score matching, respectively. When adjusted for age, sex, comorbidity, and Charlson comorbidity index score, the TVP cohort had a 68% (HR) and 66% (sHR) decreased risk compared with the simple closure cohort before propensity score matching, with a 67% decreased risk after propensity score matching in Cox proportional subdistribution hazard analysis and a 66% decreased risk in Fine-Gray proportional subdistribution hazard analysis. The LHID analysis showed a lower rate of postoperative NSAID use and a higher rate of postoperative PPI use in simple closure patients.

CONCLUSION

Our findings suggest that in the Asian population, simple closure increases the risk of repeated ulcer-associated surgery in non-HP-infected PPU patients compared with TVP patients. However, further studies are warranted.

Effects of methyl methacrylate on the excitability of the area postrema neurons in rats

OBJECTIVES

The aim of the present study is to demonstrate the effects of inhaled methyl methacrylate (MMA) on the excitability of neurons in the area postrema (AP). We also investigated the relation between vagal afferent inputs and responding cells in the AP.

METHODS

We set up two groups of experimental animals, such as rats inhaling MMA and rats inhaling room air. To visualize the changes of AP neuron excitability after inhalation of MMA for 90 min, c-Fos protein expression was identified and quantified by immunohistochemical analysis. Some rats receiving ventral gastric branch vagotomy were also subjected to the abovementioned experiment.

RESULTS

The number of c-Fos-immunoreactive (Fos-ir) cells in the MMA group was more than six times greater than that of the control group (statistically significant, p < 0.01). In vagotomized rats inhaling MMA, markedly smaller number of Fos-ir cells was identified in the AP compared to that of rats inhaling MMA without vagotomy.

CONCLUSIONS

These results indicate that inhalation of MMA increases neuronal excitability in the AP, suggesting that vagal afferent inputs are involved in the induction mechanism of Fos-ir cells by MMA.

Role of the parasympathetic nervous system in cancer initiation and progression

The nervous system plays an important role in cancer initiation and progression. Accumulated evidences clearly show that the sympathetic nervous system exerts stimulatory effects on carcinogenesis and cancer growth. However, the role of the parasympathetic nervous system in cancer has been much less elucidated. Whereas retrospective studies in vagotomized patients and experiments employing vagotomized animals indicate the parasympathetic nervous system has an inhibitory effect on cancer, clinical studies in patients with prostate cancer indicate it has stimulatory effects. Therefore, the aim of this paper is a critical evaluation of the available data related to the role of the parasympathetic nervous system in cancer.

Peripheral and central compensatory mechanisms for impaired vagus nerve function during peripheral immune activation

BACKGROUND

Determining the etiology and possible treatment strategies for numerous diseases requires a comprehensive understanding of compensatory mechanisms in physiological systems. The vagus nerve acts as a key interface between the brain and the peripheral internal organs. We set out to identify mechanisms compensating for a lack of neuronal communication between the immune and the central nervous system (CNS) during infection.

METHODS

We assessed biochemical and central neurotransmitter changes resulting from subdiaphragmatic vagotomy and whether they are modulated by intraperitoneal infection. We performed a series of subdiaphragmatic vagotomy or sham operations on male Wistar rats. Next, after full, 30-day recovery period, they were randomly assigned to receive an injection of Escherichia coli lipopolysaccharide or saline. Two hours later, animal were euthanized and we measured the plasma concentration of prostaglandin E2 (with HPLC-MS), interleukin-6 (ELISA), and corticosterone (RIA). We also had measured the concentration of monoaminergic neurotransmitters and their metabolites in the amygdala, brainstem, hippocampus, hypothalamus, motor cortex, periaqueductal gray, and prefrontal medial cortex using RP-HPLC-ED. A subset of the animals was evaluated in the elevated plus maze test immediately before euthanization.

RESULTS

The lack of immunosensory signaling of the vagus nerve stimulated increased activity of discrete inflammatory marker signals, which we confirmed by quantifying biochemical changes in blood plasma. Behavioral results, although preliminary, support the observed biochemical alterations. Many of the neurotransmitter changes observed after vagotomy indicated that the vagus nerve influences the activity of many brain areas involved in control of immune response and sickness behavior. Our studies show that these changes are largely eliminated during experimental infection.

CONCLUSIONS

Our results suggest that in vagotomized animals with blocked CNS, communication may transmit via a pathway independent of the vagus nerve to permit restoration of CNS activity for peripheral inflammation control.

Sculpting the Sculptors: Methods for Studying the Fetal Cholinergic Signaling on Systems and Cellular Scales

The non-neuronal, immunological effects of the cholinergic signaling are exerted on the system's scale of observation via the vagus nerve and on the cellular scale via α7 nicotinic acetylcholine receptor (nAChR) signaling in myeloid cells of the periphery or brain's microglia and astrocytes. The developmental effects of such multi-scale signaling can be conceived of as an example of psychoneuroimmunological (PNI) homeokinesis and, while reported in the literature, are not yet systematically well studied. To be better understood, the intricacy of the multi-scale interactions requires relevant preclinical animal models. Chronically instrumented non-anesthetized fetal sheep model comes with a strong track record of bench-to-bed translation and a large body of evidence for its strong resemblance to and relevance for human physiology on various scales of organization. Recently, there has been growing interest in pleiotropic effects of vagus nerve stimulation (VNS) on various organ systems such as innate immunity, metabolism, and emotion with implications for programming of PNI phenotype. Here we describe the procedures required to record and manipulate the vagus nerve activity in this large pregnant mammalian organism. Extending this in vivo model to in vitro, on the cellular scale, we present the method to manipulate the cholinergic signaling in ovine fetal microglia and astrocytes and analyze their responses on protein and RNA levels. Together these models can provide multi-scale-level mechanistic insights into the effects of cholinergic signaling on PNI phenotype.

Intestinal microbiota impact sepsis associated encephalopathy via the vagus nerve

OBJECTIVE

The pathogenesis of sepsis associated encephalopathy (SAE) remains poorly understood. Vagus nerve plays an important role in gut-microbiota-brain axis. This study aimed to investigate whether vague nerve is a key mediator of the impact of intestinal microbiota on SAE.

METHODS

Male rats were randomly divided into four groups (n=20): SHAM (SH) group, lipopolysaccharide (LPS) group, fecal microbiota transplantation (FMT) +LPS group, and vagotomy (VGX)+LPS+FMT group. The left cervical vagotomy was performed 30min before LPS administration in LPS+FMT+VGX group. LPS+ FMT and LPS+FMT+VGX groups received nasogastric infusion of feces from healthy donor three times a day. Fecal samples were collected every two days to monitor changes in microbiota composition by 16S rDNA analysis. Brain function was evaluated by behavioral tests and EEG. The levels of tumor necrosis factor alpha (TNF-α), interleukin (IL)-1β, IL-6, IL-10 in brain cortex were detected by ELISA. The expression of Iba-1 in brain cortex was assessed by immunohistochemistry and Western blot analysis.

RESULTS

Significant modification of microbiota composition, characterized by a profound increase of commensals in the Firmicutes phylum and depletion of opportunistic organisms in the Proteobacteria phylum, was observed in FMT groups compared to LPS group. Furthermore, we identified a reconstituted bacterial community enriched in Firmicutes and depleted of Proteobacteria. In both FMT groups the diversity of the fecal microbiota and the microbiota composition were similar to SH group. LPS mice treated with FMT demonstrated a better spatial memory and less EEG abnormalities, significantly attenuated levels of IL-1β, IL-6, TNF-α, and decreased number of Iba-1 positive microglia in the cortex, but these beneficial effects of FMT were reversed by VGX.

CONCLUSIONS

FMT can change intestinal microbiota in sepsis patients, and vagus nerve is a key mediator between intestinal microbiota and SAE. These findings suggest that FMT and vagus nerve are potential therapy targets for treating SAE.

Branched-chain amino acid supplementation restores reduced insulinotropic activity of a low-protein diet through the vagus nerve in rats

Background

Previously, we reported that a low-protein diet significantly reduced insulin secretion in response to feeding within 1 h in rats, suggesting that the insulinotropic effect of dietary protein plays an important role in maintaining normal insulin release. The current study aimed to elucidate whether deficiency of certain amino acids could diminish the insulinotropic activity and to investigate whether reduced insulin secretion in response to a low-protein diet is restored by supplementation with certain amino acids.

Methods

First, we fed male Wistar rats (5–6 rats per group) with diets deficient in every single amino acid or three branched-chain amino acids (BCAAs); within 1–2 h after the onset of feeding, we measured the plasma insulin levels by using an enzyme-linked immunosorbent assay (ELISA). As insulin secretion was reduced in BCAA-deficient groups, we fed low-protein diets supplemented with BCAAs to assess whether the reduced insulin secretion was restored. In addition, we treated the pancreatic beta cell line MIN6 with BCAAs to investigate the direct insulinotropic activity on beta cells. Lastly, we investigated the effect of the three BCAAs on sham-operated or vagotomized rats to assess involvement of the vagus nerve in restoration of the insulinotropic activity.

Results

Feeding a low-protein diet reduced essential amino acid concentrations in the plasma during an absorptive state, suggesting that reduced plasma amino acid levels can be an initial signal of protein deficiency. In normal rats, insulin secretion was reduced when leucine, valine, or three BCAAs were deficient. Insulin secretion was restored to normal levels by supplementation of the low-protein diet with three BCAAs, but not by supplementation with any single BCAA. In MIN6 cells, each BCAA alone stimulated insulin secretion but the three BCAAs did not show a synergistic stimulatory effect. The three BCAAs showed a synergistic stimulatory effect in sham-operated rats but failed to stimulate insulin secretion in vagotomized rats.

Conclusions

Leucine and valine play a role in maintaining normal insulin release by directly stimulating beta cells, and supplementation with the three BCAAs is sufficient to compensate for the reduced insulinotropic activity of the low-protein diet, through the vagus nerve.

Hepatic vagus nerve regulates Kupffer cell activation via α7 nicotinic acetylcholine receptor in nonalcoholic steatohepatitis

BACKGROUND

Nonalcoholic fatty liver disease ranges from simple steatosis to nonalcoholic steatohepatitis (NASH). Kupffer cells play a central role in promoting hepatic inflammation, which leads to the development of NASH. We investigated the anti-inflammatory effect of hepatic vagus-mediated stimulation of the α7 nicotinic acetylcholine receptor (α7nAChR) on Kupffer cells in NASH pathogenesis.

METHODS

Wild-type (WT) mice undergoing hepatic vagotomy (HV) were fed a methionine- and choline-deficient (MCD) diet for 1 week. α7nAChR knockout (α7KO) chimeric mice were generated by transplanting α7KO bone marrow cells into irradiated and Kupffer cell-deleted WT recipients. Kupffer cells were isolated from WT mice and treated with α7nAChR agonist under stimulation by lipopolysaccharide and/or palmitic acid.

RESULTS

HV aggravated MCD diet-induced NASH in both steatosis and inflammation. The hepatic inflammatory response, including the upregulation of tumor necrosis factor alpha (TNFα), interleukin (IL)-12, and monocyte chemoattractant protein 1 (MCP-1), was accelerated in HV mice, accompanied by the downregulation of PPARα pathway genes. Kupffer cells were highly activated via the phosphorylation and nuclear translocation of nuclear factor-kappa B (NF-κB) in MCD diet-fed HV mice. The α7nAchR agonist suppressed the inflammatory response of primary Kupffer cells induced by lipopolysaccharide and palmitic acid by attenuating the NF-κB cascade. α7KO chimeric mice fed an MCD diet for 1 week developed advanced NASH with highly activated Kupffer cells. The hepatic expression of TNFα, IL-12, and MCP-1 was upregulated in α7KO chimeric mice, accompanied by abnormal lipid metabolism.

CONCLUSIONS

Hepatic vagus activity regulates the inflammatory response of Kupffer cells via α7nAChR in NASH development.

Evidence of the role of the vagal nerves as a monitor in the gastrointestinal-renal axis of natriuresis in human: Effects of vagotomy

This study aimed to investigate the mechanism of gastrointestinal regulation of natriuresis. Sixteen subjects without (group I) and sixteen subjects with a truncal vagotomy (group II), were given a daily diet of 18mmol of sodium for 5days (D1-D5). The sodium deficit for this period was calculated for each subject and on the morning of day-6 (D6), their cumulative deficit (E) was given as 3% NaCl. In both groups the subjects were divided to receive the hypertonic saline either orally (Ior, IIor) or intravenously (Iiv, IIiv). During the period of low sodium diet when compared to group II subjects of group I (1) had a greater weight loss (p<0.005), (2) demonstrated a larger drop in pulse pressure (p<0.005), (3) achieved a positive sodium equilibrium later (D5 vs D4) and (4) developed a greater sodium deficit (p<0.005). During the two 12h periods of D6, both Ior and Iiv exhibited greater natriuresis during the first 12h period (p<0.0001) whereas both IIor and IIiv did so during the second 12h period (p<0.0001). On D6 Ior excreted the greatest percentage of E (E%; 35.63%±3.12%, p<0.0001) compared to Iiv (17.06%±1.78%), IIor (16.03%±3.54%) and IIiv (15.39%±2.77%) whereas E% was not different between the other subgroups. These results indicate that the differential natriuresis between oral and intravenous sodium loading in previously sodium deprived subjects, is due to a mechanism in which the vagal nerves play a significant role as part of neural reflex or via a natriuretic hormone.

The impact of bilateral vagotomy on the physostigmine-induced airway constriction in ferrets

Vagal innervations have a great role in the respiratory function and are the main route of signal transmission from respiratory neural centers into the trachea and others conducting airways. We have investigated the role of central mechanisms related to vagal neural pathways and the cholinergic outflow in tracheobronchial smooth muscle tone and lung mechanics parameters. Parameters of lung mechanics such as lung resistance (RL), dynamic compliance (Cdyn) and pressure in bypassed tracheal segment (Ptseg) were measured before and after vagotomy and asphyxia test. Before vagotomy (BV), the control measurements were obtained and physostigmine was administered systemically, in increasing dose 10, 40 and 100μg/kg body weight (bw) with 15min interval between doses. After vagotomy (AV), administration of physostigmine with the same doses as BV has been done and the asphyxia challenge was conducted as per study protocol. The values of Ptseg and RL after physostigmine administration, BV vs. AV, respectively, at maximal dose of 100μg/kg bw were 32.5±3.3cm H₂O, and 10.6±1.5cm H₂O (p<0.0001); 0.16±0.04cm H₂O/mL/s, and 0.067±0.006cm H₂O/mL/s AV (P<0.05). The Cydn values were affected after physostigmine administration only at the lowest dose of 10μg/kg bw, and BV was 0.75±0.05mL/cm H₂O vs. 0.53±0.04mL/cm H₂O AV (P<0.004). Cholinergic outflow produced increases in tracheal tone, lung resistance and a decrease in dynamic compliance before, but not after vagotomy. Our results show the high impact of central neuronal mechanism in parameters of lung mechanics and respiration. This study indicates that vagal nerves have a crucial role, in the transmission of impulses initiated from central nervous system, in regulating the respiration by contraction or relaxation of airway smooth muscle tone.

Modulation of innate immune response by the vagus nerve in experimental hepatic amebiasis in rats

The parasympathetic nervous system has a crucial role in immunomodulation of the vagus nerve, its structure provides a pathogen detection system, and a negative feedback to the immune system after the pathogenic agent has been eliminated. Amebiasis is a disease caused by the protozoan parasite Entamoeba histolytica, considered the third leading cause of death in the world. The rats are used as a natural resistance model to amoebic liver infection. The aim of this study is to analyze the interaction of Entamoeba histolytica with neutrophils, macrophages, and NK cells in livers of intact and vagotomized rats. Six groups were studied (n = 4): Intact (I), Intact + amoeba (IA), Sham (S), Sham + amoeba (SA), Vagotomized (V) and Vagotomized + amoeba (VA). Animals were sacrificed at 8 h post-inoculation of E. histolytica. Then, livers were obtained and fixed in 4% paraformaldehyde. Tissue liver slides were stained with H-E, PAS and Masson. The best development time for E. histolytica infection was at 8 h. Amoeba was identified with a monoclonal anti-220 kDa E. histolytica lectin. Neutrophils (N) were identified with rabbit anti-human neutrophil myeloperoxidase, macrophages (Mɸ) with anti-CD68 antibody and NK cells (NK) with anti-NK. Stomachs weight and liver glycogen were higher in V. Collagen increased in VA, whereas vascular and neutrophilic areas were decreased. There were fewer N, Mɸ, NK around the amoeba in the following order IA > SA > VA (p < 0.05 between IA and VA). In conclusion, these results suggest that the absence of parasympathetic innervation affects the participation of neutrophils, macrophages and NK cells in the innate immune response, apparently by parasympathetic inhibition on the cellular functions and probably for participation in sympathetic activity.

Vagotomy and subsequent development of diabetes - A nested case-control study

BACKGROUND

Vagal signaling is involved in gastric emptying and the secretion and effect of a number of hormones regulating gluco-metabolic processes and, thus, crucial for metabolic homeostasis.

PURPOSE

We hypothesized that vagotomy would increase the risk of developing type 2 diabetes and examined the association between vagotomy and subsequent development of diabetes.

METHODS

A nested case-control study was conducted with information on cases and controls from the Danish National Patient Registry. Cases included individuals with a diabetes diagnosis subsequent (>12months) to the first registration of vagotomy and/or upper gastrointestinal disease in the period 1977-2011. Controls had no subsequent diagnosis of diabetes and were matched by incidence density sampling, age and gender. Logistic regression analyses were conducted.

RESULTS

501,724 diabetes patients and 1,375,567 matched controls were included in the analysis. Vagotomy was performed on 2772 individuals and 148,489 individuals had an upper gastrointestinal diagnosis. In this combined population, 30,902 were diagnosed with diabetes. The mean follow-up was 16years. The unadjusted odds ratio for developing diabetes following vagotomy was 0.64 (95% confidence interval (CI): 0.58-0.71) and did not change in an adjusted analysis (0.64, 95% CI: 0.58-0.70). When restricting the multivariate-adjusted analysis to patients with type 2 diabetes and type 1 diabetes, respectively, the multivariate odds ratios were 0.79 (95% CI: 0.70-0.89) and 0.75 (95% CI 0.53-1.08), respectively.

CONCLUSION

Vagotomy was associated with a significantly decreased risk of developing type 2 diabetes in a population of patients with upper gastrointestinal disease.

Effect of vagotomy on the activity of cardiac autonomic ganglia: Insight from left atrial high density frequency mapping

BACKGROUND

Both extrinsic and intrinsic cardiac autonomic nervous systems are important for initiation and maintenance of atrial fibrillation (AF). We aimed to evaluate the effect of vagotomy on the activity of cardiac autonomic ganglionated plexi (GP) and the change of dominant frequency (DF) distribution in the left atrium (LA) during AF.

METHODS

A mid-sternal thoracotomy was performed in 6 dogs. High frequency stimulation was applied to locate the GPs. There were four major LA GPs, which were located near the pulmonary vein ostia, and a superior vena cava-aorta (SVC-Ao) GP that was located near the superior vena cava-right atrial junction. Acetylcholine patch was applied on GPs to induce intrinsic vagal response. Vagal denervation was performed thereafter. An Ensite Array was deployed in the LA to record atrial signals before and after vagotomy during induced AF.

RESULTS

The LA mean DF values (8.2±0.1 vs. 7.6±0.1Hz, p=0.002) were higher during GP activation before than after vagotomy. The maximal DF distribution was located at the primary GPs and the nearby secondary GPs during LA GPs activation and at the LA septum and right superior pulmonary vein during SVC-Ao GP activation before vagotomy. After vagotomy, the maximal DF distribution shifted to non-GP LA sites during activation of the GPs.

CONCLUSIONS

The findings suggest the important role of the extrinsic neural input in the activation and interaction of the intrinsic cardiac autonomic activity during cholinergic AF, whereas the non-GP LA sites were responsible for the AF induced without the physiological extrinsic neural input.

The role of autonomic efferents and uncoupling protein 1 in the glucose-lowering effect of leptin therapy

Objective

Leptin reverses hyperglycemia in rodent models of type 1 diabetes (T1D). Direct application of leptin to the brain can lower blood glucose in diabetic rodents, and can activate autonomic efferents and non-shivering thermogenesis in brown adipose tissue (BAT). We investigated whether leptin reverses hyperglycemia through a mechanism that requires autonomic innervation, or uncoupling protein 1 (UCP1)-mediated thermogenesis.

Methods

To examine the role of parasympathetic and sympathetic efferents in the glucose-lowering action of leptin, mice with a subdiaphragmatic vagotomy or 6-hydroxydopamine induced chemical sympathectomy were injected with streptozotocin (STZ) to induce hyperglycemia, and subsequently leptin treated. To test whether the glucose-lowering action of leptin requires activation of UCP1-mediated thermogenesis in BAT, we administered leptin in STZ-diabetic Ucp1 knockout (Ucp1^−/−) mice and wildtype controls.

Results

Leptin ameliorated STZ-induced hyperglycemia in both intact and vagotomised mice. Similarly, mice with a partial chemical sympathectomy did not have an attenuated response to leptin-mediated glucose lowering relative to sham controls, and showed intact leptin-induced Ucp1 expression in BAT. Although leptin activated BAT thermogenesis in STZ-diabetic mice, the anti-diabetic effect of leptin was not blunted in Ucp1^−/− mice.

Conclusions

These results suggest that leptin lowers blood glucose in insulin-deficient diabetes through a manner that does not require parasympathetic or sympathetic innervation, and thus imply that leptin lowers blood glucose through an alternative CNS-mediated mechanism or redundant target tissues. Furthermore, we conclude that the glucose lowering action of leptin is independent of UCP1-dependent thermogenesis.

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Leptin does not require vagal innervation to reverse hyperglycemia.

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Leptin therapy reverses hyperglycemia in mice with a partial chemical sympathectomy.

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Leptin reverses hyperglycemia independent of uncoupling protein 1.

Revision with Totally Hand-Sewn Gastrojejunostomy and Vagotomy for Refractory Marginal Ulcer after Laparoscopic Roux-en-Y Gastric Bypass

BACKGROUND

Marginal ulcer is not infrequent after laparoscopic Roux-en-Y gastric bypass and could result in undesirable complications, such as intractability, bleeding, or perforation. Those patients who failed medical therapy, regarded as refractory marginal ulcers, may be considered as candidates for revisional surgery. Herein, we make a video presentation of a laparoscopic revisional procedure for refractory marginal ulcer.

METHODS

A 29-year-old morbidly obese woman (initial body mass index 37.1 kg/m(2)), a non-smoker, presented with persistent epigastric pain 3 months after initial laparoscopic Roux-en-Y gastric bypass at another institution. After an exhaustive work-up there, only the gastroendoscopy revealed a marginal ulcer and she underwent medical treatment (proton pump inhibitor and sucralfate) for 3 months, but the patient's symptom aggravated and the serial gastroendoscopies still confirmed the marginal ulcer without obvious resolution after a total of 4 months proton pump inhibitor therapy, suggesting failure of medical treatment and intractability. Laparoscopic revisional procedure with totally hand-sewn gastrojejunostomy and vagotomy was performed to relieve her intractable condition.

RESULTS

The procedure took 130 min, without any intra-operative complications. Blood loss was 80 mL. The patient had an uneventful postoperative course, and the postoperative hospital stay was 3 days. She was relieved of her symptoms after this revisional surgery, and a subsequent gastroendoscopy 15 months later showed no marginal ulcers.

CONCLUSIONS

Though long-term follow-up is needed to draw a definite conclusion, totally hand-sewn gastrojejunostomy and vagotomy remains a practicable revisional procedure to relieve refractory marginal ulcers.

Effect of vagotomy on central nesfatin-1-induced decrease in gastric acid secretion

AIM: To observe the effect of gastric acid secretion decrease induced by intracerebroventricular (ICV) injection of nesfatin-1.

METHODS: Male Sprague-Dawley rats were randomly and equally divided into a control group and a nesfatin-1 group after implantation of an ICV cannula. The nesfatin-1 group was injected intracerebroventricularly with different concentrations of nesfatin-1, and the control group was treated with the same amount of distilled water (5 μL/rat). The volume of gastric secretion was measured and the amount of gastric acid was determined by titration with NaOH. H⁺/K⁺-ATPase mRNA expression was detected by real-time quantitative PCR. Activity of H⁺/K⁺-ATPase was determined indirectly by measuring K⁺-stimulated p-nitrophenyl phosphatase (pNPPase) activity. In another group of animals, rats were divided into a vagotomy and a sham group. The treatments and measurements were the same as above.

RESULTS: Intracerebroventricular infusion of nesfatin-1 significantly reduced gastric acid output, and the maximum inhibitory effect on gastric acid output was detected at a dose of 50 pmol/rat. Furthermore, nesfatin-1 decreased H⁺/K⁺-ATPase mRNA expression and activity in gastric mucosal tissue compared to the control group. The inhibitory action of nesfatin-1 on the acid output and H⁺/K⁺-ATPase expression and activity was abolished by vagotomy.

CONCLUSION: Nesfatin-1 injected intracerebroventricularly induces a dose-dependent decrease in gastric acid secretion in rats and the vagal nerve may be involved in the process of the effect of nesfatin-1.

Pancreatic polypeptide responses to isoglycemic oral and intravenous glucose in humans with and without intact vagal innervation

Secretion of pancreatic polypeptide (PP) from the pancreatic PP cells is controlled partly by vagal mechanisms. Release is stimulated by cephalic stimulation and enteral but not parenteral nutrients. Ambient glucose levels modulate circulating PP levels as hypoglycemia stimulates while hyperglycemia inhibits secretion. The glucose sensing mechanism has yet to be determined but may involve a vagal pathway. To investigate the role of enteral stimuli with or without intact vagal innervation, while controlling for the glucose excursion caused by the OGTT, we measured PP plasma levels by an in-house radioimmunoassay in truncally vagotomized (n=15) and control individuals (n=10). All participants were studied by a 50-g oral glucose tolerance test (OGTT) with or without dipeptidyl peptidase 4 (DPP-4) inhibition (DPP-4i) and a subsequent isoglycemic intravenous glucose infusion (IGII). We included measurements from the DPP-4i day to determine the potential effect of DPP-4-cleaved peptides on PP secretion. In both vagotomized and controls, oral glucose elicited PP secretion. In controls, but not in the vagotomized participants, intravenous glucose significantly inhibited PP secretion suggesting a vagal glucose sensing mechanism dependent on intact vagal innervation. DPP-4i did not alter PP secretion in either group.

Right and left vagus nerves regulate breathing by multiplicative interaction

Although it has been recognized for more than a century, we still do not know how the two vagus nerves interact to produce Hering-Breuer reflex. In the current study, we tested the hypothesis that the vagus nerves interact via a multiplicative effect. We examined the Hering-Breuer reflex before and after unilateral (first) and then bilateral (second) vagotomies in the mouse. The lung is mostly innervated homolaterally. Since the right and left lung formed 68.2 and 31.8% of total lung weight, if the interaction is mediated by an additive mechanism, unilateral vagotomy would remove the reflex effects by 68.2 and 31.8%, respectively. Instead, unilateral vagotomy removed 85.4 ± 6.0% (>68.2%) or 52.8 ± 3.7% (>31.8%) of the reflex effects on respiratory rate (n=9, P<0.05); and removed 79.1 ± 4.5% (>68.2%) or 59.3 ± 9.1% (>31.8%) of the effect on expiratory pause induced by lung inflation (n=12, P<0.05). Since the first vagotomy removes more reflex effect than the second vagotomy, we conclude that the two vagus nerves exert their Hering-Breuer reflex effects by a multiplicative effect.

One-day high-fat diet induces inflammation in the nodose ganglion and hypothalamus of mice

A high-fat diet (HFD) induces inflammation in systemic organs including the hypothalamus, resulting in obesity and diabetes. The vagus nerve connects the visceral organs and central nervous system, and the gastric-derived orexigenic peptide ghrelin transmits its starvation signals to the hypothalamus via the vagal afferent nerve. Here we investigated the inflammatory response in vagal afferent neurons and the hypothalamus in mice following one day of HFD feeding. This treatment increased the number of macrophages/microglia in the nodose ganglion and hypothalamus. Furthermore, one-day HFD induced expression of Toll-like receptor 4 in the goblet cells of the colon and upregulated mRNA expressions of the proinflammatory biomarkers Emr1, Iba1, Il6, and Tnfα in the nodose ganglion and hypothalamus. Both subcutaneous administration of ghrelin and celiac vagotomy reduced HFD-induced inflammation in these tissues. HFD intake triggered inflammatory responses in the gut, nodose ganglion, and subsequently in the hypothalamus within 24 h. These findings suggest that the vagal afferent nerve may transfer gut-derived inflammatory signals to the hypothalamus via the nodose ganglion, and that ghrelin may protect against HFD-induced inflammation.

Vagotomy reverses established allergen-induced airway hyperreactivity to methacholine in the mouse

We evaluated the role of vagal reflexes in a mouse model of allergen-induced airway hyperreactivity. Mice were actively sensitized to ovalbumin then exposed to the allergen via inhalation. Prior to ovalbumin inhalation, mice also received intratracheally-instilled particulate matter in order to boost the allergic response. In control mice, methacholine (i.v.) caused a dose-dependent increase in respiratory tract resistance (RT) that only modestly decreased if the vagi were severed bilaterally just prior to the methacholine challenge. Sensitized and challenged mice, however, manifested an airway reactivity increase that was abolished by severing the vagi prior to methacholine challenge. In an innervated ex vivo mouse lung model, methacholine selectively evoked action potential discharge in a subset of distension-sensitive A-fibers. These data support the hypothesis that the major component of the increased airway reactivity in inflamed mice is due to a vagal reflex initiated by activation of afferent fibers, even in response to a direct (i.e., smooth muscle)-acting muscarinic agonist.

Indomethacin-induced gastric ulceration in rats: Protective roles of Spondias mombin and Ficus exasperata

This study investigated the quantitative polyphenolic constituents and gastroprotective effects of aqueous leaf extracts of Spondias mombin and Ficus exasperata against indomethacin-induced gastric ulcer in rats. Ulceration was induced by a single oral administration of indomethacin (30 mg/kg body weight). Wistar rats were pretreated with esomeprazole (reference drug) at a dose of 20 mg/kg body weight, S. mombin or F. exasperata at 100 and 200 mg/kg body weight once daily for 21 days prior to ulcer induction. At the end of the experiment, gastric secretions and antioxidant parameters were evaluated. We observed that the significantly increased (p < 0.05) ulcer index, gastric volume, malondialdehyde level and pepsin activity were effectively reduced following treatment with S. mombin and F. exasperata. The extracts also markedly attenuated the reduced activity of superoxide dismutase as well as pH and mucin content in the ulcerated rats. These findings are indicative of gastroprotective and antioxidative potentials of the extracts which is also evident in the degree of % inhibition against ulceration. The available data in this study suggest that the extracts of S. mombin and F. exasperata proved to be capable of ameliorating indomethacin-induced gastric ulceration and the probable mechanisms are via antioxidative and proton pump inhibition.

Vagal afferent control of abdominal expiratory activity in response to hypoxia and hypercapnia in rats

In the present study, we tested the hypothesis that vagal afferent information modulates the pattern of expiratory response to hypercapnia and hypoxia. Simultaneous recordings of airflow, diaphragmatic (DIA) and oblique abdominal muscle (ABD) activities were performed in anesthetized (urethane, 1.2g/kg), tracheostomized, spontaneously breathing male Wistar rats (290-320g, n=12). The animals were exposed to hypercapnia (7 and 10% CO2 for 5min) and hypoxia (7% O2 for 1min) before and after bilateral vagotomy. We verified that the percentage increase in DIA burst amplitude elicited by hypercapnia and hypoxia episodes was similar between intact and vagotomized rats (P>0.05). In contrast, hypercapnia and hypoxia promoted a marked increase in ABD activity in vagotomized, but not in intact rats (P<0.01). These amplified expiratory motor changes after vagotomy were associated with enhanced expiratory airflow (P<0.01) and augmented tidal volume responses (P<0.01). Our data indicates that, in anesthetized conditions, the removal of peripheral afferent inputs facilitates the processing of active expiration in response to hypercapnia and hypoxia in rats.

Vagotomy reveals the importance of the imidazoline receptors in the cardiovascular effects of marsanidine and 7-ME-marsanidine in rats

BACKGROUND

The recently synthesized novel benzazole derivates - marsanidine (1-[(imidazolidin-2-yl)imino]indazole) and 7-Me-marsanidine (1-[(imidazolidin-2-yl)imino]-7-methylindazole) display promising effects on the circulatory system. We previously indicated that i.v. administration of both compounds decreased the mean arterial blood pressure (MAP) and heart rate (HR) in rats. The cardiovascular effect of the tested compounds may consist not only in inhibiting the sympathetic, but also in activating the parasympathetic pathways related to vagal nerves. Present experiments were performed to determine how vagotomy, with or without an α2 adrenoreceptor blockade, may affect hypotensive and HR limiting actions of marsanidine and 7-Me-marsanidine.

METHODS

Both compounds were infused i.v. (10 μg/kg b.w.) to anesthetized rats, half of which underwent vagotomy. Half the intact, and half the vagotomised rats received RX821002, an α2 adrenorereceptor inhibitor. MAP and HR were monitored directly throughout the experiment.

RESULTS

Vagotomy enhanced hypotension observed after marsanidine administration. The α2 adrenergic blockade abolished the action of marsanidine in both the intact and vagotomised rats. Vagotomy did not affect the 7-Me-marsanidine-induced decrease of MAP or HR. However, it abolished the reducing effect of the α2 adrenergic receptor blockade on the hypotension triggered by 7-Me-marsanidine.

CONCLUSION

The results show that although cardiovascular effects of marsanidine and 7-Me-marsanidine are not mediated by the vagal nerves, vagotomy enhanced sensitivity of the sympathetic pathways for the tested compounds. While the action of marsanidine in vagotomised and intact rats may be explained by activation of the α2 adrenoreceptors, the effects of 7-Me-marsanidine seem to be α2 adrenoreceptor-independent. It seems likely that activation of I1 imidazoline receptors could mediate the observed effects.

A relic or still relevant: the narrowing role for vagotomy in the treatment of peptic ulcer disease

BACKGROUND

Given the rise of medical treatment for peptic ulcer disease (PUD), surgical treatment is necessary only in select cases and emergencies. The authors assess the current relevance of surgical vagotomy to treat PUD and its complications.

DATA SOURCES

Although historically significant, selective and highly selective vagotomy is very technically challenging, and highly selective vagotomy has a relatively narrow indication and high recurrence rates. Vagotomy and gastrectomy is associated with significant side effects. Two types of vagotomy remain relevant, within a narrow scope. Truncal vagotomy and pyloroplasty is safe and efficacious through a laparoscopic approach in certain emergent cases. Vagotomy and Roux-en-Y gastrojejunostomy can be used to treat severe PUD refractory to medical management.

CONCLUSIONS

The role of vagotomy in the management of PUD has a rich history but predated pharmacologic control of acid and understanding of the role of Helicobacter pylori in the disease. Thus, the current role of vagotomy is significantly limited. Specifically, the emergent use of truncal vagotomy is warranted for patients who are either resistant or allergic to proton pump inhibitors.

Vagotomy attenuates brain cytokines and sleep induced by peripherally administered tumor necrosis factor-α and lipopolysaccharide in mice

STUDY OBJECTIVE

Systemic tumor necrosis factor-α (TNF-α) is linked to sleep and sleep altering pathologies in humans. Evidence from animals indicates that systemic and brain TNF-α have a role in regulating sleep. In animals, TNF-α or lipopolysaccharide (LPS) enhance brain pro-inflammatory cytokine expression and sleep after central or peripheral administration. Vagotomy blocks enhanced sleep induced by systemic TNF-α and LPS in rats, suggesting that vagal afferent stimulation by TNF-α enhances pro-inflammatory cytokines in sleep-related brain areas. However, the effects of systemic TNF-α on brain cytokine expression and mouse sleep remain unknown.

DESIGN

We investigated the role of vagal afferents on brain cytokines and sleep after systemically applied TNF-α or LPS in mice.

MEASUREMENTS AND RESULTS

Spontaneous sleep was similar in vagotomized and sham-operated controls. Vagotomy attenuated TNF-α- and LPS-enhanced non-rapid eye movement sleep (NREMS); these effects were more evident after lower doses of these substances. Vagotomy did not affect rapid eye movement sleep responses to these substances. NREMS electroencephalogram delta power (0.5-4 Hz range) was suppressed after peripheral TNF-α or LPS injections, although vagotomy did not affect these responses. Compared to sham-operated controls, vagotomy did not affect liver cytokines. However, vagotomy attenuated interleukin-1 beta (IL-1β) and TNF-α mRNA brain levels after TNF-α, but not after LPS, compared to the sham-operated controls.

CONCLUSIONS

We conclude that vagal afferents mediate peripheral TNF-α-induced brain TNF-α and IL-1β mRNA expressions to affect sleep. We also conclude that vagal afferents alter sleep induced by peripheral pro-inflammatory stimuli in mice similar to those occurring in other species.

Trends in Peptic Ulcer Disease and the Identification of Helicobacter Pylori as a Causative Organism: Population-based Estimates from the US Nationwide Inpatient Sample

Background:

Peptic ulcer disease can lead to serious complications including massive hemorrhage or bowel perforation. The modern treatment of peptic ulcer disease has transitioned from the control of gastric acid secretion to include antibiotic therapy in light of the identification of Helicobacter pylori as a causative infectious organism. We sought to determine trends related to this discovery by using a national database.

Materials and Methods:

Patient discharges with peptic ulcer disease and associated sequelae were queried from the Nationwide Inpatient Sample, 1993 to 2007, under the auspices of a data user agreement. To account for the Nationwide Inpatient Sample weighting schema, design-adjusted analyses were used. Standard error was calculated using SUDAAN software (Research Triangle International, NC, USA).

Results:

Decreases in the incidences of gastrointestinal perforation, gastrointestinal hemorrhage, and surgical procedures most specific to peptic ulcer disease were statistically significant over the study period [range of P value (two tailed) = 0.000 – 0.00353; significant at P < 0.001 to < 0.01]. The incidence of H. pylori rose dramatically, peaking at an estimated 97,823 cases in 1998 [SE = 3155; 95% CI = 6,184]. Since that time it has decreased and then stabilized.

Conclusions:

The identification of H. pylori as the causative agent in the majority of peptic ulcer disease has revolutionized the understanding and management of the disease. Medical conditions and surgical procedures associated with end-stage peptic ulcer disease have significantly decreased according to analysis of selected index categories. Resident physician education objectives may need to be modified in light of these trends.

Review Criteria:

We reviewed patients with peptic ulcer disease. The database used was the Nationwide Inpatient Sample, 1993 to 2007.

Message for the Clinic:

Medical therapy has resulted in decreased morbidity from H. pylori infection as it is the causative agent in the majority of peptic ulcer disease. Aggressive screening and treatment of this infection will lead to further reduction in morbidity.

Ghrelin and gastric acid secretion

Ghrelin, a novel growth hormone-releasing peptide, was originally isolated from rat and human stomach. Ghrelin has been known to increase the secretion of growth hormone (GH), food intake, and body weight gain when administered peripherally or centrally. Ghrelin is also known to stimulate the gastric motility and the secretion of gastric acid. In the previous studies, the action of ghrelin on acid secretion was shown to be as strong as that of histamine and gastrin in in-vivo experiment. In the studies, the mechanism for the action of ghrelin was also investigated. It was shown that vagotomy completely inhibited the action of ghrelin on the secretion of gastric acid suggesting that vagal nerve is involved in the mechanism for the action of ghrelin on acid secretion. As famotidine did not inhibit ghrelin-induced acid secretion in the study by Masuda et al, they concluded that histamine was not involved in the action of ghrelin on acid secretion. However, we have shown that famotidine completely inhibited ghrelin-induced acid secretion and histidine decarboxylase (HDC) mRNA was increased in gastric mucosa by ghrelin injection which is inhibited by vagotomy Our results indicate that histamine is involved in the action of ghrelin on acid secretion. Furthermore synergistic action of gastrin and ghrelin on gastric acid secretion was shown. Although gastrin has important roles in postprandial secretion of gastric acid, ghrelin may be related to acid secretion during fasting period or at night. However, further studies are needed to elucidate the physiological role of ghrelin in acid secretion.

Effect of exogenous motilin in amygdaloid nucleus on gastric motility and its underlying mechanism in rats

AIM: To investigate the effect of motilin microinjection into bilateral basomedial amygdaloid nucleus (BMA) on the gastric motility in rats, and explore its underlying mechanism.

METHODS: Forty male Wistar rats were used for four sets of experiments (Exp). Exp 1: Animals received bilateral injections of motilin (MT, 1 mg/side) or normal saline (NS, 0.5 mL/side) into BMA, and both intragastric pressure (IGP) and gastric motility frequency (GMF) were recorded to estimate the gastric motility (n = 14). Exp 2: Pretreatment of vagotomy was carried out in 12 rats, and then MT or NS was injected into BMA as in Exp1. Exp3: Sixty minutes after MT or NS injection into BMA, c-Fos protein expression was detected in the paraventricular nucleus (PVA, n = 7). Exp 4: Motilin contents were measured in five brain areas (hypothalamus, midbrain, pons, medulla, and pituitary gland), using radioimmunoassay (RIA) method (n = 7).

RESULTS: Exogenous motilin in BMA enhanced the gastric motility in rats, and this action lasted about 15 min. At the 10^th, 15^th, 20^th, 25^th min after motilin injection, the changes of IGP percentage were 19.7% ± 6.5%(P = 0.023), 62.9% ± 4.7% (P < 0.01), 45.1% ± 7.9% (P < 0.01), 29.3% ± 10.3% (P = 0.029). The changes of GMF percentage at the 15^th, 20^th min were 36.7% ± 8.5% (P < 0.01) and 19.5% ± 6.0% (P = 0.015), respectively. No obvious changes in both IGP and GMF were observed in normal saline controls. Pretreatment of subdiaphragmal vagotomy abolished the enhanced gastric motility induced by motilin injection. Motilin injection into bilateral BMA induced increased numbers of c-Fos positive cells in PVN, as compared with the saline control (53.4 ± 8.9 vs 22.5 ± 5.2, P < 0.01). Among the five tested brain areas, the highest motilin level was found in the hypothalamus area (74.3 ± 19.6 mg/kg). The motilin contents in the other four areas ranged from 7.8 ± 2.2 mg/kg to 17.3 ± 6.6 mg/kg.

CONCLUSION: Exogenous motilin in BMA can enhance the gastric motility in rats, which might rely on the amygdala-hypothalamus and brain stem-vagus pathway.

Omeprazole maintenance therapy prevents recurrent ulcer bleeding after surgery for duodenal ulcer

AIM: To evaluate the omeprazole maintenance therapy in patients with recurrent ulcer bleeding after surgery for duodenal ulcer.

METHODS: We studied 15 consecutive patients with recurrent ulcer bleeding after surgery for duodenal ulcer. Omeprazole (20 mg/d) maintenance therapy was given after ulcer healing. In addition to clinical follow-up, ambulatory 24-h gastric pH assay was performed before and during omeprazole therapy in those patients and controls with previous duodenal ulcer surgery but no ulcer recurrence.

RESULTS: All the 15 ulcers were healed after being treated with omeprazole (40 mg/d) for 2 mo. Eleven patients with two (1-9) episodes of recurrent ulcer bleeding completed the follow-up (43, 12-72 mo). None of them had a bleeding episode while on omeprazole. One patient discontinued the therapy and had recurrent bleeding. The median 24-h fraction time of gastric pH <4 in patients was 80, 46-95%, and was reduced to 32, 13-70% by omeprazole (P = 0.002).

CONCLUSION: Long-term maintenance therapy with omeprazole (20 mg/day) is effective in preventing recurrent ulcer bleeding.

ASSESSMENT OF VAGOTOMY BY POST-PRANDIAL ALKALINE TIDE

The effect of vagotomy on the post-prandial alkaline tide was assessed by measuring the fasting and postprandial urinary pH before and after vagotomy in 50 cases of chronic duodenal ulcer treated by posterior truncal vagotomy or gastrojejunostomy or pyloroplasty. Results showed that post-prandial urinary pH fell after vagotomy confirming the completeness of vagotomy. This test is safe, reliable, noninvasive and a simpler bedside procedure as compared to the conventional Hollander's insulin test.