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sentire GI-tract, and RT-PCR revealed that 11 βHSD1 expression was significantly elevatedafter fasting in ileum (C=0.6±0.1, F=1.5±0.2, RF=1.1±0.1, p,0.01). Moreover, tissues incu-bated in CORT for 20h showed a significant increase in 11βHSD1mRNA expression (1.6±0.2vs. 2.9±0.5, p,0.05). Next, the effect of CORT on myenteric neuronal networks wasinvestigated. We found that electrical stimulation induced a significantly higher Ca2+ tran-sient in synapses pre-incubated with CORT (ΔF/F0: 11±0.2 vs. 12±0.4%, p,0.01). Videoorgan bath experiments showed a significant increase (p,0.05) in synchronization of sponta-neous contractions occurring in CORT-incubated ileum. Conclusion:We show that 11βHSD1is expressed in a subset of enteric neurons and that its expression is under positive feedbackcontrol of CORT. In addition, CORT levels increase after fasting and 11 βHSD1 expressionchanges depending on the feeding conditions. Since CORT itself increases synaptic Ca2+signaling and synchronizes intestinal contractile patterns, we conclude that 11 βHSD1 servesas a molecular link between food intake and ENS activity. Further research will be neededto investigate whether 11βHSD1 could be a target for modulating ENS function.

392

Inhibitory Effect of Serum From Obese Mice on Vagal Afferent Neurons,Possible Role for HyperleptinemiaSung Jin Park, Michael J. Beyak

Work by our lab and others has demonstrated that diet induced obesity impairs responsesto satiety stimuli in vagal afferent neurons. We found that both GI projecting and non-GIprojecting neurons were similarly affected. Therefore we hypothesized that circulating factorsmay play a role. Therefore we set out to determine the effects of circulating factors presentin serum from obese mice on the excitability of vagal afferents. Methods: Mice were feddiets composed of 60% kCal from fat (obese) or 10% (lean) for 12 weeks. At 12 weeksserum was collected. Leptin levels were measured by ELISA. Nodose ganglion neurons fromcontrol mice were harvested, and incubated overnight with lean or obese mouse serum.Current clamp studies were performed and excitability of the neurons assessed. To assessthe possible role of leptin, LepR deficient db/db mice were used. Results: 60% fat fed animalswere obese and hyperleptinemic. Serum from obese mice increased rheobase (32.7 ± 3.8pA (n=15, 10%) vs 78.6 ± 16.1 pA (n=14, 60%, p,0.02, p,0.05)), decreased input resistance(471.8 ± 39.1 M (n=15, 10%) vs 345.6 ± 45.7 M V (n=14, 60%, p,0.05)) and reducednumber of action potentials at twice rheobase (4.0 ± 0.6 (n=15, 10%) vs 1.5 ± 0.2 (n=14,60%, p,0.05)). To determine the possible role of leptin in these changes we incubatedneurons with 100nM leptin overnight. Leptin treatment significantly increased rheobase(52.3 ± 7.8 pA (n=13, control) vs 100.8 ± 18.6 pA (n=12, Leptin) ) and reduced actionpotential number (3.7 ± 0.5 (n=13, control) vs 1.6 ± 0.3 (n=12, Leptin, p ,0.05). Leptinincubation also significantly inhibited the number of neurons responding to CCK and 5-HT (assessed by calcium imaging) In neurons from db/db mice, there were no significantdifferences in the effect ot 10% vs. 60% serum (p ,0.05 rheobase, action potentials, inputresistance). Conclusion: Circulating factors present in obese mouse serum inhibit excitabilityof vagal afferents. This effect is not seen in leptin receptor deficient neurons. Leptin canreproduce some of these effects, suggesting a possible role for hyperleptinemia in thesechanges.

393

Role of the Vagus Nerve in the Gut-Brain Axis Revealed by Stimulation andBlockade of the Gastric Vagus NerveHelene Johannessen, David Revesz, Yosuke Kodama, Nikki Cassie, Karolina P. Skibicka,Robert Lyle, Paulo Jorge Bettencourt Girão, Miroljub Popovic, Menno Witter, PerryBarrett, Suzanne L. Dickson, Koji Takeuchi, Baard Kulseng, Thorleif Thorlin, Elinor Ben-Menachem, Chun-Mei Zhao, Duan Chen

Background/aim: Vagal communication between the gut and brain is involved in the controlof food intake, but our understanding of its role in this and other effects is limited. Herewe sought to determine the consequences of gastric vagus nerve stimulation and blockadeon several unexplored neurobiological (behavioral and/or molecular) endpoints, includingthose linked to eating behavior but also to cognition/Alzheimer's disease. Methods: Ratsreceived vagus nerve stimulation at the site of the subdiaphragmatic trunks by an electricaldevice (stVNS) or vagal nerve (cholinergic) blockade in the gastric antrum by botulinumneurotoxin-A injection (Botox). In addition, muscarinic M3 receptor knockout mice wereexamined. Gene expression was analyzed in relevant brain areas by in situ hybridization,low density array and RNA-Seq. Gastric acid secretion and gut hormones were analyzed.Eating behavior and object recognition memory were analyzed by comprehensive laboratoryanimal monitoring system and the Can test, respectively. Results: Short-term stVNS (48 h)increased gene expression for orexigenic neuropeptides including neuropeptide Y (NPY)and agouti-related peptide (AgRP) in the arcuate nucleus (ARC) and NPY in the dorsomedialnuclei of hypothalamus, but was without effects on basal or pentagastrin-stimulated gastricacid secretion, food intake and eating behavior. Long-term stVNS (2 months) increased geneexpression for NPY and forkhead box protein A2 in the hypothalamus, and leptin and CCK2receptors, interleukin-1β, tumor necrosis factor and transforming growth factor β1 in thehindbrain, and the number of ghrelin-immunoreactive cells in the stomach. Paradoxically,the satiety ratio was increased, the food intake and body weight reduced. In the hippocampus,stVNS-induced differentially expressed genes were involved in the signaling pathways ofeating behavior, cholinergic, serotonergic, GABAergic and dopaminergic synapses, and Alzh-erimer's disease. The object recognition memory was improved by stVNS. Botox treatmenthad initially no effects on NPY, AgRP and pro-opiomelanocortin in the hypothalamus (at48 h), but increased the satiety ratio and reduced the food intake and body weight (at 1week). At 2 months after starting Botox treatment, ARC NPY expression was upregulateddespite the fact that food intake and body weight were still reduced. M3 receptor knockoutmice with upregulated hypothalamic AgRP expression had a lean phenotype with reducedfood intake and increased energy expenditure. Conclusions: In this study, we found thatthe gastric vagus nerve might regulate food intake independent of hypothalamic appetite-regulating peptides. Our findings also have potential therapeutic relevance for targeting thegastric vagus nerve (via stVNS or Botox) on the treatment of obesity, anxiety/eating disordersand even Alzheimer's disease.

S-76AGA Abstracts

394

Effects of a DDP-4 Inhibitor, Vildagliptin, on Intragastric Pressure andSatiation in HumansAlessandra Rotondo, Christopher N. Andrews, Inge Depoortere, Jan F. Tack

Glucagon-like peptides (GLP) 1 and 2 act as gastrointestinal motility modulators and anorexi-genic hormones, and are inactivated by dipeptidyl peptidase-4 (DPP-4). Our aim was toinvestigate the effect of a DPP-4 inhibitor, vildagliptin, on gastric accommodation, measuredas the decrease in intragastric pressure (IGP) during nutrient intake, and on nutrient-inducedsatiation. Methods: 12 fasted healthy volunteers (HVs) were studied on two occasions afteran overnight fast, with at least one week interval. An infusion catheter and a manometryprobe were positioned in the proximal duodenum and a forearm vein was cannulated forblood collection. After a stabilization period HVs took vildagliptin (50 mg) or placebo orallyin a randomized blinded fashion. One hour later, intraduodenal infusion (IDI) of a nutrientdrink (ND) was started (1.5 kcal/mL; 0.5 mL/min) for 30 minutes. 60 minutes later,intragastric infusion (IGI) of a ND was started (60 mL/min). During IGI, HVs scored satiationon a 0-5 scale until maximum, when the IGI was stopped. Blood samples were collectedbefore the drug and before and after IGI. The effect of vildagliptin on IGP was evaluatedby comparing the area under the curve (AUC). ELISA test was used to measure GLPsplasmatic concentration. Data are represented as mean±SEM and compared by paired t-test.Results: Vildagliptin or placebo did not affect baseline IGP or sensations, and IGP was notaffected by IDI. During IGI, IGP decreased initially and increased thereafter. The maximumpressure drop during IGI, corresponding to the accommodation response, was 4.3±0.7mmHg after vildagliptin vs. 3.0±0.4 mmHg after placebo (p=0.08). Vildagliptin significantlyincreased the AUC during IGI vs placebo (40.0±6.8 mmHg*min vs. 25.2±7.0 mmHg*min,p=0.04), but had no effect on maximum tolerated nutrient volume (769±105 ml vs. 770±78ml, ns). GLP-1 levels increased significantly 1 hour after IDI (p=0.02) and after IGI (p ,0.05)for both placebo and vildagliptin (Table), however the GLP-1 increase after IDI was greaterwith vildagliptin than placebo (0.43±0.01 vs 0.31±0.03, p=0.049). GLP-2 plasma levelswere not significantly affected by nutritional state or vildagliptin treatment. Conclusions:Vildagliptin increases gastric accommodation to a liquid meal without affecting satiation.GLP-2 plasma levels are not affected by feeding or vildagliptin treatment. In contrast, GLP-1 plasma levels increased after a meal and were further increased by vildagliptin. Theseeffects may contribute to vildagliptin's effect on the stomach.

GLP-1 plasmatic concentration

395

Protective Effect of the Postaglandin I2-IP Signal in Mcd Diet-InducedNonalcoholic Steatohepatitis in MiceShima Kumei, Koh-ichi Yuhki, Fumiaki Kojima, Hitoshi Kashiwagi, Toshikatsu Okumura,Fumitaka Ushikubi

Nonalcoholic steatohepatitis (NASH) is a hepatic manifestation of metabolic syndrome andpresents a global health issue. NASH is characterized by hepatic steatosis, inflammation andfibrosis, with increased risks for cirrhosis and hepatocellular carcinoma. Prostaglandin (PG)I2 receptor IP is expressed broadly in the liver. Although earlier investigators demonstratedthat cyclooxygenase (COX)-2, a rate-limiting enzyme for prostanoid biosynthesis, is up-regulated in the liver of NASH patients. A role of one of key prostaglandins, PGI2 in thedevelopment of NASH remain to be determined. AIM: The purpose of this study was toclarify the role of the PGI2-IP system in the development of NASH. Methods: Wild-type(WT) and IP-KO mice were fed with normal (ND) diet or methionine- and choline-deficient(MCD) diet for 2, 5, or 10 weeks. To examine the effect of beraprost (BPS), a specific IPagonist for in vivo use, it was administrated orally to mice at 1.0 mg/kg/day everydayfollowing the experimental periods. For pathohistological evaluation, NAFLD activity score(NAS) was determined by two blinded investigators. NAS was summed up by followingthree elements, steatosis and inflammation ranged from 0 to 3 (0; normal, 3; severe), andballooning ranged from 0 to 2 (0; normal, 2; severe). RESULTS: IP-KO mice fed with MCDdiet had earlier development of NASH at 5 weeks with augmented steatosis and prominentinflammatory cells infiltration (table.1). Serum transaminase levels of IP-KO mice weresignificantly higher than those of WT mice. Furthermore, IP-KO mice had higher hepaticiron deposition than WT mice (table.2), resulting in prominent oxidative stress at 10 weeks.Accordingly, a specific IP agonist beraprost improved biochemical and histological parametersof NASH in WT but not IP-KO mice (table.1), resulting in drastic suppression of NASHonset of WT mice. CONCLUSIONS: We clarified that the PGI2-IP system plays crucial rolesin the development of NASH, partly by regulating inflammatory cells infiltration, ironaccumulation and oxidative stress. Moreover, we would speculate that stimulation of IPsignaling might be a potent therapeutic strategy for NASH.Table.1 NAFLD activity score in WT or IP-KO mice fed with MCD diet