Volume 132, Issue 4, Pages 1375-1387 (April 2007) Alterations in the Brain–Gut Axis Underlying Visceral Chemosensitivity in Nippostrongylus brasiliensis-Infected Mice  Jeroen Aerssens, Kirk Hillsley, Pieter J. Peeters, Ronald de Hoogt, Andrzej Stanisz, Jia–Hui Lin, Ilse Van den Wyngaert, Hinrich W. Göhlmann, David Grundy, Ronald H. Stead, Bernard Coulie  Gastroenterology  Volume 132, Issue 4, Pages 1375-1387 (April 2007) DOI: 10.1053/j.gastro.2007.02.019 Copyright © 2007 AGA Institute Terms and Conditions

Figure 1 Effects of Nb infection and stressing housing conditions. (A) Examples of histologic changes and mast cell numbers over time before and after infection with Nb. The obvious pathology at 7 days postinfection, including regenerative epithelium, increased goblet cell numbers, increased cellularity in the lamina propria, and markedly thickened muscularis propria, which has essentially reverted to normal by day 14, whereas the increased mast cell numbers at day 7 persist after the inflammation has subsided. (B) Changes over time in mast cell number in the jejunum after Nb infection (n = 8) vs sham (n = 4) animals. There was an overall signficant effect of Nb infection on the number of mast cells (P < .0001, 1-way ANOVA), with significant differences observed at weeks 1 and 2 (P < .001, **) and 3 and 6 (P < .01, *). (C) Plasma corticosterone levels measured 3 weeks after Nb-infection or sham animals, housed under stressed or nonstressed environmental conditions for 5 weeks (sham/stressed: n = 9; infected/stressed: n = 10; sham/nonstressed: n = 12; infected/nonstressed: n = 7). Using a general linear model, there was a significant effect of stress (P = .018, *) but no effect of infection (P = .82) on plasma corticosterone levels. Gastroenterology 2007 132, 1375-1387DOI: (10.1053/j.gastro.2007.02.019) Copyright © 2007 AGA Institute Terms and Conditions

Figure 2 Assessment of visceral mechanosensitivity. Mesenteric afferent discharge measured upon a ramp balloon distention in the jejunum of mice 3–4 weeks after infection with Nb or sham, and housed under stressed or nonstressed environmental conditions. Data are represented as means ± SEM per treatment group. Gastroenterology 2007 132, 1375-1387DOI: (10.1053/j.gastro.2007.02.019) Copyright © 2007 AGA Institute Terms and Conditions

Figure 3 Assessment of visceral chemosensitivity. Changes in mesenteric afferent discharge and intraluminal pressure upon intraluminal acid perfusion with 50 mmol/L HCl in Nb-infected and sham animals housed under stressed or nonstressed conditions. (A) The effect of acid on afferent discharge over time. (B) The effect of acid on afferent discharge in the identified acute and prolonged periods (mean ± SEM). (C) The effect of acid on intraluminal pressure over time. (D) The effect of acid on intraluminal pressure in the identified acute and prolonged periods (mean ± SEM). In A and C, the start of the acid perfusion is indicated with an arrow, and the periods defined for assessing acute and prolonged changes are shaded in gray (A and C). Asterisks indicate significant (P < .05) differences between the different treatment groups (ANOVA). Gastroenterology 2007 132, 1375-1387DOI: (10.1053/j.gastro.2007.02.019) Copyright © 2007 AGA Institute Terms and Conditions

Figure 4 Spectral map analysis biplots of laser-captured visceral (A) DRG and (B) NG neurons on MG-430V2.0 Genechips. The graphs represent plots of the first 2 principal components (PC) of the weighted spectral map analysis applied on normalized microarray data. Squares depict different samples, whereas circles and yellow dots depict genes (size of the circle corresponds to the signal intensity of the gene on the array). Distances between squares are a measure for similarity between samples. Samples from different treatment groups are shown in different colors. Perimeters of the minimal surface area comprising all samples from a treatment group are drawn as a line. A positive association of a gene with a given sample (ie, an up-regulation of the gene in that sample) results in the positioning of the gene and sample on a common line through the centroid (depicted by a cross). The 10 most significantly contributing genes to differences between samples are annotated with their gene symbol. (A) Biplot of visceral DRG neurons. The first 2 PCs, together explaining 27% of the total variance in the dataset, do not discriminate the samples from the different treatment groups. (B) Biplot of visceral NG neurons. The first 2 PCs explain 32% of the total variance in the dataset, and discriminate the infected/stressed animals (n = 8) from the sham/nonstressed animals (n = 10). Samples from the infected/nonstressed animals (n = 7) and the sham/stressed animals (n = 9) are located near the centroid, indicative for a limited contribution to the total variance in the dataset. Gastroenterology 2007 132, 1375-1387DOI: (10.1053/j.gastro.2007.02.019) Copyright © 2007 AGA Institute Terms and Conditions

Figure 5 Gene expression profiles of significant genes known to be implicated in visceral chemosensitivity as measured in laser-captured visceral afferent neurons derived from NG by Affymetrix MG-430V2.0 Genechips. Expression levels are expressed as fluorescent signal intensity measured on the array after normalization (y-axis). Expression levels of individual animals are shown for the 4 different treatment groups: sham/nonstressed (red), Nb-infected/nonstressed (green), sham/stressed (blue), Nb-infected/stressed (purple). Black circles represent unreliable detections. Horizontal lines represent mean expression level in a specific treatment group. Expression profiles are provided for the following genes: Trpv1: transient receptor potential cation channel, subfamily V, member 1; Trpa1: transient receptor potential cation channel, subfamily A, member 1; P2rx4: Purinergic receptor P2X, ligand-gated ion channel 4; Kcnk4: potassium channel, subfamily K, member 4; Cckar: Cholecystokinin A receptor; Npy2r: Neuropeptide Y receptor Y2; Ntsr1: Neurotensin receptor 1; Sstr2: Somatostatin receptor 2; Glrb: glycine receptor, beta subunit; Gabrb3: gamma-aminobutyric acid receptor, subunit beta 3; Cacng2: calcium channel, voltage-dependent, gamma subunit 2; Htr3a: 5-hydroxytryptamine (serotonin) receptor 3A. Gastroenterology 2007 132, 1375-1387DOI: (10.1053/j.gastro.2007.02.019) Copyright © 2007 AGA Institute Terms and Conditions

Figure 6 Expression of Sstr2 measured by real-time quantitive PCR. Gene expression level of Sstr2 measured by real-time quantitative PCR in laser-captured visceral afferent neurons derived from DRG and NG from infected/stressed animals vs sham/nonstressed animals (sham/nonstressed DRG: n = 9; infected/stressed DRG: n = 11; sham/nonstressed NG: n = 12; infected/stressed NG: n = 11). Data are shown as the relative expression to the housekeeping gene ATPSase. Horizontal lines represent median values; statistical comparison was done by a Mann–Whitney test. A significantly decreased expression was observed in visceral NG neurons but not in DRG neurons. Gastroenterology 2007 132, 1375-1387DOI: (10.1053/j.gastro.2007.02.019) Copyright © 2007 AGA Institute Terms and Conditions

Figure 7 Effect of octreotide on mesenteric afferent activity. (A) Representative examples of in vitro mesenteric afferent recordings from a sham and an Nb-infected animal before and during treatment with 2 μmol/L octreotide. Arrows indicate the start of octreotide infusion. (B) Percentage change in mesenteric afferent activity upon octreotide treatment vs baseline in sham compared to Nb-infected mice. Data are represented as means ± SEM per treatment group; statistical comparison was done by a Mann–Whitney test. Gastroenterology 2007 132, 1375-1387DOI: (10.1053/j.gastro.2007.02.019) Copyright © 2007 AGA Institute Terms and Conditions