Neurogastroenterol Motil. 2017;e13069. wileyonlinelibrary.com/journal/nmo | 1 of 12 https://doi.org/10.1111/nmo.13069 © 2017 John Wiley & Sons Ltd Received: 21 November 2016 | Accepted: 21 February 2017 DOI: 10.1111/nmo.13069 ORIGINAL ARTICLE L. fermentum CECT 5716 prevents stress-induced intestinal barrier dysfunction in newborn rats T. Vanhaecke 1,2,3,6 | P. Aubert 1,2,3 | P.-A. Grohard 1,2,3 | T. Durand 1,2,3 | P. Hulin 2,4 | P. Paul-Gilloteaux 2,4 | A. Fournier 5 | F. Docagne 5 | A. Ligneul 6 | C. Fressange-Mazda 7 | P. Naveilhan 1,2,3 | H. Boudin 1,2,3 | P. Le Ruyet 6 | M. Neunlist 1,2,3 Abbreviations: CMC, carboxymethylcellulose; EPM, Elevated plus maze; FSA, Fluorescein–5.6 sulfonic acid; GI, Gastrointestinal; HPS, hemalun-phloxine-saffron; HRP, Horse radish perox- idase; IEB, Intestinal epithelial barrierMS, Maternal separation; NEC, Necrotizing enterocoli- tis; TJ, Tight junctions; WAS, Water avoidance stress Philippe Aubert and Pierre-Antoine Grohard contributed equally to the work. 1 INSERM U1235, Nantes, France 2 Université de Nantes, Nantes, France 3 Institut des Maladies de l’Appareil Digestif, Nantes, France 4 MicroPICell - Cellular and Tissular Imaging Core Facility of Nantes, SFR Santé F. Bonamy- FED 4203/Inserm UMS016/CNRS UMS3556, Nantes, France 5 Normandie Univ, UNICAEN, INSERM, Physiopathology and Imaging of Neurological Disorders (PhIND), Centre Cyceron, Caen, France 6 Lactalis Recherche et Développement, Retiers, France 7 Lactalis Nutrition Europe, Torcé, France Correspondence Michel Neunlist, Inserm U1235; Faculté de Médecine, Nantes, France. Email: michel.neunlist@univ-nantes.fr Funding information This work was supported by a grant from the Association Nationale de la Recherche et de la Technologie (ANRT) and Lactalis Nutrition Europe (Torcé, France) (n°2013/1189) Abstract Background: Intestinal epithelial barrier (IEB) dysfunction plays a critical role in various intestinal disorders affecting infants and children, including the development of food allergies and colitis. Recent studies highlighted the role of probiotics in regulating IEB functions and behavior in adults, but their effects in the newborn remain largely un- known. We therefore characterized in rat pups, the impact of Lactobacillus fermentum CECT 5716 (L. fermentum) on stress-induced IEB dysfunction, systemic immune re- sponse and exploratory behavior. Methods: Newborn rats received daily by gavage either L. fermentum or water. Intestinal permeability to fluorescein sulfonic acid (FSA) and horseradish peroxidase (HRP) was measured following maternal separation (MS) and water avoidance stress (WAS). Immunohistochemical, transcriptomic, and Western blot analysis of zonula occludens-1 (ZO-1) distribution and expression were performed. Anxiety-like and exploratory behavior was assessed using the elevated plus maze test. Cytokine secretion of activated splenocytes was also evaluated. Key Results: L. fermentum prevented MS and WAS-induced IEB dysfunction in vivo. L. fermentum reduced permeability to both FSA and HRP in the small intestine but not in the colon. L. fermentum increased expression of ZO-1 and prevented WAS-induced ZO-1 disorganization in ileal epithelial cells. L. fermentum also significantly reduced stress-induced increase in plasma corticosteronemia. In activated splenocytes, L. fer- mentum enhanced IFNγ secretion while it prevented IL-4 secretion. Finally, L. fermen- tum increased exploratory behavior. Conclusions & Inferences: These results suggest that L. fermentum could provide a novel tool for the prevention and/or treatment of gastrointestinal disorders associated with altered IEB functions in the newborn. KEYWORDS corticosterone, Intestinal epithelial permeability, newborn, probiotic, ZO-1 1 | INTRODUCTION The postnatal period is a critical developmental window of the gastro- intestinal (GI) tract. 1,2 Various GI functions, such as intestinal epithelial