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The protective effect of polysaccharide glucan in chickens fed low doses of T-2 toxin was assessed. The binder effect of ß-D-glucan on jejunal mucosa in relation to the expression of Na+/K+-ATPase, proliferative activity of enterocytes and number of goblet cells was investigated. A total of 40 one-day-old chickens were allocated to four groups: control (C), ß-D-glucan (G), T-2 toxin (T) and combined ß-D-glucan+T-2 toxin (GT). The chickens were individually administrated per os 1.0 mg/bird/day of ß-D-glucan derived from Candida albicans on days 11, 12, and 21 of the experiment (totally 3 mg per bird). T-2 toxin at a concentration of 1.45 μg·kg-1 was added to the feed from day 14 to day 28 of the experiment. The α subunitspecific anti-Na+/K+-ATPase antibody was used to identify the protein by immunofluorescence in the cell membrane of jejunal enterocytes. Higher expression of Na+/K+-ATPase was found in the jejunal epithelial cells and lamina propria in the chickens fed T-2 toxin and administered glucan (P < 0.05) compared to control. The number of proliferated enterocytes was higher in group T compared to group G and control (P < 0.001), as well group GT (P < 0.01). Goblet cell density did not present significant differences between groups of chickens, but group G showed the highest values. These data suggest that administration of pure T-2 toxin at low doses affects primarily the protein synthesis of actively dividing cells. Higher distribution of Na+/K+-ATPase in enterocytes of chickens in GT group suggests positive influence of glucan and mycotoxin on the ion pump. A binding effect of this immunomodulator on the digestive tract mucosa in the applied setup was not observed. Poultry, intestine, yeast, trichotecene, ion pump, immunofluorescence T-2 toxin, one of the members of the trichothecene group, is a naturally occurring mycotoxin produced by several species of fungi in the genus Fusarium. T-2 toxin at small doses can damage the mucosa of the digestive tract and impair the resorption of nutrients (Sokolović et al. 2008; Kanora and Maes 2009). The absorption of mycotoxins and their fate within the gastrointestinal tract suggest that the epithelium is repeatedly exposed to these toxins, and at higher concentration than other tissues (Grenier and Applegate 2013). Fusarium mycotoxins alter the different intestinal defence mechanisms including epithelial integrity, cell proliferation, mucus layer and immunoglobulins (Bouhet and Oswald 2005). In a study of low and moderate T-2 toxin doses, Antonissen et al. (2014) reported a decrease of the mentioned indices. The proliferative activity of enterocytes is a sign of healthy tissue turnover and maintenance (Garcia et al. 2007). Unlike in mammals, chicken enterocyte proliferation ACTA VET. BRNO 2018, 87: 371–377; https://doi.org/10.2754/avb201887040371 Address for correspondence: doc. MVDr. Viera Revajová, Phd. Institute of Pathological Anatomy University of Veterinary Medicine and Pharmacy Komenského 73, 041 81 Košice, Slovak Republic Phone: +421 915 984 708 E-mail: [email protected] http://actavet.vfu.cz/ is not localized only in the crypt region, and the site of enterocyte differentiation is not precisely localized (Uni et al. 1988). NA+/K+-ATPase is a key transport element required for the establishment of electrochemical gradients driving the cellular transport and substrate flow across epithelia. In addition, the enzyme is involved in basic processes such as maintenance and proliferation (Zouzoulas et al. 2005). A large proportion of the energy demands of the gastrointestinal tract is associated with the activity of Na+/K+-ATPase, therefore, the energy costs involved in the absorption of glucose and other nutrients are considerable (Wang et al. 2009). Many reports have been published in recent years about mycotoxin inactivation agents (mycotoxin binders) in order to reduce the toxic effects of mycotoxins in animals. The application of microorganisms capable of biotransforming certain mycotoxins into less toxic metabolites has been proposed (Jouany et al. 2005; Shetty and Jespersen 2006). The microorganisms act in the animal intestinal tract prior to the absorption of mycotoxins. Many species of bacteria and fungi have been shown to enzymatically degrade mycotoxins (Avantaggiato et al. 2004; Jouany et al. 2005). Yeast or yeast cell walls show the potential as mycotoxin binders. The cell walls harbouring polysaccharides (glucan, mannan), proteins and lipids exhibit numerous different and easy accessible adsorption centres including adsorption mechanisms (Huwig et al. 2001). The effect of the interaction of small doses of T-2 toxin and polysaccharides on the functional activity of intestinal mucosa is not known. The aim of this study was, therefore, to investigate the activity of Na+/K+-ATPase, proliferative activity of enterocytes, and goblet cell density in intestinal mucosa after 14 days administration of T-2 toxin in feed and oral application of ß-D glucan. Materials and Methods Animals A total of 40 one-day-old chickens of the Lohmann Brown hybrid were placed in wire cages with solid floors. They were allocated to four groups: control (C), ß-D-glucan (G), T-2 toxin (T), ß-D-glucan + T-2 toxin (GT); each group containing 10 chickens that were fed a diet prepared at the Institute of Pathological Anatomy of University of Veterinary Medicine and Pharmacy in Košice, corresponding to the commercial diet for chickens (HYD 02/a) but free of antimycotics. The chicks were kept in the menagerie of the Institute of Pathological Anatomy, UVMP, Košice, Slovakia (SK P 52004), in accordance with the rules and with the approval of the Ethics Committee; the experiment was authorized by the State Veterinary and Food Administration of the Slovak Republic (No. Ro-270710-221). Preparing of β-D-glucan and T-2 toxin Beta-D-glucan in powder form was obtained from Candida albicans (donated by RNDr. Ema Pavlovičová, CSc., Chemical Institute of the Slovak Academy of Science, Bratislava, Slovak Republic). One hundred mg of lyophilised ß-D-glucan were dissolved in aqua pro injectione with the final concentration of 3 mg·ml-1. The chickens were individually administered 1.0 mg/bird/day of dissolved polysaccharide per os. T-2 toxin in powder form (OEKANAL®, Sigma-Aldrich, Germany, mol. w. 466.52 g·mol-1) was dissolved in 50 ml of 96% ethanol; 2 ml were added to 1 kg of feed and then mixed thoroughly with a hand-mixer. The concentration of 1.45 μg·kg-1 of food was confirmed by the HPLC method at the State Veterinary and Food Institute (Bratislava, SNAS Reg. No. 050/S-127, Slovak Republic) together with other mycotoxins.