Histopathological study and intestinal mucous cell responses against in Nile tilapia administered with GG.

Aim: This study aimed to examine the intestinal histopathological lesions and mucous cell responses in the entire intestines of Nile tilapia administered with GG (LGG)-mixed feed, after challenge.

Materials And Methods: Intestinal samples from fish fed with control normal diet or LGG-mixed feed (10 colony-forming unit [CFU]/g feed) with or without in phosphate-buffered saline challenge (7.46 × 10 CFU/mL/fish) were collected and processed for histopathological study. The mucous cell responses were evaluated using histochemistry, using Alcian blue (AB) at pH 2.5, AB at pH 1.0, and periodic acid-Schiff-AB at pH 2.5. The quantification of the intestinal mucous cell size and the staining character of each mucin type from the entire intestine were recorded and counted.

Results: Histopathological study showed remarkable lesions only in the proximal intestine in fish infected with , while LGG-fed fish had less intestinal damage, perhaps resulting from heterophil infiltration. Furthermore, a significant (p<0.01) increase in mixed mucous cell numbers was observed mainly in the proximal intestine of all challenged fish, compared with normal diet-fed fish without challenge, and also in LGG-fed fish with challenge compared with LGG-fed fish without challenge.

Conclusion: Dietary LGG-fed Nile tilapia showed improvements in host innate immunity. In addition, LGG was effective in decreasing intestinal lesions from a-induced intestinal damage. Moreover, increasing numbers of mixed mucous cells in the proximal intestine might be indicative of certain pathological conditions in Nile tilapia after infection.