Application of transcriptome analysis: Oxidative stress, inflammation and microtubule activity disorder caused by ammonia exposure may be the primary factors of intestinal microvilli deficiency in chicken.

Ammonia (NH3), an inhaled harmful gas, is not only an important volatile in fertilizer production and ranching, but also the main basic component of haze. However, the effect and mechanism of NH3 on the intestines are still unclear. To investigate the intestinal toxicity of NH3 inhalation, morphological changes, transcriptome profiles and oxidative stress indicators of jejunum in broiler chicken exposed to NH3 for 42 days were examined. Results of morphological observation showed that NH3 exposure caused deficiency of jejunal microvilli and neutrophil infiltration. Transcriptomics sequencing identified 677 differential expressed genes (DEGs) including 358 up-regulated genes and 319 down-regulated genes. Enrichment analysis of obtained DEGs by Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) found that biological functions and pathways affected by NH3 included antioxidant function, inflammation, microtubule and nutrition transport. Relative genes validation and chemical detection confirmed that NH3-induced oxidative stress by activating CYPs and inhibiting antioxidant enzymes promoted inflammatory response and decreased microtubule activity, thus destroying the balance of nutritional transporters. Our study perfects the injurious mechanism of NH3 exposure and provides a new insight and method for environmental risk assessment.