Abstract: In order to investigate the effect of selenium-enriched lactic acid bacteria on the apoptosis of chicken small intestinal epithelial cells (CSIEC) induced by aflatoxin B₁ (AFB₁), CSIEC cultured in vitro were divided into 5 groups:control group (C), AFB₁ group (300 μmol/L AFB₁), AFB₁+0.01 Se group (300 μmol/L AFB₁+0.01 μmol/L selenium-enriched lactic acid bacteria, in terms of Se), AFB₁+0.05 Se group and AFB₁+0.1 Se group.When the cells grew to 60%-70% confluence, the culture medium of AFB₁+0.01 Se, AFB₁+0.05 Se and AFB₁+0.1 Se groups was replaced with the culture medium containing the corresponding Se concentration, and C and AFB₁ groups were replaced with normal culture medium. After 8 h, 300 μmol/L AFB₁ was added to the AFB₁-containing groups, and the culture was continued for 24 h.CCK-8 was used to detect the antagonistic effect of selenium-enriched lactic acid bacteria on the cytoactive of CSIEC induced by AFB₁.ELISA was used to detect the change of lactate dehydrogenase (LDH) activity in the culture medium.TUNEL was used to observe the effect of selenium-enriched lactic acid bacteria against AFB₁ on cell apoptosis rate.The protein levels of Bcl-2/Bax, PERK, ATF4, CHOP, GRP78, p53 and p21 associated with mitochondrial and endoplasmic reticulum stress pathways were detected by Western blotting.The results showed that the cytoactive of CSIEC in the other groups was extremely significantly lower than that in control group (P<0.01), and those in selenium-added groups were extremely significantly higher than those in AFB₁ group (P<0.01).The LDH activities in the other groups were extremely significantly higher than those in control group (P<0.01), and LDH activities in selenium-added groups were extremely significantly lower than those in AFB₁ group (P<0.01).Compared with control group, the number of TUNEL positive cells in AFB₁ group was extremely significantly increased (P<0.01);and no significant difference were found between selenium-added groups and AFB₁ group (P>0.05).Compared with control group, the protein expression levels of Bcl-2/Bax in AFB₁ group were extremely significantly decreased (P<0.01), and that in AFB₁+0.05 Se group was increased (P<0.05).Endoplasmic reticulum stress pathway protein levels showed that the protein levels of PERK, CHOP, GRP78 and p53 in AFB₁ group were extremely significantly higher than those in control group (P<0.01), protein levels of PERK and GRP78 in selenium-added groups were significantly lower than those in AFB₁ group (P<0.01).Protein levels of CHOP and p53 in AFB₁+0.05 Se and AFB₁+0.1 Se groups were extremely significantly lower or significantly lower than those in AFB₁ group (P<0.01;P<0.05).Therefore, selenium-enriched lactic acid bacteria could alleviate the apoptosis of CSIEC induced by AFB₁.

Key words: selenium-enriched lactic acid bacteria; aflatoxin; chicken small intestinal epithelial cells; cell apoptosis