The Effect of Vitamin E on Intestinal Epithelial Cells in Broiler Subjected to Heat Stress

Background: Heat stress leads to great economic losses in poultry industry because of increasing climate change globally. There are several nutrients which are generally used as to combat against heat stress. Vitamin E is one of the feed additives used to prevent losses due to heat stress. This study investigated the protective effect of vitamin E against cellular damage that may occur in intestinal epithelial cells against the heat stress. There is no information on the response of vitamin E to cellular damage in intestinal epithelial cells in broilers under heat stress. Methods: In the current study, damage and the response to damage were tried to be revealed by considering both apoptotic factors, necrosis and inflammation markers. For this purpose, a total of 30 broiler chicks were divided into three replicates and analyzed. The control group was kept at 24°C, while the heat stress group was subjected to heat stress at 35°C (5 hours/day). Finally, 300 mg/kg vitamin E (α-tocopherol acetate) was supplemented daily to the heat stress+vitamin E group while heat stress was applied at 35°C (5 h/day). Result: In the study, immuno-stainings were performed with caspase-9 to detect the intrinsic pathway of apoptosis, caspase-8 and TNF-α to detect the extrinsic pathway of apoptosis and IL-6 primary antibodies to detect the pro-inflammatory immune response. Consequently, it was determined in the study that caspase-9 activity, which was positive only in epithelial cells in all groups, increased significantly in heat stress, but vitamin E decreased this activity by 75%. However, caspase-8 activity increased with heat stress in both epithelial and connective tissue and vitamin E had a protective effect. It was observed that TNF-α activity increased with heat stress in all three parts of the small intestine, especially in the duodenum. However, this activity in the group with vitamin E was closer to the control group. IL-6 activity, an indicator of pro-inflammatory response, caused no difference between the groups. As a result, the study indicates that apoptosis may occur even if there is no acute systemic inflammation in the intestinal epithelial cells of living organisms exposed to heat stress. Additionally, this study reveals that vitamin E may reduce the effect of apoptosis in the intestines against heat stress.