الفهرس 
Effect of vitaminC, vitamin E, and alpha lipoic acid on antioxidant defense system and immune-related gene expression in chickens
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Abstract
This study was conducted to investigate the effect of vitamin C, vitamin E, and alpha lipoic acid on antioxidant defense system and some immune cytokines gene expression in chickens. Therefore, two experiments were conducted at the South China Agricultural University, Guangzhou, China. In the 1st experiment, broiler eggs (n = 90) were assigned to three equal groups after 18 days of incubation (first group was non-injected, second group was injected with saline, the third group was injected with 3 mg/egg vitamin C), where the eggs were injected in the air sac. In the 2nd experiment, 240 one-day-old chicks were assigned randomly to either a basal diet (control group) or basal diet supplemented with vitamin C (200 mg/kg diet), basal diet supplemented with vitamin E (100 mg/kg), or basal diet supplemented with alpha lipoic acid (ALA, 500 mg/kg) for 28 days from hatching. At 23 days of age, the broilers in the three groups were exposed to oxidative stress by dexamethasone (DEX) for three alternating days. The most important results could be summarized as follow: Experiment 1: In ovo injection of vitamin C significantly increased mRNA expression of glutathione peroxidase (GSH-PX) and superoxide dismutase (SOD). Whereas, the mRNA level of interleukin 1 Ý (IL-1Ý), interleukin 6 (IL-6), and tumour necrosis factor Ü (TNF-Ü) in the spleen were significantly decreased. Experiment 2: At 28 days, birds fed the ALA-supplemented diet and exposed to oxidative stress by DEX had the lowest activity levels for T-AOC, SOD, and GSH-PX in the plasma and liver (P < 0.05), and the greatest activity levels in the MDA level. ALA significantly decreased the mRNA expression levels of the IL-1Ý, IL-6, IFN-Þ, and TNF-Ü genes compared with the other groups during oxidative stress by DEX. This study suggests that, ALA is more effective for normalizing the oxidative stress induced by DEX than vitamin C or vitamin E