Effect Of γ-aminobutyric Acid On The Immune Responses And The Expressions Of Apoptosis-relatived Genes In Chicks Under Beak Trimming Stress

This experiment was undertaken to examine the effect of beak trimming stress on immune system and the expression of apoptosis-related protein(Fas and Bcl-2) in chick spleen, and to consider possible roles of GABA in this stress response.Experimental designA total of360one-day-old healthy Gushi male chicks were randomLy divided into5groups (A. B. C. D and E) with6replications per group and supplemented with GABA dissolved in drinking water at a dose of0,40,60and80mg/kg for groups A (trimmed,40mg/kg GABA). B (trimmed,60mg/kg GABA), C (trimmed,80mg/kg GABA), D (non-trimmed,0mg/kg GABA) and E (trimmed,0mg/kg GABA) respectively. All the chicks were beak trimmed on7d except the control group (group D).Trail1Effects of y-Aminobutyric acid on the immune responses in chicks under beak trimming stressTwo chickens of each pen were randomLy caught and blood on1,3,5and7d after beak trimming. The immune organ index and the serum concentration of ACTH, IgG, CD3+and CD4+were measured. ResuLts showed that relative spleen weight was significantly increased by GABA at80mg/kg(P<0.05) under beak trimming stress, whereas the relative organ weights of the bursa of fabricius and thymus were not significantly affected(P>0.05). ACTH concentration in serum was highest for chicks fed the GABA-deficient water and was significantly decreased by the supplement of GABA at d1,3and5after beak trimming(P<0.05). The supplement of GABA significantly increased the levels of CD3+and CD4+, especially at the dose of60mg/kg(P <0.05). The levels of IL-1β, TNF-α and IL-6in the serum were significantly decreased by GABA at80mg/kg(P<0.05).Trail2Effects of y-Aminobutyric acid on the splenetic expressions of cytokines and apoptosis-relatived genes in chicks under beak trimming stressOne chickens of each pen were randomLy caught and weighted before killed, immune organs were collected, total RNA were detection and reverse transcription into cDNA, SYBR Green Ⅰ real-time PCR were used to test expression level of Bcl-2. Fas, IL-1β,IL-6,and TNF-α. ResuLts showed that consumption of the dose of80mg/kg GABA significantly decreased the level of IL-1β1at d1and5after beak trimming (P<0.05). Chicks receiving the water with80mg/kg of GABA had significantly lower level of IL-6at d3after beak trimming, and a similar effect on TNF-a was found when compared with the control group E (trimmed,0mg/kg)(P<0.05). The apoptosis-related gene(Fas) expressed in the spleen was dose-dependently decreased by GABA at d1,3and7when birds were under beak trimming stress (P<0.05).80mg/kg GABA can slightly increase the expression level of Bcl-2in spleen (P>0.05).