热应激对绵羊血清免疫和抗氧化指标及相关基因相对表达量的影响

Effects of Heat Stress on Serum Immune and Antioxidative Indexes and Relative Expression of Related Genes in Sheep

本试验旨在探究热应激对绵羊血清免疫和抗氧化指标及相关基因相对表达量的影响。选取18只3岁杜蒙杂交母羊,随机分为3组:对照组为舍内自然温度环境(25.23℃);适温组安置空调,为热舒适环境(19.60℃);高温组安置暖气,为高温环境(27.19℃)。试验共28 d,于第14和28天进行颈静脉采血,分离血清并收集白细胞,测定血清免疫和抗氧化指标及白细胞中相关基因的相对表达量。结果表明:与适温组相比,1)在试验第14天,对照组和高温组血清免疫球蛋白G(IgG)含量显著降低(P<0.05),血清白细胞介素-2(IL-2)含量及其在白细胞中基因相对表达量显著升高(P<0.05),高温组血清肿瘤坏死因子-α(TNF-α)含量及其在白细胞中基因相对表达量显著升高(P<0.05);在试验第28天,对照组和高温组血清免疫球蛋白A(IgA)、IgG和免疫球蛋白M(IgM)含量显著降低(P<0.05),高温组血清白细胞介素-1(IL-1)含量及其在白细胞中白细胞介素-1β(IL-1β)基因相对表达量显著升高(P<0.05),血清IL-2含量显著降低(P<0.05);2)在试验第14天,对照组和高温组血清过氧化氢酶(CAT)活性及其在白细胞中基因相对表达量显著降低(P<0.05),白细胞中超氧化物歧化酶2(SOD2)和核转录因子2(Nrf2)基因相对表达量显著升高(P<0.05),高温组血清总抗氧化能力(T-AOC)显著降低(P<0.05),丙二醛(MDA)含量显著升高(P<0.05);在试验第28天,对照组和高温组血清CAT、谷胱甘肽过氧化物酶(GPx)、总超氧化物歧化酶(T-SOD)活性和T-AOC显著降低(P<0.05),高温组血清MDA含量显著升高(P<0.05)。综上所述,长期慢性热应激能够降低绵羊抗氧化功能,抑制机体免疫水平。

This study was conducted to evaluate the effects of heat stress on serum immune and antioxidant indexes and related gene expression of sheep. Eighteen 3-year-old Dorper×Mongolian crossbred ewes were randomly allocated into three groups:control group in natural room temperature(25.23 ℃),preference temperature group furnished with an air-conditioner(19.60 ℃),and high temperature group furnished with a radiator(27.19 ℃). The trial lasted for 28 days. Blood and leukocyte samples were collected on days 14 and 28 to analysis the immune and antioxidant indexes and relative gene expression. The results showed as follows:compared with preference temperature group,1)on day 14,the content of immunoglobulin G(IgG)in serum in control group and high temperature group was significantly decreased(P < 0. 05),while the interleukin-2(IL-2)content in serum and its gene expression in leukocyte were significantly increased(P<0.05),tumor necrosis factor-α (TNF-α)content in serum and its gene expression in leukocyte in high temperature group were significantly increased(P<0.05). On day 28,the contents of immunoglobulin A(IgA),IgG,immunoglobulin M(IgM)in serum in control group and high temperature group were significantly decreased(P <0.05),interleukin-1(IL-1)content in serum and interleukin-1β(IL-1β)gene expression in leukocyte in high temperature group were significantly increased(P<0.05),while the IL-2 content in serum was significantly decreased(P<0.05). 2)On day 14,catalase(CAT)activity in serum and its gene expression in leukocyte in control group and high temperature group were significantly decreased(P<0.05),while the genes expression of superoxide dismutase 2(SOD2)and nuclear transcription factor 2(Nrf2)in leukocyte were significantly increased(P<0.05),total antioxidant capacity(T-AOC)in serum in high temperature group was significantly decreased(P<0.05),while the content of malonaldehyde(MDA)in serum was significantly increased(P<0.05). On day 28,the activity of CAT,glutathion peroxidase(GPx),total superoxide dismutase(T-SOD)and T-AOC in serum in control group and high temperature group were significantly decreased(P<0.05),and the content of MDA in serum in high temperature group was significantly increased(P<0.05). In conclusion,chronic heat stress can reduce antioxidant capacity and suppress the immune system of sheep.