The Effects Of Nickel Chloride On Splenic Immune Function In Broiler

Two hundred and forty avian broilers were randomly divided into four groups. Broilers were provided with a control diet (corn-bean basal diet) or diets supplemented with 300,600 and 900 mg/kg nickel chloride (NiCl2), and were supplied with water and afore-mentioned diets ad libitum for 42 days. Samples were gotten at 14,28 and 42 days of age of the experiment. This study was conducted to observe the effects of NiCl2 on splenic immune function in broiler by methods of experimental pathology, flow cytometry (FCM), TUNEL, and quantitative real-time PCR (qRT-PCR) etc. Results were as follows:1. In comparison with the control group, broiler weight increased slowly, volume and weight of spleens were reduced in high Ni groups, and lymphocyte numbers were decreased in the red and white pulp. Ultra-structurally, endoplasmic reticulum and nuclear membrane was expanded, apoptotic cells were increased in high Ni groups than those of the control group.2. Activity of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px), contents of glutathione (GSH) and malondialdehyde (MDA), and the ability to inhibit hydroxyl radical were significantly decreased (P<0.05 or P<0.01) when compared with the control group.3. TUNEL and FCM results showed that number and rate of apoptotic cells were significantly increased. Bax, Bcl-2 and Caspase-3 mRNA expression levels and contents were significantly reduced (P<0.05 or P<001).4. FCM (Flow cytometry) results showed reduced CD3+, CD3+CD4+and CD3+CD8+T lymphocyte percentage, decreased CD4+/CD8+ratio, and significantly increased (P<0.05 or P<0.01) apoptotic splenocytes in comparision with the control group.5. Interleukin (IL)-2, IL-6, IL-10, IL-12, TNF-a/LITAF, IFN-y mRNA expression and protein levels were significantly down-regulated (P<0.05 or P<0.01) compared to those of the control group. Contents of IgA, IgG, IgM were significantly decreased (P<0.05 or P<001) when compared to those of the control group.6. qRT-PCR results showed that TLR4 and TLR7 mRNA expression levels were significantly down-regulated (P<0.05 or P<0.01).Results of the present research showed that dietary NiCl2 in excess of 300 mg/kg groups would cause splenic alerts as follows:① Decreased SOD, CAT, GSH-Px activity and GSH contents, increased MDA contents, and reduced ability to inhibit hydroxyl radical, which indicated splenic oxidative damage. ②NiCl2 intake caused injury on membrane structures of lymphocytes, and increased apoptotic cell numbers in the spleen, induced inhibited development of spleen and impaired splenic immune function.③ Down-regulated mRNA expression levels and contents of IL-2, IL-6, IL-10, IL-12,TNF-α and IFN-γ, decreased CD4+ and CD8+ T lymphocyte revealed that the biological function of mature T lymphocytes has been impaired, which inhibited the cellular immune function. ④Reduced IgA+ B numbers and IgA, IgG, IgM contents suggested cellular and humoral immune function had been dimpaired.⑤Down-regulated TLR4 and TLR7 mRNA indicated that the non-specifical immunity had been affected.