Effect Of CpG-ODN On Induced Mastitis By Combination Of Two Bacterial Pathogens In Rats

This study established the animal experimental (rat) mastitis model and investigated the changes of mammary immune function and the systematic immune function when experimental mastitis was induced with Staphylococcus aureus and Escherichia coli. The effects of CpG-ODN on the rat experimental mastitis were studied.1. Inducing Mastitis in Rats by Combination of Two Bacterial PathogensEighteen lactating SD rats were randomly divided into control group (n=6) and treatment group (L, H, n=12). The sterile 0.01mol·L^-1, pH7.2 PBS(CON), bacterial suspension containing lower concentration of mixture (the concentration of Staphylococcus aureus and Escherichia coli both 1×10⁵ CFU·mL^-1), higher concentration of mixture (the concentration of Staphylococcus aureus and Escherichia coli both 1×10¹² CFU·mL^-1) were inoculated into the fourth (abdominal) mammary gland via the teat duct 72 hours after parturition respectively. After 24h of inoculation, all the rats euthanatized and the mammary glands were harvested and fixed for histopathologic evaluations. Using two different characteristic pathogens to induce jointly mastitis in rats. All fixed for histopathologic evaluations, and the lower group (L) were characterized by lipid denaturation both in alveolus and mammary epithelial cell; the mammary gland structure in H group were seriously destructed, numbers of polymorphonuclear neutrophils (PMN) were accumulated in alveoli. Concentrations of IL-1 β in mammary gland (P<0.01) and serum (P<0.05) from rats increased significantly. The concentrations of IL-6 in mammary gland from L increased but H group decreased(P<0.05) significantly ,that in sera exhibited a significant decrease(P<0.01).The TNF- α level in mammary gland from L (P<0.05)and H (P<0.01)group elevated significantly, however that in sera decreased (P<0.01) significantly. The activity of NAGase in mammary gland from rats increased significantly from H (P<0.01) group. However that in sera from L and H (P<0.01) group decreased significantly. The MPO activity in mammary gland and sera elevated significantly (P<0.05). Concentrations of serum albumin in mammary gland from H (P<0.05) group increased, and...