Protective Effect Of CpG-ODN On Mammary Gland With Mastitis Induced By Two Pathogens Respectively

The mastitis model induced by Staphylococcus aureus(S.aureus) and Escherichia coli(E. coli)respectively via teat duct in rat were established successfully in this study. Therefore the protective effect of immunostimulatory CpG-ODN on immune defensive system and the inflammation-associated factors of mammary gland and systematic level by using this mastitis model were investigated and the mechanism of CpG-ODN were also included. On the basis of the study on rat, CpG-ODN was further used on goat, which confirmed the protective effect of CpG-ODN on mammary gland and the prophylaxis of mastitis. The result of this study provided a new rode for the biotherapy of mastitis.1 Establishment of Experimental Mastitis Model Induced by Staphylococcus aureus and Escherichia coli in Rat RespectivelyThirty lactating SD rats were randomly divided into control (n=6) and treatment group (SL, SH, EL, EH, n=6). The 100 μL of sterile 0.01 mol L^-1, pH 7.2 PBS(CON), bacterial suspension containing lower (2 × 10⁵ CFU mL^-1 , SL)and higher dose(2 × 10¹² CFU mL^-1, SH) of S.aureus, lower (2 × 10⁵ CFUmL^-1 , EL) and higher dose (2 × 10¹² CFUmL^-1 , EH) of E coli were inoculated into the fourth (abdominal) mammary gland via the teat duct 72 hours after parturition respectively. After 24 h of inoculation, all the rats were euthanatized and the mammary glands were harvested and fixed for histopathological evaluations. The alveolus from SL and EL group was characterized with the decreased milk secretion. The mammary gland structure in SH and EH group were seriously destroyed, numbers of polymorphonuclear neutrophils (PMN) were accumulated in alveoli. Concentrations of Interleukin-6 (IL-6) and Tumor necrosis factor-a(TNF- a) in mammary gland from SH and EH group elevated significantly, however that in sera showed no significant variation. The activity of N-acetyl-β-D-glucosaminidase(NAGase) in mammary gland from SH and EH group increased significantly, however that in sera decreased significantly. All the above measurements from SL and EL did not changed significantly.