| Endometritis is an inflammation of the endometrial lining of the uterus of dairy cows. Subclinical endometritis is also prevalent in dairy cows and has a profound negative impact on reproductive performance without clinical symptom owing to be neglected easily. Cows with subclincal endometritis had lowen conception rates and higher reproductive failure rates, compared to cows without subclinical endometritis. So it is very important to detect, diagnose and prevent subclinical endometritis earlier.Effective defense against reproductive tract invasion by environmental organisms is mediated by anatomical and functional barriers as well as, nonspecific and specific immune responses, including mucus, antibodies and phagocytic cells. To see if the cytokine, acute-phase proteins concentrations in plasma and uterine secrets, PMN and T lymphocyte percent in blood are related with postpartum endometritis and the change oxidative damage and antioxidative defense with subclinical endometritis and clinical endometritis, cytokine, acute-phase proteins concentrations and other factor were measured. In our study, Lactating Holstein cows (n=68) were given a thorough reproductive examination at postpartum 20-33 days. Based on the reproductive exam findings the cows were diagnosed and classified into three groups as clinical endometritis (n=30), subclinical endometritis (n=28) and normal (n=10). The results showed as follows:1.The total leucocyte count in blood samples with clinical endometritis and subclinical endometritis showed significant difference (P<0.01) from 21day after parturition. The percentage of polymorphonuclear neutrophils in blood and uterine secrets was higher significantly than control group. The percentage of lymphocyte decreased significantly during the first 5 weeks after parturition and rised during the last two weeks (P<0.01). The results showed that polymorphonuclear neutrophils was the first cell entered the district of inflammation are the first line of defence against bacteria. Lymphocyte activation of local tissue takes an important roles in immune defence when the involution of uterine happened and the function of uterine begin to recover.2. The concentration of IL-1,IL-6,IL-8 and TNF-a in blood and uterine secrets were significant variable (P<0.01) during inflammation after parturition, and they were increased notablely in the cows with clinical endometritis. IL-8 were variable significantly (P<0.01).at other time point and there was no differences in subclinical endometritis only at postpartum 49 day compared with normal cows. The results showed that IL-1 increased can enhance contraction and evacuation of the uterus indirectly; IL-6 can induced canleukocytosis in cows and IL-8 can increase the influx of PMN leucotyte into bovine uterus and TNF-a can enhance the releasing of IL-1,IL-6 and IL-8. It hinted that the four cytokines took the important role in systemic and local immunity defence during inflammation.3.The concentration of CRP,Hp,SAA and al-AGP with CE and SE were higher (P<0.05, P<0.01) than control group in blood and uterine secrets, especially SAA and Hp have lower concentration in normal cows and can't be detected. The results hinted that SAA and Hp in blood and uterin secrets could be sensitive indexes to detect clinical endometritis and subclinical endometritis. The different change of different inflammation factor during endometritis showed that the change of some factors in uterine secrets was more significant than in blood, such as SAA, IL-6, IL-8 et al. So the factors can selected to diagnose subclinical and clinical endometritis as a reference.4. CD4+and CD8+were activated during the inflammation of clinical endometritis and subclinical endometritis. CD4+has important role in the initial stage after parturition which presented increasing and CD8+has the leading position in the later period with increasing and company with the tendency of CD4+/CD8+descent. The percentage of B cells and the content of IgA,IgG,IgM in peripheral blood in infected dairy cows increased significantly (P<0.05, P<0.01).The results showed that humoral immunity was activated in the infected cows when cell mediated immunity was lowered and that of CE group was variable more significantly than that of SE group. IgA and IgM are synthetized by endometrial at normal time and owing to inflammation the endometrial was received oxidative damage and resulted in decrease of synthesis of IgA and IgM.5. The content of NO, ROS, MDA in serum and uterine secrets of CE group were significantly higher than control group (P<0.01); and the content of NO, ROS were variable significant (P<0.05, P<0.01) but the content of MDA showed significantly at postpartum 7th in blood and 35th-49th in uterine secrets, and there was no difference at other time dot (P>0.05). The results showed that free radicals accumulated in blood and uterine secrets in dairy cows with clinical endometritis and subclinical endometritis and resulted in oxidative damage of individual.The activity of antioxidases in serum and uterine fluid in dairy cows with clinical endometritis were significantly lower than control group (P<0.01); but there were no difference in SE group at some time except different significantly (P<0.05, P<0.01). The antioxygen activity in blood and uterine secrets increased gradually with inflammation processing. The results showed that the activity of antioxidase decreased in blood and uterine fluid during inflammation resulted in oxidative damage of cows, however antioxygen activity obtained strengthen with the recovery of systemic function.The content of vitamin E and vitamin C in serum and uterine secrets in dairy cows with clinical endometritis were significantly lower than control group (p<0.01); SE group wasn't obviously variable than CE group (P<0.05, P<0.01 or P>0.05). And the content of VE, VC and T-AOC increased gradually showed that antioxygen activity recovered gradually.The patho-injure of uterine tissue of CE group and SE group showed that free radicals caused oxidative damage of uterine tissue by lipid peroxidation. Higer inflammation, more free radical and more injury the cows were obtained.
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