| Endometritis is one of the common postpartum diseases in dairy cow,which can cause the repeated infertility,the delayed uterine involution,the decreased lactation amount and the increased rejection rate,thus leading to the huge economic losses for the dairy industry.E.coli,as the Gram-negative bacteria and one of the main pathogens of dairy cow endometritis,play an important role in the occurrence of endometritis.Progesterone(P4)has been observed to inhibit the immune defenses of uterus,however,the mechanism has not been fully revealed.Goats are small ruminants with similar reproductive performance to dairy cows.In order to investigate the mechanisms of progesterone on endometritis caused by E.coli in postpartum dairy cows,we ramdomly selected 12 healthy female postpartum goats and assgnined the goats into 4 groups:the control group,the P4 group,the E.coli group and the E.coli and P4 group co-treatment group.At 10d postpartum,the goats in P4 group and co-treatment group were pretreated with progesterone(lmg/kg,im)for 3 consecutive days,and were continued to receive progesterone treatment daily until the end of the experiment.At 13 d postpartum,the goats in the E.coli group and the co-treatment group received uterus infusion of 10mL E.coli(109cfu/mL),whereas the the goats in the control group and the P4 group received uterus infusion of 10mL saline.The peripheral blood,uterine secretions,and the endometrial tissues were collected at 0 h,2 h,6 h,10 h,16 h,24 h,36 h and 48 h after the infusion of E.coli or saline.The changes in the morphology and structures of endometrium were observed.The changes in the peripheral WBC,the PMN%of uterine secretions,the gene expressions of TLR4 and the proinflammatory cytokines,and the activations of MAPK and NF-?B signaling pathways of endometrium were detected.The results were as follows.(1)The temperature,the respiratory frequency and the heart rate:compared with the control group,the rectal temperature in E.coli group decreased(p<0.01)from 2 to 16 h.The respiratory rate increased(p<0.05)from 2 to 16 h and 48 h.And the heart rate increased from 2 to 48 h respectively(p<0.05).Compared with the E.coli group,the rectal temperature in co-treatment group increased(p<0.01)from 6 to 16 h,the respiratory rate decreased(p<0.05)from 6 to 10h,and the heart rate decreased(p<0.05)from 2 to 48 h.(2)The WBC of peripheral blood:compared with the control group,the WBC of peripheral blood in P4 group decreased(p<0.05)at 0 h,16 h and 36 h,and the number of WBC in E.coli group increased(p<0.01)at 10h.Compared with the E.coli group,the WBC of peripheral blood in co-treatment group was lower(p<0.05)at 0,10 and 36 h.(3)The redness,swelling and bleeding conditions:compared with the control group,the redness,swelling and bleeding were mild at from 10 to 24 h in P4 group.The redness,swelling and bleeding of endometrium in the E.coli group were more severe with increased numbers of bleeding points.Compared with the E.coli group,at the severity of the endometrium in co-treatment group were mild at from 10 to 48 h.(4)The PMN%of uterine secretions:compared with the control group,the PMN%of uterine secretion decreased(p<0.05)from 6 to 36 h in P4 group;and increased(p<0.05)at 2,6 and 48 h in E.coli group.Compared with the E.coli group,the PMN%of uterine secretion in co-treatment group was lower(p<0.05)at 6 h and 48 h.(5)Histopathological changes of goat endometrium:compared with the control group,the columnar epithelial cellsendometrium in E.coli group fell off from 2 h to 36 h,and a large number of PMN and lymphocytes infiltrated at 2 h and 36 h,and the cell composition was less and connective tissue was loose from 10 to 24 h.Compared with E.coli group,there was no obvious shedding of endometrial columnar epithelial cells in co-treatment group,and a small amount of PMN and lymphocytes infiltration were found in the tissues of co-treatment group.At 10 h,16 h and 24 h,there were more cell components,and the connective tissue connections were more tight.(6)The gene expressions of TLR4 and the proinflammatory cytokines:compared with the control group,the relative expression of IL-6 mRNA in P4 group was lower(p<0.05)at 6,10 and 36 h.The IL-8 gene expression decreased(p<0.05)at 36h.The gene expression of TNF-a decreased(p<0.05)at 0,2 and 36 h.The relative gene expression of TLR4 increased(p<0.01)from 10 to 48h.The gene expression of IL-1? was higher(p<0.05)in E.coli group than that in the control group from 2 to 10 h,and at 24,36,and 48h.The mRNA expression of IL-6 increased(p<0.01)from 6 to 36 h.The relative gene expression of IL-8 increased(p<0.05)from 2 to 36 h.The relative expression of TNF-a mRNA increased(p<0.01)from 10 to 36 h.Compared with the E.coli group,the TLR4 mRNA expression in co-treatment group decreased(p<0.05)at from 16 to 36 h.The mRNA expression of IL-1? decreased(p<0.01)at 10 h and 24 h.The mRNA expression of IL-6 decreased(p<0.05)at 6,10,16,24,and 36 h.The expression of IL-8 gene decreased(p<0.05)from 6 to 36 h.The gene expression of TNF-a decreased(p<0.05)from 10 to 24 h.(7)The activations of MAPK and NF-?B signaling pathways:Compared with the control group,Compared with the control,the phosphorylations in P4 group were higher(p<0.05)for p38 at all time points,and for JNK except except Oh and 10 h,but lower(p<0.01)for Erk from 2 to 48 h.The phosphorylation level of p65 in P4 group decreased(p<0.01)at 2 h.The phosphorylation level of p65 in E.coli group increased(p<0.05)after inoculation.In the E.coli group,the phosphorylation levels of JNK,Erk,p38 and NF-?B of the endometrium were higher(p<0.01)than those in the control group.The phosphorylations of JNK,Erk and p38 were all higher(p<0.01)after infusion compared with the control.Compared with the E.coli group,the phosphorylations in co-treatment group decreased(p<0.01)for JNK and Erk from 2 to 48 h,and for p38 at 36 h.the phosphorylation of p65 in co-treatment group decreased(p<0.05)at 2,10 and 36 h after inoculation.In conclusion,acute infection occured after the infusion of E.coli into the uterus of goats.It resulted in the abnormal changes of the temperature,the respiratory frequency and the heart rate,the increase of WBC in peripheral blood,the rise of PMN%in uterine secretion,pathological changes in morphology and structure of uterus,the activations of MAPK and TLR4/NF-?B signaling pathway,and the increased expressions of proinflammatory cytokines.Progesterone inhibited the activation of MAPK and TLR4/NF-?B signaling pathways and down-regulated the expressions of inflammatory cytokines,which is involved in the innate immune response of the uterus and inhibits the occurrence of inflammation. |
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