| A strain of Staphylococcus aureus was isolated from the milk of dairy cows with mastitis. Lactating mice were challenged by inoculation of Staphylococcus aureus suspension through the teat canal to induce mastitis. The mammary immunity induced by Staphylococcus aureus and the effect of baicalin on mastitis were studied through CFU counts, histological, histochemical, immunohistochemical techniques and ELISA.The results showed that a peak in colonization of the mammary glands was observed at 24h after challenge and the bacterial number decreased at 48h and increased at 72h. Pathological change of mammary gland was observed at 12h postchallenge and it became more serious with the development of mammary infection. A significant increase (P<0.01) in the number of degranulated mast cell was detected in mammary gland from model group (0.960±0.735number/field,by 40xobject lens, the following is the same) compared to control group(0.200±0.408 number/field) at 6h postchallenge. A significant increase (P<0.05) in the number of mast cell was detected in mammary gland from model group(3.320±1.069 number/field) compared to mock control group(2.080±0.954 number/field). The number of degranulated mast cell and mast cell increased with the development of infection. The number of dendritic cell increased with the development of infection and it increased significantly compared to mock control group at 48h postchallange (P<0.05) .The number of CD4+T cell in mammary gland from model mouse increased but not significantly compared to mock control group ( P >0.05 ). A significant increase (P<0.01) in the number of CD8+T cell was detected in mammary gland from model mouse (7.120±1.201number/field) compared to mock control group(5.920±0.762 number/field) at 72h postchallenge. The content of TNF-a in mammary gland from model group was significantly higher than that in mock control group at 6h postchallenge (14.041 ±0.633ng/mL versus 3.624±0.305ng/mL, respectively;P<0.01) . The content of IFN-y in mammary gland from model group was significantly higher than that in mock control group at 6h postchallenge (28.490±0.871ng/mL versus 8.214±0.327ng/mL, respectively;P<0.01) .The contents of TNF-a and IFN-γ in mammary gland from model group reached the minimum (7.182±0.437ng/mL, 7.686±0.928ng/mL, respectively) at 48h postchallenge and increased at 72h postchallenge. The immoderate degranulation of mast cell and the significant increase of TNF-a and IFN-γ in contents could be one of the main reason of acute mastitis.A significant decrease (P<0.01) in the number of bacteria was detected in mammary gland from treated group(7.189±0.232 lgCFU/g mammary gland) compared to model group(8.092±0.461 lgCFU/gmammary gland) at 24h postchallenge and the inflammation of mammary gland alleviated. A significant decrease (P<0.05) in the number of degranulated mast cell was detected in mammary gland from treated group(0.600±0.645nurnber/field) compared to model group(0.960±0.735number/field) at 6h postchallenge. It suggested that baicalin could inhibit the degranulation of mast cell, reduce inflammation medium and prevent excess inflammation. Compared to model group, CD4+T cell of treated group increased and CD8+T cell increased markedly (P<0.05) . The mammary immunity of treated group was enhanced due to the increase of CD4+/CD8+ T ratio. The contents of TNF-a and IFN-y in mammary gland from treated group were lower than that in model group at 61k 121k 241k 72h postchallenge (P<0.01) , and higher at 48h postchallenge. This suggested that baicalin could increase mammary immunity and reduce mammary inflammation through modulating the secretion of TNF-a and IFN-y. Baicalin could inhibit bacterial infection, modulate mammary immunity, reduce pathological change of mammary gland and alleviate systemic symptom. Baicalin is an effective drug for acute mastitis. |
PDF Full Text Request