Abstract: The aim of this study was to investigate protective effect of baicalin on LPS induced rabbit mastitis.Fifty healthy rabbits after parturition 7~10 d were divided into five groups randomly,including mastitis model control group (LPS,0.25 mg/kg·BW),baicalin groups with the dose 75,150 and 300 mg/kg·BW respectively,and dexamethasone (DEX) group with dose of 0.5 mg/kg·BW DEX.LPS was respectively infused into the fourth mammary glands of rabbit via the teat duct.In the baicalin and DEX groups,baicalin and DEX were injected through the auricular veins at 48 h,24 h,1 h before LPS infusion and after 8 h,32 h,56 h respectively.The rectal temperature was measured and the auricular veins blood were collected 50 h before,and 6,12,24,48,72 h after LPS infusion respectively.The following indexes at different time point were determined:(1) The pathological change of rabbit mammary gland tissues.(2) The activities of ALP,LDH,myeloperoxidase (MPO) and N-Acetyl-β-D-Glucosaminidase (NAG) in serum.(3) The levels of TNF-α,interleukin-1 (IL-1) and interleukin-6 (IL-6) in serum were measured by ELISA.The results showed that:(1) Baicalin could reduce the histopathological damage.(2) Baicalin could reduce the activities of ALP,LDH,MPO and NAG.Baicalin group (300 mg/kg·BW) had the best effect of decreasing in the activities of ALP,LDH,MPO and NAG.(3) Baicalin could reduce the level of TNF-α,IL-1,and IL-6 in serum.The level of TNF-α in serum was significantly lower than model control group in 6 h (P<0.05).The level of IL-1 in serum was significantly lower than model control group in 72 h (P<0.05).The results demonstrated that baicalin can reduce the histopathological damage and relief body symptom.The highest potent protective effect of baicalin on LPS induced rabbit mastitis was showed at the dose of 300 mg/kg·BW.

Key words: mastitis model of animal, baicalin, rabbit, LPS, anti-inflammatory activity