Study On The Mechanisms Of Pulsatilla Decoction In The Treatment Of Avian Pasteurellosis

Objective:To explore the mechanism of Pulsatillae decoction in the treatment of avian pasteurellosis,an animal model of avian Pasteurellosis was established by artificial method.Different concentrations of Pulsatillae decoction were used to treat the disease,and the optimal treatment concentration was selected to the prevention and treatment of the disease.Methods:The growth curve of Pasteurella avium was drawn,the LD50 of Pasteurella avium was determined,and the number of bacteria infected by Pasteurella avium was determined.The antibiotic susceptibility of Pulsatillae decoction to Pasteurella avium was tested in vitro.100 3-month-old chickens were randomLy divided into negative group,model group and Pulsatillae decoction（low,medium and high）dose group with 20 chickens in each group.Except the negative group,the other groups were inoculated with Pasteurella avium 5.0×10⁷ CFU/mL bacterium solution 1 mL per chicken.The model group and the negative group drank water,the low-dose group,the middle-dose group and the high-dose group drank 7.8mg/mL,15.6 mg/mL and 31.3 mg/mL Pulsatillae decoction freely,respectively.On the 1st,3rd,5th and 7th day after administration,blood was collected under wings to determine the contents of TNF-α,IL-1 and H4R in serum.Five chickens were randomLy selected from each group,weighed and killed by carotid artery bloodletting.Lung,kidney and duodenum were collected and fixed in polyformaldehyde.Pathological changes were observed by HE staining.Lung and duodenum were fixed in Carnoy’s solution,and Toluidine Blue staining was used to observe the distribution of mast cells（MC）.The contents of TNF-α,IL-1 and H4R in serum were determined by ELISA.Result:1.The correlation between OD_600nm value of Pasteurella avium liquid and viable bacteria count was not high,and there was a positive correlation only before the stable period;the higher OD_600nm value of Pasteurella avium liquid ranged from 0.3 to 0.55,and the median half lethal dose（LD50）was 5.0×10⁷CFU/mL.2.The minimum inhibitory concentration of Pulsatillae decoction on Pasteurella avian in vitro was 3.91mg/mL.3.Lung pathological score and lung coefficient was showed that the difference of negative group was significantly lower than that of treatment group and model group（P<0.01）,and the difference of model group was significantly higher than that of treatment group（P<0.05）.4.During the experiment,the number of mast cells in the lung and duodenum of the model group was significantly higher than that of the negative group（P<0.01）.On the 3rd,5th and 7th day,the number of pulmonary mast cells in the treatment group was significantly lower than that in the model group（P<0.05）.On the 1st,3rd,5th and 7th day,the number of pulmonary mast cells in the treatment group was significantly（P<0.05）or extremely significant（P<0.01）higher than that in the negative group.The number of duodenal mast cells in the treatment group was significantly lower than that in the model group（P<0.05）;the number of mast cells on the 1st,3rd,5th and 7th days was significantly higher（P<0.05）or extremely significant（P<0.01）than that in the negative group.5.The serum levels of TNF-α,IL-1 and H4R in experimental chickens infected with Pasteurella avium increased first and then decreased,and increased significantly on the 3rd or 5th day（P<0.05）or very significantly（P<0.01）.The three different concentrations of Pulsatillae decoction significantly decreased the serum levels of TNF-α,IL-1 and H4R（P<0.05）or very significantly（P<0.01）,and the middle dose（15.6 mg/mL）group had the best effect.Conclusion:1.The minimum inhibitory concentration of Pulsatillae decoction on Pasteurella avian in vitro was 3.91mg/mL.2.Pulsatillae decoction can effectively alleviate lung injury in chickens with avian pasteurellosis.3.The number of MC in lung and duodenum of Pulsatillae decoction treatment group was significantly lower than that of model group and higher than that of negative group.4.Pulsatillae decoction can significantly reduce the content of inflammatory factors TNF-α,IL-1 and H4R in the blood of chciken by infected pasteurellosis.