Study On Antiasthmatic Effect And Its Mechanism Of Baicalin On Allergic Asthma In Rats

ObjectiveThis study aims to evaluate antiasthmatic effect of Baicalin through the allergic asthma model of rats induced by Ovalbumin(OVA).Furthermore,we explore its possible mechanism of the prevention and treatment of asthma in order to provide reference for its clinical application.Methods55 female SD rats were randomly divided into 5 groups,including Control group,Modelgroup,Dexamethasone group,high dosage Baicalin group,low dosage Baicalin group.10~15 rats each group.Allergic asthma model was established by the double sensitization and continuous inspiration for 14 days.All the treatment groups were given the corresponding medicine intragastrically,24 h after first sensitization,Continuous administration for 27 days.Animals were sacrificed at 24 h after the last excitation.Blood was collected from abdominal aorta after anesthesia.After the end of the blood collection,animals were quickly dissected to collect lung tissue and airway tissue.We Evaluate the antiasthmatic effect of a Baicalin by asthma severity score,asthma latent period and pulmonary pathology.We explore the anti-inflammatory mechanism of Baicalin by bronchial pathological observation,plasma HMGB-1 level,the level of TLR4 protein in airway tissue,the level of TLR4 mRNA in airway tissue and the expression of p-p38 protein in lung tissue.At the last,We explore the effect and mechanism of airway remodeling by bronchial wall thickness,collagen deposition,airway smooth muscle thickness on bronchial airway tissue,TGF-?1 expression,the expression of p-ERK1/2 protein in lung tissue,lung tissue ERK1/2 mRNA levels.Main results 1?Allergic asthma model establishmentIn the atomization process,all rats(except for Control group)showed shortness of breath,cough,dyspnea and abdomen rhythm like action,sluggish,unresponsive and other symptoms,which meet the standard of modeling,show that the asthma model was established successfully.In addition,The results of asthma severity score and asthma latent period also show statistical difference between control group and model group(p <0.01).2? Antiasthmatic effect of Baicalin 1)The results of asthma severity score showed High and lowdosage Baicalin can significantly reduce the asthma severity score(High/low dosage Baicalin VS model group,p <0.01);2)At the end of the last stimulation,the latency of asthma in High and low dosage Baicalin were all significantly longer than that in Model group,(High/low dosage Baicalin VS model group,p <0.05);3)The results of HE staining of lung tissue showed that Baicalin groups could improve the pathological damage of lung tissue in asthmatic rats.3?Airway remodeling inhibitory effect of Baicalin 1)The results of bronchial wall thickness measurement showed that Baicalin groups can effectively reduce the thickness of bronchial wall,but there was no significant dose dependence;2)The results of Masson staining showed that Baicalin groups could improve the deposition of collagen in the airway of asthmatic rats;3)The results of immunohistochemistry showed that the expression level of ?-SMA protein in bronchial smooth muscle of rats with asthma was significantly inhibited by Baicalin,and no obvious dose dependence was observed;4)The results of immunohistochemistry showed that the expression levels of TGF-?1 protein in airway tissue of asthmatic rats were decreased by Baicalin,and a dose-dependent manner was observed;5)Immunohistochemical detection of p-ERK1/2 protein expression results showed that p-ERK1/2 protein expression levels of high/low dosage Baicalin groups were significantly decreased(p < 0.05);6)The results of ERK1/2 mRNA in lung tissue measurement showed that Baicalin groups could significantly reduce the level of ERK1/2 mRNA in lung tissue of asthmatic rats.3?Inflammation inhibitory effect of Baicalin 1)The results of HE staining showed that Baicalin groups could inhibit the airway inflammation;2)The determination of HMGB1 in plasma by ELISA showed that Baicalin groups could significantly reduce the content of HMGB1 in plasma,and no significant dose dependence was observed;3)The results of HMGB1 mRNA in the lung tissue showed that Baicalin groups had lower tendency than the model group,but the difference was not statistically significant(P>0.05);4)Immunohistochemistry was used to detect the expression of TLR-4 protein in airway tissue.The results showed that TLR-4 protein in Model group was significantly higher than Control group(p < 0.05).When compared with Model group,Baicalin groups can decrease the expression level of TLR-4 protein in airway tissue(p < 0.05);5)The results showed that Baicalin groups could significantly reduce the level of TLR-4in airway tissue(p < 0.05),which was consistent with the expression of TLR-4 protein in airway tissue;6)The levels of p-p38 protein in lung tissue were detected by immunohistochemistry and Western blotting.The results of immunohistochemistry showed that the levels of p-p38 in high dosage Baicalin group were significantly lower(p < 0.05);Western blotting results showed that Baicalin groups could decrease the level of p-p38 protein in lung tissue(p < 0.05);these results suggest that the Baicalin groups can inhibit expression of p-p38 protein in lung tissue of asthmatic rats.ConclusionUnder the conditions of this experiment,high/low dosage Baicalin group(0.32g/kg,0.08g/kg)were administered continuously for 27 days on OVA induced asthma rats has definite effect on prevention and treatment of asthma,and Baicalin can also inhibite airway remodeling.In additon,the inhibition is closely related to the mechanism of inflammation inhibition.