Mechanism Research Of Emodin Combined With Rhein On Treatment Of Paraquat Poisoning In Rats

Objective To investigate the protective effect of emodin combined with rhein on lung injury in rats with paraquat poisoning,at the same time,to study some of its mechanisms.Methods Forty healthy adult male SD rats have be selected and were randomly divided into normal control group(group A),model group(group B),emodin intervention group(group C),emodin combined with rhein intervention group(group D),each group has10 rats.Group A was given 2 ml physiological saline by gavage.Group B,C and D were given 40 mg/kg of paraquat solution and diluted into 2 ml to establish paraquat poisoning rat model.,group C was given emodin 40 mg/kg solution on the second day,group D was given 40 mg/kg emodin solution and 40 mg/kg rhein solution for 2 ml,group A and group B were given solution by gavage respectively.The process lasted 27 days,at the end of the experiment,all groups of rats were killed.Some of lung tissue was taken for hematoxylin-eosin(HE),inflammation and injury of lung tissue were observed under the microscope.The fibrosis of lung tissue was observed by Masson staining.The concentration of transforming growth factor-beta 1(TGF-? 1),connective tissue growth factor(CTGF),tumor necrosis factor-alpha(TNF-?)and interleukin-1(IL-1)in lung homogenate was determined by enzyme-linked immunosorbent assay(ELISA).The protein levels of Smad2 and Smad7 were detected by Western-blot.Results(1)General situation of rats: The control group rats had good mental state,sensitive reaction,clean fur,ruddy lips,normal water intake and excretion,and the weight growth steady.After 24 hours of PQ poisoning,rats in group B,C and D gradually showed mental depression,poor reaction,lack of activity,reduction of water intake,stool drying and even low frequency defecation in group B.Compared with the group B,the times of stool in group C and D significant increase,the feces is dilute and yellow.A few of animals hardly eat or drink water.They show obvious fatigue and sluggishness,walk unsteadily,limbs weakness,lack of activity,limbs spasms and convulsions occurred in some of the rats,withered hair.The weight of the three groups was slower than group A,and the weight gain of the C and D intervention group was faster than group B.(2)Respiratory and death: The respiratory of group A was normal,after 24 hours of paraquat poisoning the frequency of respiratory in group B,C and D were faster than group A.Respiratory distress and even death occurred in some rats after 48-72 hours of paraquat poisoning.Performance above began to alleviate until the 6th day of the experiment.Two rats in group B died within once week at the beginning of the experiment,One in group B died again from the 13 th day of the experiment.Both group C and D have One rat died within once week at the beginning of the experiment,between the 20 th and 21 st days of the experiment,there has one rat died in group C and D.(3)HE staining showed that the pulmonary tissue,bronchus and alveoli in group A were clearly.Having a complete structure,the alveolar septum was normal,the tissue was closely connected,the cytoplasm was homogeneous,and there was no obvious inflammatory cell infiltration.The lung tissue and alveoli of rats in group B were destroyed in varying degrees,alveolar septum was hyperemia,swelling,widening,narrowing of alveoli septum,part of alveolar fusion,alveolar septum thickening significantly,lymphocyte infiltration and fibrous tissue proliferation were seen in some alveolar septum.The degree of damage in lung tissue,bronchus and alveolar structure in C and D intervention groups were lighter than in group B.The degree of alveolar septum hyperemia and swelling,inflammatory cell infiltration,septal thickening and pulmonary fibrosis were less than those in group B.(4)Mason staining: There were a few blue stained fibrous tissues in the pulmonary interstitium of group A,and more blue stained fibrous tissues in group B,C and D;compared witn group C and D,there has more blue stained fibrous tissues in group B.(5)Compared with group A,the levels of TGF-?1,CTGF,TNF-a and IL-1 in lung tissue of rats in group B,C and D were significantly increased,and the contents of group C and group D were lower than group B(P < 0.05).In the TGF-?/Smad signaling pathway,the expression of Smad2 increased significantly,while the expression of Smad7 decreased.Conclusion Compared with emodin alone,emodin combined with rhein had a stronger effect on alleviating the general symptoms,shortness of breath and pulmonary fibrosis in rats of paraquat poisoning.Its mechanism may be as follows: Inhibiting the synthesis of TNF-? ?IL-1,alleviating the inflammatory reaction induced by PQ poisoning;Inhibiting the production of TGF-?1 and CTGF,alleviating EMT and ECM,thus alleviating pulmonary fibrosis;It is related to the activation of TGF-?/Smad signaling pathway by decreasing the expression of Smad2 and up-regulating the expression of Smad7.