Protective Effects Of Quercetin On Lung In Smoke Inhalation Injury In Rats

The smoke inhalation injury is respiratory and lung damage which caused by the heat and smoke. It’s pathogenesis of inflammatory mediators and peroxidation closely related.Inhalation injury still is the leading cause of death in burn patients.Flavonoids quercetin is the most widely distributed of the nature, the Before studies confirmed, quercetin has lots of Pharmacological effects,such as antioxidant, anti-inflammatory and anti-platelet aggregation.In the lipopolysaccharide-induced lung injury models,there are some lung protection of quercetin.However, there is no Animal experiments and clinical observations about the lung protection of quercetin up to now. Therefore, We through the use of quercetin intervention in the pathogenesis of inhalation injury, to test whether quercetin has a protective effect in the smoke inhalation injury.Objectives:1.Detect concentration levels of interleukin-6(IL-6), interleukin-10(IL-10),tumor necrosis factor-α (TNF-α) in serum, to research the effects of quercetin on inflammatory mediators in early smoke inhalation injury;2.Detection activity of malondialdehyde(MDA), myeloperoxidase(MPO) and superoxide dismutase(SOD) in lung homogenates, to research the effects of the quercetin on oxidation/anti-oxidation factor in early smoke inhalation injury;3.In this study, we can through the observation of quercetin on inflammatory mediators in rats after smoke inhalation injury and peroxidation, to investigate whether quercetin has a protective effect on early smoke inhalation injury, and its mechanism of protective effect.Methods:Forty-two male SD rats were divided into three groups randomly:group A(n=6), group B(n=18), and group C(n=18). The latter two groups are in accordance with6h,24h and48h after injury are each divided into three groups (B1, B2, B3, C1, C2, C3)(n=6).3h after the smoke inhalation injury, the rats in group C were all injected intraperitoneally with quercetin(200mg/kg), and the group B was injected the same volume normal saline. The control group was without treatment. At6h after injured in group A、B1and C1,24h after injured in group B2and C2, and48h after injured in group B3and C3, Collected the blood samples5ml form femoral artery and lung tissue in rats. The levels of tumor necrosis factor-α(TNF-α), interleukin-6(IL-6)and interleukin-10(IL-10) in serum and malondialdehyde (MDA), myeloperoxidase (MPO) and Superoxide dismutase(SOD) in lung tissue of rats were determined. The lung tissues were examined under microscope.Results:1. General observation:Shortness of breath, chest auscultation and wheezing, rales, tachycardia appears after the injury. Remove the injured rats to outside to rest for5minutes, the above the performance gradually disappeared. The group A without these symptoms.2.Lung specimens observation:The lungs of rats of group A on visual inspection had normal color and no congestion and edema.Group B1,group B2and group B3were found to have severe diffused and passive lung congestion, the group B3was the most obvious. ecchymosis and edema. There was no obvious sign of edema or spot bleeding of lungs in group C1,group C2and group C3,the group C3was the most obvious.3.Macroscopic observation:Group A was observed under the microscope, the lungs of rats were found to have Little exudate, diffused alveolar septum thickening and spotty hemorrhage. Group B1,group B2and group B3were found to have infiltrating inflammatory granulocytes, the group B3was the most obvious. The lung tissues from group C1,group C2and group C3were found to have uniform alveolar septa, and have infiltrating inflammatory granulocytes, the group C3was the most obvious.4.The results of TNF-α、IL-6and IL-10:Group C1compared with group B1, group C2compared with group B2and group C3compared with group B3, the level of IL-6and TNF-a were decreased (P<0.01), while IL-10was increased (P<0.01).Furthermore, from group Bi to group B3, and from group C1to group C3, the level of TNF-α, IL-6and IL-10decreased gradually (P<0.01)5.The results of MDA、MPO and SOD:Group C1compared with group B1, group C2compared with group B2and group C3compared with group B3,MP0and MDA were decreased (P<0.01), while SOD was increased (P<0.01).Furthermore, from group B1to group B3, and from group C1to group C3,the level of MPO and MDA decreased Significantly (P<0.01), while the level of SOD increased.Conclusions:1.After inhalation injury, the lung displayed that pneumonocyte became swollen, the structure of alveoli of lung destroyed and inflammatory celles infiltration. The quercetin treatment group can mitigate the above changes, and the48h group was most effectively.2.Quercetin has a protective effect on smoke inhalation injured by scavenging free radical and inhibiting proinflammatory cytokines.