Study On The Mechanism Of Sepsis-Induced Acute Lung Injury In Rat And The Preventive Effect Of Medicine

PARTⅠTHE MECHANISM OF ACTION OF NF-ΚB AND PLA2 IN LIPOPOLYSACCHARIDE-INDUCED ACUTE LUNG INJURY IN RAT【Objective】To study the pathological process of lipopolysaccharide -induced acute lung injury (ALI) in rat , and to research the mechanism of action of NF-κB and PLA2 on it.【Methods】SD male rats were randomly assigned to two groups : control group ,model group.ALI was induced by intravenous injection of LPS(6mg/kg). Control group rats were injected equal kilogram body weight Normal saline by veins. Each group was divided injected 2 hour,4 hour,8 hour,12 hour four subgroups , each subgroups has eight rats . These rats were put to death by postanesthetic at each time points. The lung wet/dry weight ratio was tested ; lung pathologic tissue score was scored by Paraffin Embedding slicing HE staining ; alveolar macrophages(AM) were extracted by bronchoalveolar lavage and tested phagotrophic function by neutral red method,apoptosis ratio by tunnel method and the protein expressions of nuclear factor-κB (NF-κB) protein65 were measured by immunohistochemistry ; and secretory phospholipase A2 typeⅡA (sPLA2ⅡA),Bcl2,Bax mRNA expression of AM were measured by RT-PCR in our experiment.【Results】Compared with control group each corresponding time point subgroup , The lung wet/dry weight ratio ,lung pathologic tissue score , AM apoptosis ratio, AM NF-κBp65 expression, and sPLA2ⅡA mRNA expression were increased and AM phagotrophic function, Bcl2 mRNA expression were decreased in model group rats(p<0.01).【Conclusion】1. The acute lung injure model was successfully duplicated by injected lipopolysaccharide in tail vein . The method is simple, easy and with stable results.2. After injected LPS ,the AM NF-κB activation, the AM sPLA2ⅡA mRNA transcription and the AM apoptosis were promoted in a time dependent manner , the degree of pulmonary injury was aggravated too . It hint that the degree of lipopolysaccharide -induced acute lung injury and the AM NF-κB activation,the AM sPLA2ⅡA mRNA transcription and the AM apoptosis have correlation. PARTⅡTHE PROTECTIVE MECHANISM OF CHLOROQUINE AND PYRROLIDINE DITHIOCARBAMATES (PDTC) ON ACUTE LUNG INJURY OF SEPSIS RAT【Objective】To study the pathological process of lipopolysaccharide- induced acute lung injury (ALI) in rat , and to research the protective effects and mechanisms of Chloroquine and PDTC on it.【Methods】SD male rats were randomly assigned to four groups : control group ,model group, Chloroquine treatment group, PDTC prevention group. ALI was induced by intravenous injection of LPS(6mg/kg). Chloroquine treatment group rats were immediately administered chloroquine (30mg/kg) by intraperitoneal injection after they had been injected LPS. PDTC prevention group rats had been administered PDTC(120mg/kg) by intraperitoneal injection before they were injected LPS.The lung wet/dry weight ratio, lung pathologic tissue score, alveolar macrophages(AM) apoptosis ratio and nuclear factor-κBp65(NF-κBp65) expression, and secretory phospholipase A2 typeⅡA(sPLA2ⅡA),Bcl2,Bax genes expression of AM were measured in our experiment. 【Results】compared with control group, The lung wet/dry weight ratio ,lung pathologic tissue score, AM apoptosis ratio, AM NF-κBp65 expression, and sPLA2ⅡA genes expression were increased and AM Bcl2 genes expression were decreased in model group rats(p<0.05). These changes were inverted in Chloroquine treatment group and PDTC prevention group rats, the degree of lung injury was markedly relieved (p<0.05).【Conclusion】1. The prophylactic PDTC administration potentially inhabit activation of NF-κB , decrease expression of sPLA2ⅡA gene in AM ; promote Bcl2 genes expression of AM, decrease AM apoptosis, which has protective function in LPS-induced ALI rats.2. In early ALI, chloroquine potentially down regulate expression of sPLA2ⅡA gene , up-regulation expression of Bcl2 genes in AM;decrease activation of NF-κB in AM ;enhance AM phagotrophic function;decrease AM apoptosis, which has protective function in LPS-induced ALI rats.