Effect of Shaofu-Zhuyu decoction on MAPK/ERK signaling pathway in rats with endometriosis

AIM: To observe the effects of Shaofu-Zhuyu decoction (SFZY) on mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) signaling pathway in the rats with endometriosis (EM), and to explore the mechanism of SFZY for treatment of EM.METHODS: Healthy female SD rats were used to establish the EM model. The rats were randomly divided into blank control group, model group, positive control group, and low dose, middle dose and high dose of SFZY groups. The pathological changes of the endometriotic tissue were observed by HE staining. The levels of tumor necrosis factor-α (TNF-α), interleukin-6(IL-6) and IL-8 in the uterine tissue were detected by ELISA. The mRNA expression of ERK, vascular endothelial growh factor (VEGF) and matrix metalloprotein-9 (MMP-9) was detected by RT-qPCR. The protein expression of nuclear factor-κB (NF-κB), MAPK and MAPK-ERK kinase (MEK) was determined by Western blot.RESULTS: Compared with model group, the levels of TNF-α, IL-6 and IL-8 in the uterine tissue of the rats in middle dose and high dose of SFZY groups were significantly decreased (P<0.05), the mRNA expression of ERK, VEGF and MMP-9 was significantly reduced, and the protein expression of NF-κB, MEK and MAPK was decreased significantly in the rat endometriotic tissues (P<0.05).CONCLUSION: SFZY may play a key role in the treatment of EM by regulating MAPK/ERK signaling pathway.     

Ultrastructural changes and significance of endometriotic rat model with HCG treatment

AIM: To investigate whether and how human chorionic gonadotropin (HCG) treatment ameliorates endometriosis in the endometriotic rat model. METHODS: The rat model of endometriosis was established and the model rats were divided into 4 groups. The rats in HCG groups were treated with 19.4, 25.8 and 51.6 IU/100 g of HCG every day (low-dose HCG, medium-dose HCG and high-dose HCG, respectively). The rats in control group were treated with 0.9% NaCl. After 15 days (3 estrous cycles), the ectopic lesion volume and ultrastructural characteristics in eutopic and ectopic endometria were investigated. RESULTS: After HCG treatment, the volume of endometriotic lesions was significantly smaller than that before treatment. Numerous and mitochondrial, endoplasmic reticulum and ribosomes were observed in the cytoplasm of eutopic and ectopic endometrium before treatment. After treatment, some cell structures were not clear, and mitochondrial cristae decreased or disappeared partly. Some cells were densed and shrinkage, autophagosome in cytoplasm increased, and mitochondria and endoplasmic reticulum swelt. CONCLUSION: HCG therapy appears to be an effective treatment for endometriosis in rats attributed to its influence on cell metabolism dysfunction of eutopic and ectopic endometria.     

Mechanism of Fuzilizhong decoction alleviating inflammatory damage of rats with non-alcoholic fatty liver disease

AIM To observe the effect of Fuzilizhong decoction on the inflammatory damage of non-alcoholic fatty liver disease （NAFLD） rats and to explore its mechanism. METHODS SPF male SD rats were randomly divided into 6 groups： control group, model group, high dose （20 mg·kg^-1·d^-1）, middle dose （10 mg·kg^-1·d^-1）, low dose （5 mg·kg^-1·d^-1） Fuzilizhong decoction group and Yishanfu （30 mg·kg^-1·d^-1）group, 8 rats in each group. A NAFLD rat modelwas established by intragastric administration of fat emulsion for 4 weeks. Then the drug was given for 4 weeks in each treatment group. HE staining was performed to observe the histopathological changes of the rat liver.The serum levels of interleukin-2（IL-2）, IL-6 and tumor necrosis factor-α（TNF-α） were measured by ELISA. The expression of toll like receptor 4（TLR4） and NF-κB p65 in liver tissues at mRNA and protein levels was determined by RT-qPCR and Western bolt,respectively. RESULTS Compared with control group, the inflammatory damage of liver tissue was more serious, the serum levels of IL-2, IL-6 and TNF-α, the mRNA expression TLR4 and NF-κB p65 in liver tissues were significantly increased in model group（P<0.05）. However, compared with model group, the liver pathological changes in each treatment group were significantly relieved, the serum levels of IL-2, IL-6 and TNF-α, the mRNA expression of TLR4 and NF-κB p65 in liver tissues were significantly reduced（P<0.05）.In addition, the changes of TLR4 and p-NF-κB p65 protein levels in liver tissue were consistent with the changes of TLR4 and NF-κB p65 mRNA. CONCLUSION Fuzilizhong decoction attenuates the inflammatory damages of NAFLD in rats by inhibiting TLR4/NF-κB p65 signaling pathway.     

Protective effects and mechanism of astragalus injection on asthmatic rats

AIM: To explore the protective effects and mechanism of astragalus injection on asthmatic rats.METHODS: OVA was injected intraperitoneally and inhaled to produce the asthmatic model.Forty rats were randomly divided into five groups: control group,asthma group and astragalus groups of high,medium and low dose.The concentrations of IL-4,IFN-γ in BALF,the expression of IL-4 mRNA,IFN-γ mRNA and phospho-p38 MAPK in lung tissues were respectively measured by ELISA,RT-PCR and Western blotting.The number of inflammatory cells in BALF and histropathology changes were observed.RESULTS: In asthmatic group,the number of inflammatory cells and the concentrations of IL-4 in BALF and the expression of IL-4 mRNA,phospho-p38 MAPK in lung tissue were higher,but IFN-γ and IFN-γ mRNA were lower than those in normal control rats (P<0.01).In astragalus group,the number of inflammatory cells,the concentrations of IL-4 in BALF and the expression of IL-4 mRNA,phospho-p38 MAPK in lung tissue were lower,but IFN-γ and IFN-γ mRNA were higher than those in normal control rats (P<0.01),and histropathology damage was alleviated significantly.The efficacies in the astragalus groups of high,medium and low dose were similar,which no significant difference was observed among them.There were positive correlations between the expression of 〖JP3〗phospho-p38 MAPK and the number of eosinophil,the concentration of IL-4,IL-4 mRNA (r=0.63,r=0.69,r=0.71,〖JP〗 P<0.01),and negative correlations between the expression of phospho-p38 MAPK and IFN-γ and IFN-γ mRNA (r=-0.65,r=-0.68,P<0.01).CONCLUSION: p38 MAPK may play a role in pathological process of asthma.Astragalus effectively treats asthma by inhibiting the expression of phospho-p38 MAPK,correcting the inbalance of IFN-γ/ IL-4 and decreasing the number of inflammatory cells.     

Effects of macrophage polarization during development of liver cirrhosis in rats

AIM: To explore the state of macrophage polarization and its relation with intestinal endotoxemia-endoplasmic reticulum stress in the development of liver cirrhosis induced by multiple pathogenic factors in rats. METHODS: The male SD rats (n=36) were randomly divided into normal control group and liver cirrhosis model group, and sacrificed at the end of the 4th, 6th and 8th weeks. The rat model of liver cirrhosis was induced by multiple pathogenic factors. The levels of alanine aminotransferase (ALT), endotoxin, homocysteine (Hcy) in the plasma, and inducible nitric oxide synthase (iNOS), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), arginase-1 (Arg-1) and interleukin-10 (IL-10) in the liver tissues were detected by ELISA. Histopathological change of the liver was observed under microscope with the staining of hematoxylin and eosin (HE) and van Gieson (VG). The expression of glucose-regulated protein 78 (Grp78), nuclear factor-kappa B (NF-κB), interferon-regulatory factor 5 (IRF5), CD86, CD206 and transforming growth factor-β1 (TGF-β1) at mRNA levels in the liver tissues were detected by the method of real-time fluorescence quantitative PCR.RESULTS: Compared with the corresponding normal control group, the levels of ALT, endotoxin, Hcy in the plasma and Grp78 mRNA in the liver tissues in liver cirrhosis model group were significantly and gradually increased (P<0.05). The mRNA expression of NF-κB, IRF5 and CD86, and the protein levels of iNOS, TNF-α and IL-6 in the liver tissues were significantly increased (P<0.05), and they successively increased from the 4th week to the 6th week and decreased reversely at the 8th week. The mRNA expression of CD206, TGF-β1, Arg-1 and IL-10 in the liver tissues were significantly increased from the 6th week to the 8th week (P<0.05), and no significant difference at the 4th week was observed. The level of endotoxin in the plasma was correlated with the mRNA expression of Grp78 in the liver tissues (P<0.01). Both endotoxin in the plasma and Grp78 mRNA in the liver tissues were correlated with the mRNA expression of CD86 and CD206 in the liver tissues (P<0.01).CONCLUSION: The pathway of liver damage-intestinal endotoxemia-endoplasmic reticulum stress-macrophage polarization may be critical in the pathogenesis of liver cirrhosis induced by multiple pathogenic factors.     

Apocynin decreases cardiac cytokines in STZ-induced diabetic cardiomyopathy

AIM: This study was to investigate the effects of apocynin on the expression of IL-1β, IL-18, TNF-α and COX-2 mRNA in the diabetic cardiomyopathy heart.METHODS: Diabetes was induced in 8-week old C57 mice with one intraperitoneal injection of streptozotocin (STZ, 100 mg/kg). The experiments were divided into 4 groups: sham (n=6), apocynin control (Apo, n=6), diabetic cardiomyopathy (STZ, n=16) and apocynin treatment (STZ+Apo, n=16). At the end of 8 weeks after induction of diabetes, cardiac functions were evaluated by echocardiography. Cardiac tissue was analyzed for the expression of IL-1β, IL-18, TNF-α, COX-2 mRNA and phosphorylated Akt by real-time RT-PCR and Western blotting, respectively.RESULTS: The expression of IL-1β, IL-18, TNF-α and COX-2 mRNA increased in diabetic cardiomyopathy heart accompanied with cardiac dysfunction. Cardiac functions were improved with decreased levels of IL-1β, IL-18, TNF-α and COX-2 mRNA expression in apocynin-treated heart. Compared with reduction of phosphorylated Akt, apocynin significantly increased phosphorylation of Akt in diabetic cardiomyopathy heart.CONCLUSION: Apocynin decreases cardiac IL-1β, IL-18, TNF-α and COX-2 mRNA expression accompanied with improved cardiac function, which associates with the increase of phosphorylated Akt in diabetic cardiomyopathy heart.     

Effects of swimming on experimental endometriosis in rats

AIM To evaluate the effect of swimming on experimental endometriosis in rats. METHODS 80 female SD rats were divided into 8 groups, including control group, model group and animals performed light exercise （swimming once a week）, moderate exercise （swimming 3 times a week）, and intense exercise （swimming 5 times a week） before or after endometriosis induction,10 rats in each group. The mRNA and protein expressions of fatty acid synthase （FAS）, matrix metalloproteinase 9 （MMP9） and proliferating cell nuclear antigen （PCNA） in endometrium of rats were detected. RESULTS The swimming before the induction of the edometriosis lesions did not prove to have aprophylactic role against endometriosis, whereas the swimming after induction of the lesions had a beneficial effect regardless of frequency, with a greater reduction in the groups practicing moderate and intense activity （P<0.05）, an increase in FAS levels and a decrease in MMP9 and PCNA levels were also observed （P<0.05）. CONCLUSION Swimming after induction of the edometriosis is beneficial for the treatment of endometriosis, the mechanism may be related to the expression of FAS, MMP9 and PCNA protein.     

Effect of pidotimod on renal function and inflammatory response in rat IgA nephropathy model

AIM:To explore the effect of pidotimod on the renal function in IgA nephropathy (IgAN) rat model, and to further study whether this effect is related to the inhibition of inflammatory response. METHODS:The SD rats (n=36) were randomly divided into control group, IgAN model group, IgAN with prednisone treatment group and IgAN with pidotimod treatment group, with 9 rats in each group. The IgAN model was induced by consecutive oral administration of bovine gamma globulin (BGG) for 8 weeks followed by injection of BGG through tail vein for 3 d. After the IgAN model was established, the drug was continuously used for 4 weeks. At the end of the treatment, the urine protein, serum creatinine and blood urea nitrogen were examined by an automated analyzer. IgA deposition in the renal tissues was observed by immunofluorescence staining. The mRNA expression levels of renal fibrosis markers transforming growth factor-β1 (TGF-β1) and fibronectin 1 in the renal tissues were detected by RT-qPCR. The mRNA and protein levels of pro-inflammatory cytokines interleukin-1β (IL-1β) and IL-6 in the renal tissues were determined by RT-qPCR and Western blot, respectively. RESULTS:No significant difference of the body weight was observed in different groups. Compared with control group, the content of urine protein, serum creatinine and blood urea nitrogen were significantly increased (P<0.01), whereas those were reversed by pidotimod treatment. The results of immunofluorescence staining showed that pidotimod inhibited IgA deposition in the IgAN rats. Pitomod treatment inhibited the mRNA expression levels of renal fibrosis markers TGF-β1 and fibronectin 1, and the mRNA and protein levels of pro-inflammatory cytokines IL-1β and IL-6 in the renal tissues of IgAN rats. CONCLUSION:Pidotimod alleviates IgAN progression in rats by inhibition of inflammatory response.     

Effect of hyperbaric oxygen on HIF-1α expression in rat experimental periodontitis with psychological stress

AIM: To investigate the effect of hyperbaric oxygen (HBO) on hypoxia-inducible factor-1α (HIF-1α) expression in rat experimental periodontitis with psychological stress. METHODS: Male special pathogen-free Wistar rats (n=120) were randomly divided into 4 groups: normal control group; psychological stress stimulation group; experimental periodontitis group: the periodontitis model was induced by wrapping 3/0 silk ligature inoculated with Porphyromonas gingivalis around the left maxillary second molar of the rats; periodontitis model with stress stimulation group. Psychological stress was removed at the 9th weeks after ligature, 6 rats from each experiment group were randomly chosen to HBO treatment. The rats were sacrificed at the 2nd, 4th, 8th and 10th weeks after ligature. Gingival index (GI) and attachment loss (AL) were measured before sacrifice. The histological changes of periodontal tissues were observed under microscope with HE staining. The expression of HIF-1α was observed by the method of immunohistochemistry. RESULTS: The sites of gingival attachment were normal in control group and psychological stress stimulation group. Periodontal pocket, and periodontal attachment loss were observed in experimental periodontitis group. The tissue damage was much serious in periodontitis model with stress stimulation group. No significant difference of GI and AL among psychological stress stimulation group and normal control group during the experiment was observed. GI and AL in periodonitis model with stress stimulating group were significantly higher than those in experimental periodontitis group at the 4th and 8th weeks (P < 0.01). The levels of GI and AL were significantly lower at the 10th weeks after HBO treatmnt than those in untreated groups (P < 0.05). No significant difference of HIF-1α expression scores among psychological stress stimulation group and normal control group was found. HIF-1α expression scores in periodonitis model with stress stimulating group was significantly higher than that in experimental periodontitis group at the 4th and 8th weeks (P < 0.01). At the 10th weeks after HBO treatment the levels of HIF-1α were significantly lower than that in untreated groups (P < 0.01). CONCLUSION: Stress stimulation may aggravate periodontitis by decreasing tissue oxygenation in rats. HBO may represent a useful way in psychological stress periodontitis therapy.     

Effects of Jiedu-Qingfei mixture on NF-κB and p38 MAPK pathways in lung tissues of rats with Mycoplasma pneumoniae infection

AIM: To observe the therapeutic effect of Jiedu-Qingfei mixture on Mycoplasma pneumoniae (MP)-infected rat lung tissues and to explore its mechanism. METHODS: SD rats (n=40) were randomly divided into 4 groups:blank control group, model group, Jiedu-Qingfei group and positive control group, with 10 rats in each group. The rats in experimental groups were slowly dripped with 1×10⁹ CFU/L MP solution into their nostrils for 4 d. One rat in each group was sacrificed for MP nucleic acid detection at the second day after inoculation, and the other rats were given gavage therapy. The rats in blank control group and model group were intragastrically given the same volume of normal saline, the rats in Jiedu-Qingfei group were given 8 mL/kg Jiedu-Qingfei mixture daily for 4 weeks, and the rats in psoitive control group were given dexmethasone sodium phosphate (0.5 mg·kg^-1·d^-1). After the experiment, the rats were killed. The serum and bronchoalveolar lavage fluid (BALF) were collected for detecting the levels of interleukin-12 (IL-12), IL-13 and TNF-α by ELISA. The right lung tissues were used for pathological observation and HE staining, while the left lung tissues were used to detect the expression of NF-κB p50, I-κBα and p38 mitogen-activated protein kinase (p38 MAPK) at mRNA and protein levels. RESULTS: The results of MP nucleic acid detection showed that all the rats except blank control group were MP nucleic acid positive, indicating that the rat model of MP infection was successfully established. On the 1st day of the treatment, the pathological scores of the lung tissues in model group and Jiedu-Qingfei group were significantly higher than those in blank control group (P<0.05). After treatment, the pathological scores of the lung tissues in mo-del group were significantly higher than those in blank control group and Jiedu-Qingfei group. The levels of IL-12 in the serum and BALF in model group were significantly lower than those in blank control group after MP infection (P<0.05), while those after treatment with Jiedu-Qingfei mixture were significantly higher than those in model group (P<0.05). The levels of IL-13 and TNF-α in the serum and BALF of MP-infected rats were increased significantly, while those after treatment with Jiedu-Qingfei mixture were significantly lower than those in model group (P<0.05). The mRNA expression levels of NF-κB p50 and p38 MAPK in model group were increased significantly (P<0.01). After treatment, the mRNA expression levels of NF-κB p50 and p38 MAPK were decreased significantly compared with model group (P<0.01). The mRNA expression level of I-κBα in model group was significantly lower than that in control group. After treatment, the mRNA expression of I-κBα in Jiedu-Qingfei group was significantly higher than that in model group (P<0.05). The protein levels of NF-κB p50 and p38 MAPK in the lung tissues of model group were significantly higher than those of blank control group. After treatment, the protein expression of NF-κB p50 and p38 MAPK was decreased significantly. The protein level of I-κBα in model group was significantly lower than that in blank control group, and after treatment with Jiedu-Qingfei mixture, the protein expression level of I-κBα was increased significantly (P<0.05). CONCLUSION: Jiedu-Qingfei mixture may attenuate lung tissue inflammation caused by MP through NF-κB and p38 MAPK pathways.     

Inhibitory effects of right cervical sympathetic trunk transection on inflammatory response after acute myocardial infarction in rats and its influence on HMGB1/TLR4/NF-κB signaling pathway

AIM: To observe the effects of transection of right cervical sympathetic trunk (TCST) on inflammatory response and expression of high mobility group box 1 (HMGB1) and TLR4/NF-κB signaling pathway in the rats after acute myocardial infarction (AMI). METHODS: AMI model was established by ligation of left anterior descending coronary artery in SD rats, then the model rats were randomly divided into MI group and MI+TCST group. MI+TCST model was performed by transection of right cervical sympathetic trunk after left anterior descending coronary artery ligation. The rats in MI group and MI+TCST group were divided into 1, 3, 7, 14 and 28 d subgroups, and another sham operation group threading without ligation, with 8 rats in above each group. After modeling for 4 weeks, the cardiac function was measured by echocardiography. All rats were killed to harvest the hearts for mesuring cardiac hypertrophy index. The myocardial tissue close to infarction was observed with HE staining. The relative mRNA expression levels of HMGB1, tumor necrosis factor α(TNF-α) and interleukin (IL)-6 at different time points were detected by real-time PCR. The protein expression of HMGB1 and TLR4 at different time points after AMI was determined by Western blot. The effect of transection of right cervical sympathetic trunk on the expressions of HMGB1 and TLR4/NF-κB signaling pathway was also analyzed.RESULTS: Compared with the MI group, left ventricular ejection fraction (LVEF) and left ventricular shorterning fraction (LVFS) were significantly higher (P<0.05), left ventricular end-diastole dimension (LVEDd), left ventricular end-systole dimension (LVESd) and cardiac hypertrophy index were significantly lower (P<0.05), and the mRNA levels of HMGB1, TNF-α and IL-6 decreased significantly in MI+TCST group (P<0.05). Western blot results revealed that the protein expression level of HMGB1 increased in the infarct border zone at 3 d, and reached its peak at 7 d, then gradually decreased, and at 28 d after MI in MI group was still significantly higher than that in sham group (P<0.05). The protein expression of TLR4 was consistent with that of HMGB1. Transection of right cervical sympathetic trunk reduced protein expression of HMGB1 and TLR4/NF-κB signaling pathway-related proteins (P<0.05).CONCLUSION: Transection of right cervical sympathetic trunk improves ventricular remodeling and maintaining cardiac function. The mechanism may be related to inhibiting HMGB1/TLR4/NF-κB signaling pathway to reduce inflammatory response.     

Effects of sex on chronic pancreatitis induced by L-arginine in Kunming mice

AIM: To explore the effect of sex on the formation of chronic pancreatitis (CP) by comparing the differences in L-arginine-induced CP model between male and female mice.METHODS: Male (n=42) and female (n=42) Kunming mice were randomly divided into 4 groups:female control group, female CP group, male control group and male CP group (n=18 in each control group, n=6 at each time point; n=24 in each CP group, n=8 at each time point). The mice in CP groups were intraperitoneally injected with 20% L-arginine (3 g/kg, twice/d, 1 d/week). After modeling for 2 weeks, 4 weeks and 6 weeks, the mice were anesthetized and sacrificed. The morphological changes and the degree of fibrosis in the pancreas were observed by HE and Masson staining. The positive expression rate of F4/80 in the pancreatic tissues was observed by the method of immunohistochemistry. The mRNA expression of interleukin-6 (IL-6), α-smooth muscle actin (α-SMA) and fibronectin (FN) in the pancreas were detected by real-time PCR. The protein of pancreas was extracted to detect the expression of α-SMA and FN by Western blot.RESULTS: At 2 weeks, 4 weeks and 6 weeks after intraperitoneal injection of L-arginine, the pancreatic tissues were obviously injured and exhibited different degrees of fibrosis in female and male CP groups. At the same time, there were significant differences in the degree of pancreatic injury between male and female mice, and the degree of pancreatic lesion in the male mice was significantly more severe. The positive rate of F4/80 in the pancreas of male CP mice was significantly higher than that in female CP group at the same time point after modeling. At every time point, the mRNA expression of IL-6 in the pancreas was increased in both female and male CP groups, but that in male CP group was higher (P<0.05). The fibrosis indexes, α-SMA and FN, were both highly expressed at mRNA and protein levels after modeling, but compared with the female group, the time of positive expression in male mice was earlier and the expression level was higher (P<0.05).CONCLUSION: The CP model is successfully established by intraperitoneal injection of 20% L-arginine, and a difference in the degree of pathologic alteration in pancreas between male and female mice exists. CP is more effectively induced by L-arginine in male mice, and the degree of fibrosis is more pronounced. The reason may be related to the sensitivity of male mice to L-arginine, causing more serious inflammatory response. Therefore, male mice are more suitable for establishing CP animal model.     

Alterations of phospholamban expression and cardiac sarcoplasmic reticulum Ca2+-ATPase activity in diabetic rats

AIM:To investigate the alterations of phospholamban (PLB) expression and cardiac sarcoplasmic reticulum (SR) Ca2+-ATPase activity,and the change of cardiac function in rats with diabetes mellitus (DM).METHODS: The diabetes mellitus in male Wistar rats was induced by intraperitoneal injection of streptozotocin.The levels of PLB mRNA and PLB protein,the activity of SR Ca2+-ATPase and the left ventricular hemodynamics parameters were measured 4　weeks,6 weeks and 8 weeks after DM was induced in rats,while the normal rats served as control group.RESULTS: There was no significant difference in PLB mRNA level and protein level between 4-week-DM rats and normal control rats.6-week-DM rats and 8-week-DM rats had markedly increased PLB mRNA and protein level compared with normal control rats.SR Ca2+-ATPase activity was not significantly changed in 4-week-DM rats compared with normal control rats,and was markedly depressed in 6-week-DM rats and 8-week-DM rats.LVSP,LVEDP and ±dp/dtmax were not significantly changed in 4-week-DM rats compared with normal control rats.In 6-week-DM rats and 8-week-DM rats,LVSP and ±dp/dtmax were decreased,LVEDP was increased compared with normal control rats.CONCLUSION: The elevated levels of PLB mRNA and PLB protein contribute to SR Ca2+-ATPase activity reduction,which leads to cardiac dysfunction in DM rats.     

Changes of endoplasmic reticulum stress-related molecules CHOP and TRB3 in rat fibrotic liver

AIM: To observe the changes of endoplasmic reticulum stress-related molecules CCAAT/enhancer-binding protein homologous protein(CHOP) and Tribbles homolog 3（TRB3） in the process of liver fibrosis induced by carbon tetrachloride (CCl4). METHODS: Male Wistar rats weighing 180 g to 200 g were divided into 4-week normal control group, 8-week normal control group, 4-week liver fibrosis group and 8-week liver fibrosis group. The rats in liver fibrosis groups were induced by subcutaneous injection of 40% CCl4 for 4 weeks or 8 weeks. The pathological changes of the liver were observed under light microscope. The protein level of ATF6 was determined by Western blotting. The protein and mRNA levels of CHOP and TRB3 in the liver were analyzed by immunohistochemistry, Western blotting and real-time PCR, respectively. The apoptosis of hepatocytes was measured by TUNEL assay. RESULTS: Pseudolobuli formed in the liver tissue of hepatic fibrotic rats. Compared with the control rats, the protein level of p90ATF6 was obviously decreased, the protein level of p50ATF6 was obviously increased, and the protein and mRNA levels of CHOP and TRB3 were obviously higher in the hepatocytes of hepatic fibrotic rats. The apoptosis of hepatocytes was also increased in 4-week and 8-week fibrosis groups. CONCLUSION: In the process of liver fibrosis induced by 40% CCl4, the obviously increased expression of endoplasmic reticulum stress-related molecules CHOP and TRB3 at protein and mRNA levels indicates that endoplasmic reticulum stress may play an important role in the liver fibrosis by promoting the apoptosis of hepatocytes.