Experimental models of non-alcoholic fatty liver disease in rats

Non-alcoholic fatty liver disease(NAFLD)is the most common chronic liver disease in the Western world,and it persists at a high prevalence.NAFLD is characterised by the accumulation of triglycerides in the liver and includes a spectrum of histopathological findings,ranging from simple fatty liver through non-alcoholic steatohepatitis(NASH)to fibrosis and ultimately cirrhosis,which may progress to hepatocellular carcinoma.The pathogenesis of NAFLD is closely related to the metabolic syndrome and insulin resistance.Understanding the pathophysiology and treatment of NAFLD in humans has currently been limited by the lack of satisfactory animal models.The ideal animal model for NAFLD should reflect all aspects of the intricate etiopathogenesis of human NAFLD and the typical histological findings of its different stages.Within the past several years,great emphasis has been placed on the development of an appropriate model for human NASH.This paper reviews the widely used experimental models of NAFLD in rats.We discuss nutritional,genetic and combined models of NAFLD and their pros and cons.The choice of a suitable animal model for this disease while respecting its limitations may help to improve the understanding of its complex pathogenesis and to discover appropriate therapeutic strategies.Considering the legislative,ethical,economical and health factors of NAFLD,animal models are essential tools for the research of this disease.

Animal bone growth experiment of rapid-growing rats in different stress environment and its mathematical model

The aim of this study is to explore a way that quantify the qualitative equation of bone growth and remodeling which was based on the animal Experiment of rapid-growing Rats in Different Stress Environment. These results were proved to be of good stability and identification precision with the numerical method of inversion. It suggested that the growing coefficient and the threshold in function were variables changing with time and space. The idea and method used in the research of bone growth and remodeling adaptation in this paper also provided clue and reference to establish other models for living system.

Protective effect of liraglutide on the myocardium of type 2 diabetic rats by inhibiting polyadenosine diphosphate-ribose polymerase-1

BACKGROUND In recent years,studies have found that the occurrence and development of diabetic cardiomyopathy(DCM)is closely related to an increase in polyadenosine diphosphate-ribose polymerase-1(PARP-1)activity.PARP-1 activation could be involved in the pathophysiological process of DCM by promoting oxidative stress,the inflammatory response,apoptosis and myocardial fibrosis.AIM To investigate the mechanism of liraglutide in improving myocardial injury in type 2 diabetic rats,further clarified the protective effect of liraglutide on the heart,and provided a new option for the treatment of DCM.METHODS Forty healthy male SD rats aged 6 wk were randomly divided into two groups,a normal control group(n=10)and a model group(n=30),which were fed an ordinary diet and a high-sugar and high-fat diet,respectively.After successful modeling,the rats in the model group were fed a high-glucose and high-fat diet for 4 wk and randomly divided into a model group and an intervention group(further divided into a high-dose group and a low-dose group).The rats were fed a high-glucose and high-fat diet for 8 wk and then started drug intervention.Blood samples were collected from the abdominal aorta to detect fasting blood glucose and lipid profiles.Intact heart tissue was dissected,and its weight was used to calculate the heart weight index.Haematoxylin and eosin staining was used to observe the pathological changes in the myocardium and the expression of PARP-1 in the heart by immunohistochemistry.RESULTS The body weight and heart weight index of rats in the model group were significantly increased compared with those in the normal control group,and those in the intervention group were decreased compared with those in the model group,with a more obvious decrease observed in the high-dose group(P<0.05).In the model group,myocardial fibers were disordered,and inflammatory cells and interstitial fibrosis were observed.The cardiomyopathy of rats in the intervention group was improved to different degrees,the myocardial fibers were arranged neatly,and the myocardial cells were clearly striated;the improvement was more obvious in the high-dose group.Compared with the normal control group,the expression of PARP-1 in myocardial tissue of the model group was increased,and the difference was statistically significant(P<0.05).After liraglutide intervention,compared with the model group,the expression of PARP-1 in myocardial tissue was decreased,and the reduction was more obvious in the high-dose group(P<0.05)but still higher than that in the normal control group.CONCLUSION Liraglutide may improve myocardial injury in type 2 diabetic rats by inhibiting the expression of myocardial PARP-1 in a dose-dependent manner.

Features of animal models of complex partial epilepsy established through unilateral,bilateral and alternate-side kindling at hippocampus of rats

BACKGROUND： Electrical stimulation kindling model, having epilepsy-inducing and spontaneous seizure and other advantages, is a very ideal experimental animal model. But the kindling effect might be different at different sites. OBJECTIVE： To compare the features of animal models of complex partial epilepsy established through unilateral, bilateral and alternate-side kindling at hippocampus and successful rate of modeling among these 3 different ways. DESIGN： A randomized and controlled animal experiment SETTING： Department of Neurology, Qilu Hospital, Shandong University MATERIALS： Totally 60 healthy adult Wistar rats, weighing 200 to 300 g, of either gender, were used in this experiment. BL-410 biological functional experimental system （Taimeng Science and Technology Co. Ltd, Chengdu） and SE-7102 type electronic stimulator （Guangdian Company, Japan） were used in the experiment. METHODS： This experiment was carried out in the Experimental Animal Center of Shandong University from April to June 2004. After rats were anesthetized, electrode was implanted into the hippocampus. From the first day of measurement of afterdischarge threshold value, rats were given two-square-wave suprathreshold stimulation once per day with 400 μA intensity, 1ms wave length, 60 Hz frequency for 1 s duration. Left hippocampus was stimulated in unilateral kindling group, bilateral hippocampi were stimulated in bilateral kindling group, and left and right hippocampi were stimulated alternately every day in the alternate-side kindling group. Seizure intensity was scored： grade 0： normal, 1： wet dog-like shivering, facial spasm, such as, winking, touching the beard, rhythmic chewing and so on; 2： rhythmic nodding; 3： forelimb spasm;4： standing accompanied by bilateral forelimb spasm;5： tumbling, losing balance, four limbs spasm. Modeling was successful when seizure intensity reached grade 5. t test was used for the comparison of mean value between two samples. MAIN OUTCOME MEASURES： Comparison of the successful rate of modeling, the times of stimulation to reach intensity of grade 5, the lasting time of seizure of grade 3 of rats in each group. RESULTS： Four rats of alternate-side kindling group dropped out due to infection-induced electrode loss, and 56 rats were involved in the result analysis. The successful rate of unilateral kindling group, bilateral kin- dling group and alternate-side kindling group was 55%（11/20）,100%（16/16）and 100%（20/20）, respective- ly. The stimuli to reach the grade 5 spasm were significantly more in the bilateral kindling group than in the unilateral kindling group [（30.63±3.48）, （19.36±3.47）times, t=8.268, P 〈 0.01], and those were significantly fewer in the alternate-side kindling group than in the unilateral kindling group [（ 10.85±1.98）times, t=-8.744, P 〈 0.01]. The duration of grade 3 spasm was significantly longer in the bilateral kindling group than in the unilateral kindling group [（9.75±2.59）, （3.21 ±1.58）days,t=-8.183,P 〈 0.01], Among 20 successful rats of al- ternate-side kindling group, grade 5 spasm was found in the left hippocampi of 11 rats, but grade 3 spasm in their right hippocampi; Grade 5 spasm was found in the right hippocampi of the other 9 rats, grade 4 spasm in the left hippocampus of 1 rat and grade 3 of 8 rats. CONCLUSION ： The speed of establishing epilepsy seizure model by alternate-side kindling is faster than that by unilateral kindling, while that by bilateral kindling is slower than that by unilateral kindling. The successful rate is very high to establish complex partial epilepsy with alternate-side or bilateral kindling. Epilepsy seizure established by alternate-side kindling has antagonistic effect of kindling and the seizure duration of grade 3 spasm is prolonged.

Long-Term Animal Feeding Trial of the Refined Konjac Meal Ⅱ. Effects of the Refined Konjac Meal on the Aging of the Brain, Liver, and Cardiovascular Tissue Cells in Rats

Rats of both sexes were fed on a basal feed containing 1% refined konjac meal (RKM) for 18 months and the effects of RKM on the cell aging were observed. A comparable group fed on the basic feed was used as the control. Results obtained demonstrate that the long-term feeding of RKM to rats can delay the course of cell aging of the gliocyte, cadiomyocyte, and the endothelial cell of the large and medium arteriases, hence it is likely to delay the occurrence of arteriosclerosis and improve the functions of the brain, heart and vascular system.

Gastrin,somatostatin,and experimental disturbance of the gastrointestinal tract in rats

INTRODUCTIONThe field of gastrointestinal hormones has expanded at a dizzying rate[1-4].Gastrointestinal hormones as regulatory peptides that appear to be major components of bodily integration and have important regulatory actions on physioligical function of the gastrointestinal tract .The successful isolation of some gastrointestinal hormones and the development of sensitive methods for their detection have led to the unexpected finding that they also exist in the brain .

Effects of vitamin E on experimental hepatic fibrosis in rats

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Effect of Acupuncture on Free Radicals in Rats with Early Experimental Spinal Cord Injury

Effect of acupuncture on free radicals after spinal cord injury was observed in rats with experimental spinal cord injury (SCI). Results indicated that within 24 hours after SCI malondialdehyde (MDA) increased progressively, 2 hours after SCI it reached the peak; and the superoxide dismutase (SOD) activity decreased significantly at the same hours, the decrease being the most marked 2-6 hours after SCI. The MDA content in the acupuncture group was significantly lower (P

Alteration of Nitric Oxide Synthase in Experimental Spinal Cord Injury in Rats

In order to detect the role of NO to the secondary damage following spinal cord injury (SCI). NOS in the injury site (T\-8) were studied using a rat SCI model induced by Allens weight drop method (10 g2.5 cm). The results suggested that activities of NOS significantly increased in 10 min\, 1\,2\,4\,8 h. The results indicated that NO was related to SCI. The rise of NO following SCI might lead to secondary spinal cord damage.\;

An Experimental Study on Somatostatin Receptors in the Brains of Hepatic Encephalopathy Rats

The present study was undertaken to evaluate the effect of somatostatin (SS) receptor,a brain-gut peptide receptor which is capable of inhibiting central neurons, on the pathogenesis of hepatic encephalopathy (HE).By means of radioligand binding assay, SS receptors in crude synaptosomal membrane of rat brains were investigated in a rat model of HE induced by partial hepatectomy following carbon tetrachloride intoxication and in controls. Binding to SS receptor was studied using125 I-SS as radiolgand Scatchard analysis of binding data was linear, yielding a dissociation constant (Kd) of 3.99 ±0.22 nmol/L and a maximal binding capacity (Bmax) of 238± 14.2 fmol/mg of protein in HE rats.Only increased Bmax values were observed (P< 0.005),while the Kd values were statistically unchanged (P>0.50),in HE rats as compared with those in controls.The results suggest that the changes of SS receptors in brains play a significant role in the pathogenesis of HE.The mechanism of HE induced by the alterations of SS receptors in the brains was discussed in this paper.

A comparative study of two methods for establishing a chronic non‑bacterial prostatitis model in rats‑

Objective:To compare the biological characteristics and stability of the chronic non-bacterial prostatitis(CNP)model in rats induced by the depot combined with estrogen induction method and the autoimmune response induction method.Methods:The CNP rat model was prepared using the depot combined with 17β-estradiol induction method in the depot hormone group and three concentrations of prostate protein homogenate at 40 mg/mL,20 mg/mL and 10 mg/mL in the autoimmune group,respectively.The degree of prostate tissue damage was evaluated by pathology(HE staining),and the immunoturbidimetric method was used to evaluate the contents of immunoglobulins IgA,IgM and IgG.ELISA was used to evaluate interleukin-1β(IL-1β),interleukin-10(IL-10),tumor necrosis factor-α(TNF-α)and high-sensitivity-C-reactive protein(hs-CRP),and electrochemiluminescence was used to evaluate the expression level of testosterone(T),and the two model methods were compared.Results:Compared with the sham-operated group,the body mass of rats in both models was significantly lower in the depot hormone group and autoimmune group before extraction(P<0.01,P<0.01),and histopathology of the prostate in both models showed destruction of glandular structure and a significant increase in inflammatory cells.Compared with the depot hormone group and the autoimmune group,the histopathological changes and inflammatory pathological scores of prostate and the contents of immune indexes IgA,IgM and IgG were significantly different in the depot hormone group(P<0.05,P<0.05,P<0.05),and the levels of IL-1β,IL-10,TNF-α,hs-CRP and T were significantly changed in the autoimmune group(P<0.01).The comparison between the high,medium and low dose groups of the autoimmune group,in which the pathological changes in the medium dose of the autoimmune group were slightly better than the other two groups between the groups,but the changes in IL-1β,IL-10,TNF-α,hs-CRP,and T in the low dose of the autoimmune group were the most significant(P<0.05).Conclusion:The pathological tissues of the chronic non-bacterial prostatitis model established by the depot combined with estrogen induction method and the autoimmune response induction method both showed significant changes,and the comprehensive indexes indicated that the depot combined with estrogen induction method was a more appropriate modeling choice.

A chronic ulcerative colitis model in rats

INTRODUCTIONIn recent years,there have been many reports aboutanimal model to investigate drugs for inflammatorybowel diseases (IBD).The experimental animalmodel often used is acetic acid-induced damage ofcolonic muscosa.In the present study,this animalmodel was investigated by administering variousconcentrations of TNBS.

Therapeutic effect of Zijin capsule in liver fibrosis in rats

AIM To confirm the therapeutic effect of Zijin capsule on liver fibrosis in rat model. METHODS Model group: bovine serum albumin (BSA) Freund′s incomplete adjuvant 0 5ml was injected subdermally at d 1, d 15 , d 22 , d 29 and d 36 for primary sensitization. Seven days after the fifth injection, BSA antibody in the serum was detected by double agar diffusion method. Normal saline of 0 4ml was injected through cauda vein to BSA antibody positive rat twice a week for fifteen times. Traditional Chinese medicine (TCM) decoction group and Zijin capsule group: In the attack injection period, Chinese medicinal decoction or Zijin capsule was given ig, the others were the same as in the model group. NS was used in the control group. The collagen content of rat liver was determined by Bergman′s method and expressed as ±s . The liver pathological changes were divided into four grades and expressed as the avarage of the total rank sum. RESULTS The collagen content (mg/g) of the liver in the control group (7 2±1 9) was significantly lower than that in the other groups; it was higher in the model group (31 7±16 6) than that in the two therapeutic groups; and lower in Zijin capsule group (9 7±2 8) than that in the TCM decoction group (11 5±5 3). The pathological changes were more aggravated in the model group (37 4) than those in the two therapeutic groups; and more severe in the TCM decoction group (30.2) than in the Zijin capsule group (22.9) CONCLUSION The therapeutic effect of Zijin capsule on the model was confirmed.

Comprehensive and innovative techniques for livertransplantation in rats: A surgical guide

AIM: To investigate our learning curves of orthotopic liver transplantation (OLT) in rats and the most important factor for successful surgery. METHODS: We describe the surgical procedures for our rat OLT model, and determined the operator learning curves. The various factors that contributed to successful surgery were determined. The most important surgical factors were evaluated between successful and unsuccessful surgeries.RESULTS: Learning curve data indicated that 50 cases were required for operator training to start a study. Operative time, blood loss, warm ischemic time, anhepatic phase, unstable systemic hemodynamic state, and body temperature after surgery significantly affected surgery success by univariate analysis, while the anhepatic phase was the most critical factor for success by multivariate analysis. CONCLUSION: OLT in rats is the only liver transplantation model that provides clinically relevant and reliable results. Shortened anhepatic phase is key to success in this model.

Biliary tract injury caused by different relative warm ischemia time in liver transplantation in rats

BACKGROUND: There is a controversy over the degree of liver and biliary injury caused by the period of secondary warm ischemia. A liver autotransplantation model was adopted because it excludes the effects of infection and immunological rejection on bile duct injury. This study was undertaken to assess biliary tract injury caused by relative warm ischemia (secondary warm ischemia time in the biliary tract) and reperfusion. METHODS: One hundred and two rats were randomly divided into 5 groups: group I (control); groups 11 to V, relative warm ischemia times of 0 minute, 30 minutes, I hour and 2 hours. In addition to the levels of serum alkaline phosphatase, and total bilirubin, pathomorphology assessment and TUNEL assay were performed to evaluate biliary tract damage. RESULTS: Under the conditions that there were no significant differences in warm ischemia time, cold perfusion time and anhepatic phase, group comparisons showed statistically significant differences. The least injury occurred in group H (portal vein and hepatic artery reperfused simultaneously) but the most severe injury occurred in group V (biliary tract relative warm ischemia time 2 hours). CONCLUSIONS: Relative warm ischemia is one of the factors that result in bile duct injury, and the relationship between relative warm ischemia time the bile injury degree is time-dependent. Simultaneous arterial and portal reperfusion is the best choice to avoid the bile duct injury caused by relative warm ischemia. (Hepatobiliary Pancreat Dis Int 2009; 8: 247-254)

Low G preconditioning reduces liver injury induced by high +Gz exposure in rats

AIM:To investigate the effect of repeated lower +Gzexposure on liver injury induced by high +Gz exposure in rats.METHODS:Sixty male Wister rats were randomly divided into a blank control group,a low G preconditioning group(LG)(exposed to +4 Gz/5 min per day for 3 d before +10 Gz/5 min exposure),and a +10 Gz/5 min group(10G)(n = 20 in each group).Blood specimens and liver tissue were harvested at 0 h and 6 h after +10 Gz/5 min exposure.Liver function was analyzed by measuring serum alanine transaminase(ALT) and aspartate aminotransferase(AST) levels,and liver injury was further assessed by histopathological observation.Malondialdehyde(MDA),superoxide dismutase(SOD) and Na+-K+-ATPase were determined in hepatic tissue.RESULTS:The group LG had lower ALT,AST,and MDA values at 0 h after exposure than those in group 10 G.SOD values and Na+-K+-ATPase activity in the LG group were higher than in group 10 G 0 h post-exposure.Hepatocyte injury was significantly less in group LG than in group 10 G on histopathological evaluation.CONCLUSION:It is suggested that repeated low +Gz exposure shows a protective effect on liver injury induced by high +Gz exposure in rats.

Effect of endotoxin on portal hemodynamic in rats

AIM: To study the effects of endotoxin on portal hemodynamic of normal and noncirrhotic portal hypertensive rats. METHODS: Normal rats were intraperitoneally injected with 0.1, 0.25, 0.5, 1.0, 2.0, 4.0mg.kg(-1) of lipopolysaccharide(LPS) respectively, portal vein ligation(PVL) and intrahepatic portal occlusion (IPO) rats as well as sham-operated rats were treated with an intraperitoneal injection of 1.0mg.kg(-1) of LPS, the portal vein pressure(PVP), portal venous flow(PVF), inferior vena cava pressure(IVCP) and portal vein resistance(PVR) were detected 4 hours after injection. RESULTS: PVF of the 5 groups of rats accepting intraperitoneal injection of LPS were increased from 14.0 to 18.0, 22.2, 26.2, 34.8, 39.6, 38.8 mL.min(-1) 4 hours after injection of LPS(P【0.01). PVP of the 4 groups of rats accepting more than 0.1mg/kg.b.w of LPS was increased from 1.04 to 1.25, 1.50, 1.80, 1.95, 2.05 kPa(P【0.01). The increments of PVF and PVP were in a dose-dependent manner of LPS. PVR of the 5 groups of rats was decreased from 51 to 42,44,48,45,44,47 kPa.min.L(-1) (P【0.05) and no dose-dependent manner was observed. PVF of PVL, IPO and sham-operated rats increased from 22.6 to 32.8, 22.0 to 28.0, 14.0 to 34.8 mL.min(-1) (P【0.01), and PVP increased from 1.86 to 2.24, 1.74 to 1.95, 1.04 to 1.80 kPa(P【0.01), PVR decreased from 71 to 61, 67 to 61, 52 to 44 kPa.min.L(-1) after intraperitoneal injection of 1mg.kg(-1) of LPS. The increments of PVF and PVP of PVL and IPO rats were significantly less than the sham-operated rats(P【0.01), There was no significant difference between the amounts of PVR decreased in the two groups of PHT model rats and sham-operated rats(P】0.05) after intraperitoneal injection 1mg.kg(-1) of LPS. CONCLUSION: Endotoxin could prompt portal hypertension of the normal and noncirrhotic portal hypertensive rats by increasing portal blood flow mainly.

Heparin improves organ microcirculatory disturbances in caerulein-induced acute pancreatitis in rats

AIM:Microcirculatory disturbances are important early pathophysiological events in various organs during acute pancreatitis.The aim of the study was to evaluate changes in microperfusion of the pancreas,liver,kidney,stomach, colon,skeletal muscle,and to investigate the influence of heparin on the organ microcirculation in caerulein-induced experimental acute pancreatitis. METHODS:Acute pancreatitis was induced by 4 intraperitoneal injections of caerulein(Cn)(15 μg/kg).The organ microcirculation was measured by laser Doppler flowmetry.Serum interleukin 6 and hematocrit levels were analysed. RESULTS:Acute pancreatitis resulted in a significant drop of microperfusion in all examined organs.Heparin administration(2×2.5 mg/kg)improved the microcirculation in pancreas(36.9±4% vs 75.9±10%),liver(56.6±6% vs 75.2±16%),kidney (45.1±6% vs 79.3±5%),stomach (65.2±8% vs 78.1±19%),colon(69.8±6% vs 102.5±19%), and skeletal muscle (59.2±6% vs 77.9±13%).Heparin treatment lowered IL-6(359.0±66 U/mL vs 288.5±58 U/mL) and hematocrit level(53±4% vs 46±3%). CONCLUSION:Heparin administration has a positive influence on organ microcirculatory disturbances accompanying experimental Cn-induced acute pancreatitis.

Gastrin,somatostatin,G and D cells of gastric ulcer in rats

AIM: To investigate the relationship among gastrin, somatostatin, G and D cells in gastric ulcer and in its healing process in rats. METHODS: Fourty-nine Wistar rats were divided into 7 groups. The gastric ulcer model was induced by acetic acid successfully. The gastrin and the somatostatin in rat plasma, gastric fluid and antral tissue were measured by radioimmunoassay(RIA). G and D cells in antral mucosa were analyzed with polyclonal antibody of gastrin and somatostatin by immunohistochemical method and Quantimet 500 image analysis system. RESULTS: In gastric ulcer, the level of gastrin in plasma, gastric fluid, and antral tissue increased, that of somatostatin declined, and the disorder gradually recovered to the normal level in the healing process. Immunohistochemical technique of G and D cells in antral mucosa demonstrated that the number of G cells increased and that of D cells decreased, both areas of G and D cells declined, the ratio of number and area of G/D increased in gastric ulcer, and the disorder gradually recovered in the healing process. CONCLUSION: In gastric ulcer, the increased gastrin secreted by G cells, the declined somatostatin secreted by D cells, and the disordered G/D cell ratio can lead to gastrointestinal dysfunction.

Distribution of nitric oxide synthase in stomach myenteric plexus of rats

AIM: To study the distribution of nitric oxide synthase (NOS) in rat stomach myenteric plexus. METHODS: The distribution of NOS in gastric wall was studied in quantity and location by the NADPH-diaphorase (NDP) histochemical staining method and whole mount preparation technique. RESULTS: NOS was distributed in whole stomach wall, most of them were located in myenteric plexus, and distributed in submucosal plexus.The shape of NOS positive neurons was basically similar, most of them being round and oval in shape. But their density, size and staining intensity varied greatly in the different parts of stomach. The density was 62+/-38 cells mm(2) (antrum), 43+/-32 cells/mm(2) (body), and 32+/-28 cells mm(2) (fundus), respectively. The size and staining intensity of NOS positive neurons in the fundus were basically the same, the neurons being large and dark stained, while they were obviously different in antrum. In the body of the stomach, the NOS positive neurons were in an intermediate state from fundus to antrum. There were some beadlike structures which were strung together by NOS positive varicosities in nerve fibers, some were closely adherent to the outer walls of blood vessels. CONCLUSION: Nitric oxide might be involved in the modulation of motility, secretion and blood circulation of the stomach, and the significant difference of NOS positive neurons in different parts of stomach myenteric plexus may be related to the physiologic function of stomach.