Development Of Non-alcoholic Fatty Liver Disease In Rats Research Articles

Modification of a model of non-alcoholic fat liver disease in rats with a сombination of a hypercaloric diet and hypodynamia

Introduction. Non-alcoholic fatty liver disease (NAFLD) is the most common liver disease in the world, and non-alcoholic steatohepatitis is the second most common cause of liver transplantation in the adult population. An urgent task is to find and develop an optimal model of NAFLD in laboratory animals, which would reproduce all the features of this disease in the clinic.Aim. Modification of the NAFLD model in laboratory animals (rats), which allows the obtained data to be transmitted to humans as fully as possible.Materials and methods. The study was conducted on 52 outbred white male rats of the same age. As the basis of the model, a hypercaloric high-fat diet was used with the addition of food appeal enhancers (sodium glutamate and liquid shrimp extract) and for the first-time conditions of hypodynamia were used – restriction of the motor activity of animals using specially designed cells, in which an individual 11 × 18 cm cell was allocated for each individual. The duration of the study was 12 months. In the course of the experiment, body weight, physical performance, biochemical parameters of blood serum and urine in dynamics were assessed, and lethality was recorded. After the end of the study, the mass of internal organs, visceral and epididymal fat was analyzed, and a histological examination of the liver was performed.Results and discussion. In the course of the experimental study, the development of NAFLD in rats of the control group of animals was histologically confirmed. A high mortality rate was revealed in the group of animals with pathology. Compared with animals of the intact group, a statistically significant increase in their body weight, liver weight, visceral and epididymal fat, a decrease in physical performance, disturbances in lipid, carbohydrate and protein metabolism were revealed, as well as signs of deterioration of the protein synthesis and excretory functions of the liver.Conclusion. A number of advantages of the NAFLD model with a combination of a hypercaloric diet and hypodynamic conditions were revealed, including the similarity of the conditions for the formation and pathogenesis of the disease in experimental animals and humans, which ensures the adequacy of data translation from preclinical practice to clinical practice.

ARGININE/CITRULLINE CYCLE CHANGES IN DIET-INDUCED RAT MODEL OF NON-ALCOHOLIC FATTY LIVER DISEASE

The aim: to study the Arginine / Citrulline-cycle features on a diet-induced rat model of non-alcoholic fatty liver disease (NAFLD). Materials and methods: The studies were carried out on 20 white non-linear adult rats, including 10 (50%) males, 10 (50%) females, weighing 160-220 g. NAFLD was modeled by a 9-week fast food diet. The level of arginine and citrulline, and the arginase activity were investigated in the animals' liver homogenates and in the blood. The morphological analysis of liver tissues changes was done. Results: NAFLD modeling using a 9-week fast food diet resulted in maximum weight gain in male rats (р<0.05). Female rats had 3 times more accumulation of intra-abdominal fat than male rats in the main group (р<0.05). Histopathologic liver examination confirmed NAFLD development in rats on a fast food diet during 9 weeks (р<0.05). NAFLD led to an increment of arginine level in the blood and liver homogenate in the main group compared to controls (р<0.05). NAFLD development was accompanied by a decrease in arginase activity and citrulline level in the blood and liver homogenate compared to control (р<0.05). Conclusions: The experimental rat model of NAFLD showed the Arginine / Citrulline cycle disorders, that were characterized by an increased arginine level, a decreased arginase activity and citrulline concentration in the blood and liver tissues.

Green tea extract prevents the development of nonalcoholic liver steatosis in rats fed a high-fat diet.

Green tea contains many polyphenolic constitutes, which might prevent non-alcoholic fatty liver disease (NAFLD). We aimed to investigate whether green tea extract (GTE) given at doses reflecting habitual consumption of green tea beverages prevents development of NAFLD in rats fed a high-fat diet (HFD). Twenty-four male Wistar rats were randomly divided into four equal groups (two study and two control groups). The study groups received a HFD (approximately 50% energy from fat), enriched with 1.1% and 2.0% GTE, respectively, for a total of 56 days. The control groups were fed a HFD alone and normal standardised diet (low-fat diet), respectively, for the same period of time. The percentage of hepatocytes affected by steatosis in the HFD group (median [1st-3rd quartile]: 25% [12-34%]) was higher (p < 0.033 and p < 0.050, respectively) than in the HFD-2.0%GTE group (9% [3-18%]) and normal diet group (10% [5-18%]). No significant differences were observed for the group consuming HFD-1.1%GTE, in which intermediate results were observed (15% [4-30%]). This finding points towards the hepatoprotective potential of GTE in preventing dietary-induced liver steatosis. In view of the increasing incidence of overweight and obesity a simple and cheap dietary modification, such as GTE supplementation, could prove to be useful clinically.

Effect of quercetin on morphological changes in nonalcoholic fatty liver disease in high fructose-fed rats

The aim of this study was to examine the effect of polyphenol quercetin on morphological changes in nonalcoholic fatty liver disease (NAFLD) in rats fed high-fructose diet. For 20 weeks animals (n=8 in each group) of the 1st group were given standard diet and water; the 2nd group - standard diet and 20% fructose solution; the 3rd group - standard diet with quercetin supplementation (0.1%) and 20% fructose solution. Formalin-fixed and paraffin-embedded liver samples were sectioned, stained (hematoxilin and eosin, Van Gieson's stain), evaluated with the use of the SAF and NAS scales. Histological assessment did not reveal pathology in the structure of the liver of the 1st group rats (S0A0F0; NAS - 0, fibrosis - 0). The 2nd group rat livers disclosed micro-, mid- and macrovesicular steatosis, inflammation without ballooning, pericellular and periportal fibrosis (S2A1F2; NAS - 3, fibrosis - 2). Quercetintreated rats exhibited in liver significantly less steatosis without significant changes in inflammation and fibrosis features (S1A1F2; NAS - 2, fibrosis - 2) compared with rats of the 2nd group. The data obtained demonstrate the ability of quercetin to inhibit the development of NAFLD in rats fed a diet with a high content of fructose, by reducing the severity of hepatostatosis.

Comparison of Three Different Diet-Induced Non Alcoholic Fatty Liver Disease Protocols in Rats: A Pilot Study

Background: There are many methods for inducing non-alcoholic fatty liver disease (NAFLD) in experimental animals. Due to the diversity of these methods and different variables involved in choosing the appropriate one, this study aimed to examine the effect of three different diets on development of NAFLD in rats. Methods: Twelve rats were divided to receive a standard, high fat high fructose (HFHFr), high cholesterol high fructose (HCHFr) or high fat high sucrose diet (HFHS); with access to tap water, fructose or sucrose solutions. The liver histopathological and biochemical assessments were examined after 40 and 60 days. Results: According to the histological findings, after 60 days of dietary exposures, all three experimental groups showed evidence of fatty changes; however a higher grade of ballooning and NAFLD activity score was found in the HFHFr compared with the other groups. Furthermore, all three diets induced a non-significant increase in serum liver enzymes relative to the control diet. Conclusion: This study indicates that HFHFr diet induce higher grade of hepatic steatosis and ballooning degenerations after 60 days in comparison with the other groups. So HFHFr diet can be considered as a suitable method for inducing of fatty liver for nutritional and pharmacological studies.

Prevention of NAFLD development in rats with obesity via the improvement of pro/antioxidant state by cerium dioxide nanoparticles.

BackgroundOne of the pathogenic mechanisms of the nonalcoholic fatty liver disease (NAFLD) is the accumulation of reactive oxygen species, which in turn aggravates the disease progress. We have investigated novel cerium dioxide nanoparticles (nCeO2) due to their promising antioxidant auto-regenerative ability and low toxicity.Methods30 white male Wistar rats were divided into 3 groups: control, monosodium glutamate (MSG)-induced obesity and MSG treated with nCeO2 (MSG+nCeO2) groups. Newborn rats of control group were injected with saline (control). MSG− and MSG+nCeO2 groups were injected with MSG (4 mg/g concentration, 8 μl/g volume) between the 2nd and the 10th days of life subcutaneously [13]. At the age of 1 month, rats of group II were administered water 2.9 ml/kg orally, MSG+nCeO2 group received 1 mM solution of nCeO2 1 mg/kg orally. 4-months rats were sacrificed and the liver was harvested for histological and biochemical analysis. To assess the morphological changes in the liver we used NAS (NAFLD activity score). The content of lipid peroxidation products and enzymatic activity of superoxide dismutase (SOD) and catalase in the liver were studied by standard biochemical methods [Refs].ResultsIn 4-month rats we found significantly lower total score (1.3±0.26 vs 3.6±0.34, p<0.001), degree of steatosis (1.1±0.18 vs 2.1±0.18, p<0.001), manifestation of lobular inflammation (0.2±0.13 vs 1.2±0.2, p<0.001) and ballooning degeneration (0.0±0.0 vs 0.3±0.15, p=0.034) due to NAS in the nCeO2 group compared to the MSG-group. nCeO2 significantly decreased lipid peroxidation in the liver tissue, namely it reduced the conjugated dienes content by 27% (p<0.05), TBA-products – by 43% (p<0.05) and Schiff bases – by 21% (p<0.05).ConclusionsDue to its antioxidant properties nCeO2 significantly reduces the incidence of NASH and improves the main NAFLD histological features.

Garlic-Derived S-Allylmercaptocysteine Ameliorates Nonalcoholic Fatty Liver Disease in a Rat Model through Inhibition of Apoptosis and Enhancing Autophagy

Our previous study demonstrated that administration of garlic-derived antioxidant S-allylmercaptocysteine (SAMC) ameliorated hepatic injury in a nonalcoholic fatty liver disease (NAFLD) rat model. Our present study aimed to investigate the mechanism of SAMC on NAFLD-induced hepatic apoptosis and autophagy. Adult female rats were fed with a high-fat diet for 8 weeks to develop NAFLD with or without intraperitoneal injection of 200 mg/kg SAMC for three times per week. During NAFLD development, increased apoptotic cells and caspase-3 activation were observed in the liver. Increased apoptosis was modulated through both intrinsic and extrinsic apoptotic pathways. NAFLD treatment also enhanced the expression of key autophagic markers in the liver with reduced activity of LKB1/AMPK and PI3K/Akt pathways. Increased expression of proapoptotic regulator p53 and decreased activity of antiautophagic regulator mTOR were also observed. Administration of SAMC reduced the number of apoptotic cells through downregulation of both intrinsic and extrinsic apoptotic mechanisms. SAMC also counteracted the effects of NAFLD on LKB1/AMPK and PI3K/Akt pathways. Treatment with SAMC further enhanced hepatic autophagy by regulating autophagic markers and mTOR activity. In conclusion, administration of SAMC during NAFLD development in rats protects the liver from chronic injury by reducing apoptosis and enhancing autophagy.