An Accessible and Pragmatic Experimental Model of Nonalcoholic Fatty Liver Disease

Establishment and metabonomics analysis of nonalcoholic fatty liver disease model in golden hamster

The aim is to establish a model of nonalcoholic fatty liver disease (NAFLD) caused by feeding with high-fat, high-fructose, and high-cholesterol diet (HFFCD) in golden hamsters, and to investigate the characteristics of the NAFLD model and metabolite changes of liver tissue. Golden hamsters were fed HFFCD or control diets for six weeks. Body weight, abdominal fat index, and liver index was assessed, serum parameters, hepatic histology, and liver metabolites were examined. The results showed that body weight, abdominal fat, and liver index of hamsters were significantly increased in the model group, the level of serum total cholesterol (TC), triglyceride (TG), and low density lipoprotein-cholesterol (LDL-C) were significantly increased in model group as well, and high density lipoprotein-cholesterol (HDL-C) was significantly decreased. In addition, lipid deposition in liver tissue formed fat vacuoles of different sizes. Metabonomics analysis of the liver showed that the metabolic pathways of sphingolipid, glycerophospholipids, and arginine biosynthesis were disordered in the NAFLD model. The modeling method is simple, short time, and uniform. It can simulate the early fatty liver caused by common dietary factors, and provides an ideal model for the study of the initial pathogenesis and therapeutic drugs for NAFLD.

Administration of hydro-alcoholic extract of spinach improves oxidative stress and inflammation in high-fat diet-induced NAFLD rats

Background

Nonalcoholic fatty liver disease (NAFLD) is the most common liver disease worldwide. The aim of this study was to evaluate the effects of hydro-alcoholic extract of spinach (HES) on hepatic and serum measurements of NAFLD in a rat model.

Methods

In the prevention phase, 18 Sprague–Dawley rats were fed a high-fat diet, a high-fat diet plus 400 mg/kg HES, or a chow diet for seven weeks. For the treatment phase, after the induction of NAFLD, they were fed a high-fat diet, a high-fat diet plus 400 mg/kg HES, a chow diet, or a chow diet plus 400 mg/kg HES for four weeks (n = 6).

Results

Administration of HES combined with high-fat diet in rats was associated with decreased food intake (P < 0.01), weight loss (P = 0.01), and increased superoxide dismutase (SOD) (P = 0.02) enzyme activity in the liver, at the end of the prevention phase. hs-CRP (P < 0.05), PTX-3 (P < 0.05), and TNF-α (P < 0.05) gene expression in the liver were decreased and PPAR-γ (P < 0.05) gene expression in the liver was increased by spinach intake, both in the prevention and treatment phases. Furthermore, administration of spinach in the treatment phase increased serum TAC (P = 0.03) and hepatic GPX (P = 0.01) enzyme activity.

Conclusion

Taking into account the potential beneficial effects of HES on prevention and treatment of NAFLD in the present study, to confirm these findings, we propose that further clinical trials be conducted on human subjects with NAFLD.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12906-021-03396-x.

Adverse impact of egg consumption on fatty liver is partially explained by cardiometabolic risk factors: A population-based study

BACKGROUND AND AIMS

We evaluated the association of egg consumption with liver tests (LTs) and non-alcoholic fatty liver disease (NAFLD). This relationship is poorly documented.

METHODS

The National Health and Nutrition Examination Survey (NHANES, 2005-2010) database was used. Analysis of covariance, adjusted linear and logistic regression models were used.

RESULTS

Of the 14,369 participants, 46.8% were men and 45.2% had NAFLD. After correction for several variables including: age, gender, race, education, poverty to income ratio, alcohol intake, energy intake, smoking, and physical activity - fatty liver index (FLI), serum aspartate aminotransferase (AST) alanine aminotransferase (ALT) were 36.9, 25.8 (U/L) and 23.9 (U/L), respectively, in the first tertile (T1) reaching 68.7, 34.9 and 36.5, respectively, in the third tertile (T3) (p < 0.001 for all comparisons). In the model with same covariates, there was significant positive linear relationship between FLI (standard β coefficient (β): 0.196), AST (β: 0.099) and ALT (β: 0.112) with egg consumption and participants in the highest tertile (T3) of egg consumption had 11% higher chance of NAFLD compared with T1 (odds ratio: 1.11 and 95% confidence interval: 1.07-1.17). Of note, after more correction for triglycerides, hypertension and diabetes, the significant link between egg consumption and LTs and/or NAFLD attenuated and disappeared.

CONCLUSION

Our findings highlight the adverse role of egg consumption on LTs and likelihood of NAFLD. These associations seem to be attributable to cardio-metabolic risk factors. These findings require confirmation to improve our understanding of the role of egg consumption in the pathogenesis of NAFLD.

The effects of hydroalcoholic extract of spinach on prevention and treatment of some metabolic and histologic features in a rat model of nonalcoholic fatty liver disease

BACKGROUND

This study evaluated the effects of hydroalcoholic extract of spinach (HES) on nonalcoholic fatty liver disease (NAFLD). In the prevention phase, 18 Sprague-Dawley rats were fed a high-fat diet, a high-fat diet plus 400 mg kg^-1 HES, or a chow diet for 7 weeks. For the treatment phase, after the induction of NAFLD, they were fed a high-fat diet, a high-fat diet plus 400 mg kg^-1 HES, a chow diet, or chow diet plus 400 mg kg^-1 HES for 4 weeks (n = 6).

RESULTS

Weight gain (P = 0.01), food intake (P < 0.01), serum glucose (P = 0.01), triglyceride (TG) (P = 0.02), low-density lipoprotein cholesterol (LDL-c) (P = 0.01), aspartate aminotransferase (AST) (P = 0.02), liver steatosis, and the nonalcoholic fatty liver disease (NAFLD) activity score (NAS) (P < 0.01) in the high-fat group were statistically higher than in the other groups at the end of the prevention phase. Feeding spinach extract to rats on a high-fat diet decreased serum glucose (P = 0.01), total cholesterol (TCh) (P < 0.01), AST (P = 0.01), alkaline phosphatase (ALP) (P < 0.01), and liver steatosis (P < 0.01) in the treatment phase.

CONCLUSION

Overall, spinach extract showed beneficial effects in the prevention and treatment of NAFLD. © 2019 Society of Chemical Industry.

Adipose Tissue Inflammation and Oxidative Stress: the Ameliorative Effects of Vitamin D

Obesity is a low-grade inflammatory disease and is associated with numerous comorbidities. The current study was aimed to evaluate the effects of vitamin D administrations on markers of inflammation and oxidative stress in adipose tissue of high-fat diet-induced obese rats. In the beginning of the study, 40 rats were divided into two groups: normal diet and high-fat diet (HFD) for 16 weeks; then, each group was subdivided into two groups including ND, ND + vitamin D, HFD, and HFD + vitamin D. Vitamin D supplementation was done for 5 weeks at 500 IU/kg dosage. Tumor necrosis factor (TNF)-α, interleukin (IL)-1β, monocyte chemoattractant protein (MCP)-1, transforming growth factor (TGF)-β and IL-6 concentrations and markers of oxidative stress including glutathione peroxidase (GPx), superoxide dismutase (SOD), malondialdehyde (MDA), and catalase (CAT) concentrations in adipose tissue of rats were determined using ELISA kits and spectrophotometry methods, respectively. Vitamin D treatment led to a significant reduction in adipose tissue TNF-α concentrations in both ND + vitamin D and HFD + vitamin D groups (P < 0.05). Adipose tissue MCP-1 concentration also reduced in HFD + vitamin D group compared with HFD group. Among markers of oxidative stress in adipose tissue, SOD and GPx concentrations significantly increased in adipose tissue of HFD + vitamin D treated group compared with other groups (P < 0.05). Reduced food intake and weight gain was also occurred after vitamin D treatment. Vitamin D improved adipose tissue oxidative stress and inflammatory parameters in obese rats. Vitamin D treatment was also associated with decreased food intake and decreased weight gain in animals under a high-fat diet. Further studies are needed to better clarify the underlying mechanisms.

Pomegranate juice prevents development of non-alcoholic fatty liver disease in rats by attenuating oxidative stress and inflammation

BACKGROUND

The effects of pomegranate juice (PJ) on the risk factors of non-alcoholic fatty liver disease (NAFLD)/non-alcoholic steatohepatitis (NASH) have been reported previously; however, the effects on NAFLD and its prevention have not yet been clarified. The present study aimed to evaluate the effects of PJ consumption with respect to the prevention of NAFLD/NASH development. Sprague-Dawley rats were fed either a high-fat, high sugar diet (model group); a high-fat, high sugar diet plus PJ (model+PJ); or a chow diet ad libitum for 7 weeks. Serum levels of fasting glucose, triglyceride, cholesterol, liver enzymes, insulin and hepatic tumor necrosis factor-α and tissue growth factor-β gene expression were determined. Hepatic histology was examined by hemotoxylin and eosin staining.

RESULTS

The model+PJ group had significantly lower hepatic steatosis, ballooning, lobular inflammation and portal inflammation (P < 0.001); lower hepatic pro-inflammatory and pro-fibrotic gene expression (P < 0.001); and lower plasma levels of alanine aminotransferase (P = 0.026), aspartate aminotransferase (P = 0.041), insulin (P < 0.001), triglycerides (P = 0.041) and glucose (P = 0.009) compared to the model group; however, weight gain, food intake and plasma high-density lipoprotein levels were not significantly different between these two groups.

CONCLUSION

The data obtained in the present study indicate that the regular consumption of PJ can prevent NAFLD even in the presence of the other risk factors such as obesity, hypercholesterolemia, and high energy, fat and sugar intakes. © 2016 Society of Chemical Industry.

Egg consumption and risk of non-alcoholic fatty liver disease

AIM

To evaluate the association between egg consumption and risk of non-alcoholic fatty liver disease (NAFLD) development.

METHODS

This case-control study was conducted on individuals who were referred to two hepatology clinics in Tehran, Iran in 2015. The study included 169 patients with NAFLD and 782 controls. Egg consumption was estimated using a validated food frequency questionnaire. The participants were categorized according to the frequency of their egg consumption during the previous year: Less than two eggs per week, two to three eggs per week, and four or more eggs per week.

RESULTS

In the crude model, participants who consumed 2 to 3 eggs per week, were 3.56 times more likely to have NAFLD in comparison to those who consumed less than 2 eggs per week (OR: 3.56; 95%CI: 2.35-5.31). Adjustment for known risk factors of NAFLD strengthened this significant association so that individuals have consumed two to three eggs per week had 3.71 times higher risk of NAFLD than those who have eaten less than two eggs per week (OR: 3.71; 95%CI: 1.91, 7.75).

CONCLUSION

Our data indicate that higher egg consumption in common amount of usage is associated with higher risk of NAFLD.

Insulin deficiency: A possible link between obesity and cognitive function

BACKGROUND

Epidemiological studies proposed a linear connection between developing dementia including Alzheimer's disease (AD) and obesity. Adiposity, insulin resistance and dementia indicated probable mechanistic links in this process. Indeed, it has been known that optimum insulin action in the brain plays critical role in cognitive function; whereas, insulin resistance in obese individuals finally leads to insulin deficiency in central nervous system (CNS) and down regulation of the efficiency of insulin uptake from periphery into CSF. In the current study, we aimed to assess correlation between increased body weight and insulin resistance with CSF to serum ratio of insulin and to evaluate the correlation between CSF to serum ratio of insulin with cognitive function in high fat diet induced obese rats.

METHODS AND MATERIAL

Twelve male Wister rats were randomly divided into two groups receiving Diet 1 (D1, 10% fat) and Diet 2 (D2, 59% fat) for 16 weeks. Weight was recorded weekly to assure body weight gain. Morris Water Maze (MWM) task was designed to assess spatial learning memory function. Finally, blood samples were collected for determining fasting serum glucose using enzymatic spectrophotometric method, insulin levels by ELISA kit and homeostasis model assessment of insulin resistance (HOMA-IR) were calculated. Fasting Cerebrospinal Fluid (CSF) insulin was also measured by ELISA kit.

RESULT

D1 and D 2 groups both experienced weight gain but weight gain in D2 group were significantly higher. A significant correlation between CSF to serum ratio of insulin with weight (r=0.882, p=0.001) and HOMA-IR index (r=0.798, p=0.002) was reported. Moreover, the present study indicated significant correlations between CSF to serum ratio of insulin and escape latency time in first (r=0.631, p=0.028), second (r=0.716, p=0.009) and third (r=0.609, p=0.036) day of MWM test and probe time of MWM test (r=0.762, p=0.004).

CONCLUSION

Increased body weight induced by high fat diet and insulin resistance in rats led to down regulation of CSF to serum ratio of insulin in the current research. Brain insulin deficiency may be responsible for possible decline of cognitive function in obesity. More researches are needed to better clarify the underlying mechanisms and also to confirm the similar findings in human studies.

Vitamin D administration, cognitive function, BBB permeability and neuroinflammatory factors in high-fat diet-induced obese rats

OBJECTIVES

The purpose of this research was to investigate the effects of vitamin D administration on cognitive function, nuclear factor-κB (NF-κB), brain-derived neurotrophic factor (BDNF) concentration in the hippocampus and blood-brain barrier (BBB) permeability in high-fat diet (HFD)-induced obese rats.

METHODS

Male Wistar rats were fed either a control diet or HFD for 16 weeks (n=20); then, each group was randomized into two subgroups supplemented orally with 500 IU kg^-1 vitamin D for 5 weeks. A Morris water maze (MWM) test was performed at the 21st week to examine cognitive function. BBB permeability was characterized by Evans blue dye in the hippocampus. BDNF and NF-κB concentrations in the hippocampus and serum vitamin D concentrations were also measured.

RESULTS

HFD led to a significant delay in escape latency time and reduced time of MWM probe test because of increased NF-κB and decreased BDNF concentrations in the hippocampus. Vitamin D supplementation in the HFD group significantly reduced body weight, NF-κB concentrations, BBB permeability and increased BDNF concentrations in the hippocampus.

CONCLUSIONS

Vitamin D reversed HFD-induced cognitive impairments by reduction of the NF-κB and elevation of BDNF concentrations and modulation of the BBB permeability in rats' hippocampus.

The Effects of Onion Consumption on Prevention of Nonalcoholic Fatty Liver Disease

It is well known that dietary intakes play a pivotal role in pathogenesis of nonalcoholic fatty liver disease (NAFLD)/nonalcoholic steatohepatitis (NASH); however, the role of each component of diet has not yet been elucidated. Our objective was to evaluate the effects of onion consumption on prevention of NAFLD/NASH development. Sprague-Dawley rats were fed either high-fat, high sugar diet (model group), or high-fat, high sugar diet plus 7% onion powder (model + onion), or chow diet ad libitum for 7 weeks. Serum levels of fasting glucose, triglyceride, cholesterol, liver enzymes, insulin, and hepatic tumor necrosis factor-alpha (TNF-α) gene expression were determined. Hepatic histology was examined by H&E stain. Model + onion group had significantly lower hepatic steatosis, ballooning, lobular inflammation, and portal inflammation (p < 0.001), lower hepatic TNF-α gene expression (p < 0.001), lower plasma levels of ALT (p = 0.026), AST (p = 0.041), insulin (p < 0.001), TG (p = 0.041), and glucose (p = 0.009) compared with model group; however, weight gain, food intake, plasma total cholesterol and LDL levels were not significantly different between these two groups. Our data indicate that regular consumption of onion can prevent NAFLD even in the presence of the other risk factors such as obesity, hypercholesterolemia, and high energy, fat, and sugar intakes.

The Impact of Vitamin D Supplementation on Neurodegeneration, TNF-α Concentration in Hypothalamus, and CSF-to-Plasma Ratio of Insulin in High-Fat-Diet-Induced Obese Rats

There is growing evidence that obesity can lead to neurodegeneration induced by pro-inflammatory cytokines such as tumor necrosis factor (TNF-α). Moreover, obesity is associated with reduced transport of insulin through the blood-brain barrier (BBB). Insulin deficiency in the brain especially in the hypothalamus region has neurodegenerative and obesity-promoting effects. Because of the anti-inflammatory and neuroprotective effects of vitamin D, in the current experimental study, we aimed to investigate the effects of vitamin D supplementation on neurodegeneration, TNF-α concentration in the hypothalamus, and cerebrospinal fluid (CSF) to serum ratio of insulin in high-fat-diet-induced obese rats. At the first phase of the study, the rats were divided into two groups: (1) normal diet (ND, 10% fat) and (2) high-fat diet (HFD, 59% fat) and were fed for 16 weeks. In the second phase, each group was subdivided into four groups including the following: ND, normal diet + vitamin D, HFD, and HFD + vitamin D. Weight was measured and recorded weekly. Vitamin D supplementation for 5 weeks at 500 IU/kg dosage was used. One week after vitamin D supplementation, daily food intake was recorded. At week 22, blood was collected to determine fasting serum glucose, vitamin D, and insulin concentrations, and the homeostasis model assessment of insulin resistance (HOMA-IR) was calculated. CSF samples were also collected to measure insulin concentrations, and the hypothalamus was dissected to determine TNF-α concentration. HFD significantly increased TNF-α concentrations and degenerated neurons in the hypothalamus (P = 0.02). We also observed a significant reduction of CSF-to-serum ratio of insulin in HFD group (P = 0.03). The HOMA-IR test indicated significant increment of insulin resistance in HFD-fed rats (P = 0.006). Vitamin D supplementation in HFD group significantly reduced weight (P = 0.001) and food intake (P = 0.008) and increased CSF-to-serum ratio of insulin (P = 0.01). Furthermore, vitamin D decreased insulin resistance in the HFD group (P = 0.008). Vitamin D had no significant effect on degenerated neurons and TNF-α concentration in the hypothalamus. According to our findings, vitamin D improved brain insulin homeostasis and modulated food intake and body weight in high-fat-diet-induced obese rats. Further studies are needed to better clarify the underlying mechanisms.

The effects of onion consumption on treatment of metabolic, histologic, and inflammatory features of nonalcoholic fatty liver disease

Background

The aim of this study was to evaluate the effects of onion powder consumption on treatment of Non-alcoholic Fatty Liver Disease (NAFLD) in an experimental model of disease.

Methods

Sprague–Dawley rats were fed high-fat (HF) diet for seven weeks to induce the NAFLD. Then, they were treated by either the same diet (HF), or high-fat diet plus 7 % onion powder (HF + onion), or chow diet (control), or chow diet plus 7 % onion powder (control + onion)ad libitum for four weeks. Serum levels of fasting glucose, triglyceride, cholesterol, liver enzymes, insulin, and hepatic tumor necrosis factor-alpha (TNF-α) gene expression were determined. Hepatic histology was examined by Hematoxylin and Eosin stain.

Results

Dietary food intakes and weigh gain were significantly more in animals fed control + onion diet in comparison to the other groups. Animals fed control or control + onion diet had significantly lower plasma levels of hepatic enzymes, lipid profile, glycemic indices, and hepatic TNF-α gene expression as compared with HF diet fed groups; however, there was no significant difference in the histopathologic features of NAFLD among different groups.

Conclusion

Our results indicate that onion consumption can be effective in NAFLD management when it is combined with a healthy diet.

Electronic supplementary material

The online version of this article (doi:10.1186/s40200-016-0248-4) contains supplementary material, which is available to authorized users.