Protective effects of Gingko biloba on thioacetamide-induced fulminant hepatic failure in rats

Drug-induced-acute liver failure: A critical appraisal of the thioacetamide model for the study of hepatic encephalopathy

Hepatic encephalopathy (HE) following acute and chronic liver failure is defined as a complex of neuropsychiatric abnormalities, such as discrete personal changes, sleep disorder, forgetfulness, confusion, and decreasing the level of consciousness to coma. The use and design of suitable animal models that represent clinical features and pathological changes of HE are valuable to map the molecular mechanisms that result in HE. Among different types of animal models, thioacetamide (TAA) has been used extensively for the induction of acute liver injury and HE. This agent is not directly hepatotoxic but its metabolites induce liver injury through the induction of oxidative stress and produce systemic inflammation similar to that seen in acute HE patients. In this short review article, we shortly review the most important pathological findings in animal models of acute HE following the administration of TAA.

Contributions of microdialysis to new alternative therapeutics for hepatic encephalopathy

Hepatic encephalopathy (HE) is a common complication of cirrhosis, of largely reversible impairment of brain function occurring in patients with acute or chronic liver failure or when the liver is bypassed by portosystemic shunts. The mechanisms causing this brain dysfunction are still largely unclear. The need to avoid complications caused by late diagnosis has attracted interest to understand the mechanisms underlying neuronal damage in order to find markers that will allow timely diagnosis and to propose new therapeutic alternatives to improve the care of patients. One of the experimental approaches to study HE is microdialysis; this technique allows evaluation of different chemical substances in several organs through the recollection of samples in specific places by semi-permeable membranes. In this review we will discuss the contributions of microdialysis in the understanding of the physiological alterations in human hepatic encephalopathy and experimental models and the studies to find novel alternative therapies for this disease.

Attenuating effect of Ginkgo biloba leaves extract on liver fibrosis induced by thioacetamide in mice

The purpose of this study is to investigate the effect of Ginkgo biloba leaves extract on experimental liver fibrosis induced by thioacetamide (TAA) in male albino mice. The experimental mice were divided into four groups. The mice of the first group were served as control. The experimental animals of the second group were given 150 mg/kg body weight of TAA by intraperitoneal injection, twice weekly, for 9 weeks. The mice of the third group were exposed to TAA and supplemented with G. biloba leaves extract. The animals of the fourth group were supplemented with G. biloba leaves extract. The levels of plasma alanine aminotransferase, aspartate aminotransferase, gamma-glutamyl transferase, alkaline phosphatase, triglycerides, cholesterol, and low-density lipoprotein cholesterol were statistically increased while the levels of plasma total protein, albumin, glucose, and high-density lipoprotein cholesterol were significantly decreased. The levels of liver superoxide dismutase, glutathione, glycogen and total protein were notably declined, whereas the level of total lipid was increased in mice of the second group. Furthermore, microscopic examination of liver sections from mice treated with TAA showed an abnormal morphology characterized by nodular transformations in liver parenchyma which surrounded by fibrous septa. Administration of G. biloba leaves extract reduced extent and development of fibrous septa, liver cells change, and biochemical alterations in mice exposed to TAA. This study showed that G. biloba leaves extract has a potential activity against TAA-induced liver fibrosis and suggested that the chemical constituents of G. biloba are effective in modulation of oxidative stress induced by TAA.

Sterically stable liposomes improve the therapeutic effect of hepatic stimulator substance on fulminant hepatic failure in rats

BACKGROUND AND AIMS

Few drugs have been confirmed to be effective for fulminant hepatic failure (FHF). The purpose of this study was to prepare sterically stable liposomes (SSL) encapsulating hepatic stimulator substance (HSS) and determine their therapeutic effect on FHF.

METHODS

HSS were encapsulated into SSL (HSS-SSL). FHF was induced in rats by thioacetamide (TAA) injection (400mg/kg, three times with a 24-h interval). The agents, including HSS-SSL, SSL, HSS, and sodium chloride (NS), were each injected intravenously 2h after the second and the third TAA injection.

RESULTS

Freshly prepared HSS-SSL had a mean size of 93.59nm and the average encapsulation efficiency was 37.20%. HSS encapsulated in SSL showed a longer half life and more potent target to injured livers than free HSS. Twenty-four hours after the third TAA-injection, the survival rate of HSS-SSL-treated rats (80%) was significantly higher than that of rats treated with NS (20%), SSL (25%), or HSS (50%). Histopathologic examination showed that there was the least necrosis and inflammation in the livers of HSS-SSL-treated rats. The incidence of stage 3 or 4 hepatic encephalopathy in HSS-SSL-treated rats was significantly lower than that in rats treated with other agents. The serum pro-inflammatory cytokine levels and hepatic lipid peroxidation levels were both markedly reduced, while hepatocyte proliferative rate was markedly increased after HSS-SSL treatment.

CONCLUSION

Encapsulation by SSL markedly improved the therapeutic effect of HSS on FHF in rats. Encapsulation by SSL may be an effective approach to enhance the therapeutic potency of drugs for FHF.

Protective role of Ginkgo biloba against hepatotoxicity and nephrotoxicity in uranium-treated mice

The aim of the present study was to investigate the protective role of Ginkgo biloba leaf extract against uranium (U)-induced toxicity in Swiss albino mice. The mice were randomly divided into six groups, each consisting of six animals: Group I (control) received tap water alone, Group II received U at a dose of 5 mg/kg of body weight, Group III received G. biloba at a dose of 50 mg/kg of body weight, Group IV received G. biloba at a dose of 150 mg/kg of body weight, Group V received G. biloba (50 mg/kg of body weight) and U (5 mg/kg of body weight), and Group VI received G. biloba (150 mg/kg of body weight) and U (5 mg/kg of body weight) by oral gavage for 5 days. Serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), blood urea nitrogen (BUN), and creatinine levels were determined to assess liver and kidney function, respectively. Also, liver and kidney samples were taken for the determination of tissue malondialdehyde (MDA) and reduced glutathione (GSH) levels, and histopathological changes in liver and kidneys were investigated. The results indicated that there was a significant increase (P < .05) in selected serum parameters. Serum AST, ALT, BUN, and creatinine levels significantly increased in mice treated with U alone when compared to the other groups. Moreover, U-induced oxidative damage caused a significant decrease in GSH levels and a significant increase in MDA levels of liver and kidney tissues. Treatment with G. biloba produced amelioration in biochemical indices of hepatotoxicity and nephrotoxicity according to Group II. Each dose of G. biloba provided significant protection against U-induced toxicity, and its strongest effect was observed at a dose of 150 mg/kg of body weight. In vivo results showed that G. biloba extract is a potent protector against U-induced toxicity, and its protective role is dose-dependent.

An antibody of TNF-alpha did not prevent thioacetamide-induced hepatotoxicity in rats

Tumor necrosis factor (TNF)-α antibodies have been shown to reduce liver damage in different models. We investigated the effects of infliximab (a TNF-α antibody) on liver damage in thioacetamide (TAA)-induced hepatotoxicity in rats. Group 1 (n = 8) was the control group. In group 2 (n = 8), the TAA group, the rats received 300 mg/kg intraperitoneal (ip) TAA daily for 2 days. In group 3 (n = 8), the TAA + Infliximab (INF) group, infliximab (5 mg/kg ip daily) was administered 48 hours before the first dose of TAA daily for 2 days and was maintained for 4 consecutive days. In group 4 (n = 8), the INF group, the rats received only ip infliximab (5 mg/kg) daily. Livers were excised for histopathological and biochemical tests (thiobarbituric-acid-reactive substances [TBARS], and myeloperoxidase [MPO]). Serum ammonia, aspartate transaminase (AST), alanine transaminase (ALT), TNF-α, liver TBARS and MPO levels, and liver necrosis and inflammation scores in the TAA group were significantly higher than in the control and INF groups (all p < 0.01). All parameters except AST were not significantly different between TAA and TAA + INF. In conclusion, our results suggest that oxidative stress plays an important role in TAA-induced hepatotoxicity, and infliximab does not improve oxidative liver damage.

Royal jelly (honey bee) is a potential antioxidant against cadmium-induced genotoxicity and oxidative stress in albino mice

Cadmium (Cd) is a highly toxic heavy metal that induces genotoxic damage in the body. Besides, Cd induces oxidative damage in various tissues by altering antioxidant defence enzymes system. In this study, we investigated the protective role of royal jelly (RJ) on Cd-induced genotoxicity and oxidative stress in mice. For this aim, the micronucleus (MN) test in erythrocytes and exfoliated cells of buccal mucosa and the chromosome aberration (CA) test in bone marrow cells were applied. In addition, the levels of reduced glutathione (GSH) and malondialdehyde (MDA) were evaluated in the liver and kidneys. Thirty-six animals were divided into six groups: the control group received distilled water alone, whereas mice in the treatment groups received RJ alone (100 and 250 mg/kg of body weight), Cd alone (2 mg/kg of body weight), and RJ+Cd. Cd toxicity resulted in a significant (P < .05) increase in CAs, abnormal metaphase number, and MN formation. Cd also caused a decrease in mitotic index. Oral administration of RJ at two doses (100 and 250 mg/kg of body weight) showed significant (P < .05) suppression of mutagenic effects of Cd. Moreover, Cd-induced oxidative damage caused a significant decrease in GSH level and a significant increase in MDA level in the liver and kidneys. Treatment with two doses of RJ caused a significant recovery in antioxidant status of GSH and a significant inhibition of MDA production. It could be concluded that RJ has a protective role against Cd-induced genotoxicity and oxidative stress in mice, due to its antioxidant effects.

An overview of animal models for investigating the pathogenesis and therapeutic strategies in acute hepatic failure

Acute hepatic failure (AHF) is a severe liver injury accompanied by hepatic encephalopathy which causes multiorgan failure with an extremely high mortality rate, even if intensive care is provided. Management of severe AHF continues to be one of the most challenging problems in clinical medicine. Liver transplantation has been shown to be the most effective therapy, but the procedure is limited by shortage of donor organs. Although a number of clinical trials testing different liver assist devices are under way, these systems alone have no significant effect on patient survival and are only regarded as a useful approach to bridge patients with AHF to liver transplantation. As a result, reproducible experimental animal models resembling the clinical conditions are still needed. The three main approaches used to create an animal model for AHF are: surgical procedures, toxic liver injury and infective procedures. Most common models are based on surgical techniques (total/partial hepatectomy, complete/transient devascularization) or the use of hepatotoxic drugs (acetaminophen, galactosamine, thioacetamide, and others), and very few satisfactory viral models are available. We have recently developed a viral model of AHF by means of the inoculation of rabbits with the virus of rabbit hemorrhagic disease. This model displays biochemical and histological characteristics, and clinical features that resemble those in human AHF. In the present article an overview is given of the most widely used animal models of AHF, and their main advantages and disadvantages are reviewed.