Concise review of current concepts on nomenclature and pathophysiology of hepatic encephalopathy

Agmatine improves liver function, balance performance, and neuronal damage in a hepatic encephalopathy induced by bile duct ligation

INTRODUCTION

In the current study, we investigate whether oral administration of agmatine (AGM) could effectively reduce motor and cognitive deficits induced by bile duct ligation (BDL) in an animal model of hepatic encephalopathy (HE) through neuroprotective mechanisms.

METHODS

The Wistar rats were divided into four groups: sham, BDL, BDL+ 40 mg/kg AGM, and BDL+ 80 mg/kg AGM. The BDL rats were treated with AGM from 2 weeks after the surgery for 4 consecutive weeks. The open field, rotarod, and wire grip tests were used to assess motor function and muscle strength. The novel object recognition test (NOR) was performed to evaluate learning and memory. Finally, blood samples were collected for the analysis of the liver markers, the animals were sacrificed, and brain tissues were removed; the CA1 regions of the hippocampus and cerebellum were processed to identify apoptosis and neuronal damage rate using caspase-3 immunocytochemistry and Nissl staining.

RESULTS

The serological assay results showed that BDL severely impaired the function of the liver. Based on histochemical findings, BDL increased the neuronal damage in CA1 and Purkinje cells, whereas apoptosis was significantly observed only in the cerebellum. AGM treatment prevented the increase of serum liver enzymes, balance deficits, and neuronal damage in the brain areas. Apoptosis partially decreased by AGM, and there were no differences in the performance of animals in different groups in the NOR.

CONCLUSIONS

The study suggests AGM as a potential treatment candidate for HE because of its neuroprotective properties and/or its direct effects on liver function.

Nitrogenous compounds in the saliva and blood of cirrhotic patients: a cross-sectional study

OBJECTIVES

Serum increase of nitrogenous compounds (NC) in cirrhotic patients has been associated with the development of hepatic encephalopathy (HE). However, the relation between NC in saliva and HE is unclear. The objective of this study is to measure the levels of nitric oxide and urea in the blood and saliva in 38 cirrhotic patients and correlate them with clinical characteristics and presence and grades of HE.

MATERIAL AND METHODS

Automated enzymatic colourimetric assays were performed to determine the levels of NC. Diagnosis and severity of HE were determined based on the West Haven criteria and by using the inhibitory control test.

RESULTS

HE was diagnosed in 89.47% of the patients, with the majority (60.50%) presenting covert HE. With regard to the measurement of NC, although nitric oxide is moderately correlated with its amount in blood and saliva (r = 0.630; P < 0.001), only salivary levels were associated with the presence of ascites and ecchymosis (P = 0.013 and P = 0.030, respectively). In patients with HE, the serum levels of urea were higher (P = 0.013) than those in patients without HE or minimal HE.

CONCLUSIONS

Nitrogenous compounds in the saliva were correlated with neither the presence nor grades of HE, whereas in the blood, only urea was positively correlated with the severity and presence of HE.

CLINICAL RELEVANCE

Saliva is an excellent fluid for diagnosing several diseases, but it does not seem to be able to collaborate with the identification of HE.

The Association between Hepatic Encephalopathy and Diabetic Encephalopathy: The Brain-Liver Axis

Hepatic encephalopathy (HE) is one of the main consequences of liver disease and is observed in severe liver failure and cirrhosis. Recent studies have provided significant evidence that HE shows several neurological symptoms including depressive mood, cognitive dysfunction, impaired circadian rhythm, and attention deficits as well as motor disturbance. Liver disease is also a risk factor for the development of diabetes mellitus. Diabetic encephalopathy (DE) is characterized by cognitive dysfunction and motor impairment. Recent research investigated the relationship between metabolic changes and the pathogenesis of neurological disease, indicating the importance between metabolic organs and the brain. Given that a diverse number of metabolites and changes in the brain contribute to neurologic dysfunction, HE and DE are emerging types of neurologic disease. Here, we review significant evidence of the association between HE and DE, and summarise the common risk factors. This review may provide promising therapeutic information and help to design a future metabolic organ-related study in relation to HE and DE.

Anxiety in rats with bile duct ligation is associated with activation of JNK3 mitogen-activated protein kinase in the hippocampus

We examine the anxiety-like behaviors in rats with bile duct ligation (BDL), as well as its relationship with the expression of JNK3 and P38 MAPKs in rat hippocampus. Male Wistar rats undergo either sham operation or BDL as a rat model of cirrhotic HE. The anxiety-like behaviors are determined using a light/dark box test two hours befor the surgery on day 1 and on days 7, 14, 21 and 28 of BDL. The gene and protein expression levels of JNK3 and p38 in the hippocampus were examined respectively with qPCR and western blotting methods on day 28 of BDL. The results revealed that anxiety was increased in the cirrhotic HE model rats during 28 days of BDL. The molecular data indicated that the gene expression of Jnk3 and protein levels of JNK3, as well as phospho-JNK3, significantly increased in the hippocampus of the cirrhotic HE model rats compared to the sham control group. However, the results revealed no significant changes in the gene expression and the protein levels of p38 as well as phospho-p38 in the hippocampus of the cirrhotic HE model rats compared to the sham control group. We conclude that the increases in the expression and activation of JNK3 MAPK in the hippocampus may underlie, at least partly, the anxiety-like behaviors in rats with cirrhotic HE.

Effects of erythropoietin on bile duct ligation-induced neuro-inflammation in male rats

Hepatic encephalopathy (HE) is a brain disorder as a result of liver failure. Previous studies have indicated that erythropoietin (EPO) has neuroprotective effects in different neurological diseases. This study addressed the therapeutic effect of a four-week treatment with EPO on neuronal damages in bile duct-ligated rats. Forty male Wistar rats (250–280 g) were used in the present study. The animals were randomly divided into four groups consisting of 10 animals each, including sham, sham + EPO, bile duct ligation (BDL), and BDL + EPO. EPO was intraperitoneally administered every other day (5,000 U/Kg) in the last four weeks after BDL. Biochemical and histological studies were performed to evaluate neurodegeneration. The results revealed that BDL increases the level of hepatic enzymes and total bilirubin. Furthermore, neurodegeneration was significantly increased in the BDL group compared to sham groups. EPO preserved hepatic enzymes and total bilirubin in the treated group. In addition, EPO significantly decreased the neurodegeneration in BDL + EPO compared to the BDL group. Results of this study showed that EPO has neuroprotective effects in the rat model of HE, possibly due to its anti-inflammatory and anti-oxidant properties. Complementary studies are required to clarify the exact mechanisms.

Iron and manganese-related CNS toxicity: mechanisms, diagnosis and treatment

INTRODUCTION

Iron (Fe) and manganese (Mn) are essential nutrients for humans. They act as cofactors for a variety of enzymes. In the central nervous system (CNS), these two metals are involved in diverse neurological activities. Dyshomeostasis may interfere with the critical enzymatic activities, hence altering the neurophysiological status and resulting in neurological diseases. Areas covered: In this review, the authors cover the molecular mechanisms of Fe/Mn-induced toxicity and neurological diseases, as well as the diagnosis and potential treatment. Given that both Fe and Mn are abundant in the earth crust, nutritional deficiency is rare. In this review the authors focus on the neurological disorders associated with Mn and Fe overload. Expert commentary: Oxidative stress and mitochondrial dysfunction are the primary molecular mechanism that mediates Fe/Mn-induced neurotoxicity. Although increased Fe or Mn concentrations have been found in brain of patients, it remains controversial whether the elevated metal amounts are the primary cause or secondary consequence of neurological diseases. Currently, treatments are far from satisfactory, although chelation therapy can significantly decrease brain Fe and Mn levels. Studies to determine the primary cause and establish the molecular mechanism of toxicity may help to adapt more comprehensive and satisfactory treatments in the future.

Treatment with Melatonin Improves Cognitive Behavior and Motor Skills in a Rat Model of Liver Fibrosis

INTRODUCTION AND AIM

Patients with liver cirrhosis (LC) and minimal hepatic encephalopaty have a higher accident rate. LC impairs the normal sleep-awake cycle and produces disturbances in behavior, cognition and motor skills. Abnormal melatonin (MT) levels have also been identified in LC. Administration of MT may regulate circadian rhythms and prevent the oxidative damage. We studied the effects of MT on spatial memory acquisition (SMA) and motor skills in a liver fibrosis model (LF)s.

MATERIALS AND METHODS

Forty-five rats, divided into 4 groups. [G1: LF; G2: LF + MT; G3: MT; G4: Healthy control (HC)]. LF was induced by carbon tetrachloride intraperitoneal injection (0.2 mL/kg) for 5 months. MT was administered during 5 weeks (0.4 mg/kg/day). SMA was evaluated by using the Morris Water Maze protocol where the escape latency (EL) and mean speed were measured. Data were registered by SMART®.

RESULTS

The EL measurement analyzed by two way ANOVA: cirrhosis presented a higher EL than controls or those treated with MT suggesting impaired memory acquisition which is rescued by MT treatment. The mean speed analysis revealed that LF presented higher speed than LF+MT or HC, suggesting that LF affects motor skills, which are improved by MT. To discard whether EL is affected by altered motor skills in LF treated with MT, we compared the average EL and speed between days 2 and 6 of the training protocol. Speed was not improved during the trials unlike EL, suggesting that memory acquisition is independent of motor skills.

CONCLUSION

These findings suggest that MT improves cognition and motor skills in the LF model.

Sepsis in Patients With Cirrhosis

Patients with cirrhosis are at high risk for sepsis and sepsis-related mortality. Aggressive treatment aimed at avoidance of hypoperfusion and prompt identification and treatment of the causative organism can improve patients' survival. Fluid administration is the first-line treatment to improve perfusion to vital organs; however, care should be taken to assess true intravascular volume status. In patients with adequate intravascular volume, vasopressors are then added to support blood pressure. Complications of cirrhosis often worsen in the setting of sepsis. Portosystemic encephalopathy, pulmonary complications, renal complications, adrenal insufficiency, malnutrition, and insufficient glucose control all must be considered and treated to support a patient with cirrhosis through sepsis. The quality of care that these patients receive ultimately influences their survival.

Treatment of Overt Hepatic Encephalopathy

Hepatic encephalopathy (HE) is defined by an altered mental status in the setting of portosystemic shunting, with or without cirrhosis. The basis of HE is probably multi-factorial, but increased ammonia delivery to the brain is thought to play a pivotal role. Medical therapies have typically focused on reducing blood ammonia concentrations. These measures are moderately effective, but further improvements will require identification of new therapeutic targets. Two medications, lactulose and rifaximin, are currently approved for the treatment of HE in the USA - new compounds are available off-label, and are in clinical trials. The presence of HE is associated with a higher risk of death in cirrhotic patients. Liver transplantation typically cures HE, but HE does not increase the MELD score, and therefore does not contribute to the likelihood of liver transplantation.

Viability assessment of magnetic resonance spectroscopy for the detection of minimal hepatic encephalopathy severity

OBJECTIVE

To evaluate regional cerebral metabolic changes in minimal hepatic encephalopathy (MHE) patients using magnetic resonance spectroscopy (MRS) in 3T scanner.

MATERIALS AND METHODS

This study comprised 30 cirrhotic patients with MHE, 29 cirrhotic patients without MHE and 30 healthy volunteers. Single-voxel proton MRS data in the anterior cingulate cortex (ACC) and basal ganglia were acquired using a 3-T scanner. The concentrations of N-acetylaspartate (NAA), mI (myo-inositol), glutamate (Glu), glutamine (Gln) and creatine (Cr) were obtained by LC-model software. Statistical analysis was performed to evaluate the differences between the three groups.

RESULTS

There was a significant increase in Glu for the cirrhotic patients, particularly the MHE patients. There was an elevation of Gln in the cirrhotic patients, but not in all cirrhotic patients or controls. There was a significant decrease in mI for the cirrhotic patients, but no significant difference between the two cirrhosis groups. There was no significant difference in NAA between the three groups.

CONCLUSIONS

MRS using a 3-T MR scanner could detect cerebral metabolic changes in cirrhotic patients with MHE. Glu levels were elevated in cirrhotic patients with MHE; Glu levels could be used as a sensitive indicator to evaluate the severity of MHE in patients with cirrhosis.

Role of neurosteroids in hepatic encephalopathy

Hepatic encephalopathy (HE) is a neuropsychiatric manifestation of chronic or acute liver disease. Neurosteroids are synthesized from cholesterol and its precursors by glial cells, oligodendrocytes and neurons in the brain. The mechanisms by which neurosteroids affect brain function may involve both genetic and non-genetic effects. On one hand, neurosteroids bind and modulate different types of neuronal membrane receptors, including gamma-amino butyric acid-A receptor (GABA-A), N-methyl-D-aspartic acid receptor (NMDA), 5-hydroxytryptamine 3 (5-HT3) and opioid receptors which have been showed to be involved in HE. On the other hand, some neurosteroids bind to intracellular receptors through which they also regulate gene expression. Of note, neurosteroids play a role in the pathogenesis of HE through inhibiting long-term potentiation. Neurosteroids might provide a new avenue for HE treatment.