Increased densities of peripheral-type benzodiazepine receptors in brain autopsy samples from cirrhotic patients with hepatic encephalopathy

Peripheral-type benzodiazepine receptors were evaluated using the specific ligand [3H]-PK 11195 in brain homogenates from nine cirrhotic patients who died in hepatic coma and from an equal number of age-matched control subjects. Histopathological studies showed evidence of severe Alzheimer type II astrocytosis in the brains of all cirrhotic patients. Saturation-binding assays revealed a single saturable binding site for [3H]-PK 11195 in brain, with affinities in the 2- to 3-nmol/L range. Diazepam was found to be a relatively potent inhibitor of 3H-PK 11195 binding (IC50 = 253 nmol/L), whereas the central benzodiazepine antagonist Ro 15-1788 displaced 3H-PK 11195 binding with low affinity (IC50 greater than 40 mumols/L). Densities of [3H]-PK 11195 binding sites were found to be increased by 48% (p less than 0.01) and 25% (p less than 0.05) in frontal cortex and caudate nuclei, respectively, from cirrhotic patients. Densities of [3H]-PK 11195 binding sites in frontal cortex from two nonencephalopathic cirrhotic patients were not significantly different from control values. No concomitant changes of affinities of these binding sites were observed. Because it has been suggested that peripheral-type benzodiazepine receptors may be localized on mitochondrial membranes and may therefore be involved in cerebral oxidative metabolism, the alterations observed in this study could be of pathophysiological significance in hepatic encephalopathy.     

Chronic hepatic encephalopathy in cirrhotic patients and spontaneous portacaval anastomosis. Portal angiographic and manometric study

Portal angiographic and manometric studies were prospectively carried out in 9 cirrhotic patients with spontaneous chronic portal-systemic encephalopathy. Hepatic encephalopathy presented as coma in 8 patients, and was the first manifestation of chronic liver disease in 6 cases. Hemodynamic studies showed a) a large single spontaneous portacaval anastomosis (gastrorenal, splenorenal, gradient (mean +/- SD = 16.3 +/- 5.4 mm Hg); c) a wedge hepatic venous pressure higher than portal pressure in 8 cases (difference: 1-11 mm Hg).     

Increased availability of central benzodiazepine receptors in patients with chronic hepatic encephalopathy and alcohol related cirrhosis

BACKGROUND/AIMS: To measure cerebral benzodiazepine receptor binding using (11)C-flumazenil positron emission tomography in patients with stable chronic hepatic encephalopathy, who were also characterised by proton magnetic resonance spectroscopy. METHODS: Six abstinent patients of mean age 61 years with alcohol related cirrhosis and grade I-II hepatic encephalopathy and 11 matched healthy volunteers were studied. Each patient's encephalopathy was defined according to clinical, psychometric, electroencephalographic, and magnetic resonance spectroscopy criteria. Using positron emission tomography, the brain volume of distribution of (11)C-flumazenil was obtained; this reflects benzodiazepine receptor availability. Proton magnetic resonance spectra were acquired at 1.5 T using a multivoxel technique; peak area ratios were calculated for choline, glutamine/glutamate, N-acetylaspartate, and creatine resonances. RESULTS: The mean volume of distribution of (11)C-flumazenil was significantly higher in the cortex, cerebellum, and the basal ganglia in the patients compared with controls (p<0.001). In the patient group, the mean glutamine/glutamate to creatine ratio was significantly increased and the mean choline to creatine ratio was significantly decreased in all brain areas, compared with healthy volunteers. However, the N-acetylaspartate to creatine ratio was unchanged compared with controls. CONCLUSIONS: The spectroscopy results reflect the cerebral metabolic derangement associated with hepatic encephalopathy. Stable grade I-II chronic hepatic encephalopathy in alcohol related cirrhosis may be associated with increased cerebral benzodiazepine receptor availability. However, a direct effect of previous chronic exposure to alcohol cannot be excluded.     

Effects of the histamine H(1) receptor blocker, pyrilamine, on spontaneous locomotor activity of rats with long-term portacaval anastomosis

To find out whether the changes in the brain histaminergic system are involved in the pathophysiology of portal-systemic encephalopathy, we examined the effects of histamine H(1) receptor blockade on spontaneous locomotor activity, feeding, and circadian rhythmicity in rats with portacaval anastomosis (PCA). Pyrilamine, an H(1) receptor blocker (15 mg/kg/day), was delivered with osmotic minipumps. Spontaneous locomotor activity was recorded for 72 hours in the open-field with an electromagnetic detector. Food intake was monitored twice daily at the end of the light (7 PM) and the dark (7 AM) phases for 3 days. Histamine H(1) receptor density in the suprachiasmatic nucleus (SCN) was examined with receptor autoradiography, employing [(3)H]pyrilamine. PCA surgery led to decreased movement time and velocity and flattened amplitude of the circadian rhythms of locomotion and feeding. In sham-operated rats, pyrilamine significantly decreased the movement time and velocity, as well as the total food consumption and completely abolished the circadian rhythmicity of locomotion. In contrast, pyrilamine increased the movement time and velocity in PCA-operated rats, particularly in the dark phase, and improved the precision of the circadian rhythms of locomotion and feeding. Histamine H(1) receptor density was not altered by PCA surgery, whereas pyrilamine treatment led to the complete blockade of H(1) receptors in both sham- and PCA-operated rats. We suggest that histaminergic imbalance has contributed to the generation and maintenance of the decreased spontaneous locomotor activity and altered circadian rhythmicity following PCA surgery in the rat, probably via an H(1) receptor-mediated mechanism.     

肝硬化肝性脑病大鼠脑水通道蛋白-4的表达与脑水肿的关系

目的:探讨肝硬化肝性脑病脑水肿的发生机制,为治疗脑水肿新方法的发现提供理论依据.方法:实验大鼠随机分为正常组(n=10)、正常氨负荷组(n=10)、肝硬化组(n=20)和肝硬化氨负荷组(n=20).后2组给予400 g/L CCl4橄榄油,按0.2 mL/kg腹腔注射.2次/wk,共12wk.前两组给与橄榄油.注射剂量、部位、频次、时间同后两组.正常氨负荷组、肝硬化氨负荷组分别在最后1次给药2d后,给与乙酸胺盲肠注射.4组大鼠通过尾静脉注射伊文恩蓝(EB)应用干式生化法测量动脉血氨,比色法测量EB含量,干-湿重法测量脑含水量,免疫组化法染色并通过图像分析系统分析脑组织中AQP4的表达.结果:肝硬化组动脉血氨与正常组、正常氨负荷组比较有差异性(97.20±29.66 μmol/Lvs 42.62±10.11,59.33±15.06 μmol/L,均P＜0.05),肝硬化氨负荷组的动脉血氨(420.18±75.91 μmol/L)与其他各组比较有明显的差异性(P＜0.01).肝硬化组EB和脑含水量与正常组、正常氨负荷组比较没有差异性.而肝硬化氨负荷组与其他各组比较有差异性(1.96±0.55 μg/g vs 1.41±0.46,1.19±0.38,1.05±0.18 μg/g;75.14±5.68 vs 65.58±4.14,62.14±2.29,66.27±4.57,均P＜0.05).肝硬化大鼠AQP4表达部位与正常大鼠一致,但肝硬化大鼠给与氨负荷后,无论是平均吸光度还是显色阳性面积均较正常组增高(P＜0.05).结论:AQP4可能在肝硬化肝性脑病大鼠脑水肿形成中起一定的作用.     

Nutritional assessment in cirrhotic patients with hepatic encephalopathy

Hepatic encephalopathy(HE) is one of the worst complications of liver disease and can be greatly influenced by nutritional status. Ammonia metabolism, inflammation and muscle wasting are relevant processes in HE pathophysiology. Malnutrition worsens the prognosis in HE, requiring early assessment of nutritional status of these patients. Body composition changes induced by liver disease and limitations superimposed by HE hamper the proper accomplishment of exams in this population, but evidence is growing that assessment of muscle mass and muscle function is mandatory due to the role of skeletal muscles in ammonia metabolism. In this review, we present the pathophysiological aspects involved in HE to support further discussion about advantages and drawbacks of some methods for evaluating the nutritional status of cirrhotic patients with HE, focusing on body composition.     

Increased concentrations of histamine and its metabolite,tele-methylhistamine and down-regulation of histamine H3 receptor sites in autopsied brain tissue from cirrhotic patients who died in hepatic coma

BACKGROUND/AIMS: Hepatic encephalopathy (HE) is a serious neuropsychiatric complication of chronic liver disease. To determine whether changes in the central histaminergic system are a feature of human HE, we studied histamine, tele-methylhistamine, and presynaptic autoregulatory H(3) receptors in cerebral cortex and caudate-putamen obtained at autopsy from six cirrhotic patients and six appropriately matched controls. METHODS: Histamine was assayed by HPLC; tele-methylhistamine by GC-MS. H(3) receptors were studied by in vitro receptor binding using [3H]R-alpha-methylhistamine as ligand. RESULTS: In HE patients, there was a significant fourfold increase of histamine in caudate-putamen and a significant increase in all cortical regions studied. tele-Methyhistamine was also increased and the densities of histamine H(3) receptor sites were significantly decreased in patient material. CONCLUSIONS: These findings are consistent with activation of the histaminergic system in HE. Given that histamine participates in the regulation of arousal and circadian rhythmicity, they indicate that induction of central histamine mechanisms may contribute to the development of neuropsychiatric symptoms, such as sleep disturbances and altered circadian rhythms in chronic HE and suggest that pharmacological manipulation of the histaminergic system could be beneficial in the treatment of HE in chronic liver failure.     

Identifying minimal hepatic encephalopathy in cirrhotic patients by measuring spontaneous brain activity

It has been demonstrated that minimal hepatic encephalopathy (MHE) is associated with aberrant regional intrinsic brain activity in cirrhotic patients. However, few studies have investigated whether altered intrinsic brain activity can be used as a biomarker of MHE among cirrhotic patients. In this study, 36 cirrhotic patients (with MHE, n?=?16; without MHE [NHE], n?=?20) underwent resting-state functional magnetic resonance imaging (fMRI). Spontaneous brain activity was measured by examining the amplitude of low-frequency fluctuations (ALFF) in the fMRI signal. MHE was diagnosed based on the Psychometric Hepatic Encephalopathy Score (PHES). A two-sample t-test was used to determine the regions of interest (ROIs) in which ALFF differed significantly between the two groups; then, ALFF values within ROIs were selected as classification features. A linear discriminative analysis was used to differentiate MHE patients from NHE patients. The leave-one-out cross-validation method was used to estimate the performance of the classifier. The classification analysis was 80.6 % accurate (81.3 % sensitivity and 80.0 % specificity) in terms of distinguishing between the two groups. Six ROIs were identified as the most discriminative features, including the bilateral medial frontal cortex/anterior cingulate cortex, posterior cingulate cortex/precuneus, left precentral and postcentral gyrus, right lingual gyrus, middle frontal gyrus, and inferior/superior parietal lobule. The ALFF values within ROIs were correlated with PHES in cirrhotic patients. Our findings suggest that altered regional brain spontaneous activity is a useful biomarker for MHE detection among cirrhotic patients.     

Aromatic and branched-chain amino acids in autopsied brain tissue from cirrhotic patients with hepatic encephalopathy

Concentrations of the branched-chain amino acids (BCAAs) valine, leucine, and isoleucine and the aromatic amino acids (AAAs) phenylalanine and tyrosine were measured in three areas of dissected brain tissue obtained at autopsy from nine cirrhotic patients who died in hepatic encephalopathy. The controls were an equal number of subjects free from neurological, psychiatric or hepatic diseases, matched for age and time interval from death to freezing of autopsied brain samples. Amino acids were measured using high-performance liquid chromatography with fluorimetric detection. In brain tissue of cirrhotic patients, no changes in BCAA concentrations were observed compared with controls. On the other hand, phenylalanine levels were found to be increased 141% in prefrontal cortex, 86% in frontal cortex and 26% in caudate nucleus, and tyrosine content was increased by 71% in prefrontal cortex and 28% in frontal cortex with no significant increase in caudate nucleus. Alterations in the concentration of AAAs may lead to disturbances of monoamine neurotransmitters in brain. Such changes could play a role in the pathogenesis of hepatic encephalopathy resulting from chronic liver disease in man.     

Affinities and densities of high-affinity [3H]muscimol (GABA-A) binding sites and of central benzodiazepine receptors are unchanged in autopsied brain tissue from cirrhotic patients with hepatic encephalopathy

The integrity of GABA-A receptors and of central benzodiazepine receptors was evaluated in membrane preparations from prefrontal cortex and caudate nuclei obtained at autopsy from nine cirrhotic patients who died in hepatic coma and an equal number of age-matched control subjects. Histopathological studies revealed Alzheimer Type II astrocytosis in all cases in the cirrhotic group; controls were free from neurological, psychiatric or hepatic diseases. Binding to GABA-A receptors was studied using [3H]muscimol as radioligand. The integrity of central benzodiazepine receptors was evaluated using [3H]flunitrazepam and [3H]Ro15-1788. Data from saturation binding assays was analyzed by Scatchard plot. No modifications of either affinities (Kd) or densities (Bmax) of [3H]muscimol of central benzodiazepine binding sites were observed. These findings do not support recent suggestions that alterations of either high-affinity GABA or benzodiazepine receptors play a significant role in the pathogenesis of hepatic encephalopathy.     

Efficient hepatic uptake of chylomicron remnant cholesterol in rats with a portacaval anastomosis

Portacaval-shunted and sham-operated male rats, fed ad libitum and of similar weight, were studied 2-3 weeks after surgery. At this time serum cholesterol levels did not differ significantly between the two groups, whereas serum triacylglycerols and phospholipids were lower in the shunted group. These animals also showed an increased serum bile acid level and an increased serum estradiol to testosterone ratio. The metabolism of native chyle labeled with [3H]cholesterol and [14C]linoleic acid or of preformed chylomicron remnants with the same labeling was studied in the groups of rats. Ten minutes after intravenous injection of chylomicron remnants 10.6 +/- 0.5% (means +/- SEM, n = 8) of the injected [3H]cholesterol and 7.6 +/- 0.4% of the [14C]linoleic acid were found per 1 g liver in the portacaval-shunted rats; the corresponding figures in the sham-operated group (n = 8) were 6.4 +/- 0.4 and 4.9 +/- 0.3, respectively (p less than 0.001 for both 3H and 14C). Thus, despite a greater than 40% reduction of liver weight induced by the shunting procedure, the total liver uptake of chylomicron remnants was not significantly decreased. The uptake of chylomicron lipids per unit liver weight was normal in the atrophic livers of portacaval-shunted rats also when very large loads of chyle were administered.     

Inflammation and hepatic encephalopathy: ibuprofen restores learning ability in rats with portacaval shunts

One of the neurological alterations in patients with minimal or overt hepatic encephalopathy is cognitive impairment. This impairment is reproduced in rats with chronic liver failure due to portacaval shunt (PCS). These rats show decreased ability to learn a conditional discrimination task in a Y-maze, likely due to reduced function of the glutamate-nitric oxide (NO)-cyclic guanosine monophosphate (cGMP) pathway in brain. It has been proposed that inflammation exacerbates the neuropsychological alterations induced by hyperammonemia, suggesting that inflammation-associated alterations may contribute to cognitive impairment in hepatic encephalopathy. This study assessed whether treatment with an anti-inflammatory drug, ibuprofen, is able to restore the function of the glutamate-NO-cGMP pathway in cerebral cortex in brain in vivo and/or learning ability in PCS rats. We show that PCS rats have increased levels of interleukin-6 and increased activities of cyclooxygenase and of inducible NO synthase in cerebral cortex, indicating the presence of inflammation. Chronic treatment with ibuprofen normalizes cyclooxygenase and inducible NO synthase activities but not interleukin-6 levels. Moreover, ibuprofen normalizes the function of the glutamate-NO-cGMP pathway in cerebral cortex in vivo and completely restores the ability of rats with chronic liver failure to learn the Y-maze task. This supports that inflammation contributes to the cognitive impairment in hepatic encephalopathy. CONCLUSION: the results reported point to the possible therapeutic utility of decreasing inflammation in the treatment of the cognitive deficits in patients with minimal or overt hepatic encephalopathy.     

Increased turnover of Gc-globulin in patients with hepatic encephalopathy

BACKGROUND: A low serum level (< 100 mg/L) of the actin-scavenger Gc-globulin is a prognostic marker of non-survival in fulminant hepatic failure (FHF). It is unknown whether decreased production or increased consumption (or both) is responsible for the low Gc-globulin levels. METHODS: Ten patients with FHF and four patients with acute or chronic liver disease (AOCLD) with hepatic encephalopathy (HE) grades II-IV were included. Eight patients with cirrhosis (chronic liver disease, CLD) without HE served as controls. Total, free, and actin-bound Gc-globulin were measured in samples from an artery, a central vein, and a hepatic vein. In 12 patients (9 FHF, 3 AOCLD), concentrations were measured before and after high volume plasmapheresis (HVP). RESULTS: Total Gc-globulin was reduced to 21%, 40%, and 43% of the normal level in the FHF, AOCLD, and CLD groups, respectively, whereas bound Gc-globulin was within normal range in all patients. The Gc:actin complex ratio was increased 3.8, 2.5, and 1.9-fold compared with normal levels. Total, free, and bound serum Gc-globulin levels did not differ among arterial, systemic venous, or hepatic venous blood. Total Gc-globulin rose to >100 mg/L in all patients after HVP, whereas bound Gc-globulin remained unchanged. The Gc-globulin production rate in FHF and AOCLD patients was increased to 4.1 +/- 1.3 mg/min compared to literature values of 0.6 mg/min in healthy individuals. The estimated half-life of total Gc-globulin was shorter in the patients compared to healthy individuals (127 +/- 56 min and 870 min, respectively). CONCLUSIONS: Gc-globulin levels were reduced in patients with FHF and AOCLD because a 7-fold increase of Gc-globulin production rate could not compensate for the accelerated clearance. Bound Gc-globulin was maintained within normal levels in all circumstances studied, indicating a possible regulatory role of this parameter in the clearance of actin.     

肝性脑病大鼠脑超微结构的改变

目的：通过观察肝性脑病大鼠脑部分区域及氨对体外培养大鼠神经元超微结构的改变,讨论其病理发生机制。方法选用健康雄性SD大鼠12只,随机分为肝性脑病模型组和正常对照组两组,每组6只。用电子透射显微镜观察硫代乙酰胺诱导的肝性脑病大鼠和体外氨中毒大鼠皮质神经元的超微结构。结果肝性脑病大鼠神经元细胞数量减少;神经元线粒体肿胀,尼氏体数量明显减少;可见凋亡各期表现。神经胶质细胞细胞器减少,黑质的超微结构改变程度较基底核略重。体外培养氨中毒神经元变化：神经元细胞数量明显减少;细胞明显水肿,线粒体明显肿胀,尼氏体显著减少;可见不同时期的凋亡表现。结论肝性脑病大鼠脑超微结构改变明显,其主要机制可能与氨中毒引起的神经元凋亡有关。     

Effect of H pylori infection and its eradication on hyperammo-nemia and hepatic encephalopathy in cirrhotic patients

AIM: To investigate the relationship between H pylori infection, blood ammonia concentration and hepatic encephalopathy (HE), and the effect of H pylori eradication in cirrhotic patients.METHODS: From July 2003 to January 2005, 457 cirrhotic patients in five regions of Zhejiang Province were enrolled. Patients were evaluated for demographics, number connection test, H pylori infection, liver impairment, blood ammonia concentration and HE. Patients with H pylori infection were given 1 wk therapy with omeprazole plus clarithromycin and tinidazole. 14C urea breath test was performed and mental symptoms and blood ammonia level were reassessed after bacterium eradication.RESULTS: Overall H pylori infection rate was 60.6%, and HE occurred in 47.5% of cirrhotic patients. Subclinical HE (SHE) was detected in 55 of 117 cirrhotic patients. Blood ammonia concentration in H pylori negative (n = 180) and positive (n = 277) cirrhotic patients was 53.8 ± 51.4 and 78.4 ± 63.6 nmol/L, respectively (P < 0.01), which was significantly reduced to 53.5 ± 37.7 nmol/L after bacterium eradication (n = 126) (P < 0.01). Blood ammonia was 97.5 ± 81.0 nmol/L in H py/ori-positive cirrhotic patients, and this did not significantly change in those with persistent infection after H pylori eradication (n = 11). HE was more frequently observed in patients with H pylori infection than in those without (58.5% vs 30.6%, P < 0.01). HE rate significantly dropped to 34.1% after H pylori eradiation (P < 0.01). H pylori prevalence significantly differed among cirrhotic patients with HE (74.4%), SHE (69.1%), and those without HE (53.2%) (P < 0.05). Blood ammonia level was significantly different among cirrhotic patients with HE (94.5 ± 75.6 nmol/L), SHE (59.9 ± 49.2 nmol/L), and without HE (47.3 ± 33.5 nmol/L) (P < 0.05). Logistic regression analysis showed that blood ammonia concentration, Child-Pugh stage, upper gastrointestinal bleeding, electrolyte disturbance, and urea nitrogen were risk factors for HE.CONCLUSION: H pylori infection is an important factor for inducing high blood ammonia concentration and HE in cirrhotic patients. H pylori eradication may be helpful for treatment and prevention of HE.