Cognitive function in patients with alcoholic and nonalcoholic chronic liver disease.

The aim of the present study was to characterize the neurophysiological profile of cognitive impairment associated with patients with chronic alcoholic and nonalcoholic liver disease. The authors evaluated 43 patients with cirrhotic liver disease: 19 patients with chronic alcohol ingestion and 24 nonalcoholic patients who had been infected with hepatitis B or C virus. Eleven healthy subjects were included as control subjects. A battery of 12 psychological tests was used to investigate cognitive deficits in the patients with chronic liver disease. It was observed that alcoholic patients with chronic liver disease showed a more important cognitive deterioration than those affected by hepatitis B or C virus.

Bile acids content in brain of common duct ligated rats.

INTRODUCTION: Cholestasis leads to liver cell death, fibrosis, cirrhosis, and eventually liver failure. Bile duct ligated rats constitute an interesting model to study the mechanism of cholestasis, and its action on several organs and tissues, including the brain. AIM: To analyze brain bile acids individually in ligated rats to evaluate if its profile is altered towards a more toxic condition in cholestasis. MATERIAL AND METHODS: Male Wistar rats were used and separated in two groups: bile duct ligated rats and sham operated rats (n = 5 in each group). Bile acid profile was assessed in brain homogenates. Alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase determinations, bilirubin and ammonia plasma concentration were also measured in both groups. RESULTS: Although the total amount of bile acids in control animal brains showed a higher concentration than in bile duct ligated rats, the bile acid profile in this group was found more toxic composition than in controls. Lithocholic acid was present in brain in higher concentration (87.4 % of total brain bile acids) in ligated rats and absent in controls. Alkaline phosphatase, bilirubin and ammonia were significantly higher in bile duct ligated rats than in control group. CONCLUSION: It was found a toxic brain bile acid profile during hepatic cholestasis which could be one of the explanations of hepatic encephalopathy observed in cholestatic diseases.

Hepatic encephalopathy: An approach to its multiple pathophysiological features.

Hepatic encephalopathy (HE) is a neuropsychiatric complex syndrome, ranging from subtle behavioral abnormalities to deep coma and death. Hepatic encephalopathy emerges as the major complication of acute or chronic liver failure. Multiplicity of factors are involved in its pathophysiology, such as central and neuromuscular neurotransmission disorder, alterations in sleep patterns and cognition, changes in energy metabolism leading to cell injury, an oxidative/nitrosative state and a neuroinflammatory condition. Moreover, in acute HE, a condition of imminent threat of death is present due to a deleterious astrocyte swelling. In chronic HE, changes in calcium signaling, mitochondrial membrane potential and long term potential expression, N-methyl-D-aspartate-cGMP and peripheral benzodiazepine receptors alterations, and changes in the mRNA and protein expression and redistribution in the cerebral blood flow can be observed. The main molecule indicated as responsible for all these changes in HE is ammonia. There is no doubt that ammonia, a neurotoxic molecule, triggers or at least facilitates most of these changes. Ammonia plasma levels are increased two- to three-fold in patients with mild to moderate cirrhotic HE and up to ten-fold in patients with acute liver failure. Hepatic and inter-organ trafficking of ammonia and its metabolite, glutamine (GLN), lead to hyperammonemic conditions. Removal of hepatic ammonia is a differentiated work that includes the hepatocyte, through the urea cycle, converting ammonia into GLN via glutamine synthetase. Under pathological conditions, such as liver damage or liver blood by-pass, the ammonia plasma level starts to rise and the risk of HE developing is high. Knowledge of the pathophysiology of HE is rapidly expanding and identification of focally localized triggers has led the development of new possibilities for HE to be considered. This editorial will focus on issues where, to the best of our knowledge, more research is needed in order to clarify, at least partially, controversial topics.

Hepatic encephalopathy, ammonia, glutamate, glutamine and oxidative stress.

This review addresses recent and not so recent works that emphasize on the mechanisms by which liver damage can induce encephalopathy. Hepatic encephalopathy constitutes an intriguing complication in severe liver acute and chronic disease, whose pathophysiology is still not completely understood. In this pathology, alterations in normal brain function are associated with morphological and functional impairments of astrocytes and neurons. A wide spectrum of psychoneurological symptoms has been described and the anatomical substratum is usually associated with brain edema and intracranial hypertension, as well as with changes in the function of brain cells. An increase in blood ammonia, toxic to the brain, depends on the activity of the enzyme glutamine synthetase, the glutamine/glutamate cycle and the brain capacity to eliminate toxic substances. When the concentration of the excitotoxic neurotransmitter glutamate is increased, it acts as a toxic agent, especially when its specific transporters are altered and its uptake is decreased. Glutamine has also been recently considered a toxic substance when its concentration is high, and consequently contributes to brain edema. Finally, the formation of reactive oxygen species, basically produced by mitochondria, influence with their toxic action on membrane lipids, proteins and DNA. In conclusion we suggest that at least these four elements are involved directly in the mechanism of hepatic encephalopathy.

Glutamine synthetase activity and glutamate uptake in hippocampus and frontal cortex in portal hypertensive rats.

AIM: To study glutamine synthetase (GS) activity and glutamate uptake in the hippocampus and frontal cortex (FC) from rats with prehepatic portal vein hypertension. METHODS: Male Wistar rats were divided into sham-operated group and a portal hypertension (PH) group with a regulated stricture of the portal vein. Animals were sacrificed by decapitation 14 d after portal vein stricture. GS activity was determined in the hippocampus and FC. Specific uptake of radiolabeled L-glutamate was studied using synaptosome-enriched fractions that were freshly prepared from both brain areas. RESULTS: We observed that the activity of GS increased in the hippocampus of PH rats, as compared to control animals, and decreased in the FC. A significant decrease in glutamate uptake was found in both brain areas, and was more marked in the hippocampus. The decrease in glutamate uptake might have been caused by a deficient transport function, significantly and persistent increase in this excitatory neurotransmitter activity. CONCLUSION: The presence of moderate ammonia blood levels may add to the toxicity of excitotoxic glutamate in the brain, which causes alterations in brain function. Portal vein stricture that causes portal hypertension modifies the normal function in some brain regions.

Reyes's syndrome, encephalopathy, hyperammonemia and acetyl salicylic acid ingestion in a city hospital of Buenos Aires, Argentina.

Twelve cases of Reye's syndrome are presented with different degrees of encephalopathy, hyperammonemia and hypoglycemia; associated to acetyl salicylic acid (ASA) ingestion. The aim of the present retrospective study was to describe our experience in selected patients with Reye's syndrome associated to the ASA ingestion and to underline the influence of hyperammonemia on Reye's encephalopathy. All the cases presented moderate hyperbilirubinemia, elevated alanine aminotransferase, aspartate aminotransferase with an average of 302+/-205 UI/L and 285+/-149 UI/L respectively. Arterial blood ammonia averaged 172.4+/-71.3 micromol/L and glycaemia averaged 35.2+/-17.0 mg/dl. A high mortality was found in our series (41.7%). Considering that encephalopathy is the leading syndrome in these cases, the influence of ammonia on brain tissue was described. Glutamate is an excitotoxic neurotransmitter, capable to produce neuron and astrocyte damage and apoptosis. The presence of ASA could cause the onset of the mitochondrial permeability transition and the mitochondrial swelling in the astrocyte, leading to hyperammonemia. In Reye's syndrome, hyperammonemia and perhaps the increase of glutamate are the leading factors in the mechanism of brain damage and encephalopathy. Aspirin must be carefully administrated and controlled by professionals. Furthermore, parents must be informed about the risks in the use of this drug in children.

Oxidative stress and hippocampus in a low-grade hepatic encephalopathy model: protective effects of curcumin.

AIM: The present study was performed on prehepatic portal hypertensive rats, a model of low-grade hepatic encephalopathy, designed to evaluate whether oxidative stress was a possible pathway implicated in hippocampal damage and if so, the effect of an anti-oxidant to prevent it. METHODS: Prehepatic portal hypertension was induced by a regulated portal vein stricture. Oxidative stress was investigated by assessing related biochemical parameters in rat hippocampus. The effect of the anti-oxidant curcumin, administered in a single i.p. dose of 100 mg/kg on the seventh, ninth and eleventh days after surgery, was evaluated. RESULTS: Oxidative stress in the rat hippocampal area was documented. Curcumin significantly decreased tissue malondialdehyde levels and significantly increased glutathione peroxidase, catalase and superoxide dismutase activities in the hippocampal tissue of portal hypertensive rats. CONCLUSION: Oxidative stress was found to be implicated in the hippocampal damage and curcumin protected against this oxidative stress in low-grade hepatic encephalopathic rats. These protective effects may be attributed to its anti-oxidant properties.

Involvement of serum apolipoprotein AI and B100 and lecithin cholesterol acyl transferase in alcoholic cirrhotics.

Lipoproteins are synthesized by the liver and secreted to plasma. Chronic alcoholic intoxication produces frequently cirrhosis and concomitantly alterations in liver metabolism. Thirty patients with alcoholic cirrhosis and 83 healthy controls were selected for this study. Apolipoprotein A1, B100, lecithin cholesterol acyltransferase, responsible for cholesterol esterification and seudocholinesterase enzyme activity not related to lipid metabolism, as a referent of proteins synthesized by the liver were analyzed. In 7 patients serum tiobarbituric acids, catalase, glutathione peroxidase were measured, as exponent of the presence of oxidative stress. Our results showed a significant decrease in lipoproteins, lecithin cholesterol acyltransferase and seudocholinesterase activities. An increase in serum tiobarbituric acids and a decrease in both antioxidant enzymes were found as well. In conclusion, alcohol cirrhotic liver decreases the production of liver proteins including those related to lipid metabolism, allowing the formation of steatosis and/or necrosis. Moreover oxidative stress participate possible as a major mechanism in liver damage.

Altered blood-brain barrier permeability in rats with prehepatic portal hypertension turns to normal when portal pressure is lowered.

AIM: To study the blood-brain barrier integrity in prehepatic portal hypertensive rats induced by partial portal vein ligation,at 14 and 40 d after ligation when portal pressure is spontaneously normalized. METHODS: Adult male Wistar rats were divided into four groups: Group I: Sham14d , sham operated; Group II: PH14d , portal vein stenosis; (both groups were used 14 d after surgery); Group III: Sham40d, Sham operated and Group IV: PH40d Portal vein stenosis (Groups II and IV used 40 d after surgery). Plasma ammonia,plasma and cerebrospinal fluid protein and liver enzymes concentrations were determined. Trypan and Evans blue dyes, systemically injected,were investigated in hippocampus to study blood-brain barrier integrity. Portal pressure was periodically recorded. RESULTS: Forty days after stricture, portal pressure was normalized, plasma ammonia was moderately high, and both dyes were absent in central nervous system parenchyma. All other parameters were reestablished. When portal pressure was normalized and ammonia level was lowered, but not normal, the altered integrity of blood-brain barrier becomes reestablished. CONCLUSION: The impairment of blood-brain barrier and subsequent normalization could be a mechanism involved in hepatic encephalopathy reversibility.Hemodynamic changes and ammonia could trigger blood-brain barrier alterations and its reestablishment.

Bile acid profiles by capillary electrophoresis in intrahepatic cholestasis of pregnancy.

ICP (intrahepatic cholestasis of pregnancy) is characterized by pruritus and biochemical cholestasis, including raised SBAs (serum bile acids) and, usually, elevated aminotransferases levels. However, AHP (asymptomatic hypercholanaemia of pregnancy) is defined as the presence of total SBA levels above the cut-off value (11 microM) in healthy pregnant women, thus elevation of total SBAs do not necessarily reflect an ICP condition. The aim of the present study was to describe clinical, obstetric, perinatal and biochemical findings, as well as the SBA profile, in pregnant women studied in the third trimester of pregnancy in order to define characteristic patterns of individual bile acids that enable women with ICP to be distinguished from AHP and healthy pregnancies. Free and conjugated ursodeoxycholic (UDCA), cholic (CA), lithocholic (LCA), deoxycholic (DCA) and chenodeoxycholic (CDCA) acids were evaluated by CE (capillary electrophoresis) in 41 patients (15 of them simultaneously by HPLC), in 30 healthy pregnant women and in 10 non-pregnant women. A highly significant correlation between CE and HPLC for total SBAs (r=0.990) and for individual SBAs was found. Normal pregnant women had higher total SBA levels than non-pregnant women (due to an increase in taurine-conjugated dihydroxy SBAs). Women with ICP had higher levels of total SBAs, the free/conjugated ratio, LCA, CA, CDCA and DCA than normal pregnant women. Newborns from women with ICP had lower birth weight and gestational age. Women with AHP had higher levels of conjugated dihydroxy SBAs than normocholanaemic patients, without any evidence of a clinical difference. In conclusion, the present study has shown a clear difference in SBA profiles between ICP and normal pregnancies (including AHP), involving a shift towards a characteristic hydrophobic composition in women with ICP.

Hepatic morphological changes and oxidative stress in chronic streptozotocin-diabetic rats.

Oxidative stress (OS) is a biological entity quoted as responsible for several pathologies including diabetes. Diabetes mellitus (DM) has been also associated to human cirrhosis. The present work was designed to study the occurrence of OS as well as morphologic alterations in rat livers following induction of DM. Two groups of rats were used: Control and Diabetic. DM was induced in the second group by streptozotocin (STZ) in a single dose of 60 mg/kg, injected i.p. The occurrence of OS was determined in liver homogenates by measuring the hydroperoxide-initiated chemiluminescence and the activity of antioxidant enzymes (superoxide dismutase, catalase and glutathione peroxidase). Liver sinusoids were morphometrically analyzed. In conclusion, livers from the diabetic group did not show evidence of the occurrence of OS, as it would be expected, but dilation of hepatic sinusoids was documented and it was significantly different from control group.

Hippocampal mitochondrial dysfunction with decreased mtNOS activity in prehepatic portal hypertensive rats.

Portal hypertension is a major complication of human cirrhosis that frequently leads to central nervous system dysfunction. In our study, rats with prehepatic portal hypertension developed hippocampal mitochondrial dysfunction as indicated by decreased respiratory rates, respiratory control and mitochondrial nitric oxide synthase (mtNOS) activity in mitochondria isolated from the whole hippocampus. Succinate-dependent respiratory rates decreased by 29% in controlled state 4 and by 42% in active state 3, and respiratory control diminished by 20%. Portal hypertensive rats showed a decreased mtNOS activity of 46%. Hippocampal mitochondrial dysfunction was associated with ultrastructural damage in the mitochondria of hippocampal astrocytes and endothelial cells. Swollen mitochondria, loss of cristae and rupture of outer and inner membrane was observed in astrocytes and endothelial cells of the blood-brain barrier in parallel with the ammonia gradient. It is concluded that the moderate increase in plasma ammonia that followed portal hypertension was the potential primary cause of the observed alterations.

Hyperammonemia, brain edema and blood-brain barrier alterations in prehepatic portal hypertensive rats and paracetamol intoxication.

AIM: To study the blood-brain barrier integrity, brain edema, animal behavior and ammonia plasma levels in prehepatic portal hypertensive rats with and without acute liver intoxication. METHODS: Adults male Wistar rats were divided into four groups. Group I: sham operation; II: Prehepatic portal hypertension, produced by partial portal vein ligation; III: Acetaminophen intoxication and IV: Prehepatic portal hypertension plus acetaminophen. Acetaminophen was administered to produce acute hepatic injury. Portal pressure, liver serum enzymes and ammonia plasma levels were determined. Brain cortex water content was registered and trypan blue was utilized to study blood brain barrier integrity. Reflexes and behavioral tests were recorded. RESULTS: Portal hypertension was significantly elevated in groups II and IV. Liver enzymes and ammonia plasma levels were increased in groups II, III and IV. Prehepatic portal hypertension (group II), acetaminophen intoxication (group III) and both (group IV) had changes in the blood brain-barrier integrity (trypan blue) and hyperammonemia. Cortical edema was present in rats with acute hepatic injury in groups III and IV. Behavioral test (rota rod) was altered in group IV. CONCLUSION: These results suggest the possibility of another pathway for cortical edema production because blood brain barrier was altered (vasogenic) and hyperammonemia was registered (cytotoxic). Group IV, with behavioral altered test, can be considered as a model for study at an early stage of portal-systemic encephalopathy.

Does hepatomegaly alter iron-dependent oxidative effects in human plasma?

A four-fold increase in the iron content of normal subjects was detected in plasma after 5 hours of iron administration. Iron supplementation had a surprisingly erratic effect on four patients with hepatomegaly secondary to heart insufficiency, since the increase in the iron content in the plasma after iron-dextran administration was either within the control range or significantly lower, independently of the initial values. Thiobarbituric acid reactive substances (TBARS) content was 2.5 +/- 0.2 and 4.3 +/- 0.4 microM for control and hepatomegalic subjects, respectively. The TBARS basal level was increased by iron supplementation. The difference between TBARS content in hepatomegalic and control subjects, after 5 hours of iron administration, was increased by 50% as compared to the difference in the basal content of TBARS. alpha-Tocopherol (alpha-T) content in plasma from subjects with hepatomegaly showed a significant decrease (-41%) as compared to control subjects. No significant difference over the basal level of alpha-T was measured after 5 hours of iron administration in any subject. The data presented here suggest that abnormal liver condition affects iron-dependent oxidative stress in plasma. Moreover, alpha-T does not seem to be the main antioxidant to control iron-dependent oxidative stress in plasma.

Cambios funcionales en el sistema nervioso central de ratas hipertensas portales prehepáticas / Functional alterations in central nervous system of prehepatic portal hypertensive rats

La hipertensión portal prehepática experimental produce alteraciones morfológicas en la barrera hematoencefálica (BHE), astrogliosis y angiogénesis en áreas CA4 y CA1 del hipocampo. El objetivo fue estudiar los posibles cambios funcionales de la BHE en ratas HP. Métodos: Se usaron ratas Wistar Kyoto macho de 240g las que se dividieron en: GI (n=8) hipertensas portales por estrechez reglada de la vena porta; GII (n=6) con operación simulada (sham). Se determinaron la integridad funcional de la BHE por Trypan Blue (TB, Reynolds), concentración proteica (CP) en líquido cefaloraquídeo (LCR, Bradford), actividad eléctrica cortical (EEG), contenido de agua en cerebro (gravidimetría) y test conductuales: Animex, rigthing reflex, dolor y Rotarod. El TB fue positivo en áreas perivasculares e hipocampo solo en el GI; la CP en LCR (ug/ml) fue (X±ESM); GI: 40.6±6.8 y GII: 16.5±4.2 (p<0.005) y en plasma (mg/ml): GI: 108.8±7.6 y GII: 87.4±2 (NS). El EEG se mostró alterado con predominancia de onda delta para GI: 0.551±0.033 y GII: 0.342±0.031 (p<0.008), el porcentaje de agua por g/tejido cerebral fue GI: 79.21±0.2, GII: 78.95±0.18 (NS). Estos resultados demuestran la existencia de cambios funcionales en la BHE con una presentación subclínica de encefalopatía hepática en ratas con HP.

Cambios funcionales en el sistema nervioso central de ratas hipertensas portales prehepáticas / Functional alterations in central nervous system of prehepatic portal hypertensive rats

La hipertensión portal prehepática experimental produce alteraciones morfológicas en la barrera hematoencefálica (BHE), astrogliosis y angiogénesis en áreas CA4 y CA1 del hipocampo. El objetivo fue estudiar los posibles cambios funcionales de la BHE en ratas HP. Métodos: Se usaron ratas Wistar Kyoto macho de 240g las que se dividieron en: GI (n=8) hipertensas portales por estrechez reglada de la vena porta; GII (n=6) con operación simulada (sham). Se determinaron la integridad funcional de la BHE por Trypan Blue (TB, Reynolds), concentración proteica (CP) en líquido cefaloraquídeo (LCR, Bradford), actividad eléctrica cortical (EEG), contenido de agua en cerebro (gravidimetría) y test conductuales: Animex, rigthing reflex, dolor y Rotarod. El TB fue positivo en áreas perivasculares e hipocampo solo en el GI; la CP en LCR (ug/ml) fue (X±ESM); GI: 40.6±6.8 y GII: 16.5±4.2 (p<0.005) y en plasma (mg/ml): GI: 108.8±7.6 y GII: 87.4±2 (NS). El EEG se mostró alterado con predominancia de onda delta para GI: 0.551±0.033 y GII: 0.342±0.031 (p<0.008), el porcentaje de agua por g/tejido cerebral fue GI: 79.21±0.2, GII: 78.95±0.18 (NS). Estos resultados demuestran la existencia de cambios funcionales en la BHE con una presentación subclínica de encefalopatía hepática en ratas con HP. (AU)