Problems with animal models of chronic liver disease: suggestions for improvement in standardization

AdhMMP8 Vector Administration in Muscle: An Alternate Strategy to Regress Hepatic Fibrosis

The development of several vaccines against the SARS-CoV2 virus and their application in millions of people have shown efficacy and safety in the transfer of genes to muscle turning this tissue into a protein-producing factory. Established advanced liver fibrosis, is characterized by replacement of hepatic parenchyma by tissue scar, mostly collagen type I, with increased profibrogenic and proinflammatory molecules gene expression. Matrix metalloproteinase 8 (MMP-8) is an interstitial collagen-degrading proenzyme acting preferentially on collagen type I when activated. This study was carried out to elucidate the effect of an intramuscularly delivered adenoviral vector containing proMMP-8 gene cDNA (AdhMMP8) in male Wistar rats with experimental advanced liver fibrosis induced by thioacetamide. Therapeutic effects were monitored after 1, 2, or 3 weeks of a single dose (3 × 1011 vp/kg) of AdhMMP8. Circulating and liver concentration of MMP-8 protein remained constant; hepatic fibrosis decreased up to 48%; proinflammatory and profibrogenic genes expression diminished: TNF-α 2.28-fold, IL-1 1.95-fold, Col 1A1 4-fold, TGF-β1 3-fold and CTGF 2-fold; and antifibrogenic genes expression raised, MMP-9 2.8-fold and MMP-1 10-fold. Our data proposes that the administration of AdhMMP8 in muscle is safe and effective in achieving liver fibrosis regression at a comparable extent as when the adenoviral vector is delivered systemically to reach the liver, using a minimally invasive procedure.

Protective effect of fu-qi granule on carbon tetrachloride-induced liver fibrosis in rats

AIM: To investigate the efficacy of fu-qi granule (FQG) on carbon tetrachloride (CCl₄) induced liver fibrosis in rats and the underlying mechanisms.

METHODS: Sixty rats were randomly divided into six groups: normal control group, CCl₄ induced liver fibrosis group, AnluoHuaxianWan group and three treatment groups of FQG. Treatment of rats with intraperitoneal injection of carbon tetrachloride solution at 0.3 mL per 100 g body weigh twice a week for 8 wk. The normal control group the rats were given the media (olive oil) at the same time. In the first 2 wk, rats were raised with feedstuff (80% corn meal, 20% lard, 0.5% cholesterol). Serum samples were collected for alanine transaminase, aspartate aminotransferase, alkaline phosphatase, albumin, total protein assay and typical histopathological changes was observed in Hematoxylin-eosin staining sections. Smooth muscle alpha actin (α-SMA) was analyzed with immunohistochemistry. Mammalian target of rapamycin (mTOR) and hypoxia-inducible factor-1 (HIF-1α) expressions were detected by Western blotting. Tissue inhibitor of matrix metalloproteinases-1 (TIMP-1) and matrix metalloproteinases-9 (MMP-9) were measured with semi-quantitative reverse transcriptase-polymerase chain reaction.

RESULTS: FQG significantly reduced the serum levels of alanine transaminase, aspartate aminotransferase, alkaline phosphatase and increased the serum contents of albumin, total protein in rats with liver fibrosis. Moreover, FQG promoted extracellular matrix degradation by increasing MMP-9 and inhibiting TIMP-1 and α-SMA. mTOR and HIF-1α expression in liver significantly decreased in the rats treated with FQG.

CONCLUSION: The results indicated that FQG significantly reverse fibrosis induced by CCl₄, which should be developed as a new and promising preparation for the prevention of liver fibrosis.

Ideal Experimental Rat Models for Liver Diseases

There are many limitations for conducting liver disease research in human beings due to the high cost and potential ethical issues. For this reason, conducting a study that is difficult to perform in humans using appropriate animal models, can be beneficial in ascertaining the pathological physiology, and in developing new treatment modalities. However, it is difficult to determine the appropriate animal model which is suitable for research purposes, since every patient has different and diverse clinical symptoms, adverse reactions, and complications due to the pathological physiology. Also, it is not easy to reproduce identically various clinical situations in animal models. Recently, the Guide for the Care and Use of Laboratory Animals has tightened up the regulations, and therefore it is advisable to select the appropriate animals and decide upon the appropriate quantities through scientific and systemic considerations before conducting animal testing. Therefore, in this review article the authors examined various white rat animal testing models and determined the appropriate usable rat model, and the pros and cons of its application in liver disease research. The authors believe that this review will be beneficial in selecting proper laboratory animals for research purposes.

Restrictive model of compensated carbon tetrachloride-induced cirrhosis in rats

AIM: To develop a simplified and quick protocol to induce cirrhosis and standardize models of partial liver resection in rats.

METHODS: In Fischer F344 rats two modified protocols of phenobarbital-carbon tetrachloride (CCl₄) (dilution 50%) gavage to induce cirrhosis (frequency adjusted according to weight, but each subsequent dose was systematically administered) were tested, i.e. the rapid and slow protocols. Prothrombin time (PT) and total bilirubin (TB) were also evaluated. Animals from the rapid group underwent 15% hepatectomy and animals from the slow group underwent 70% hepatectomy.

RESULTS: Rapid protocol: This corresponded to 1 gavage/4 d over 6 wk (mortality 30%). Mean PT was 35.2 ± 2.8 s (normal: 14.5 s), and mean TB was 1.8 ± 0.2 mg/dL (normal: 0.1 mg/dL). Slow protocol: This corresponded to 1 gavage/6 d over 9 wk (mortality 10%). Mean PT was 11.8 ± 0.2 s (normal: 14.5 s), and mean TB was 0.4 ± 0.04 mg/dL (normal: 0.1 mg/dL). Pathological analyses were performed in both protocols which showed persistent cirrhosis at 3 mo. Rat mortality in the rapid gavage group who underwent 15% hepatectomy and in the slow gavage group who underwent 70% hepatectomy was 50% and 70%, respectively.

CONCLUSION: Our modified model is a simplified method to induce cirrhosis which is rapid (6 to 9 wk), efficient and stable up to 3 mo. Using this method, “Child Pugh A” or “Child Pugh BC” cirrhotic rats were obtained. Our models of cirrhosis and hepatectomy can be used in various situations focusing on postoperative survival.

Early changes of the portal tract on microcomputed tomography images in a newly-developed rat model for Budd-Chiari syndrome

BACKGROUND AND AIM

The effect of increased sinusoidal pressure on the portal tract in Budd-Chiari syndrome (BCS) is as yet not elucidated. Our aim was to investigate portal changes in a newly-developed rat model for BCS.

METHODS

We created an outflow obstruction in Sprague-Dawley rats (n = 6) by diameter reduction of the inferior vena cava. Left and right liver lobes with portal vein contrast were scanned using microcomputed tomography, and volumes of the portal tree and liver parenchyma were computed by the ANALYZE software program.

RESULTS

Portal branching density was significantly lower in BCS than the shams, and decreased over time (P < 0.01). There was a significant drop in volume of both parenchyma and the portal tree in the left but not right lobes. At 6 weeks post-surgery, the perfusion index (i.e. ratio between both volumes) became equal to (left) or even higher than (right) the shams, suggesting a new equilibrium with preserved portal perfusion. Histological findings were consistent with those observed in humans.

CONCLUSION

As early as day 2, a significant loss of peripheral portal branches was seen, which progressed over time. Inter-lobar differences in vascular abnormalities suggest compensatory mechanisms. Despite a decrease in both liver and portal vein volume, relative portal perfusion appeared spared.

Animal models of portal hypertension

Animal models have allowed detailed study of hemodynamic alterations typical of portal hypertension and the molecular mechanisms involved in abnormalities in splanchnic and systemic circulation associated with this syndrome. Models of prehepatic portal hypertension can be used to study alterations in the splanchnic circulation and the pathophysiology of the hyperdynamic circulation. Models of cirrhosis allow study of the alterations in intrahepatic microcirculation that lead to increased resistance to portal flow. This review summarizes the currently available literature on animal models of portal hypertension and analyzes their relative utility. The criteria for choosing a particular model, depending on the specific objectives of the study, are also discussed.

Functional abnormalities of the motor tract in the rat after portocaval anastomosis and after carbon tetrachloride induction of cirrhosis

INTRODUCTION

Hepatic encephalopathy is a neurologic syndrome secondary to liver failure that causes cognitive and motor abnormalities. Impairment in the function of the first neuron of the motor tract (corticospinal tract) has been demonstrated in patients with cirrhosis and minimal hepatic encephalopathy.

AIM

Investigate the function of the first neuron of the motor tract in experimental models of minimal hepatic encephalopathy.

MATERIAL AND METHODS

Rats with portocaval anastomosis (n = 8) and rats with carbon tetrachloride induced cirrhosis (n = 11) underwent neurophysiological recording under light anesthesia with propofol. Motor evoked potentials were elicited applying a transcranial electric pulse and were recorded in the tibialis anterior muscle. The effect of the dose of anesthesia was assessed in a group of normal rats (n = 10).

RESULTS

Rats with portocaval anastomosis exhibited a decrease in motor evoked potentials amplitude following surgery (67 +/- 11 to 41 +/- 16%, P < 0.001). Cirrhotic rats exhibited an increase in motor evoked potentials latency after the appearance of ascites (4.65 +/- 0.43 to 5.15 +/- 0.67 ms., P = 0.04). Increasing doses of propofol produced a decrease in the amplitude and an increase in the latency of motor evoked potentials.

CONCLUSION

It is possible to reproduce functional abnormalities of the central motor tract in rats with portocaval anastomosis and carbon tetrachloride induced cirrhosis. The development of motor abnormalities in experimental models of minimal hepatic encephalopathy offers the possibility to investigate the mechanisms involved in the pathogenesis of hepatic encephalopathy and test therapeutic strategies.

Animal models of portal hypertension

Animal models have allowed detailed study of hemodynamic alterations typical of portal hypertension and the molecular mechanisms involved in abnormalities in splanchnic and systemic circulation associated with this syndrome. Models of prehepatic portal hypertension can be used to study alterations in the splanchnic circulation and the pathophysiology of the hyperdynamic circulation. Models of cirrhosis allow study of the alterations in intrahepatic microcirculation that lead to increased resistance to portal flow. This review summarizes the currently available literature on animal models of portal hypertension and analyzes their relative utility. The criteria for choosing a particular model, depending on the specific objectives of the study, are also discussed.

Brain edema and inflammatory activation in bile duct ligated rats with diet-induced hyperammonemia: A model of hepatic encephalopathy in cirrhosis

Studies of the pathogenesis of hepatic encephalopathy are hampered by the lack of a satisfactory animal model. We examined the neurological features of rats after bile duct ligation fed a hyperammonemic diet (BDL+HD). Six groups were studied: sham, sham pair-fed, hyperammonemic, bile duct ligation (BDL), BDL pair fed, and BDL+HD. The BDL+HD rats were made hyperammonemic via an ammonia-containing diet that began 2 weeks after operation. One week later, the animals were sacrificed. BDL+HD rats displayed an increased level of cerebral ammonia and neuroanatomical characteristics of hepatic encephalopathy (HE), including the presence of type II Alzheimer astrocytes. Both BDL and BDL+HD rats showed activation of the inflammatory system. BDL+HD rats showed an increased amount of brain glutamine, a decreased amount of brain myo-inositol, and a significant increase in the level of brain water. In coordination tests, BDL+HD rats showed severe impairment of motor activity and performance as opposed to BDL rats, whose results seemed only mildly affected. In conclusion, the BDL+HD rats displayed similar neuroanatomical and neurochemical characteristics to human HE in liver cirrhosis. Brain edema and inflammatory activation can be detected under these circumstances.

Changes in liver and plasma acetylcholinesterase in rats with cirrhosis induced by bile duct ligation

Classical studies of cholinesterase activity during liver dysfunction have focused on butyrylcholinesterase (BuChE), whereas acetylcholinesterase (AChE) has not received much attention. In the current study, liver and plasma AChE levels were investigated in rats with cirrhosis induced after 3 weeks of bile duct ligation (BDL). BDL rats showed a pronounced decrease in liver AChE levels (approximately 50%) compared with sham-operated (non-ligated, NL) controls; whereas liver BuChE appeared unaffected. A selective loss of tetrameric (G4) AChE was detected in BDL rats, an effect also observed in rats with carbon tetrachloride-induced cirrhosis. In accordance, SDS-PAGE analysis showed that the major 55-kd immunoreactive AChE band was decreased in BDL as compared with NL. A 65-kd band, attributed in part to inactive AChE, was increased as became the most abundant AChE subunit in BDL liver. The overall decrease in AChE activity in BDL liver was not accompanied by a reduction of AChE transcripts. The loss of G4 was also reflected by changes observed in AChE glycosylation pattern attributable to different liver AChE forms being differentially glycosylated. BDL affects AChE levels in both hepatocytes and Kupffer cells; however, altered AChE expression was mainly reflected in an alteration in hepatocyte AChE pattern. Plasma from BDL rats had approximately 45% lower AChE activity than controls, displaying decreased G4 levels and altered lectin-binding patterns. In conclusion, the liver is an important source of serum AChE; altered AChE levels may be a useful biomarker for liver cirrhosis.

Modelos animales en el estudio de la hipertensión portal

Animal models allow detailed study of the hemodynamic alterations in portal hypertension syndrome and of the molecular mechanisms involved in the abnormalities in splenic and systemic circulation associated with this syndrome. Models of prehepatic portal hypertension can be used to study alterations in the splenic circulation and the physiopathology of hyperdynamic circulation. Moreover, models of cirrhosis allow the alterations in intrahepatic microcirculation that lead to increased resistance to portal flow to be studied. The present review summarizes currently available animal models of portal hypertension and analyzes their relative utility in investigating the distinct disorders associated with this entity. The criteria for the choice of a particular model, depending on the specific objectives of the study, are also discussed.

Animal models in the study of episodic hepatic encephalopathy in cirrhosis

The availability of an animal model is crucial in studying the pathophysiological mechanisms of disease and to test possible therapies. Now, there are several models for the study of liver diseases, but there still remains a lack of a satisfactory animal model of chronic liver disease with hepatic encephalopathy (HE) and abnormalities in nitrogen metabolism, as seen in humans. In rats, two models of chronic HE are widely used: rats after portacaval anastomosis (PCA) and rats with chronic hyperammonemia. The first one mimics the situation induced in cirrhosis by collateral circulation, and has the problem of the absence of hepatocellular injury. The model of hyperammonemia is useful to study the effect of ammonia as a brain toxic substance, but also lacks liver failure. Bile-duct ligation has been used to induce cirrhosis and could also be a model of HE, probably with the addition of a precipitant factor. An ideal model of HE in chronic liver disease must have liver cirrhosis and a precipitant factor of HE; it must also show neuropathological characteristic findings of HE, neurochemical alterations in the main pathways impaired in these complications of cirrhosis, and low-grade brain edema.

Bile duct ligation plus hyperammonemia in rats reproduces the alterations in the modulation of soluble guanylate cyclase by nitric oxide in brain of cirrhotic patients

Modulation of soluble guanylate cyclase (sGC) by nitric oxide (NO) is altered in brain from cirrhotic patients. The aim of this work was to assess whether an animal model of cirrhosis, bile duct ligation, alone or combined with diet-induced hyperammonemia for 7-10 days reproduces the alterations in NO modulation of sGC found in brains from cirrhotic patients. sGC activity was measured under basal conditions and in the presence of NO in cerebellum and cerebral cortex of the following groups of rats: controls, bile duct ligation without or with hyperammonemia and hyperammonemia without bile duct ligation. In cerebellum activation of sGC by NO was significantly lower in bile duct ligated rats with (12 +/- five-fold) or without (14 +/- six-fold) hyperammonemia than in control rats (23 +/- seven-fold). In cerebral cortex activation of sGC by NO was higher in rats with bile duct ligation with hyperammonemia (124 +/- 30-fold) but not without hyperammonemia (59 +/- 15-fold) than in control rats (66 +/- 11-fold). The combination of bile duct ligation and hyperammonemia reproduces the alterations in the modulation of soluble guanylate cyclase by NO found in cerebral cortex and cerebellum of cirrhotic patients while bile duct ligation or hyperammonemia alone reproduces the effects in cerebellum but not in cerebral cortex.

Evaluation of two experimental models of hepatic encephalopathy in rats

The serious neuropsychological repercussions of hepatic encephalopathy have led to the creation of several experimental models in order to better understand the pathogenesis of the disease. In the present investigation, two possible causes of hepatic encephalopathy, cholestasis and portal hypertension, were chosen to study the behavioral impairments caused by the disease using an object recognition task. This working memory test is based on a paradigm of spontaneous delayed non-matching to sample and was performed 60 days after surgery. Male Wistar rats (225-250 g) were divided into three groups: two experimental groups, microsurgical cholestasis (N = 20) and extrahepatic portal hypertension (N = 20), and a control group (N = 20). A mild alteration of the recognition memory occurred in rats with cholestasis compared to control rats and portal hypertensive rats. The latter group showed the poorest performance on the basis of the behavioral indexes tested. In particular, only the control group spent significantly more time exploring novel objects compared to familiar ones (P < 0.001). In addition, the portal hypertension group spent the shortest time exploring both the novel and familiar objects (P < 0.001). These results suggest that the existence of portosystemic collateral circulation per se may be responsible for subclinical encephalopathy.

Effect of insulin-like growth factor-I on nitrogen balance and intestinal galactose transport in rats with moderate liver cirrhosis

The malnutrition caused by liver cirrhosis (LC) often worsens the course of the disease. Patients affected by LC often have a low bioavailability of the anabolic liver peptide insulin-like growth factor (IGF)-I. The present study was undertaken to investigate the effect of low doses of IGF-I on the nutritional status and in vivo jejunal transport of D-galactose in anatomically, pathologically and biochemically confirmed moderate, non-ascitic, cirrhotic rats. LC was experimentally induced in growing rats by inhalation of CCl4 and addition of phenobarbital to drinking water. Both the nutritional status, as evaluated by N balance, and in vivo intestinal transport of D-galactose, were significantly impaired in cirrhotic rats. As compared with healthy rats, administration of 20 microg human recombinant IGF-I/kg body weight for 14 d to cirrhotic rats significantly improved N balance variables and restored in vivo intestinal transport of the sugar. However, IGF-I had no effect on the steatorrhoea associated with LC. These results suggest that low doses of IGF-I may have beneficial effects on the malnutrition associated with moderate LC.

Comparison between two warm ischemic models in experimental liver transplantation in pigs

BACKGROUND

Experimental models of warm ischemia in liver transplantation have been employed to study the mechanisms and treatment of ischemia reperfusion injury.

METHODS

We compared a control group without (group A, n = 10) versus two models of warm ischemia of liver transplants in pigs: namely, occlusion of the hepatic artery and portal vein for 30 minutes (group B, n = 23) and extraction of the liver 60 minutes after cardiac arrest (group C, n = 5). Liver function tests, coagulation studies, and liver biopsies were performed during the first 24 hours post-liver transplant.

RESULTS

Clamping of the hepatic vasculature in group B produced a significant liver injury compared with the control group: elevation of the ALT and an abnormal 1-hour post-revascularization biopsy similar to that observed in the cardiac arrest group C. The transaminase levels were lower among group A animals (P <.05). But the hepatic synthetic functions as reflected in the protrombin time (PT) were not affected in group B versus group A. The alteration in PT with respect to the initial value was similar among group A and group B animals, which were significantly less than that in group C (P <.05).

CONCLUSIONS

Occlusion of the hepatic artery and portal vein, a simple surgical maneuver, causes moderate damage to a liver graft but less alteration of hepatic synthetic function. Clamping of the hepatic vasculture obtains more long-term survivors after OLT than cardiac arrest.

Preclinical models of hepatic encephalopathy

Hepatic encephalopathy is a multifactorial neuropsychiatric syndrome accompanying acute or chronic liver failure. Techniques for developing animal models of hepatic encephalopathy associated with acute or chronic liver failure, or vascular shunting are illustrated. In addition, the behavioral and biochemical characteristics of these models are described.

Combination treatment of hepatic encephalopathy due to thioacetamide-induced fulminant hepatic failure in the rat with benzodiazepine and opioid receptor antagonists

BACKGROUND/AIMS

Treatment of hepatic encephalopathy with drugs acting on the target organ of this syndrome, the brain, is unsatisfactory. Combination treatment with different neurotransmitter receptor antagonists may be a rational option to optimize treatment.

METHODS

The effects of various doses of the benzodiazepine receptor antagonist Ro 15-3505 and the opioid receptor antagonist naloxone, alone or in combination, were tested on hepatic encephalopathy in rats with thioacetamide-induced hepatic failure in an open-field activity meter. Comparison of single and combination treatment was also done using a neurological test battery. In addition, we compared survival of treatment-responder rats with treatment non-responders.

RESULTS

Naloxone dose dependently increased ambulatory activity and improved neurological score. Ro 15-3505 also improved ambulatory activity and neurological score; however, the improvement was less evident at higher doses. Combination treatment was not superior to single treatment. Survival was increased in treatment-responder rats.

CONCLUSIONS

The failure of combination treatment with Ro 15-3505 and naloxone to further improve hepatic encephalopathy may suggest that the two neurotransmitter systems are interrelated or that hepatic encephalopathy may not be further improved by drugs acting on the brain.

Effects of a branched-chain amino acid-enriched diet on chronic hepatic encephalopathy in dogs

A decreased ratio of branched-chain amino acids (BCAA) to aromatic amino acids (AAA) is considered an important pathogenetic factor in hepatic encephalopathy (HE). A relationship between the deranged BCAA/AAA ratio and dopaminergic dysfunction through the formation of "false" neurotransmitters has been postulated. The intermediate lobe of the pituitary is more pronounced in dogs than in humans and because it is primarily under dopaminergic inhibitory influence, it may serve as an indicator of alterations in dopaminergic neurotransmission. We investigated the effects of a diet with a high BCAA/AAA ratio (HR) and an isonitrogenous diet with a low BCAA/AAA ratio (LR) on several physical and biochemical parameters including pituitary function in dogs with portocaval shunts and 40% hepatectomy and in sham-operated pair-fed controls, in a double-blind, randomized cross-over study. Portocaval-shunted dogs had hyperammonemia (33+/-3 microM (mean +/- SEM) before and 214+/-21 after surgery)) and signs of HE. Their BCAA/AAA ratio in plasma and CSF decreased from 4.3+/-0.3 and 2.3+/-0.3 before surgery to 1.3+/-0.1 and 0.5+/-0.1 after surgery, respectively. These parameters remained unaltered in the control dogs. The consumption of the LR diet was significantly higher than consumption of the HR diet. In the portocaval-shunted dogs, plasma ammonia concentration was higher on the HR diet than on the LR diet (344+/-52 v 246+/-45) and the HE grade was worse. The BCAA/AAA ratio remained abnormal in HE dogs during the feeding of both diets. The basal and haloperidol-stimulated release of alpha-melanotropin and cortisol in plasma were not significantly different between or within groups during any period. In contrast, urinary cortisol excretion was increased in the HE dogs after surgery (urinary cortisol:creatinine ratio (x10(-6)) 8.5+/-1.4 before and 30.4+/-8.9 after surgery). The basal plasma concentration of adrenocorticotropin in HE dogs was decreased after surgery (68.3+/-10.2 ng/L before and 40.8+/-4.4 after surgery). This indicates a non-pituitary-dependent hyperresponsiveness of the adrenals. We conclude from these results that chronic HE in dogs is not associated with an abnormal dopaminergic neurotransmission at least at the level of the pituitary, and that it is not the content of the dietary neutral amino acids but rather the total protein intake that may have a beneficial effect on HE.

Endotoxins enhance hepatocarcinogenesis induced by oral intake of thioacetamide in rats

AIM:To clarify whether endotoxin is of pathogenic importance for hepatocarcinogenesis,or the increased cancer risk results solely from the cirrhotic process.METHODS:The rat model of hepatoma was treated by the intake of 0.03% thioacetamide in drinking water for six months. During induction of hepatoma, rats were additionally treated with splenectomy and/or lipopolysaccharide administration.The liver nuclear DNA index and proliferation index were quantitatively analyzed by flow cytometry. Hepatic histology was examined with light and electron microscopes. Plasmic endotoxin concentration and gamma-glutamyl transpeptidase activity were measured, and hepatoma incidence was recorded.RESULTS: Thioacetamide induced cirrhosis and hepatoma in Wistar rats with histology or regenerative nodule, fibrosis and neoplastic foci were quite similar to the pathogenic process of human cirrhosis leading to hepatoma. In comparison with TAA controls (DNA index: 1.15 plus minus 0.21), exo-endotoxin increased the DNA index by 7.8% (1.24 plus minus0.25, P < 0.02) and hepatoma rate by 16.7. Splenectomy-induced enteric endotoxemia increased the DNA index by 25% (1.44plus minus0.15, P < 0.01) and hepatoma rate by 33%. A summation of the effects of these two factors increased the DNA index by 36% (P < 0.01)and hepatoma incidence by 50%, moreover, the level of endotoxemia showed a close relation with DNA index (r = 0.96, P < 0.01), as well as with the occurrence rate of hepatoma (r = 0.00, P < 0.01). Histological findings further verified such alterations.CONCLUSION:Lipopolysaccharide administration and/or splenectomy-induced enterogenic endotoxemia may enhance rat hepatocarcinogenesis induced by oral intake of thioacetamide.

High prevalence of sleep disturbance in cirrhosis

Sleep disturbance is a classic sign of hepatic encephalopathy. However, there are limited data regarding its prevalence in cirrhotic patients without overt hepatic encephalopathy. We assessed the characteristics of sleep in cirrhosis using a sleep questionnaire (n = 44) and actigraphy (n = 20). The results were compared with those of subjects with chronic renal failure and those of healthy controls. Presence of subclinical hepatic encephalopathy, chronotypology profile, and individual's affective state were also analyzed. The questionnaire indicated an elevated number of cirrhotic patients (47.7%) and patients with chronic renal failure (38.6%) who complained of unsatisfactory sleep compared with healthy controls (4.5%, P < .01). Actigraphy corroborated the deterioration of sleep parameters in cirrhotic patients with unsatisfactory sleep. The sleep disturbance in cirrhosis was not associated with clinical parameters nor with cognitive impairment. Cirrhotic subjects and patients with chronic renal failure with unsatisfactory sleep showed higher scores for depression and anxiety, raising the possibility that the effects of chronic disease may underlie the pathogenesis of sleep disturbance. However, in contrast to chronic renal failure, unsatisfactory sleep in cirrhosis was associated with delayed bedtime, delayed wake-up time, and evening chronotypology. In conclusion, a sleep disturbance is frequent in cirrhotic patients without hepatic encephalopathy and may be related to abnormalities of the circadian timekeeping system.

Stenosis of a portacaval anastomosis affects circadian locomotor activity in the rat: a multivariable analysis

The study of hepatic encephalopathy is limited by the lack of standardized experimental models to assess behavior. We have shown that rats continuously monitored while running on a wheel show abnormalities of the circadian rhythm of locomotor activity after portacaval anastomosis (PCA), such that entrainment of running activity to the light-dark cycle is severely impaired. To identify factors that affect postoperative circadian behavior, we have performed a multivariable analysis of 69 sham-operated controls and 107 rats after PCA. Our results indicate that shunt stenosis, as determined by the pressure gradient from the splenic pulp to the inferior vena cava, ameliorated the postoperative deterioration of the circadian rhythm. In addition, postoperative behavior was affected by preoperative performance, diet, and gender. Postoperative body weight gain, spleen weight, and liver atrophy did not impact this model. Because shunt stenosis is known to ameliorate hepatic encephalopathy in humans, our findings support the validity of this behavioral end point as a correlate of hepatic encephalopathy. Measurement of the pressure gradient across the anastomosis and achievement of sufficient preoperative entrainment appear critical for the standardization of the model.

Portal systemic encephalopathy

The goal of this article is to update the status of Portal systemic encephalopathy (PSE) in the light of new data. First, PSE is the context of other types of hepatic encephalopathy. Subsequently, current views of the pathogenesis of the disorder are discussed, followed by an analysis of therapeutic options. Diagnosis will not be considered, as no major new developments have recently been documented in this area.

Gender and diurnal effects on specific open-field behavioral patterns in the portacaval shunted rat

Hepatic encephalopathy (HE) is a frequently observed neuropsychiatric syndrome with unknown pathogenesis in patients suffering from chronic liver failure. The portacaval shunted (PCS) rat has been extensively used as an experimental model for HE and for studying the effects of portal-systemic shunting. Previous behavioral studies on PCS rats have shown a number of abnormalities but there is no consensus about which abnormalities are characteristic. We therefore made a thorough descriptive study of 100 male and female PCS rats and sham-operated controls four to six weeks after the shunting procedure in an open field. The frequency, duration and average time sequence of various kinds of defined spontaneous behavioral patterns were investigated during both night and day in order to assess behavioral differences between PCS rats and sham-operated controls. The results indicate differences especially regarding motor exploratory behaviors such as forward locomotion and rearing. There were also differences in eating and sniffing behaviors. Our results show that the overall behavioral alteration seen in PCS rats compared to sham-operated controls is that of hypoactivity.

Glutamine, myo-inositol, and organic brain osmolytes after portocaval anastomosis in the rat: implications for ammonia-induced brain edema

Brain myo-inositol, an organic osmolyte, is decreased in cirrhotic patients with hepatic encephalopathy but appears unchanged in fulminant hepatic failure. An osmoregulatory response to the increase in brain glutamine may explain the decrease in brain myo-inositol; if this is the case, organic osmolytes may account for differences in the development of brain edema seen in acute or chronic liver failure. The response of myo-inositol and nine other organic osmolytes to the increase in brain glutamine at different time intervals after portacaval anastomosis (PCA) in the rat was studied. Organic osmolytes were measured in brain tissue and cerebrospinal fluid. Water in cerebral cortex was measured after ammonia infusion with the gravimetric method. Six weeks after PCA, despite an increase in brain glutamine (PCA, 16.4 +/- 2 mmol.kg wt-1.kg wt-1; sham, 5 +/- 1 mmol.L-1.kg wt-1), the content of total organic osmolytes did not increase (PCA, 44.1 +/- 3; sham, 43 +/- 4) because of a decrease of other osmolytes (myo-inositol, 54%; urea, 39%; taurine, 33%; and glutamate, 8%). Brain myo-inositol was lower at 3 weeks (3.4 +/- 0.5 kg wt-1) than at 1 day after PCA (4.7 +/- 0.5 kg wt-1). An ammonia infusion resulted in brain edema at both time points. In conclusion, the reduction in brain myo-inositol in PCA rats is accompanied by the decrease of other organic osmolytes, supporting the view that changes in myo-inositol reflect an osmoregulatory response. The decrease in brain myo-inositol is more marked as time elapses after PCA. In a model in which short-term and large doses of ammonia were infused, the decrease in brain myo-inositol did not prevent the development of brain swelling. Understanding brain osmoregulatory mechanisms may provide new insights into hepatic encephalopathy and brain edema in fulminant hepatic failure.

Glutamine metabolism and neuropathological disorders in experimental hepatic encephalopathy: effect of transplanted hepatocytes

BACKGROUND

Physiopathology of hepatic encephalopathy remains unclear. Recent studies have suggested that ammonia would not act by itself but through an increase in glutamine in the brain. We have previously demonstrated that transplantation of syngeneic hepatocytes into the spleen was able to correct both behavioral deficits and plasma amino acid changes observed in portacaval shunted rats. The aim of the present work was to show a correlation between the correction of chronic hepatic encephalopathy by means of intrasplenic hepatocyte transplantation and two parameters, brain glutamine concentration and ultrastructural aspects of astrocytes.

METHODS

Inbred male Wistar Furth rats were divided into three groups: sham-operated rats (n = 10), rats subjected to portacaval shunt (n = 10), and rats subjected to portacaval shunt and intrasplenic hepatocellular transplantation of 10(7) hepatocytes isolated from livers of syngeneic rats (n = 10). Chronic hepatic encephalopathy was quantified 30 and 60 days after operation by means of nose-poke exploration and spontaneous activity. Pathologic examination and measurement of glutamine concentrations in the corpus striatus and in the cerebral cortex were performed 60 days after operation.

RESULTS

Portacaval shunt rats showed reduced spontaneous activity and nose-poke exploration scores. After portacaval shunt a significant glutamine increase occurred in the corpus striatus and in the cerebral cortex when compared with sham rats (p < 0.05). Ultrastructural examination showed modification of astrocytes named Alzheimer type II after portacaval shunt. Correction of behavioral abnormalities by means of intrasplenic hepatocyte transplantation was associated with partial correction of striatal glutamine increase and with decrease in astrocyte alterations. Cortex glutamine concentration in portacaval shunt-intrasplenic hepatocyte transplantation group and in portacaval shunt rats did not differ significantly.

CONCLUSIONS

These data show that intrasplenic hepatocyte transplantation not only prevents neurologic disorders of hepatic encephalopathy but can also decrease glutamine and ultrastructural alterations in the corpus striatus in an experimental model of chronic liver failure. These data are in favor of the involvement of glutamine in chronic hepatic encephalopathy. These results suggest that intrasplenic hepatocyte transplantation might be of therapeutic interest in chronic liver failure.

Influence of dietary nucleotides on liver structural recovery and hepatocyte binuclearity in cirrhosis induced by thioacetamide

Intake of thioacetamide in drinking water causes liver cirrhosis in rats, which exhibit many changes similar to human disease. Nucleotides play an important part in major cellular functions, and recent studies suggest that dietary nucleotides may be considered 'semi-essential' nutrients in situations when an inadequate dietary supply may affect the growth of tissues with a rapid turnover rate. The aim of this study was to assess the effect of dietary nucleotides on lesions in thioacetamide-cirrhotic rats, and to calculate the proportion of mono and binucleated hepatocytes in different experimental groups. Rats were given cirrhosis by oral intake of thioacetamide in the drinking water (300 mg/l) for four months. One group was treated with a standard nucleotide free diet, and another group was treated with the same diet supplemented with 250 mg of nucleotides per 100 g of diet for one and two weeks. A striking reduction (mean (SEM)) in the proportion of binucleated cells was seen in thioacetamide-cirrhotic rats (4.8 (1.3) v 21.4 (1.0)), showing a change in the mitotic mechanism in focal lesions. Cirrhotic rats that consumed a semipurified diet supplemented with nucleotides during two weeks showed considerable histological regeneration of the injured liver. These animals had significantly higher proportion of binucleated cells than did animals at the beginning of the recovery period (8.2 (1.2) v 4.8 (1.3)). In the second week of recovery, both types of diet (F = 5.54, p < 0.05) and the previous administration of thioacetamide (F = 142.82, p < 0.001) had significant effects on the percentage of binucleated hepatocytes.

Muscle ammonia and glutamine exchange during chronic liver insufficiency in the rat

The aim of this study was to investigate the role of skeletal muscle in ammonia and glutamine metabolism during chronic hyperammonemia induced by liver insufficiency. The hindquarter ammonia and amino acid fluxes and muscle tissue concentrations were studied in two rat models of chronic liver insufficiency, portacaval shunting and portacaval shunting plus bile-duct ligation, as well as in sham-operated animals, 7 and 14 days after surgery, and in normal, unoperated rats. To reduce nutritional influences, portacaval-shunted rats and sham-operated rats were pair-fed to portacaval shunt biliary obstruction rats. Arterial ammonia levels were elevated in both liver insufficiency groups. In the portacaval shunting plus bile-duct ligation group, arterial glutamine levels were elevated compared with sham-operated controls. No net hind-quarter ammonia uptake was observed in any of the groups, despite hyperammonemia in the chronic liver insufficiency groups. Hindquarter glutamine release was always increased in the liver insufficiency groups compared with sham-operated controls, despite similar muscle glutamine levels in the sham-operated and hyperammonemic groups, suggesting enhanced muscle glutamine synthesis in the latter groups. Muscle ammonia levels were always increased and muscle glutamate decreased in the hyperammonemic groups, probably indicating glutamate consumption by enhanced glutamine synthesis. The increased phenylalanine tissue concentrations and efflux in portacaval shunt/biliary obstruction rats suggest that enhanced net muscle protein breakdown, amino acid catabolism and transamination, rather than ammonia uptake from the blood furnish amino acids and ammonia for enhanced glutamine synthesis. These experiments suggest that nutritional factors are important in explaining altered muscle metabolism during chronic liver insufficiency.

Animal models of hepatic encephalopathy and hyperammonemia

Animal models of chronic liver disease with hyperammonemia are currently available to investigators. Two in particular have been utilized extensively. Carbon tetrachloride induced (CCl4) cirrhosis in the rat and portacaval shunt in the same species and other animals particularly the dog. In regards to hepatic encephalopathy, however, the CCl4 cirrhosis rat model seems to display few behavioral changes unless very advanced decompensated cirrhosis is produced. Further work should be done on this model to verify the development of encephalopathy and to improve reproducibility. The portacaval shunt rat on the other hand clearly has a consistent albeit subtle set of behavioral changes. Recent improvements in detecting these changes and more importantly showing reversal or improvement by neomycin or a low protein diet are a major advance. Hopefully, more laboratories will be able to reproduce this reversible change in behavior. Experiences gained from 7 years of using the portacaval shunt rat and other models of liver disease are described.

Renal ammonia and glutamine metabolism during liver insufficiency-induced hyperammonemia in the rat

Renal glutamine uptake and subsequent urinary ammonia excretion could be an important alternative pathway of ammonia disposal from the body during liver failure (diminished urea synthesis), but this pathway has received little attention. Therefore, we investigated renal glutamine and ammonia metabolism in midly hyperammonemic, portacaval shunted rats and severely hyperammonemic rats with acute liver ischemia compared to their respective controls, to investigate whether renal ammonia disposal from the body is enhanced during hyperammonemia and to explore the limits of the pathway. Renal fluxes, urinary excretion, and renal tissue concentrations of amino acids and ammonia were measured 24 h after portacaval shunting, and 2, 4, and 6 h after liver ischemia induction and in the appropriate controls. Arterial ammonia increased to 247 +/- 22 microM after portacaval shunting compared to controls (51 +/- 8 microM) (P < 0.001) and increased to 934 +/- 54 microM during liver ischemia (P < 0.001). Arterial glutamine increased to 697 +/- 93 microM after portacaval shunting compared to controls (513 +/- 40 microM) (P < 0.01) and further increased to 3781 +/- 248 microM during liver ischemia (P < 0.001). In contrast to controls, in portacaval shunted rats the kidney net disposed ammonia from the body by diminishing renal venous ammonia release (from 267 +/- 33 to -49 +/- 59 nmol/100 g body wt per min) and enhancing urinary ammonia excretion from 113 +/- 24 to 305 +/- 52 nmol/100 g body wt per min (both P < 0.01). Renal glutamine uptake diminished in portacaval shunted rats compared to controls (-107 +/- 33 vs. -322 +/- 41 nmol/100 g body wt per min) (P < 0.01). However, during liver ischemia, net renal ammonia disposal from the body did not further increase (294 +/- 88 vs. 144 +/- 101 nmol/100 g body wt per min during portacaval shunting versus liver ischemia). Renal glutamine uptake was comparable in both hyperammonemic models. These results indicate that the rat kidney plays an important role in ammonia disposal during mild hyperammonemia. However, during severe liver insufficiency induced-hyperammonemia, ammonia disposal capacity appears to be exceeded.

Changes in expression of the albumin, fibronectin and type I procollagen genes in CCl4-induced liver fibrosis: effect of pyridoxol L,2-pyrrolidon-5 carboxylate

The protective activity of pyridoxol L,2-pyrrolidon-5 carboxylate (metadoxine) was investigated in a rat model of carbon tetrachloride (CCL4)-induced hepatic fibrosis. After 6 weeks of CCl4 treatment, the animals developed fibrosis and inflammation of the liver while those treated with CCl4 + metadoxine had less severe lesions (P < 0.05). Since in liver fibroplasia there are quantitative changes of the extracellular matrix components and almost invariably a decrease in albumin synthesis, we have also investigated by Northern blot analysis the expression of the cellular fibronectin, pro-alpha 2(I)collagen and albumin genes. There were striking increases in fibronectin and pro-alpha 2(I)collagen mRNA contents in the livers of CCL4-treated animals and these enhancements were less evident in the metadoxine-treated rats. In contrast, albumin mRNA levels, almost identical in control and metadoxine-treated rats, were lower in the CCl4-treated animals. These data suggest that metadoxine might slow the development of CCl4-mediated liver fibrosis.

Alterations in mitochondrial function and morphology in chronic liver disease: pathogenesis and potential for therapeutic intervention

Studies assessing mitochondrial function and structure in livers from humans or experimental animals with chronic liver disease, including liver cirrhosis, revealed a variety of alterations in comparison with normal subjects or control animals. Depending on the etiology of chronic liver disease, the function of the electron transport chain and/or ATP synthesis was found to be impaired, leading to decreased oxidative metabolism of various substrates and to impaired recovery of the hepatic energy state after a metabolic insult. Changes in mitochondrial structure include megamitochondria with reduced cristae, dilatation of mitochondrial cristae and crystalloid inclusions in the mitochondrial matrix. The most important strategies to maintain an adequate mitochondrial function per liver are mitochondrial proliferation and increases in the activity of critical enzymes or in the content of cofactors per mitochondrion. Possibilities to assess hepatic mitochondrial function and to treat mitochondrial dysfunction in patients with chronic liver disease are discussed.

Metabolic adaptation of the kidney to hyperammonemia during chronic liver insufficiency in the rat

The aim of this study was to evaluate the role of renal ammonia and glutamine metabolism in the metabolic adaptation to chronic liver insufficiency-induced hyperammonemia in the rat. To this purpose, urinary excretion, renal net exchange and tissue concentrations of ammonia and amino acids were measured in anesthetized, normal control rats that did not undergo surgery, in control rats that underwent sham surgery, in rats that underwent portacaval shunting and in rats that underwent both portacaval shunting and bile duct ligation. Rats that underwent sham surgery and portacaval shunting were pair-fed with rats that underwent portacaval shunting and biliary obstruction, to correct for anorexia in that group, and all rats that were operated on were studied 7 and 14 days after surgery. Arterial ammonia and glutamine levels were elevated in groups that underwent portacaval shunting and portacaval shunting plus biliary obstruction at all time points. At days 7 and 14, total renal ammonia production decreased in rats that underwent portacaval shunting and in rats that underwent portacaval shunting plus biliary obstruction, associated with a 50% decrease in net renal glutamine uptake and strongly diminished net ammonia release into the renal vein, which was most prominent in the group that underwent portacaval shunting plus biliary obstruction. Urinary ammonia excretion was similar in rats that underwent portacaval shunting and in those that underwent sham surgery but was increased more than 200% at days 7 and 14 in rats that underwent portacaval shunting plus biliary obstruction. In this group, in contrast to portacaval-shunted rats, the kidney appeared to be an organ of net ammonia disposal from the body. In separate experiments in unanesthetized, unrestrained rats, similar changes in urinary ammonia excretion were observed without changes in arterial pH, excluding an effect of anesthesia or pH on the obtained results. These results indicate that the kidney plays an important role in the metabolic adaptation to hyperammonemia during chronic liver insufficiency in the rat.

Cerebral cortex ammonia and glutamine metabolism in two rat models of chronic liver insufficiency-induced hyperammonemia: influence of pair-feeding

Enhanced cerebral cortex ammonia uptake, subsequent glutamine synthesis, and glutamine release into the bloodstream have been hypothesized to deplete cerebral cortex glutamate pools. We investigated this hypothesis in rats with chronic liver insufficiency-induced hyperammonemia and in pair-fed controls to rule out effects of differences in food intake. Cerebral cortex plasma flow and venous-arterial concentration differences of ammonia and amino acids, as well as cerebral cortex tissue concentrations, were studied 7 and 14 days after surgery in portacaval-shunted/bile duct-ligated, portacaval-shunted, and sham-operated rats, while the latter two were pair-fed to the first group, and in normal unoperated ad libitum-fed control rats. At both time points, arterial ammonia was elevated in the chronic liver insufficiency groups and arterial glutamine was elevated in portacaval shunt/biliary obstruction rats compared to the other groups. In the chronic liver insufficiency groups net cerebral cortex ammonia uptake was observed at both time points and was accompanied by net glutamine release. Also in these groups, cerebral cortex tissue glutamine, many other amino acid, and ammonia levels were elevated. Tissue glutamate levels were decreased to a similar level in all operated groups compared with normal unoperated rats, irrespective of plasma and tissue ammonia and glutamine levels. These results demonstrate that during chronic liver insufficiency-induced hyperammonemia, the rat cerebral cortex enhances net ammonia uptake and glutamine release. However, the decrease in tissue glutamate concentrations in these chronic liver insufficiency models seems to be related primarily to nutritional status and/or surgical trauma.

Do benzodiazepine ligands contribute to hepatic encephalopathy?

1. Levels of BZ receptor ligands are elevated in the brain of animal models of FHF and humans with FHF. Some of these ligands have agonist properties and some are known 1, 4-BZs which bind to the DS receptor. Much of the BZ receptor ligand activity in HE is unidentified and it is possible that some may bind to receptor subtypes other than the DS receptor. 2. Average levels of BZ receptor ligands in the brain in HE do not appear to be sufficient to augment GABAergic tone to a degree that would result in severe encephalopathy (i.e. coma). However, these ligands have a heterogeneous distribution in the brain and their neuroinhibitory effects may be potentiated by increased availability of GABA at GABAA receptors. Furthermore, that these ligands may contribute to HE is suggested by anecdotal reports of ameliorations of HE being induced in a majority of patients by the BZ receptor antagonist flumazenil. 3. The response of HE to flumazenil in humans is usually incomplete and in animal models may be modest. Potential explanations for these findings include pharmacokinetics, BZ receptor subtype specificity and higher levels of BZ receptor ligands in the brain in humans with HE than in animal models. 4. Certain BZ receptor ligands e.g. Ro 15-3505 and Ro 15-4513, that are structurally related to flumazenil, are more efficacious at ameliorating HE than flumazenil in animal models. These findings may be more dependent on differences in BZ receptor subtype specificity than differences in intrinsic activity. The properties of an ideal BZ receptor ligand for administration to a patient with HE would appear to be: (i) antagonist action at BZ receptors, (ii) no intrinsic activity apparent after a conventional pharmacologic dose, (iii) high specificity and affinity for BZ receptors, (iv) slow metabolism, and (v) absence of toxic effects. Promising ligands, such as Ro 15-3505, with weak partial inverse agonist actions and hence analeptic potential, require careful evaluation of their therapeutic index before clinical application. 5. BZ receptor ligands may be useful in the management of HE. Specifically, they may be given IV: (i) to reverse effects of exogenous BZs; (ii) to aid in the differential diagnosis of encephalopathy; (iii) to provide prognostic information; and (iv) to optimize brain function. They may also be given orally with the objective of reducing dietary protein intolerance in patients with chronic liver disease.

Portal-systemic shunting and the disruption of circadian locomotor activity in the rat

To determine if the extent of portal-systemic shunting (PSS) influences the disruption of circadian function in chronic liver disease, locomotor activity was examined in two rat models with varying degrees of PSS, i.e., portal vein ligation (PVL) and end-to-side portacaval anastomosis (PCA). Animals were housed in individual activity cages under conditions of 12 hour light/12 hour darkness (weeks 0-3), then under conditions of constant dim light (weeks 4-7). Cages were equipped with running wheels connected to a continuous recorder, and daily tracings of running activity were recorded for 7 weeks. Computer analysis of wheel revolutions per hour with a chi 2 periodogram was used to calculate Qp, a measure of the amplitude of a circadian rhythm. The degree of PSS was measured by means of radioactive microspheres injected into the ileocolic vein and spleen. PVL rats were found to have PSS from the splenic and mesenteric territories of 88% and 27%, respectively; circadian periodicity was maintained in all PVL rats. PCA rats had complete shunting (greater than 99%) and showed a range of disrupted circadian rhythms from blunting of the amplitude to complete absence of the locomotor activity rhythm. This spectrum of disorganization occurred in spite of similar degrees of liver atrophy and weight gain. Whereas PCA in rats markedly disturbs the circadian rhythm of locomotor activity, animals with considerably less PSS from PVL exhibit normal behavior. The extent of PSS could be a variable affecting the expression of circadian rhythms in liver disease.

Metabolic and hemodynamic responses of bivascularly perfused rat liver to nerve stimulation, noradrenaline, acetylcholine and glucagon in thioacetamide-induced micronodular cirrhosis

Thioacetamide-induced rat cirrhosis was characterized by single-cell necroses, fibrosis, nodular parenchyma, decrease in parenchymal volume density and an increase in liver weight per body weight so that the total amount of parenchyma was not altered. The glycogen content was normal, and signs of decompensation were not found. Isolated livers were single-pass perfused by way of both the hepatic artery and the portal vein. In the normal livers stimulation of the nerve plexuses around the hepatic artery or portal vein (7.5 Hz; 2 msec) and infusions of noradrenaline (1 mumol/L) by way of either vessel and of acetylcholine (10 mumol/L) by way of the artery only increased glucose output, reduced both portal and arterial flow and increased the intravascular pressures. Glucagon (0.5 nmol/L) augmented glucose release and had no hemodynamic effects. In chronically thioacetamide-injured livers all stimuli caused smaller metabolic alterations per gram of liver weight and decreased portal flow more and arterial flow less with stronger enhancements of intravascular pressures than in the controls. The lowered metabolic responsiveness per gram of cirrhotic liver was largely compensated by the increase in liver weight. Thus despite massive histological alterations and pronounced increases in stimulation-dependent resistances - predominantly in the portal system - cirrhotic rat livers responded in their glucose metabolism to nervous and hormonal stimuli in almost the same manner as normal livers.

Intrasplenic hepatocellular transplantation corrects hepatic encephalopathy in portacaval-shunted rats

The aim of this work was to evaluate the effect of intrasplenic hepatocellular transplantation on hepatic encephalopathy in an experimental model of chronic liver failure induced by end-to-side portacaval shunt in the rat. Inbred male Wistar Furth rats were divided into three groups: rats subjected to portacaval shunt (n = 10), rats subjected to portacaval shunt and intrasplenic hepatocellular transplantation of 10(7) hepatocytes isolated from livers of syngeneic rats (n = 10) and sham-operated rats (n = 10). Behavior tests were performed in a blind fashion at 3 wk, at 2 mo and at 3 mo after surgery. Spontaneous activity and nose-poke exploration by individual rats were studied in automated open field boxes equipped with infrared cells. Each cell beam interruption was automatically recorded on a microcomputer and transformed into a score index (counts/hour). Plasma levels of amino acids, ammonia and total biliary acids were measured. Portacaval shunt rats showed reduced spontaneous activity and nose-poke exploration scores. Intrasplenic hepatocellular transplantation significantly increased spontaneous activity after 2 mo and improved nose-poke exploration after 3 wk. At 3 mo, spontaneous activity and nose-poke exploration in portacaval shunt/intrasplenic hepatocellular transplantation rats were not significantly different from those of sham rats. Increases in plasma ammonia levels after portacaval shunt were not corrected. Amino acid imbalance and bile acid concentration in plasma were partially corrected by intrasplenic hepatocellular transplantation. These data show that intrasplenic hepatocellular transplantation can correct the neurological symptoms of hepatic encephalopathy in an experimental model of chronic liver failure and suggest that intrasplenic hepatocellular transplantation might be of therapeutic interest in chronic liver failure.

Fuel homeostasis and carnitine metabolism in rats with secondary biliary cirrhosis

Energy metabolism is abnormal in patients and experimental animals with liver cirrhosis. To help better understand the abnormalities, fuel homeostasis and carnitine metabolism were studied in fed and 24-hr-starved rats with secondary biliary cirrhosis induced by bile duct ligation for 4 wk. Plasma ketone body concentrations were decreased by 67% in starved, bile duct-ligated rats compared with control rats. In contrast, plasma nonesterified fatty acid concentrations were not different between bile duct-ligated and control rats in the fed or the fasted state. Plasma triglyceride concentrations showed the expected decrease with starvation in control rats, but were increased with starvation in bile duct-ligated rats. Urinary excretion of dicarboxylic acids was increased in both fed and fasted bile duct ligated-rats compared with the respective control groups. Compared with control rats, hepatic total carnitine content (per gram of liver) was increased by 24% in fed and by 36% in fasted, bile duct-ligated rats. Fed, bile duct-ligated rats had an increased short-chain acylcarnitine-to-carnitine ratio in liver, plasma and urine compared with control rats. Analysis of the hepatic coenzyme A pool showed decreased coenzyme A content in fed and fasted bile duct-ligated rats compared with control rats. Hepatic long-chain acylcarnitine and long-chain acyl-coenzyme A content increased with starvation both in control and bile duct-ligated rats. The rise in plasma nonesterified fatty acid concentration and hepatic long-chain acylcarnitine and long-chain acylcoenzyme A contents with starvation in bile duct-ligated rats are consistent with unaltered hepatic availability of fatty acids.(ABSTRACT TRUNCATED AT 250 WORDS)

The influence of portacaval anastomosis on gonadal and anterior pituitary hormones in a rat model standardized for gender, food intake, and time after surgery

Portacaval anastomosis causes delayed growth, decreased testes and liver weights, and elevated estradiol serum levels in male rats compared with sham-operated controls. Female rats treated with portacaval anastomosis grow at a normal rate despite changes in liver weight and estradiol levels similar to those observed in the male rats. This study examined the pituitary gonadal axis in both genders in this animal model. The rats receiving portacaval anastomosis were compared with both pair-fed and sham-operated control groups. Portacaval anastomosis decreased serum testosterone and increased estradiol in the male animals, while both testosterone and estradiol were increased in the females compared with gender-matched pair-fed and sham controls. Because pair feeding lowers male testosterone to a lesser extent, impaired nutrition may partially account for the decrease in the males treated with portacaval anastomosis. The ratio of estradiol to testosterone increased following anastomosis in male rats, but it was decreased in similarly treated females. Portacaval and anastomosis decreased luteinizing hormone without changing follicle-stimulating hormone in both male and female rats compared with sham-operated controls. Growth hormone was significantly decreased in male portacaval-treated rats compared with sham- and pair-fed animals. Increased insulin levels were found in both male and female pair-fed and portacaval anastomosis-treated animals. These data suggest that following portacaval anastomosis in rats, growth, serum testosterone, estradiol to testosterone ratios, and growth hormone are altered in a gender-specific manner with gender-independent changes in insulin and luteinizing hormone levels. These gender-specific effects may protect the portacaval anastomosis-treated female rat from growth retardation.

The effect of portal-systemic shunting on hepatic sex hormone receptors in male rats

Signs of feminization are seen in men with cirrhosis of alcoholic but also of nonalcoholic origin even in the absence of markedly increased plasma estrogen levels. Recently identified alterations of hepatic sex hormone receptor levels have provided a hypothetical mechanism for the pathogenesis of the feminization seen in cirrhotic men. The aim of the present study was to determine the effect of experimental portal-systemic shunting in adult male rats on hepatic sex hormone receptor levels, plasma sex hormones, and two markers for sex hormone action in the liver. The following alterations were found in male rats with surgically created portacaval shunts compared with sham-operated controls: the hepatic content of cytosolic estrogen receptors was reduced by 35% and the cytosolic androgen receptors content by 59%; plasma levels of estradiol increased 6.7-fold while those of testosterone were reduced by 71%; the estrogen-responsive ceruloplasmin levels were decreased by 31% and the androgen-responsive male-specific estrogen binder by 72%. Based on these data, it can be concluded that portal-systemic shunting reduces the hepatic cytoplasmic content of several sex hormone related proteins. These changes are paralleled by a decreased estrogen responsiveness of the liver, as evidenced by the plasma ceruloplasmin level.

Evidence for modulation of hepatic mass by estrogens and hepatic "feminization"

Animals with end-to-side portacaval shunts and sham-operated animals, wherein the body weight and liver weight of the animals varied spontaneously over a considerable range, were studied. The relationships between hepatic androgen- and estrogen-receptor content, serum testosterone and estradiol levels and hepatic mass were characterized. Animals with portacaval shunts were smaller than those without shunts. Moreover, they had reduced serum levels of testosterone and estradiol. The reduction in serum testosterone was greater than that of estradiol. As a result, the calculated estrogen/testosterone ratio of the two groups of animals was greater for the portacaval shunt animals than for the controls. The dissociation constant values for the androgen receptor and estrogen receptor in the liver did not differ between groups. The activity of the androgen receptor (p less than 0.01) and estrogen receptor (p less than 0.05) was reduced markedly in the animals with portacaval shunts compared with controls. Moreover, the hepatic cytosolic estrogen receptor activity--but not that of the androgen receptor--correlated with the measured hepatic mass in both groups of animals. These data suggest that hepatic feminization is either associated with or is a hepatic regenerative signal in the rat.

Increased brain uptake of gamma-aminobutyric acid in a rabbit model of hepatic encephalopathy

Transfer of the inhibitory neurotransmitter gamma-aminobutyric acid across the normal blood-brain barrier is minimal. One prerequisite for gamma-aminobutyric acid in plasma contributing to the neural inhibition of hepatic encephalopathy would be that increased transfer of gamma-aminobutyric acid across the blood-brain barrier occurs in liver failure. The aim of the present study was to determine if brain gamma-aminobutyric acid uptake is increased in rabbits with stage II-III (precoma) hepatic encephalopathy due to galactosamine-induced fulminant hepatic failure. A modification of the Oldendorf intracarotid artery-injection technique was applied. [3H] gamma-aminobutyric acid, [14C] butanol, and 113mIn-labeled serum protein (transferrin) were injected simultaneously 4 s before decapitation. The ipsilateral brain uptake index of gamma-aminobutyric acid was determined from measurements of the 3 isotopes in 5 brain regions. Uncorrected or simple brain uptake indices of [3H] gamma-aminobutyric acid and [113mIn] transferrin were calculated using [14C] butanol as the highly extracted reference compound. The [113mIn] transferrin data were also used to "correct" the brain uptake index of [3H] gamma-aminobutyric acid for intravascular retention of [3H] gamma-aminobutyric acid. The methodology adopted minimized problems attributable to rapid [3H] gamma-aminobutyric acid metabolism, and slow brain washout and recirculation of the radiolabeled tracers. Both the uncorrected and corrected brain uptake indices of gamma-aminobutyric acid as well as the simple brain uptake index of transferrin were significantly increased in both stage II and III hepatic encephalopathy in all brain regions studied. Moreover, these brain uptake indices were significantly greater in stage III hepatic encephalopathy than in stage II hepatic encephalopathy. These findings indicate that transfer of gamma-aminobutyric acid from plasma to brain extracellular fluid is increased in the model of hepatic encephalopathy studied; hence, they provide support for the hypothesis that plasma-derived gamma-aminobutyric acid may contribute to the neural inhibition of hepatic encephalopathy due to fulminant hepatic failure.