L-carnitine alleviates alcohol-induced liver damage in rats: role of tumour necrosis factor-alpha

Acetyl-L-carnitine attenuates chronic ethanol-induced oxidative stress, ER stress and apoptosis in rat gastric tissue

Consuming alcohol affects almost all organs. Acetaldehyde, formed as the main product as a result of alcohol metabolism, causes the production of free superoxide radicals when oxidized, and accordingly oxidative and apoptotic processes are triggered. There are studies showing that carnitine has effects on oxidative and apoptotic processes that occur in various conditions. However, the mechanisms showing the effects of L-carnitine on these effects of alcohol have not been fully elucidated. In our study, the effects of acetyl-L-carnitine administration on the molecular mechanisms of oxidative stress, endoplasmic reticulum stress, and apoptotic parameters in gastric tissue of rats chronically exposed to alcohol were investigated. Hematoxylin-eosin staining was used for histopathological studies. Endoplasmic reticulum stress markers were detected with immunohistochemical staining and western blotting. Apoptotic index was evaluated by terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) assay. Total oxidant and antioxidant status were examined by ELISA. Our results showed that chronic alcohol administration caused a significant increase in TOS levels, an indicator of oxidative stress, the levels of ER-stress-associated proteins XBP1, GRP78, and CHOP, and % apoptotic index values in rat gastric tissues. Additionally, it was determined that acetyl-L-carnitine administration caused an improvement in those values. Based on our data, we can conclude that acetyl-L-carnitine has a tissue protective effect by scavenging free oxygen radicals and reducing ER stress-related proteins XBP1, GRP78, and CHOP and apoptosis in chronic ethanol-administered rats, and that this natural antioxidant may be beneficial in the treatment of oxidative stress-induced diseases.

Liver Lipidomics Analysis Revealed the Novel Ameliorative Mechanisms of L-Carnitine on High-Fat Diet-Induced NAFLD Mice

The beneficial effects of L-carnitine on non-alcoholic fatty liver disease (NAFLD) were revealed in previous reports. However, the underlying mechanisms remain unclear. In this study, we established a high fat diet (HFD)-induced NAFLD mice model and systematically explored the effects and mechanisms of dietary L-carnitine supplementation (0.2% to 4%) on NAFLD. A lipidomics approach was conducted to identify specific lipid species involved in the ameliorative roles of L-carnitine in NAFLD. Compared with a normal control group, the body weight, liver weight, concentrations of TG in the liver and serum AST and ALT levels were dramatically increased by HFD feeding (p < 0.05), accompanied with obvious liver damage and the activation of the hepatic TLR4/NF-κB/NLRP3 inflammatory pathway. L-carnitine treatment significantly improved these phenomena and exhibited a clear dose–response relationship. The results of a liver lipidomics analysis showed that a total of 12 classes and 145 lipid species were identified in the livers. Serious disorders in lipid profiles were noticed in the livers of the HFD-fed mice, such as an increased relative abundance of TG and a decreased relative abundance of PC, PE, PI, LPC, LPE, Cer and SM (p < 0.05). The relative contents of PC and PI were significantly increased and that of DG were decreased after the 4% L-carnitine intervention (p < 0.05). Moreover, we identified 47 important differential lipid species that notably separated the experimental groups based on VIP ≥ 1 and p < 0.05. The results of a pathway analysis showed that L-carnitine inhibited the glycerolipid metabolism pathway and activated the pathways of alpha-linolenic acid metabolism, glycerophospholipid metabolism, sphingolipid metabolism and Glycosylphosphatidylinositol (GPI)-anchor biosynthesis. This study provides novel insights into the mechanisms of L-carnitine in attenuating NAFLD.

Effect of l-carnitine supplementation on lead acetate-induced liver cell apoptosis and inflammation: role of caspase-3 and glycogen synthase kinase-3β enzymes

AIM

The study aimed at studying the hepatoprotective effect of l-carnitine against lead (Pb) acetate-induced hepatocellular injury, emphasizing the role of caspase-3 and glycogen synthase kinase-3β in hepatocellular apoptosis and inflammation.

MATERIALS AND METHODS

Male Wistar rats were used. The experimental approach involved estimation of the liver enzymes' serum levels. Oxidative and inflammatory biomarkers were measured in hepatic tissue homogenates. Paraffin-embedded hepatic sections were prepared for histopathology and immunohistochemistry. Quantitative determination of the phosphorylated glycogen synthase kinase-3 beta was performed.

KEY FINDINGS

The serum showed a significant elevation in ALT, AST, and LDH; tissue homogenates showed significant elevation in lipid peroxide and inflammatory biomarkers with significant reduction in reduced glutathione in the Pb acetate-treated group. Co-administration of l-carnitine with Pb acetate produced significant reduction in liver enzymes with significant improvement in oxidant, antioxidant and inflammatory markers. Lead acetate treatment significantly reduced the phosphorylated glycogen synthase kinase-3 beta, while l-carnitine enhanced its phosphorylation. Histopathological examination showed inflammatory reaction around blood vessels with fatty degeneration in hepatocytes of the Pb acetate intoxicated group. l-Carnitine caused a decrease in hepatic damage with minimal vascular alterations in central vein. Caspase-3 expression in hepatocytes was decreased in Pb-treated group supplemented with l-carnitine.

SIGNIFICANCE

Our study reveals that oxidative stress and inflammation participate in Pb acetate-induced hepatocellular injury. Glycogen synthase kinase-3β and caspase-3 play role in Pb acetate-induced hepatic damage. l-Carnitine shows significant protective effects against hepatocellular apoptosis and inflammation induced by Pb acetate through antioxidant, anti-inflammatory and anti-apoptotic pathways in part mediated by GSK-3β inhibition.

Carnitine in Alcohol Use Disorders: A Scoping Review

Recent studies in alcohol use disorders (AUDs) have demonstrated some connections between carnitine metabolism and the pathophysiology of the disease. In this scoping review, we aimed to collate and examine existing research available on carnitine metabolism and AUDs and develop hypotheses surrounding the role carnitine may play in AUD. A scoping review method was used to search electronic databases in September 2019. The database search terms used included "alcohol, alcoholism, alcohol abuse, alcohol consumption, alcohol drinking patterns, alcohol-induced disorders, alcoholic intoxication, alcohol-related disorders, binge drinking, Wernicke encephalopathy, acylcarnitine, acetyl-l-carnitine, acetylcarnitine, carnitine and palmitoylcarnitine." The inclusion criteria included English language, human-based, AUD diagnosis and measured blood or tissue carnitine or used carnitine as a treatment. Of 586 studies that were identified and screened, 65 underwent abstract review, and 41 were fully reviewed. Eighteen studies were ultimately included for analysis. Data were summarized in an electronic data extraction form. We found that there is limited literature available. Alcohol use appears to impact carnitine metabolism, most clearly in the setting of alcoholic cirrhosis. Six studies found carnitine to be increased in AUD, of which 5 were conducted in patients with alcoholic cirrhosis. Only 3 placebo-controlled trials were identified and provide some support for the use of carnitine in AUD to decrease cravings, anhedonia, and withdrawal and improve cognition. The increase in plasma carnitine in alcoholic cirrhosis may be related to disordered fatty acid metabolism and oxidative stress that occurs in AUD. The multiple possible therapeutic effects carnitine could have on ethanol metabolism and the early evidence available for carnitine supplementation as a treatment for AUD provide a foundation for future randomized control trials of carnitine for treating AUD.

Combined effects of moderate exercise and short-term fasting on markers of immune function in healthy human subjects

This study aimed to investigate the effects of a short-term (36 h) fasting period combined with an acute bout of exercise on markers of immune function and inflammation in healthy human subjects. Fourteen moderately trained male subjects (aged 19-39 yr) participated in a 36-h fasting trial (FA-T), followed by an acute bout of moderate exercise (60% V̇o_2max). After 1 wk, the same subjects, as their own control, participated in a nonfasting trial (NFA-T) in which they performed an exercise trial of the same duration and intensity. Blood samples were taken before, immediately after, and 1 h after each exercise bout and analyzed for several immunological and metabolic markers. At baseline, fasting subjects showed lower levels of T cell apoptosis, lymphocyte-proliferative responses, IL-6, monocyte chemoattractant protein-1 (MCP-1), insulin, and leptin (P < 0.05) as well as higher levels of neutrophil oxidative burst and thiobarbituric acid reactive substances (TBARS) than those in the NFA-T (P < 0.05). After the exercise protocol, fasted subjects revealed higher T cell apoptosis, neutrophil oxidative burst, TBARS, TNFα, and MCP-1 levels as well as lower levels of lymphocyte-proliferative response, IL-6, insulin, and leptin than those in the NFA-T (P < 0.05). Short-term fasting aggravates perturbations in markers of immune function, and inflammation was induced by an acute moderate-intensity exercise protocol.

Relation of plasma carnitine and aminotransferases to alcohol dose and time of dependence

BACKGROUND

Serum aspartate, alanine aminotransferases (AST, ALT), and plasma carnitine are all indirect biomarkers of alcohol abuse. Carnitine transfers long-chain fatty acids from cytoplasm to mitochondria for β-oxidation. The aim of the study was to determine the relationship between daily alcohol intake, time of alcohol dependence, plasma carnitine, and serum aminotransferases.

PATIENTS

We studied 26 men who were addicted for 2-30 years, consuming ethanol from 75 to 700 g/day (alcoholic group), as well as 17 healthy men (control group).

RESULTS

In alcoholics, compared to the controls, we found: a significant increase in serum: AST (p = 0.0014), ALT (p = 0.0071), AST/ALT ratio (p < 0.000); significantly lower plasma free carnitine (FC) (p = 0.0316) and total carnitine (TC) (p = 0.0349); and a significant negative correlation between FC (r = -0.6200; R² = 0.3844; p = 0.0007), TC (r = -0.4365; R² = 0.1905; p = 0.0258), and time of alcohol dependence, suggesting carnitine as an indirect marker of alcohol abuse. We did not find any significant correlation between FC, TC, and levels of alcohol or aminotransferase activity.

CONCLUSION

In the alcoholic group, there was an increase in serum activity of AST, ALT, and AST/ALT ratio that confirms liver injury. In addition, we found low plasma FC and TC, which may indicate damage to mitochondrial β-oxidation caused by alcohol metabolites. The significantly higher plasma FC and TC in patients consuming the most, compared to patients consuming smaller doses of alcohol, may be caused by a lower carnitine demand of injured liver cells, decreased urinary carnitine excretion by impaired renal tubules, and leakage of carnitine into the blood from damaged muscles by the higher quantities of alcohol. The negative correlation between carnitine concentration and time of alcohol dependence may suggest the potential use of carnitine for treatment of alcohol abuse.

Effect of ethanol on lipid metabolism

Hepatic lipid metabolism is a series of complex processes that control influx and efflux of not only hepatic lipid pools, but also organismal pools. Lipid homeostasis is usually tightly controlled by expression, substrate supply, oxidation and secretion that keep hepatic lipid pools relatively constant. However, perturbations of any of these processes can lead to lipid accumulation in the liver. Although it is thought that these responses are hepatic arms of the 'thrifty genome', they are maladaptive in the context of chronic fatty liver diseases. Ethanol is likely unique among toxins, in that it perturbs almost all aspects of hepatic lipid metabolism. This complex response is due in part to the large metabolic demand placed on the organ by alcohol metabolism, but also appears to involve more nuanced changes in expression and substrate supply. The net effect is that steatosis is a rapid response to alcohol abuse. Although transient steatosis is largely an inert pathology, the chronicity of alcohol-related liver disease seems to require steatosis. Better and more specific understanding of the mechanisms by which alcohol causes steatosis may therefore translate into targeted therapies to treat alcohol-related liver disease and/or prevent its progression.

Early-Phase Alcoholic Liver Disease: An Update on Animal Models, Pathology, and Pathogenesis

Alcoholic liver disease (ALD) remains to be one of the most common etiology of liver disease and is a major cause of morbidity and mortality worldwide. The pathologic stages of ALD comprises of steatosis, steatohepatitis, and fibrosis/cirrhosis. Steatosis and steatohepatitis represents the early phase of ALD and are precursor stages for fibrosis/cirrhosis. Numerous research efforts have been directed at recognizing cofactors interacting with alcohol in the pathogenesis of steatosis and steatohepatitis. This review will elucidate the constellation of complex pathogenesis, available animal models, and microscopic pathologic findings mostly in the early-phase of ALD. The role of endotoxin, reactive oxygen species, alcohol metabolism, and cytokines are discussed. Understanding the mechanisms of early-phase ALD should provide insight into the development of therapeutic strategies and thereby decrease the morbidity and mortality associated with ALD.

l-carnitine protects human hepatocytes from oxidative stress-induced toxicity through Akt-mediated activation of Nrf2 signaling pathway

In our previous study, l-carnitine was shown to have cytoprotective effect against hydrogen peroxide (H2O2)-induced injury in human normal HL7702 hepatocytes. The aim of this study was to investigate whether the protective effect of l-carnitine was associated with the nuclear factor erythroid 2 (NFE2)-related factor 2 (Nrf2) pathway. Our results showed that pretreatment with l-carnitine augmented Nrf2 nuclear translocation, DNA binding activity and heme oxygenase-1 (HO-1) expression in H2O2-treated HL7702 cells, although l-carnitine treatment alone had no effect on them. Analysis using Nrf2 siRNA demonstrated that Nrf2 activation was involved in l-carnitine-induced HO-1 expression. In addition, l-carnitine-mediated protection against H2O2 toxicity was abrogated by Nrf2 siRNA, indicating the important role of Nrf2 in l-carnitine-induced cytoprotection. Further experiments revealed that l-carnitine pretreatment enhanced the phosphorylation of Akt in H2O2-treated cells. Blocking Akt pathway with inhibitor partly abrogated the protective effect of l-carnitine. Moreover, our finding demonstrated that the induction of Nrf2 translocation and HO-1 expression by l-carnitine directly correlated with the Akt pathway because Akt inhibitor showed inhibitory effects on the Nrf2 translocation and HO-1 expression. Altogether, these results demonstrate that l-carnitine protects HL7702 cells against H2O2-induced cell damage through Akt-mediated activation of Nrf2 signaling pathway.

Alterations in Hepatic FGF21, Co-Regulated Genes, and Upstream Metabolic Genes in Response to Nutrition, Ketosis and Inflammation in Peripartal Holstein Cows

In rodents, fibroblast growth factor 21 (FGF21) has emerged as a key metabolic regulator produced by liver. To gather preliminary data on the potential importance of FGF1, co-regulated genes, and upstream metabolic genes, we examined the hepatic mRNA expression in response to nutrition and inflammation in dairy cows. In experiment 1, induction of ketosis through feed restriction on d 5 postpartum upregulated FGF21, its co-receptor KLB, and PPARA but only elicited a numerical increase in serum FGF21 concentration. In experiment 2, cows in control (CON) or receiving 50 g/d of L-carnitine (C50) from -14 through 21 d had increased FGF21, PPARA, and NFIL3 on d 10 compared with d 2 postpartum. In contrast, compared with CON and C50, 100 g/d L-carnitine (C100) resulted in lower FGF21, KLB, ANGPTL4, and ARNTL expression on d 10. In experiment 3, cows were fed during the dry period either a higher-energy (OVE; 1.62 Mcal/kg DM) or lower-energy (CON; 1.34 Mcal/kg DM) diet and received 0 (OVE:N, CON:N) or 200 μg of LPS (OVE:Y, CON:Y) into the mammary gland at d 7 postpartum. For FGF21 mRNA expression in CON, the LPS challenge (CON:Y) prevented a decrease in expression between d 7 and 14 postpartum such that cows in CON:N had a 4-fold lower expression on d 14 compared with d 7. The inflammatory stimulus induced by LPS in CON:Y resulted in upregulation of PPARA on d 14 to a similar level as cows in OVE:N. In OVE:Y, expression of PPARA was lower than CON:N on d 7 and remained unchanged on d 14. On d 7, LPS led to a 4-fold greater serum FGF21 only in OVE but not in CON cows. In fact, OVE:Y reached the same serum FGF21 concentration as CON:N, suggesting a carryover effect of dietary energy level on signaling mechanisms within liver. Overall, results indicate that nutrition, ketosis, and inflammation during the peripartal period can alter hepatic FGF21, co-regulated genes, and upstream metabolic genes to various extents. The functional outcome of these changes merits further study, and in particular the mechanisms regulating transcription in response to changes in energy balance and feed intake.

Efficacy and safety of entecavir plus carnitine complex (GODEX®) compared to entecavir monotherapy in patient with ALT elevated chronic hepatitis B: randomized, multicenter open-label trials. The GOAL study

Background/Aims

Carnitine and vitamin complex (Godex®) is widely used in patients with chronic liver disease who show elevated liver enzyme in South Korea. The purpose of this study is to identify the efficacy and safety of carnitine from entecavir combination therapy in Alanine aminotransferase (ALT) elevated Chronic Hepatitis B (CHB) patients.

Methods

130 treatment-naïve patients with CHB were enrolled from 13 sites. The patients were randomly selected to the entecavir and the complex of entecavir and carnitine. The primary endpoint of the study is ALT normalization level after 12 months.

Results

Among the 130 patients, 119 patients completed the study treatment. The ALT normalization at 3 months was 58.9% for the monotherapy and 95.2% for the combination therapy (P<0.0001). ALT normalization rate at 12 months was 85.7% for the monotherapy and 100% for the combination group (P=0.0019). The rate of less than HBV DNA 300 copies/mL at 12 months was not statistically significant (P=0.5318) 75.9% for the monotherapy, 70.7% for the combination and it was. Quantification of HBsAg level was not different from the monotherapy to combination at 12 months. Changes of ELISPOT value to evaluate the INF-γ secretion by HBsAg showed the increasing trend of combination therapy compare to mono-treatment.

Conclusions

ALT normalization rate was higher in carnitine complex combination group than entecavir group in CHB. Combination group was faster than entecavir mono-treatment group on ALT normalization rate. HBV DNA normalization rate and the serum HBV-DNA level were not changed by carnitine complex treatment.

Pharmacological evaluation of a β-hydroxyphosphonate analogue of l-carnitine in obese Zucker fa/fa rats

In this study, we evaluated the effect of an analogue of l-carnitine on parameters involved with Metabolic Syndrome in obese Zucker rats. Twenty-four rats were treated for 5 weeks with l-carnitine (300 mg/kg) and its analogue at two concentrations (100 and 250 mg/kg) to assess their impact on glucose, triglycerides and cholesterol in liver and blood samples, as well as the amount of liver glycogen. Liver slices were also analysed. The analogue reduced the levels of glucose, triglycerides and cholesterol in liver and the level of triglycerides in serum. At 100 mg/kg, the analogue proved more effective than l-carnitine in improving the biochemical alterations present in liver. The amount of liver glycogen content was higher in obese animals treated with both l-carnitine and the analogue. No changes on insulin and leptin were observed in animals treated. l-carnitine and its analogue reduced the microvesicular fatty infiltration in liver. This study demonstrated that the analogue tested is more potent and efficient than l-carnitine and improves the pharmacological profile of l-carnitine.

Effects of Puerariae Radix Extract on Endotoxin Receptors and TNF-α Expression Induced by Gut-Derived Endotoxin in Chronic Alcoholic Liver Injury

Kudzu (Pueraria lobata) is one of the earliest medicinal plants used to treat alcohol abuse in traditional Chinese medicine for more than a millennium. However, little is known about its effects on chronic alcoholic liver injury. Therefore, the present study observed the effects of puerariae radix extract (RPE) on chronic alcoholic liver injury as well as Kupffer cells (KCs) activation to release tumor necrosis factor alpha (TNF-α) induced by gut-derived endotoxin in rats and macrophage cell line. RPE was observed to alleviate the pathological changes and lipids deposition in liver tissues as well as the serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), and hepatic gamma-glutamyl transpeptidase (GGT) activity. Meanwhile, RPE inhibited KCs activation and subsequent hepatic TNF-α expression and downregulated the protein expression of endotoxin receptors, lipopolysaccharide binding protein (LBP), CD14, Toll-like receptor (TLR) 2, and TLR4 in chronic alcohol intake rats. Furthermore, an in vitro study showed that RPE inhibited the expression of TNF-α and endotoxin receptors, CD14 and TLR4, induced by LPS in RAW264.7 cells. In summary, this study demonstrated that RPE mitigated liver damage and lipid deposition induced by chronic alcohol intake in rats, as well as TNF-α release, protein expression of endotoxin receptors in vivo or in vitro.

Effects of L-carnitine against oxidative stress in human hepatocytes: involvement of peroxisome proliferator-activated receptor alpha

BACKGROUND

Excessive oxidative stress and lipid peroxidation have been demonstrated to play important roles in the production of liver damage. L-carnitine is a natural substance and acts as a carrier for fatty acids across the inner mitochondrial membrane for subsequent beta-oxidation. It is also an antioxidant that reduces metabolic stress in the cells. Recent years L-carnitine has been proposed for treatment of various kinds of disease, including liver injury. This study was conducted to evaluate the protective effect of L-carnitine against hydrogen peroxide (H2O2)-induced cytotoxicity in a normal human hepatocyte cell line, HL7702.

METHODS

We analyzed cytotoxicity using MTT assay and lactate dehydrogenase (LDH) release. Antioxidant activity and lipid peroxidation were estimated by reactive oxygen species (ROS) levels, activities and protein expressions of superoxide dismutase (SOD) and catalase (CAT), and malondialdehyde (MDA) formation. Expressions of peroxisome proliferator-activated receptor (PPAR)-alpha and its target genes were evaluated by RT-PCR or western blotting. The role of PPAR-alpha in L-carnitine-enhanced expression of SOD and CAT was also explored. Statistical analysis was performed by a one-way analysis of variance, and its significance was assessed by Dennett's post-hoc test.

RESULTS

The results showed that L-carnitine protected HL7702 cells against cytotoxity induced by H2O2. This protection was related to the scavenging of ROS, the promotion of SOD and CAT activity and expression, and the prevention of lipid peroxidation in cultured HL7702 cells. The decreased expressions of PPAR-alpha, carnitine palmitoyl transferase 1 (CPT1) and acyl-CoA oxidase (ACOX) induced by H2O2 can be attenuated by L-carnitine. Besides, we also found that the promotion of SOD and CAT protein expression induced by L-carnitine was blocked by PPAR-alpha inhibitor MK886.

CONCLUSIONS

Taken together, our findings suggest that L-carnitine could protect HL7702 cells against oxidative stress through the antioxidative effect and the regulation of PPAR-alpha also play an important part in the protective effect.

L-Carnitine induces recovery of liver lipid metabolism in cancer cachexia

Cancer cachexia causes metabolic alterations with a marked effect on hepatic lipid metabolism. L-Carnitine modulates lipid metabolism and its supplementation has been proposed as a therapeutic strategy in many diseases. In the present study, the effects of L-carnitine supplementation on gene expression and on liver lipid metabolism-related proteins was investigated in cachectic tumour-bearing rats. Wistar rats were assigned to receive 1 g/kg of L-carnitine or saline. After 14 days, supplemented and control animals were assigned to a control (N), control supplemented with L-carnitine (CN), tumour-bearing Walker 256 carcinosarcoma (TB) and tumour-bearing supplemented with L-carnitine (CTB) group. The mRNA expression of carnitine palmitoyltransferase I and II (CPT I and II), microsomal triglyceride transfer protein (MTP), liver fatty acid-binding protein (L-FABP), fatty acid translocase (FAT/CD36), peroxisome proliferator-activated receptor-alpha (PPAR-alpha) and organic cation transporter 2 (OCTN2) was assessed, and the maximal activity of CPT I and II in the liver measured, along with plasma and liver triacylglycerol content. The gene expression of MTP, and CPT I catalytic activity were reduced in TB, who also showed increased liver (150%) and plasma (3.3-fold) triacylglycerol content. L-Carnitine supplementation was able to restore these parameters back to control values (p<0.05). These data show that L-carnitine preserves hepatic lipid metabolism in tumour-bearing animals, suggesting its supplementation to be of potential interest in cachexia.

The influence of L-carnitine suplementation on the antioxidative abilities of serum and the central nervous system of ethanol-induced rats

The brain is exceptionally susceptible to oxidative stress that may be caused by xenobiotics such as ethanol. Alcohol metabolism is accompanied by enhanced free radical formation and a decrease in antioxidant abilities. However, L-carnitine appears to have antioxidant properties and the ability to regulate ethanol metabolism. The present study was designed to estimate the effect of L-carnitine on the antioxidant capacity of the rat brain and blood serum. For 5 weeks during the study, L-carnitine was given to rats in the amount of 1.5 g/1 l of drinking water, and from the second week the rats were intragastrically treated with ethanol. A significant decrease in the activity of antioxidant enzymes (Cu,Zn-SOD, GSH-Px, GSSG-R and CAT) and in the level of non-enzymatic antioxidants (vitamin C, E, A, GSH and GSH-t) as well as a significant increase in the level of GSSG in the brain and blood serum of ethanol intoxicated rats have been demonstrated. It has also been shown that alcohol caused a significant increase in the level of lipid peroxidation products-lipid hydroperoxides, malondialdehyde and 4-hydroxynonenal-and an increase in dityrosine, as well as a decrease in tryptophan-markers of protein oxidative modifications. The administration of L-carnitine to ethanol intoxicated rats partially normalized the activity of the examined enzymes and the level of the above non-enzymatic antioxidants. Moreover, L-carnitine significantly protects lipids and proteins against oxidative modifications. In conclusion, it has been proved that L-carnitine protects rat brain and blood serum against oxidative stress formation and it is possible that this small molecular amine has a similar beneficial effect on the human CNS.

Neuroprotective strategies in drug abuse-evoked encephalopathy

Encephalopathy is evidenced as an altered mental state with various neurological symptoms, such as memory and cognitive problems. The type of a substance-evoked encephalopathy will depend on the drug, substance, or combination being abused. The categories into which we could place the various abused substances could be tentatively divided into stimulants, amphetamines, hallucinogens, narcotics, inhalants, anesthetics, anabolic steroids, and antipsychotics/antidepressants. Other factors that may underlie encephalopathy, such as infectious agents, environmental, and other factors have also to be taken into account. Drugs of abuse can be highly toxic to the CNS following acute, but more so in chronic exposure, and can produce significant damage to other organs, such as the heart, lungs, liver, and kidneys. The damage to these organs may be at least partially reversible when drug abuse is stopped but CNS damage from repeated or prolonged abuse is often irreversible. The major pathways for the organ and CNS toxicity could be related to ischemic events as well as increased cell damage due to metabolic or mitochondrial dysfunction resulting in increased excitotoxicity, reduced energy production, and lowered antioxidant potential. These susceptibilities could be strengthened by the use of antioxidants to combat free radicals (e.g., vitamin E, lipoic acid); trying to improve energy generation by using mitochondriotropic/metabolic compounds (e.g., thiamine, coenzyme Q10, carnitine, riboflavin); by reducing excitotoxicity (e.g., glutamate antagonists) and other possible strategies, such as robust gene response, need to be investigated further. The drug-abuse-evoked encephalopathy still needs to be studied further to enable better preventative and protective strategies.

Failure of carnitine in improving hepatic nitrogen content in alcoholic and non-alcoholic malnourished rats

AIMS

To investigate the effect of carnitine supplementation on alcoholic malnourished rats' hepatic nitrogen content.

METHODS

Malnourished rats, on 50% protein-calorie restriction with free access to water (malnutrition group) and malnourished rats under the same conditions with free access to a 20% alcohol/water solution (alcohol group) were studied. After the undernourishment period (4 weeks with or without alcohol), both groups were randomly divided into two subgroups, one of them nutritionally recovered for 28 days with free access to a normal diet and water (recovery groups) and the other re-fed with free access to diet and water plus carnitine (0.1 g/g body weight/day by gavage) (carnitine groups). No alcohol intake was allowed during the recovery period.

RESULTS

The results showed: i) no difference between the alcohol/no alcohol groups, with or without carnitine, regarding body weight gain, diet consumption, urinary nitrogen excretion, plasma free fatty acids, lysine, methionine, and glycine. ii) Liver nitrogen content was highest in the carnitine recovery non-alcoholic group (from 1.7 to 3.3 g/100 g, P<0·05) and lowest in alcoholic animals (about 1.5 g/100g). iii) Hepatic fat content (~10 g/100 g, P>·05) was highest in the alcoholic animals.

CONCLUSION

Carnitine supplementation did not induce better nutritional recovery.

Nutrition in heart failure: an update

PURPOSE OF REVIEW

Chronic heart failure (CHF) is increasingly recognized as a multisystem disease with important comorbidities such as anemia, insulin resistance, autonomic dysbalance, or cardiac cachexia.

RECENT FINDINGS

Apart from these perturbations, increasing evidence points to alterations in intestinal morphology, permeability, and absorption function in patients with CHF. This review provides an overview of the sonographic, histological, and functional abnormalities of different gastrointestinal regions. This intestinal dysfunction and disturbed intestinal barrier may lead to both the chronic inflammatory state and catabolic/anabolic imbalance as seen in cardiac cachexia, as a terminal stage of CHF, which carries a particularly poor prognosis. This review highlights the current knowledge of nutritional abnormalities that may occur in CHF, including fat, carbohydrates, proteins, water, and micronutrients. The regulation of feeding is discussed, as are nutritional strategies with potentially anti-inflammatory effects in the treatment of CHF.

SUMMARY

The gut and its role for inflammation and dietary interventions in heart failure patients are a crucial target of further heart failure research.

L-Carnitine in the lipid and protein protection against ethanol-induced oxidative stress

Chronic ethanol intoxication induces oxidative stress participating in the development of many diseases. Nutrition and the interaction of food nutrients with ethanol metabolism may modulate alcohol toxicity. One such compound is l-carnitine (l-3-hydroxy-4-N,N,N-trimethylaminobutyrate), which also reveals antioxidant abilities. The present study has been designed to investigate the effect of l-carnitine as an antioxidant on the serum and liver of rats chronically intoxicated with ethanol. Rats received l-carnitine solution (1.5g/1L) for 5 weeks and/or were treated intragastrically with ethanol for 4 weeks. In the serum and liver, the level of nonenzymatic antioxidants and lipid and protein oxidation markers were determined. It was shown that alcohol caused the increase in the level of lipid peroxidation products-conjugated dienes (by about 70% and 60% in the liver and blood serum, respectively), malondialdehyde (MDA) (by about 60% and 30% in the liver and blood serum, respectively), 4-hydroxynonenal (4-HNE) (by about 35% and 25% in the liver and blood serum, respectively), and changes in the level of protein oxidative markers-increase in dityrosine and decrease in tryptophan (by about 40%) in the serum and liver of rats. Moreover, the decrease in vitamin E level (by about 30%) and the level of glutathione (GSH) (by about 20% in the liver and blood serum) was also observed. Administration of l-carnitine to rats intoxicated with ethanol significantly protects lipids and proteins against oxidative modifications in the serum and liver. The level of conjugated dienes, MDA, and 4-HNE was decreased by about 30%, 30%, and 20% in the liver, respectively, and by about 20%, 10%, and 10% in the blood serum in comparison to the ethanol group. Moreover, the level of tryptophan was increased and dityrosine decreased by about 10% and 20% in the liver, respectively, and by about 30% and 10% in the blood serum in comparison to the ethanol group. l-carnitine partially protects nonenzymatic antioxidants against oxidative stress. The level of vitamin E was increased by about 20% and the level of GSH was increased by about 25% in the liver and blood serum in comparison to the ethanol group. It is possible that beneficial effect of l-carnitine is connected with its abilities to scavenge free radicals and to chelate metal ions.

Nutritional and anti-inflammatory interventions in chronic heart failure

Currently, there are 5 million individuals with chronic heart failure (CHF) in the United States who have poor clinical outcomes, including high death rates. Observational studies have indicated a reverse epidemiology of traditional cardiovascular risk factors in CHF; in contrast to trends seen in the general population, obesity and hypercholesterolemia are associated with improved survival. The temporal discordance between the overnutrition (long-term killer) and undernutrition (short-term killer) not only can explain some of the observed paradoxes but also may indicate that malnutrition, inflammation, and oxidative stress may play a role that results in protein-energy wasting contributing to poor survival in CHF. Diminished appetite or anorexia and nutritional deficiencies may be both a cause and a consequence of this so-called malnutrition-inflammation-cachexia (MIC) or wasting syndrome in CHF. Neurohumoral activation, insulin resistance, cytokine activation, and survival selection-resultant genetic polymorphisms also may contribute to the prominent inflammatory and oxidative characteristics of this population. In patients with CHF and wasting, nutritional strategies including amino acid supplementation may represent a promising therapeutic approach, especially if the provision of additional amino acids, protein, and energy includes nutrients with anti-inflammatory and antioxidant properties. Regardless of the etiology of anorexia, appetite-stimulating agents, especially those with anti-inflammatory properties such as megesterol acetate or pentoxyphylline, may be appropriate adjuncts to dietary supplementation. Understanding the factors that modulate MIC and body wasting and their associations with clinical outcomes in CHF may lead to the development of nutritional strategies that alter the pathophysiology of CHF and improve outcomes.

Alcohol-induced oxidative stress

Alcohol-induced oxidative stress is linked to the metabolism of ethanol involving both microsomal and mitochondrial systems. Ethanol metabolism is directly involved in the production of reactive oxygen species (ROS) and reactive nitrogen species (RNS). These form an environment favourable to oxidative stress. Ethanol treatment results in the depletion of GSH levels and decreases antioxidant activity. It elevates malondialdehyde (MDA), hydroxyethyl radical (HER), and hydroxynonenal (HNE) protein adducts. These cause the modification of all biological structures and consequently result in serious malfunction of cells and tissues.

A growing burden: the pathogenesis, investigation and management of non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is the most common hepatic disorder in western countries, and its incidence is increasing. This review outlines the significant health burden posed by NAFLD and discusses what is presently known about its pathogenesis, including the roles of the metabolic syndrome, obesity, insulin resistance, hepatic steatosis, reactive oxygen species, inflammatory cytokines and adipocytokines. The way in which NAFLD is clinically diagnosed is described, and areas of uncertainty surrounding its investigation are identified, before discussing the relative merits of the limited treatment options available and looking ahead to potential therapeutic strategies for the future.

High Doses of Stavudine Induce Fat Wasting and Mild Liver Damage without Impairing Mitochondrial Respiration in Mice

Objective

Stavudine (d4T), a nucleoside reverse-transcriptase inhibitor (NRTI), can induce lipoatrophy, fatty liver, hyperlactataemia and abnormal liver tests. NRTI toxicity is usually ascribed to mitochondrial DNA (mtDNA) depletion and impaired mitochondrial respiration. However, NRTIs could have effects unrelated to mtDNA. Recently, we reported that 100 mg/kg/day of d4T stimulated fatty acid oxidation (FAO) in mouse liver, and reduced body fatness without depleting white adipose tissue (WAT) mtDNA. We hypothesized that higher d4T doses could further reduce adiposity, while inhibiting hepatic FAO.

Methods

Mice were treated for 2 weeks with d4T (500 mg/kg/day), L-carnitine (200 mg/kg/day) or both drugs concomitantly. Body fatness was assessed by dual energy X-ray absorptiometry, and investigations were performed in plasma, liver, muscle and WAT.

Results

D4T reduced the gain of body adiposity, WAT leptin, whole body FAO and plasma ketone bodies, and increased liver triglycerides and plasma aminotransferases with mild ultrastructural abnormalities in hepatocytes. Plasma lactate and respiratory chain activities in tissues were unchanged. Stearoyl-CoA desaturase (SCD-1), an enzyme negatively regulated by leptin, was overexpressed in liver. High doses of β-aminoisobutyric acid (BAIBA), a d4T catabolite, increased plasma ketone bodies. Although L-carnitine did not correct body adiposity, it prevented d4T-induced impairment of FAO and liver abnormalities.

Conclusions

D4T overdosage triggers fat wasting, leptin insufficiency and mild liver damage, without causing respiratory chain dysfunction. Overexpression of SCD-1 reduces fatty acid oxidation and overcomes the stimulating effect of BAIBA on hepatic FAO. L-carnitine does not correct leptin insufficiency but prevents d4T-induced impairment of FAO and liver damage.

L-Carnitine ameliorates methotrexate-induced oxidative organ injury and inhibits leukocyte death

Methotrexate (MTX), a folic acid antagonist widely used for the treatment of a variety of tumors and inflammatory diseases, affects normal tissues that have a high rate of proliferation, including the hematopoietic cells of the bone marrow and the gastrointestinal mucosal cells. To elucidate the role of free radicals and leukocytes in MTX-induced oxidative organ damage and the putative protective effect of L-carnitine (L-Car), Wistar albino rats were administered a single dose of MTX (20 mg/kg) followed by either saline or L-Car (500 mg/kg) for 5 days. After decapitation of the rats, trunk blood was obtained, and the ileum, liver, and kidney were removed for histological examination and for the measurement of malondialdehyde (MDA) and glutathione (GSH) levels, myeloperoxidase (MPO) activity, and collagen content. Our results showed that MTX administration increased the MDA and MPO activities and collagen content and decreased GSH levels in all tissues, while these alterations were reversed in L-Car-treated group. The elevated serum TNF-alpha level observed following MTX treatment was depressed with L-Car. The oxidative burst of neutrophils stimulated by Annexin V was reduced in the saline-treated MTX group, while L-Car abolished this inhibition. Similarly, flow cytometric measurements revealed that leukocyte apoptosis was increased in MTX-treated animals, while L-Car reversed these effects. Severe degeneration of the intestinal mucosa, liver parenchyma, and glomerular and tubular epithelium observed in the saline-treated MTX group was improved by L-Car treatment. These results suggest that L-Car, possibly via its free radical scavenging and antioxidant properties, ameliorates MTX-induced oxidative organ injury and inhibits leukocyte apoptosis. Thus, supplementation with L-Carnitine as an adjuvant therapy may be promising in alleviating the systemic side-effects of chemotherapeutics.

Links between nutrition, drug abuse, and the metabolic syndrome

Nutritional deficiency in combination with drug abuse may increase risk of developing the metabolic syndrome by augmenting cell damage, excitotoxicity, reducing energy production, and lowering the antioxidant potential of the cells. We have reviewed here the following points: effects of drugs of abuse on nutrition and brain metabolism; effects of nutrition on actions of the drugs of abuse; drug abuse and probability of developing metabolic syndrome; role of genetic vulnerability in nutrition/drug abuse and brain damage; and the role of neuroprotective supplements in drug abuse. Nutrition education is an essential component of substance abuse treatment programs and can enhance substance abuse treatment outcomes. The strategies available, in particular the nutritional approach to protect the drug abusers from the metabolic syndrome and other diseases are discussed.

An anti-inflammatory and antioxidant nutritional supplement for hypoalbuminemic hemodialysis patients: a pilot/feasibility study

BACKGROUND

A low serum albumin concentration < 3.8 g/dL, a marker of malnutrition-inflammation complex syndrome, is observed in approximately half of all maintenance hemodialysis (MHD) patients in the United States and is strongly associated with increased mortality.

OBJECTIVES

We hypothesized that a novel oral nutritional intervention with anti-inflammatory and antioxidant properties taken during routine dialysis sessions is well tolerated and corrects hypoalbuminemia in MHD patients.

DESIGN

Controlled clinical study.

SETTING

An outpatient dialysis facility affiliated with a tertiary care community medical center with six equally distributed hemodialysis shifts and 163 MHD patients.

PATIENTS

Among all MHD outpatients of three selected HD shifts (n = 81 patients), 21 subjects had a serum albumin level < 3.8 g/dL. One patient who was hospitalized before the intervention was excluded. The other three dialysis shifts, with 82 MHD outpatients including 20 hypoalbuminemic subjects, were observed as concurrent controls.

INTERVENTION

The nutritional intervention included one can of Oxepa and one can of Nepro to be taken together orally during each routine hemodialysis session for 4 weeks. Each can contains 237 mL fluid. Oxepa provides 355 calories and 14.8 g protein per can, includes maltodextrin, medium-chain triglycerides, borage oil, and refined and deodorized fish oil, and is designed for critically ill patients with inflammation and oxidative stress. Each can of Oxepa includes 1,020 mg gamma-linolenic acid, 3,100 mg caprylic acid, 1,080 mg eicosapentaenoic acid, 75 mg taurine, 2,840 IU vitamin A activity, 75 IU vitamin E, and 200 mg vitamin C. Nepro provides 475 calories and 16.7 g protein per can; includes high-oleic safflower oil, corn syrup solids, and fructo-oligosaccharides; and is tailored for the nutritional needs of MHD patients. Oxepa and Nepro also contain L-carnitine, 43 mg and 62 mg, respectively.

MAIN OUTCOME MEASURES

Serum albumin pretrial and posttrial.

RESULTS

Studied outpatients (12 men and 8 women) were aged 60.4 +/- 13.0 (SD) years. Three patients had started MHD treatment between 1.5 and 3 months before the intervention. Nine patients were diabetic. Preintervention serum albumin, 3.44 +/- 0.34 g/dL (mean +/- SD) increased to 3.68 +/- 0.34 g/dL (P = .001) 4 weeks after the start of the intervention. In 16 patients, serum albumin level increased by 0.2 to 1.3 g/dL, whereas in 4 patients the serum albumin level decreased by 0.2 to 0.6 g/dL. Three patients reported diarrhea, and one diabetic patient had increased serum glucose values. No other side effects were noted. In 20 control outpatients not receiving nutritional intervention, serum albumin did not change from 3.46 +/- 0.20 to 3.47 +/- 10.44 g/dL (P = .47).

CONCLUSIONS

In hypoalbuminemic MHD patients, a short-term in-center nutritional intervention with one can of Nepro and one can of Oxepa during HD is practical, convenient, well-tolerated, and associated with a significant increase in serum albumin level. Well-designed randomized placebo-controlled clinical trials are needed to verify the safety and effectiveness of this nutritional intervention and its impact on clinical outcome in hypoalbuminemic MHD patients.

Mitochondrial dysfunction in NASH: causes, consequences and possible means to prevent it

Calorie-enriched diet and lack of exercise are causing a worldwide surge of obesity, insulin resistance and lipid accretion in liver (i.e. hepatic steatosis), which can lead to steatohepatitis. Steatosis and nonalcoholic steatohepatitis (NASH) can also be induced by drugs such as amiodarone, tamoxifen and some antiretroviral drugs, including stavudine and zidovudine. There is accumulating evidence that mitochondrial dysfunction (more particularly respiratory chain deficiency) plays a key role in the physiopathology of NASH whatever its initial cause. In contrast, the mitochondrial beta-oxidation of fatty acids can be either increased (as in insulin resistance-associated NASH) or decreased (as in drug-induced NASH). However, in both circumstances, generation of reactive oxygen species (ROS) by the damaged respiratory chain can be augmented. ROS generation in an environment enriched in lipids in turn induces lipid peroxidation which releases highly reactive aldehydic derivatives (e.g. malondialdehyde) that have diverse detrimental effects on hepatocytes and other hepatic cells. In hepatocytes, ROS, reactive nitrogen species and lipid peroxidation products further impair the respiratory chain, either directly or indirectly through oxidative damage to the mitochondrial genome. This consequently leads to the generation of more ROS and a vicious cycle occurs. Mitochondrial dysfunction can also lead to apoptosis or necrosis depending on the energy status of the cell. ROS and lipid peroxidation products also increase the generation of several cytokines (TNF-alpha, TGF-beta, Fas ligand) playing a key role in cell death, inflammation and fibrosis. Recent investigations have shown that some genetic polymorphisms can significantly increase the risk of steatohepatitis and that several drugs can prevent or even reverse NASH. Interestingly, most of these drugs could exert their beneficial effects by improving directly or indirectly mitochondrial function in liver. Finding a drug, which could fully prevent oxidative stress and mitochondrial dysfunction in NASH is a major challenge for the next decade.

Role of osteopontin in hepatic neutrophil infiltration during alcoholic steatohepatitis

Alcoholic liver disease (ALD) is a major complication of heavy alcohol (EtOH) drinking and is characterized by three progressive stages of pathology: steatosis, steatohepatitis, and fibrosis/cirrhosis. Alcoholic steatosis (AS) is the initial stage of ALD and consists of fat accumulation in the liver accompanied by minimal liver injury. AS is known to render the hepatocytes increasingly sensitive to toxicants such as bacterial endotoxin (LPS). Alcoholic steatohepatitis (ASH), the second and rate-limiting step in the progression of ALD, is characterized by hepatic fat accumulation, neutrophil infiltration, and neutrophil-mediated parenchymal injury. However, the pathogenesis of ASH is poorly defined. It has been theorized that the pathogenesis of ASH involves interaction of increased circulating levels of LPS with hepatocytes being rendered highly sensitive to LPS due to heavy EtOH consumption. We hypothesize that osteopontin (OPN), a matricellular protein (MCP), plays an important role in the hepatic neutrophil recruitment due to its enhanced expression during the early phase of ALD (AS and ASH). To study the role of OPN in the pathogenesis of ASH, we induced AS in male Sprague-Dawley rats by feeding EtOH-containing Lieber-DeCarli liquid diet for 6 weeks. AS rats experienced extensive fat accumulation and minimal liver injury. Moderate induction in OPN was observed in AS group. ASH was induced by feeding male Sprague-Dawley rats EtOH-containing Lieber-DeCarli liquid diet for 6 weeks followed by LPS injection. The ASH rats had substantial neutrophil infiltration, coagulative oncotic necrosis, and developed higher liver injury. Significant increases in the hepatic and circulating levels of OPN was observed in the ASH rats. Higher levels of the active, thrombin-cleaved form of OPN in the liver in ASH group correlated remarkably with hepatic neutrophil infiltration. Finally, correlative studies between OPN and hepatic neutrophil infiltration was corroborated in a simple rat peritoneal model where enhanced peritoneal fluid neutrophil infiltration was noted in rats injected OPN intraperitoneally. Taken together these data indicate that OPN expression induced during ASH may play a significant role in the pathogenesis of ASH by stimulating neutrophil transmigration.

Effect of chronic ethanol administration on hepatic eNOS activity and its association with caveolin-1 and calmodulin in female rats

Although chronic and excessive alcohol consumption is associated with liver disease, the mechanism of alcoholic liver injury is still not clear. Whether reduced hepatic production of nitric oxide, which is evident in models of liver injury, is associated with alcohol-induced liver injury has not been investigated. We measured nitric oxide synthase (NOS) activity in the liver of pair-fed rats receiving liquid diet with or without alcohol [3% (vol/vol)] for 12 wk. Compared with control rats, hepatic NOS activity was significantly reduced in alcohol-treated rats along with the evidence of liver injury. Interestingly, there was no difference in the hepatic expression of endothelial NOS (eNOS) between ethanol-fed and pair-fed rats. We then tested the hypothesis that an imbalance between the binding of eNOS with inhibitory and stimulatory proteins may underlie the reduced activity of eNOS because eNOS catalytic activity is regulated partly through dynamic interactions with the inhibitory protein caveolin-1 and the stimulatory protein calmodulin. We found that hepatic caveolin-1 was markedly increased in alcohol-treated rats compared with control rats, whereas calmodulin remained unaltered. The binding of caveolin-1 and calmodulin with eNOS was increased and decreased, respectively, in alcohol-treated rats. Our results suggest that chronic alcohol intake attenuates hepatic eNOS activity by increasing the expression of the inhibitory protein caveolin-1 and enhancing its binding with eNOS.

Kidney insufficiency and nutrient-based modulation of inflammation

PURPOSE OF REVIEW

Patients with chronic kidney disease have a high cardiovascular mortality rate. Despite recent advances in dialysis techniques, over 20% of US dialysis patients die every year. Protein-energy malnutrition and inflammation are common and usually concurrent in chronic kidney disease patients, and have been implicated as the main cause of high mortality. We reviewed the pathophysiology of the malnutrition-inflammation complex syndrome and its potential modulation by dietary and other nutritional interventions in chronic kidney disease patients.

RECENT FINDINGS

The malnutrition-inflammation complex syndrome is a main cause of the atherosclerotic cardiovascular disease epidemic in chronic kidney disease. This may be by virtue of the syndrome's inflammatory components. Malnutrition and inflammation lead to weight loss over time, i.e. cachexia in slow motion, and result in decreased serum cholesterol and homocysteine levels. A 'reverse epidemiology' of cardiovascular risk factors is observed in chronic kidney disease, in that obesity, hypercholesterolemia and hyperhomocysteinemia are paradoxically associated with better survival. Among the possible etiologies of the malnutrition-inflammation complex syndrome, anorexia, low nutrient intake and oxidative stress are theoretically amenable to dietary modulation; however, the bulk of findings are epidemiological.

SUMMARY

There is no consensus as to how to correct the malnutrition-inflammation complex syndrome in chronic kidney disease patients. Because the malnutrition-inflammation complex syndrome is multifactorial, its correction probably requires a battery of simultaneous interventions, rather than one single modality. Clinical trials focusing on the syndrome are currently non-existent and are therefore urgently required to improve poor clinical outcome in chronic kidney disease patients.

L-carnitine could not improve hepatic warm ischemia-reperfusion injury despite ameliorated blood flow

BACKGROUND

Carnitine is applied to ameliorate ischemia-reperfusion (I/R) injury of several organs. However, application to hepatic I/R injury is not frequently reported. The aim of this study was to elucidate the effect of exogenous carnitine administration to ameliorate the warm hepatic I/R injury.

MATERIALS AND METHODS

Male Wistar rats were divided into two groups, a carnitine group (Car);100 mg/kg of l-carnitine administration and a control group (C); vehicle administration. Thirty minutes after administration, the left hepatic lobes were given 60-min ischemia and then reperfused. Plasma alanine aminotransferase (ALT), aspartate aminotransferase (AST), glutamate dehydrogenase (GLDH), tumor necrosis factor (TNF)-alpha, and lipoperoxides (LPO) were measured. Hepatic adenosine triphosphate (ATP) concentration was also measured. The hepatic blood flow was estimated using a Laser Doppler. The presence of apoptosis in the livers was evaluated by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) staining.

RESULTS

In group Car, the blood flow of the left hepatic lobes was better recovered during the reperfusion period than in group C (P < 0.0001). Plasma levels of ALT, AST, GLDH, and TNF-alpha at 1 h after reperfusion were not significantly different between the groups. Although there were no statistical significances, ALT, AST, and TNF-alpha levels in group Car at 24 h after reperfusion tended to be higher than in group C. Plasma LPO levels were not different between the two groups. Also hepatic ATP concentration was not different between the two groups. TUNEL positive liver cells were visible only in group Car at 24 h after reperfusion, but not in the controls.

CONCLUSIONS

Although carnitine administration improved the hepatic blood flow during the reperfusion period, we could not demonstrate a protective effect to the hepatic warm I/R injury.

Hepatocyte proliferation is the possible mechanism for the transient decrease in liver injury during steatosis stage of alcoholic liver disease

Steatosis is a frequent pathologic stage in alcoholic liver disease (ALD). Although the mechanisms for increased susceptibility of steatotic liver to injury have been postulated, the ability of these hepatocytes to proliferate and withstand injury is unknown. There are conflicting reports on the status of hepatocyte regeneration following chronic alcohol ingestion. Hence, the objective of this study was to investigate the temporal dynamics between the pattern of liver injury and hepatocyte proliferation during the steatosis stage of ALD. Alcoholic steatosis was induced in male Sprague-Dawley rats by feeding an ethanol (EtOH)-containing Lieber-DeCarli liquid diet for a period of 5 weeks. Microvesicular steatosis was evident in H&E sections by three weeks in the EtOH-treated rats, which further developed into panlobular macrovesicular steatosis by 5 weeks. Plasma transaminase activities indicated progressive increase in liver injury peaking at 3 weeks with significant but mild decrease at 4 and 5 weeks. CYP2E1 protein and activity was significantly increased in EtOH-fed rats as measured by Western blot and pNP hydroxylation assay. PCNA analysis of liver sections indicated that EtOH-treated rats had a significantly higher number of cells in S phase of cell division at weeks 1 (3.20 +/- 0.19), 2 (7.03 +/- 0.92), and 3 (4.23 +/- 1.41) when compared to controls (1.5 +/- 0.22). NF-kappaB DNA binding and Cyclin D1 proteins increased significantly in the EtOH-treated rats corresponding with enhanced hepatic proliferation. These data suggest the transient decline in liver injury during alcoholic steatosis is due to enhanced NF-kappaB-dependent hepatocyte proliferation.

Mitochondrial Glutathione and Chemically Induced Stress Including Ethanol

The mechanisms of alcohol toxicity as related to mitochondrial dysfunction and the glutathione-dependent protective systems are reviewed. The pathophysiology of ethanol-induced liver damage is defined in terms of an early phase and a late phase. CYP2E1 dependent toxicity appears closely related to oxidative stress injury with possible roles of peroxynitrite, TNFalpha, protein adducts, and enhanced protein expression. Modulation of mitochondrial glutathione affects mitochondrial function and cell survival with superoxide and hydrogen peroxide generation being crucial to mitochondrial membrane permeability transition and apoptosis.