Abrupt termination of an ethanol regimen provokes ventricular arrhythmia and enhances susceptibility to the arrhythmogenic effects of epinephrine in rats

A New Non-Obese Steatohepatitis Mouse Model with Cardiac Dysfunction Induced by Addition of Ethanol to a High-Fat/High-Cholesterol Diet

Non-obese metabolic dysfunction-associated steatotic liver disease (MASLD) has been associated with cardiovascular-related mortality, leading to a higher mortality rate compared to the general population. However, few reports have examined cardiovascular events in non-obese MASLD mouse models. In this study we created a mouse model to mimic this condition. In this study involving seven-week-old C57BL/6J male mice, two dietary conditions were tested: a standard high-fat/high-cholesterol diet (STHD-01) and a combined diet of STHD-01 and ethanol. Over periods of 6 and 12 weeks, we analyzed the effects on liver and cardiac tissues using various staining techniques and PCR. Echocardiography and blood tests were also performed to assess cardiac function and liver damage. The results showed that mice on the ethanol-supplemented STHD-01 diet developed signs of steatohepatitis and cardiac dysfunction, along with increased sympathetic activity, as early as 6 weeks. At 12 weeks, more pronounced exacerbations accompanied with cardiac dilation, advanced liver fibrosis, and activated myocardial fibrosis with sympathetic activation were observed. This mouse model effectively replicated non-obese MASLD and cardiac dysfunction over a 12-week period using a combined diet of STHD-01 and ethanol. This dietary approach highlighted that both liver inflammation and fibrosis, as well as cardiac dysfunction, could be significantly worsened due to the activation of the sympathetic nervous system. Our results indicate that alcohol, even when completely metabolized on the day of drinking, exacerbates the progression of non-obese MASLD and cardiac dysfunction.

Chronic ethanol consumption plus an atherogenic diet cause metabolic steatohepatitis with advanced liver fibrosis in apolipoprotein E/low-density lipoprotein receptor double-knockout mice

BACKGROUND

Nonalcoholic steatohepatitis is the inflammatory subtype of nonalcoholic fatty liver disease with a high risk of progression to liver fibrosis. We investigated metabolic steatohepatitis with advanced liver fibrosis in apolipoprotein E/low-density lipoprotein receptor double-knockout (AL) mice fed a co-diet of ethanol with a low-carbohydrate-high-protein-high-fat atherogenic diet (AD) for 16 weeks. We also examined the underlying mechanisms, especially hepatic sympathetic activation, involved in the effects.

METHODS

We maintained 12-week-old male AL mice on AD and a standard chow diet (SCD) with or without ethanol treatment for 16 weeks. Age-matched male C57BL/6J mice on SCD without ethanol treatment served as controls. We conducted blood biochemical, histopathological, and fluorescence immunohistochemical, and reverse transcriptase polymerase chain reaction studies.

RESULTS

AL mice showed significant hyperlipidemia. AD induced increased body weight, hepatic steatosis, and hepatic damage; ethanol and the AD co-diet resulted in hepatic sympathetic activation accompanied by hepatic steatosis, lobular inflammation, bridging fibrosis, and hepatic damage. Hepatic Kupffer cells (KCs) and hepatic stellate cells (HSCs), which showed sympathetic activation, produced 4.4- to 9.4-fold more inflammatory factors (KC and KC-derived tumor necrosis factor-α, and chemokine [C-C motif] ligand 2) and 2.0- to 32.0-fold more fibrosis factors (HSC and HSC-derived transforming growth factor β1 and collagen 1a1); all p < 0.05 vs. controls.

CONCLUSIONS

We created a model of metabolic steatohepatitis with advanced liver fibrosis from coexisting hyperlipidemia and hepatic sympathetic activation in AL mice on a co-diet of ethanol and AD. KCs and HSCs became the cellular targets of hepatic sympathetic activation, which could play a role in the initiation and progression of metabolic steatohepatitis with advanced liver fibrosis.

Alcohol consumption combined with dietary low-carbohydrate/high-protein intake increased the left ventricular systolic dysfunction risk and lethal ventricular arrhythmia susceptibility in apolipoprotein E/low-density lipoprotein receptor double-knockout mice

Alcohol abuse is positively associated with cardiovascular disease. Dietary low-carbohydrate/high-protein (LCHP) intake confers a greater mortality risk. Here, the impact of ethanol consumption in combination with dietary LCHP intake on left ventricular (LV) systolic function and lethal ventricular arrhythmia susceptibility were investigated in apolipoprotein E/low-density lipoprotein receptor double-knockout (AL) mice. The underlying mechanisms, cardiac sympathovagal balance, beta-adrenergic receptor (ADRB) levels, and gap junction channel protein connexin 43 (Cx43) expression, were examined. Male AL mice fed an LCHP diet with or without ethanol were bred for 16 weeks. Age-matched male AL and wild-type mice received standard chow diet and served as controls. The following were used to assess LV systolic function, lethal ventricular arrhythmia susceptibility, cardiac sympathovagal balance, Cx43 expression, and ADRB levels: The results demonstrated that ethanol consumption in combination with dietary LCHP intake worsened LCHP-induced LV systolic dysfunction in AL mice and enhanced their susceptibility in the ventricular arrhythmia-evoked test. There were concomitant increases in LV weight, LF/HF ratio shown by HRV, TH, ADRB1, ADRB2, and Cx43 expressions by LV fluorescence immunohistochemistry, and LV Cx43 messenger ribonucleic acid expression by PCR. In AL mice, alcohol consumption combined with dietary LCHP intake may thus promote a shift in cardiac sympathovagal balance toward sympathetic predominance, the increases in beta-adrenergic receptors (ADRB1 and ADRB2), and then affect the gap junction channel protein Cx43, which in turn could contribute to increased risks of LV systolic dysfunction and susceptibility to lethal ventricular arrhythmia.

Alcohol Consumption in Combination with an Atherogenic Diet Increased Indices of Atherosclerosis in Apolipoprotein E/Low-Density Lipoprotein Receptor Double-Knockout Mice

BACKGROUND

Alcohol abuse and adherence to atherogenic diet (AD; a low-carbohydrate-high-protein diet) have been positively associated with cardiovascular disease. In addition, it has been demonstrated clinically that dietary intake is increased on days when alcohol is consumed. Here, the additive effects of ethanol (EtOH) and AD on atherosclerosis, a major underlying cause of cardiovascular disease, were investigated in apolipoprotein E/low-density lipoprotein receptor double-knockout (KO) mice. The mechanisms, especially aortic oxidative stress damage, were highlighted.

METHODS

Twelve-week-old male KO mice on AD with or without EtOH treatment were bred for 4 months. Age-matched male C57BL/6J mice on a standard chow diet without EtOH treatment served as controls. Analyses were conducted using ultrasound biomicroscopy, histopathological and fluorescence immunohistochemical examinations, Western blots, and polymerase chain reaction.

RESULTS

KO mice on AD with EtOH treatment showed increases in aortic maximum intima media thickness, hypoechoic plaque formation, and mean Oil-Red-O content. These results were associated with enhanced ratio of aortic 8-hydroxy-2'-deoxyguanosine (8-OHdG)-immunopositive area to the metallothionein (MT) immunopositive area and suppression of AD-induced up-regulated aortic Mt1, Mt2, and upstream stimulatory factor 1 mRNA expressions. Moreover, 8-OHdG was expressed in the nuclei of CD31- and alpha smooth muscle actin-immunopositive cells, and the up-regulated mRNA expressions of aortic nitric oxide synthase 3 and platelet-derived growth factors were only observed in the KO mice on AD with EtOH treatment.

CONCLUSIONS

Alcohol abuse and adherence to AD may promote the shift of aortic oxidative stress and antioxidative stress balance toward oxidative stress predominance and reduced antioxidative stress, which may be partly due to the decrease in MT at the cell biological level and down-regulation of Mt at the gene level, which in turn could play a role in the up-regulation of endothelial dysfunction-related and vascular smooth muscle cell proliferation-related gene expression and the progression of atherosclerosis in mice with hyperlipidemia.

Acute restraint stress provokes sudden cardiac death in normotensive rats and enhances susceptibility to arrhythmogenic effects of adrenaline in spontaneously hypertensive rats

BACKGROUND

A high incidence of cardiovascular events and sudden cardiac death (SCD) has been reported following unexpected acute psychosocial stress. The possible pathways by which acute restraint stress (ARS), a kind of acute psychosocial stress, leads to SCD were determined.

METHODS

Using 16-week-old male normotensive Wistar Kyoto rats (WKY, n=24) as controls and spontaneously hypertensive rats (SHR, n=24) as the hypertensive subjects with left ventricular hypertrophy (LVH), we assessed ARS-related incidence of SCD, cardiac and myocardial autonomic nervous system dysfunction, gap junction connexin-43 (Cx43) channel remodeling, and ventricular repolarization abnormality, based on electrocardiography, an adrenaline test, heart rate variability (HRV), and reverse transcriptase polymerase chain reaction analyses. Rats with ARS were introduced into restrainers that allowed head, limb, and tail movement.

RESULTS

In normotensive hearts without LVH, ARS induced a higher incidence of SCD attributed to lethal bradycardia, increased cardiac and myocardial sympathetic activation, and gap junction Cx43 channel remodeling, as evidenced by the increases in the ratio of low-frequency and high-frequency powers in HRV, the ratio of myocardial neuropeptide Y (NPY) and acetylcholinesterase (AChE) mRNA expressions, and the up-regulation of LV Cx43 mRNA expression; in hypertensive hearts with LVH, ARS enhanced susceptibility to the malignant arrhythmogenic effects of the adrenaline test (a kind of sympathetic stimuli) accompanied by abnormal ventricular repolarization, as evidenced by increased incidence of ventricular tachycardia and/or ventricular fibrillation during the adrenaline test and prolonged QTc immediately after ARS.

CONCLUSIONS

ARS may trigger cardiac and myocardial sympathetic predominance, and then induce gap junction Cx43 channel remodeling, finally leading to lethal bradycardia in normotensive WKY. ARS-induced abnormal ventricular repolarization may be responsible for ARS-enhanced susceptibility to sympathetic stimulation in SHR with LVH. Expressions of myocardial NPY, AChE, and Cx43 genes, HRV, QTc and LVH measures showed diagnostic and prognostic potential for predicting ARS-induced SCD.

Adrenergic Inhibition with Dexmedetomidine to Treat Stress Cardiomyopathy during Alcohol Withdrawal: A Case Report and Literature Review

Stress (Takotsubo) cardiomyopathy is a form of reversible left ventricular dysfunction with a heightened risk of ventricular arrhythmia thought to be caused by high circulating catecholamines. We report a case of stress cardiomyopathy that developed during severe alcohol withdrawal successfully treated with dexmedetomidine. The case involves a 53-year-old man with a significant history of alcohol abuse who presented to a teaching hospital with new-onset seizures. His symptoms of acute alcohol withdrawal were initially treated with benzodiazepines, but the patient later developed hypotension, and stress cardiomyopathy was suspected based on ECG and echocardiographic findings. Adjunctive treatment with the alpha-2-adrenergic agonist, dexmedetomidine, was initiated to curtail excessive sympathetic outflow of the withdrawal syndrome, thereby targeting the presumed pathophysiology of the cardiomyopathy. Significant clinical improvement was observed within one day of initiation of dexmedetomidine. These findings are consistent with other reports suggesting that sympathetic dysregulation during alcohol withdrawal produces ideal pathobiology for stress cardiomyopathy and leads to ventricular arrhythmogenicity. Stress cardiomyopathy should be recognized as a complication of alcohol withdrawal that significantly increases cardiac-related mortality. By helping to correct autonomic dysregulation of the withdrawal syndrome, dexmedetomidine may be useful in the treatment of stress-induced cardiomyopathy.

Ethanol and liver: Recent insights into the mechanisms of ethanol-induced fatty liver

Alcoholic fatty liver disease (AFLD), a potentially pathologic condition, can progress to steatohepatitis, fibrosis, and cirrhosis, leading to an increased probability of hepatic failure and death. Alcohol induces fatty liver by increasing the ratio of reduced form of nicotinamide adenine dinucleotide to oxidized form of nicotinamide adenine dinucleotide in hepatocytes; increasing hepatic sterol regulatory element-binding protein (SREBP)-1, plasminogen activator inhibitor (PAI)-1, and early growth response-1 activity; and decreasing hepatic peroxisome proliferator-activated receptor-α activity. Alcohol activates the innate immune system and induces an imbalance of the immune response, which is followed by activated Kupffer cell-derived tumor necrosis factor (TNF)-α overproduction, which is in turn responsible for the changes in the hepatic SREBP-1 and PAI-1 activity. Alcohol abuse promotes the migration of bone marrow-derived cells (BMDCs) to the liver and then reprograms TNF-α expression from BMDCs. Chronic alcohol intake triggers the sympathetic hyperactivity-activated hepatic stellate cell (HSC) feedback loop that in turn activates the HSCs, resulting in HSC-derived TNF-α overproduction. Carvedilol may block this feedback loop by suppressing sympathetic activity, which attenuates the progression of AFLD. Clinical studies evaluating combination therapy of carvedilol with a TNF-α inhibitor to treat patients with AFLD are warranted to prevent the development of alcoholic liver disease.

Alcohol and Heart Disease in the Forensic Setting

The impacts of chronic high levels of ethanol consumption on cardiovascular structure and function are reviewed as they pertain to forensic pathology practice. Both hypertrophy and remodeling of the myocardium as well as physiological revision of electrical conduction through the heart can occur in a progressive fashion. A discussion about the likely underappreciated spectrum of structural heart disease that may be seen in individuals with chronic alcohol dependence is presented. Finally, brief reference to the collision between alcohol, cardiovascular disease, and forensically relevant scenarios is provided.

Carvedilol improves ethanol-induced liver injury via modifying the interaction between oxidative stress and sympathetic hyperactivity in rats

AIM

Oxidative stress is a major pathway mediating ethanol hepatotoxicity and liver injury. We previously found that carvedilol, which can block the sympathetic nervous system via β1-, β2- and α1-adrenoreceptors, modifies ethanol-induced production of lipogenesis- and fibrogenesis-related mediators from hepatic stellate cells (HSC). In the present study, we assessed the effects of carvedilol on ethanol-induced liver injury, hepatic insulin resistance, and the interaction between oxidative stress and sympathetic hyperactivity in rats with alcoholic fatty liver disease (AFLD).

METHODS

Male Wistar rats were pair-fed for 49 days and divided into four groups: control and ethanol liquid-diet-fed rats with and without 7-day carvedilol treatment. Rats' sympathetic activity, hepatic oxidative stress, hepatic insulin resistance and liver injury were evaluated based on biochemical analysis, enzyme-linked immunosorbent assay, fluorescence immunohistochemistry, western blot and reverse transcriptase polymerase chain reaction.

RESULTS

Forty-nine days of ethanol consumption induced the increases in circulating noradrenaline metabolite (3-methoxy-4-hydroxyphenylglycol), hepatic noradrenaline and 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels, the downregulation of hepatic insulin receptor substrate-1 gene expression, and the accumulation of fatty droplets within hepatocytes with the increased hepatic triglyceride and blood alanine aminotransferase levels. All of these changes were modified by carvedilol treatment. 8-OHdG was detected in activated HSC and suppressed by carvedilol treatment based on fluorescence immunohistochemical double-staining analysis.

CONCLUSION

Carvedilol may modify the interaction between the oxidative stress and the sympathetic hyperactivity, and then contribute to attenuating the development of AFLD in rats. Additionally, oxidative stress may be responsible for the activation of HSC during the early stage of alcoholic liver disease.

Heart rate turbulence during acute alcohol withdrawal syndrome

BACKGROUND

Alcohol withdrawal syndrome is associated with an increased incidence of cardiac arrhythmias and sudden cardiac death. Heart rate turbulence (HRT) parameters were applied during withdrawal to estimate cardiac regulation during treatment with clomethiazole.

METHODS

Twenty-two patients suffering from alcohol withdrawal syndrome were included in the study. Heart rate regulation was obtained by means of Holter ECG analyzing time intervals before medication, and 2 and 6h after medication. Slope and onset of HRT were calculated in addition to heart rate variability (HRV) parameters. Furthermore, we calculated the slope and the onset of ectopic beat-like events.

RESULTS

Heart rate variability parameters indicated a minor reduction of vagal modulation during withdrawal syndrome. Especially, the fractal scaling exponent BBI alpha1 (4-16) indicated the autonomic shift. In contrast to HRV parameters, no significant changes were observed in the HRT parameters. Significant correlations were observed between severity of withdrawal, as assessed by the AWS scale, and the fractal scaling exponent BBI alpha2 (16-64), and the onset and the slope of HRT of ectopic beat-like activity.

CONCLUSION

Increased sympathetic modulation during withdrawal and clomethiazole treatment is not associated with changes of heart rate turbulence parameters predictive of cardiac death after myocardial infarction.

Carvedilol attenuates the progression of alcohol fatty liver disease in rats

BACKGROUND

Hepatosteatosis is an essential step in liver disease progression. However, the mechanisms that mediate the progression of hepatosteatosis and the optimal inhibitor of them remain largely unclear. The sympathetic nervous system (SNS) is responsible for the lipid metabolism and the accumulation of collagen that occurs in an injured liver. Medicines that inhibit this pathway may be a relevant treatment for the hepatosteatosis, and then reduce the liver injury that progresses through the stage of steatosis to fibrosis.

METHODS

Using an ethanol-liquid-diet-fed rat model of alcohol fatty liver disease (AFLD), we studied the effects of carvedilol, which can block the SNS completely via β1, β2, and α1 adrenergic receptors, on the sympathetic tone, hepatosteatosis, and fibrosis based on histological, immunohistochemical, Western blot, and reverse transcriptase polymerase chain reaction analyses.

RESULTS

Carvedilol inhibited the ethanol-induced whole-body and hepatic sympathetic activities based on the serum 3-methoxy-4-hydroxyphenylglycol level and hepatic tyrosine hydroxylase expression. Carvedilol attenuated the hepatosteatosis, as evidenced by reduced hepatic triglyceride level and the accumulation of fatty droplets within hepatocytes, down-regulated fatty acid synthase and sterol regulatory element binding protein-1, and up-regulated peroxisome proliferator-activated receptor-α. No fibrosis signs were shown in our rat model. Carvedilol inhibited ethanol-induced the thickening of zone 3 vessel walls, reduced the activation of hepatic stellate cells (HSCs), and decreased the induction of collagen, transforming growth factor β1, and tissue inhibitor of metalloproteinases-1. Tumor necrosis factor α (TNF-α) was expressed on the activated HSCs and inhibited by carvedilol based on the immunohistochemical double staining analysis.

CONCLUSIONS

Ethanol metabolism-induced lipogenesis may trigger the SNS-activated HSCs feedback loop, and then induct the activated HSCs and the activated HSCs-derived TNF-α, the mediator of lipogenesis, overproduction. Carvedilol may block this feedback loop via antisympathetic activity and demonstrate its preventive role on the development of hepatosteatosis in rat with AFLD.

Importance of genetic background for risk of relapse shown in altered prefrontal cortex gene expression during abstinence following chronic alcohol intoxication

Alcoholism is a relapsing disorder associated with excessive consumption after periods of abstinence. Neuroadaptations in brain structure, plasticity and gene expression occur with chronic intoxication but are poorly characterized. Here we report identification of pathways altered during abstinence in prefrontal cortex, a brain region associated with cognitive dysfunction and damage in alcoholics. To determine the influence of genetic differences, an animal model was employed with widely divergent responses to alcohol withdrawal, the Withdrawal Seizure-Resistant (WSR) and Withdrawal Seizure-Prone (WSP) lines. Mice were chronically exposed to highly intoxicating concentrations of ethanol and withdrawn, then left abstinent for 21 days. Transcriptional profiling by microarray analyses identified a total of 562 genes as significantly altered during abstinence. Hierarchical cluster analysis revealed that the transcriptional response correlated with genotype/withdrawal phenotype rather than sex. Gene Ontology category overrepresentation analysis identified thyroid hormone metabolism, glutathione metabolism, axon guidance and DNA damage response as targeted classes of genes in low response WSR mice, with acetylation and histone deacetylase complex as highly dimorphic between WSR and WSP mice. Confirmation studies in WSR mice revealed both increased neurotoxicity by histopathologic examination and elevated triidothyronine (T3) levels. Most importantly, relapse drinking was reduced by inhibition of thyroid hormone synthesis in dependent WSR mice compared to controls. These findings provide in vivo physiological and behavioral validation of the pathways identified. Combined, these results indicate a fundamentally distinct neuroadaptive response during abstinence in mice genetically selected for divergent withdrawal severity. Identification of pathways altered in abstinence may aid development of novel therapeutics for targeted treatment of relapse in abstinent alcoholics.