Elevations in plasma angiotensin II with prolonged ethanol treatment in rats

Reactive Oxygen Species Are Central Mediators of Vascular Dysfunction and Hypertension Induced by Ethanol Consumption

Consumption of high amounts of ethanol is a risk factor for development of cardiovascular diseases such as arterial hypertension. The hypertensive state induced by ethanol is a complex multi-factorial event, and oxidative stress is a pathophysiological hallmark of vascular dysfunction associated with ethanol consumption. Increasing levels of reactive oxygen species (ROS) in the vasculature trigger important processes underlying vascular injury, including accumulation of intracellular Ca2+ ions, reduced bioavailability of nitric oxide (NO), activation of mitogen-activated protein kinases (MAPKs), endothelial dysfunction, and loss of the anticontractile effect of perivascular adipose tissue (PVAT). The enzyme nicotinamide adenine dinucleotide phosphate (NADPH) oxidase plays a central role in vascular ROS generation in response to ethanol. Activation of the renin-angiotensin-aldosterone system (RAAS) is an upstream mechanism which contributes to NADPH oxidase stimulation, overproduction of ROS, and vascular dysfunction. This review discusses the mechanisms of vascular dysfunction induced by ethanol, detailing the contribution of ROS to these processes. Data examining the association between neuroendocrine changes and vascular oxidative stress induced by ethanol are also reviewed and discussed. These issues are of paramount interest to public health as ethanol contributes to blood pressure elevation in the general population, and it is linked to cardiovascular conditions and diseases.

The effect of telmisartan, an angiotensin receptor blocker, on alcohol consumption and alcohol-induced dopamine release in the nucleus accumbens

Alcohol use disorder remains a major health problem. The mesocorticolimbic dopaminergic system, including the nucleus accumbens region and multiple neural circuits, is involved in its complex underlying mechanism. For instance, alcohol intake stimulates the central and peripheral renin-angiotensin system and increases angiotensin II levels, which predominantly affect angiotensin 1 receptors both in the periphery and in the brain. In this study, we aimed to investigate the effects of the intracerebroventricularly-administered angiotensin 1 receptor blocker telmisartan on the alcohol consumption of male Sardinian alcohol-preferring (sP) rats and on the alcohol-induced dopamine levels in the nucleus accumbens region in Wistar rats. Acute intracerebroventricular administration of telmisartan (100 nM) reduced the alcohol intake for 24 hours without affecting food and water consumption in sP rats. Acute intracerebroventricular injection of the opioid receptor antagonist naloxone (75 nM), tested as a reference compound, also reduced the alcohol consumption in sP rats; however, naloxone's effect lasted only for 30 minutes. In microdialysis experiments, telmisartan administered intracerebroventricularly did not change dopamine levels in the nucleus accumbens that had been induced by acute intraperitoneal alcohol administration in Wistar rats. According to these results, further studies are needed to elucidate the role of the renin-angiotensin system on alcohol use disorder pathophysiology.

Constrictor responses of cerebral resistance arterioles in male and female rats exposed to prenatal alcohol

While it is known that dilation of cerebral arterioles to NOS-dependent agonists is impaired in rats exposed to prenatal alcohol, no studies have examined the influence of prenatal alcohol on constrictor response of cerebral arterioles. Our goal was to determine whether constrictor responses of cerebral resistance arterioles are altered by prenatal exposure to alcohol and if any changes differed as a function of age or sex. We fed Sprague-Dawley rat dams a liquid diet with or without alcohol (3% ethanol) for the duration of their pregnancy. We then examined reactivity of cerebral arterioles to thromboxane (U-46619; 0.01 and 0.1 µM), arginine vasopressin (0.1 and 1 nM), and angiotensin II (1 and 10 µM) in four groups of offspring: control male and female, and prenatal alcohol male and female at two different ages (adolescent: 4-6 weeks old and adult: 14-16 weeks old). Constriction of cerebral arterioles to U-46619 and AVP were similar in male and female rats regardless of exposure to prenatal alcohol and age. Similarly, adolescent male and female rats showed no difference to angiotensin II following prenatal exposure to alcohol. However, alcohol-exposed females exhibited an unexpected dilation to the high concentration of angiotensin II in adulthood, which was absent in males. We suggest that the findings from these studies may have implications regarding the susceptibility of the brain to cerebral ischemic damage. We speculate that impaired vasodilation, coupled with preserved vasoconstriction, can lead to a scenario favoring a decrease in cerebral blood flow during times of increased metabolic demand.

Interaction between ALDH2 rs671 and life habits affects the risk of hypertension in Koreans: A STROBE observational study

Aldehyde dehydrogenase-2 (ALDH2) is associated with the risk of hypertension, and the effects of lifestyle factors on blood pressure vary according to genotype. Among the Han Chinese, the risk of hypertension is lower in the group with the rs671 A allele than in the group with the G allele, and there is a significant association between the frequency of fried food consumption and hypertension. However, the A allele significantly increases the risk of hypertension with increased fried food intake. This study aimed to investigate the effect of the relationship between ALDH2 polymorphism and complex lifestyle habits (fried food consumption and exercise) on hypertension.rs671 polymorphisms of ALDH2 were examined using Korean genome and epidemiology data from 8157 hypertensive cases and 9550 controls. Further, we investigated whether the A allele is protective against hypertension in Koreans and explored the effect of the combination of fried food intake and exercise habits on hypertension by genotype.The genotype frequencies of rs671, which is specific to East Asia, were 2.51% AA, 26.66% GA, and 70.83% GG in the Korean population. The group with inactive aldehyde dehydrogenase-2 had a low odds ratio [OR = 0.75 (95% CI:0.69-0.80), P = 4.35 × 10-14] of hypertension, and low metabolism of acetaldehyde. Subjects carrying the A allele exhibited an increased risk of hypertension with increased fried food intake without exercise [OR = 2.256 (95% CI:1.094-4.654), P = .028].ALDH2 polymorphism and complex lifestyle habits (fried food consumption and exercise) are associated with the risk of hypertension. Further, the A allele is associated with a low risk of hypertension, but it increases the risk of hypertension as fried food intake without exercise increases.

Hypotensive and Antihypertensive Properties and Safety for Use of Annona muricata and Persea americana and Their Combination Products

Introduction

In the management of hypertension (a cardiovascular disease and the leading metabolic risk factor in noncommunicable diseases) with herbal medicines, efficacy and safety are of uttermost concern. This study sought to establish hypotensive, antihypertensive, drug interaction, and safety for use of the aqueous leaf extracts of Annona muricata (AME), Persea americana (PAE), or their combination products (CAPE). Methodology. Systolic and diastolic blood pressure (SBP and DBP), mean arterial blood pressure (MAP), and heart rate (HR) were measured in normotensive Sprague-Dawley rats treated with 50-150 mg/kg of AME, PAE, or CAPE to establish a hypotensive effect. "Combination index" was calculated to establish interaction between AME and PAE. The antihypertensive effect of CAPE was established by measuring SBP, DBP, MAP, and HR in ethanol-sucrose- and epinephrine-induced hypertension. Full blood count, liver and kidney function tests, and urinalysis were determined in ethanol/sucrose-induced hypertension to establish safety for use.

Results

AME, PAE, and CAPE significantly (p ≤ 0.001) decreased BP in both normotensive and hypertensive animals. Effects of CAPE 1, CAPE 2, and CAPE 3 were synergistic (combination indices of 0.65 ± 0.07, 0.76 ± 0.09, and 0.87 ± 0.07, respectively). There was a significant decrease (p ≤ 0.01 - 0.001) in SBP and MAP with 100 mg/kg CAPE 1 and 75 mg/kg CAPE 2 treatment in hypertension as well as with nifedipine (p ≤ 0.001) treatment. Epinephrine-induced hypertension in anesthetized cats was significantly and dose-dependently inhibited (p < 0.05 - 0.001) by 25-100 mg/ml CAPE 1 and 37.5-75 mg/ml CAPE 2. CAPE administration had no deleterious effect (p > 0.05) on full blood count, liver and kidney function, and urine composition in hypertensive rats.

Conclusion

The aqueous leaf extracts of Annona muricata, Persea americana, and their combination products possess antihypertensive properties, with combination products showing synergism and safety with use.

The role of dietary salt and alcohol use reduction in the management of hypertension

Introduction: Despite the improved treatment protocol of hypertension, the magnitude of the disease and its related burden remains raised. Hypertension makes up the leading cause of stroke, kidney disease, arterial disease, eye disease, and cardiovascular disease (CVD) growth. Areas covered: This review provides the overview of the role of dietary salt and alcohol use reduction in the management of hypertension, a brief history of alcohol, the vascular endothelium functions, the effects of alcohol use on blood pressure (BP), the mechanisms of alcohol, brief history of salt, the effects of dietary salt intake on BP, and the mechanisms of salt. Expert opinion: Studies found that high dietary salt intake and heavy alcohol consumption have a major and huge impact on BP while both of them have been identified to increase BP. Also, they raise the risk of hypertension-related morbidity and mortality in advance. On the other way, the dietary salt and alcohol use reduction in the management of hypertension are significant in the control of BP and its related morbidity and mortality. Further, studies suggested that the dietary salt and alcohol use reductions are the cornerstone in the management of hypertension due to their significance as part of comprehensive lifestyle modifications.

Association of Chronic Khat Chewing with Blood Pressure and Predictors of Hypertension Among Adults in Gurage Zone, Southern Ethiopia: A Comparative Study

Purpose

The leaves of the Khat plant contain amphetamine-like compounds which are implicated in the development of hypertension. The increase in blood pressure coincides with the plasma cathinone level. Other factors associated with hypertension are being overweight, obesity, cigarette smoking, alcohol use, physical inactivity, unhealthy diet, and stress. Thus, this study assessed the association of chronic khat chewing with hypertension and other factors associated with hypertension.

Patients and Methods

Acommunity based comparative cross-sectional study was undertaken from October 5, 2018 to February 15, 2019 in Gurage zone, southern Ethiopia. A total of 1200 adults (600 chewers and 600 non-chewers) aged 18 − 65 years were selected using a convenience sampling method. The data was collected by an interviewer-administered questionnaire plus physical measurements and were carried out at a fixed time of the day in the morning (7: 00 am–10:00 am). Linear regression and binary logistic regression analysis were performed to identify the determinant factors of blood pressure. The test of statistically significant association was declared by using 95% CI and p-value less than 0.05.

Results

A total of 1198 adults participated in the study giving a response rate of 99.8%. The mean age of Khat chewers were 34 (± 11.27) and non-chewers were 34.73 (± 11.48) years. The mean values of systolic blood pressure and diastolic blood pressure were higher in chewers than in non-chewers (p < 0.001). The prevalence of diastolic blood pressure > 80mmHg was significantly higher among Khat chewers than in non-chewers (17.4% versus 8.7%, p < 0.001). The duration of Khat chewing was significantly associated with systolic blood pressure (Beta coefficient = 0.83, p < 0.001) and diastolic blood pressure (Beta coefficient = 0.51, p < 0.001). The sex, age, BMI and alcohol were significantly associated with both systolic and diastolic blood pressure.

Conclusion

Chronic Khat chewing, male sex, BMI and alcohol were associated with increased systolic and diastolic blood pressure. To assess the cause and effect relationship between chronic Khat chewing and hypertension further studies with better defined cohorts and basic science studies need to be undertaken.

Moderation of alcohol consumption as a recommendation in European hypertension management guidelines: a survey on awareness, screening and implementation among European physicians

OBJECTIVES

Moderation of alcohol consumption is included as a class I, level of evidence A recommendation in the current European guidelines for the management of hypertension. We investigated its awareness and self-reported implementation among European physicians across different specialties and workplaces.

DESIGN AND SETTING

A cross-sectional survey study conducted in two annual German meetings (German Society of Cardiology and the German Society of Internal Medicine) and two annual European meetings (European Society of Hypertension and European Society Cardiology) in 2015.

PARTICIPANTS

1064 physicians attending the European meetings were interviewed including 52.1% cardiologists, 29.2% internists and 8.8% general practitioners.

MAIN OUTCOME MEASURES

Physician screening of alcohol consumption, awareness and self-implementation of the recommendation of the current European guidelines about moderation of alcohol consumption for the management of hypertension.

RESULTS

Overall, 81.9% of physicians reported to generally quantify alcohol consumption in patients with hypertension. However, only 28.6% and 14.5% of participants reported screening alcohol consumption in their patients with newly detected or treatment-resistant hypertension. Physicians recommended a maximum alcohol intake of 13.1±11.7 g/day for women (95% CI 12.3 to 13.8) and 19.9±15.6 g/day for men (95% CI 18.8 to 20.9). In case of moderate to high alcohol consumption, 10.3% would manage only hypertension without addressing alcohol consumption, while 3.7% of the physicians would do so in case of alcohol dependence (p<0.001).

CONCLUSIONS

The average amount of alcohol intake per day recommended by European physicians in this survey was in agreement with the guidelines. The low number of physicians that screen for alcohol consumption in patients with newly detected and with treatment-resistant hypertension indicates an important deficit in the management of hypertension.

Thirst sensation and oral dryness following alcohol intake

Substantial acute and chronic intakes of alcohol or ethanol (EtOH) severely influence oral sensations, such as thirst and oral dryness (dry mouth, xerostomia). Thirst sensation and oral dryness are primarily caused by the activation of neurons in brain regions, including the circumventricular organs and hypothalamus, which are referred to as the dipsogenic center, and by a decrease in salivary secretion, respectively. The sensation of thirst experienced after heavy-alcohol drinking is widely regarded as a consequence of EtOH-induced diuresis; however, EtOH in high doses induces anti-diuresis. Recently, it has been proposed that the ethanol metabolite acetaldehyde induces thirst via two distinct processes in the central nervous system from EtOH-induced diuresis, based on the results of animal experiments. The present review describes new insights regarding the induction mechanism of thirst sensation and oral dryness after drinking alcohol.

Alcohol effects on cardiac function

The consumption of ethanol can have both beneficial and detrimental effects on the function of the heart and cardiovascular system, depending on the amount consumed. Low-to-moderate amounts of ethanol intake are associated with improvements in cardiac function and vascular health. On the other hand, ethanol chronically consumed in large amounts acts as a toxin to the heart and vasculature. The cardiac injury produced by chronic alcohol abuse can progress to heart failure and eventual death. Furthermore, alcohol abuse may exacerbate preexisting heart conditions, such as hypertension and cardiomyopathy. This article focuses on the molecular mechanisms and pathophysiology of both the beneficial and detrimental cardiac effects of alcohol.

Associations between aldehyde dehydrogenase 2 (ALDH2) genetic polymorphisms, drinking status, and hypertension risk in Japanese adult male workers: a case-control study

OBJECTIVES

We sought to identify associations between aldehyde dehydrogenase 2 (ALDH2), alcohol consumption, and hypertension in Japanese men.

METHODS

The study participants were 1,225 male Japanese workers. We collected lifestyle information, body measurements, blood biochemical parameters, blood pressure measurements, and ALDH2 genotyping data during medical examinations conducted between March 2004 and January 2005 at a work facility and an affiliated company. Lifestyle data on alcohol intake and smoking were collected using self-administered questionnaires at the same time as when the aforementioned measurements were obtained.

RESULTS

The genotype frequencies of ALDH2 genetic polymorphisms were 62.6, 32.7, and 4.7% for *1/*1, *1/*2, and *2/*2, respectively. Systolic blood pressure and diastolic blood pressure in the *1/*2 or *2/*2 group were significantly lower than those in the *1/*1 group (P < 0.001). Multiple regression analysis (stepwise method) for blood pressure according to ALDH2 genetic polymorphism revealed that the amount of daily alcohol intake affected systolic blood pressure in participants who harbored the ALDH2 genetic polymorphism *1/*2 or *2/*2.

CONCLUSIONS

The interaction between alcohol intake and ALDH2 genetic polymorphisms might affect systolic blood pressure in adult male workers.

Angiotensin type 1 receptor mediates chronic ethanol consumption-induced hypertension and vascular oxidative stress

OBJECTIVES

We hypothesized that chronic ethanol intake enhances vascular oxidative stress and induces hypertension through renin-angiotensin system (RAS) activation.

METHODS AND RESULTS

Male Wistar rats were treated with ethanol (20% v/v). The increase in blood pressure induced by ethanol was prevented by losartan (10mg/kg/day; p.o. gavage), a selective AT1 receptor antagonist. Chronic ethanol intake increased plasma renin activity (PRA), angiotensin converting enzyme (ACE) activity, plasma angiotensin I (ANG I) and angiotensin II (ANG II) levels and serum aldosterone levels. No differences on plasma osmolality and sodium or potassium levels were detected after treatment with ethanol. Ethanol consumption did not alter ACE activity, as well as the levels of ANG I and ANG II in the rat aorta or mesenteric arterial bed (MAB). Ethanol induced systemic and vascular oxidative stress (aorta and MAB) and these effects were prevented by losartan. The decrease on plasma and vascular nitrate/nitrite (NOx) levels induced by ethanol was prevented by losartan. Ethanol intake did not alter protein expression of ACE, AT1 or AT2 receptors in both aorta and MAB. Aortas from ethanol-treated rats displayed decreased ERK1/2 phosphorylation and increased protein expression of SAPK/JNK. These responses were prevented by losartan. MAB from ethanol-treated rats displayed reduced phosphorylation of p38MAPK and ERK1/2 and losartan did not prevent these responses.

CONCLUSIONS

Our study provides novel evidence that chronic ethanol intake increases blood pressure, induces vascular oxidative stress and decreases nitric oxide (NO) bioavailability through AT1-dependent mechanisms.

Alcohol-induced hypertension: Mechanism and prevention

Epidemiological, preclinical and clinical studies established the association between high alcohol consumption and hypertension. However the mechanism through which alcohol raises blood pressure remains elusive. Several possible mechanisms have been proposed such as an imbalance of the central nervous system, impairment of the baroreceptors, enhanced sympathetic activity, stimulation of the renin-angiotensin-aldosterone system, increased cortisol levels, increased vascular reactivity due to increase in intracellular calcium levels, stimulation of the endothelium to release vasoconstrictors and loss of relaxation due to inflammation and oxidative injury of the endothelium leading to inhibition of endothelium-dependent nitric oxide production. Loss of relaxation due to inflammation and oxidative injury of the endothelium by angiotensin II leading to inhibition of endothelium-dependent nitric oxide production is the major contributors of the alcohol-induced hypertension. For the prevention of alcohol-induced hypertension is to reduce the amount of alcohol intake. Physical conditioning/exercise training is one of the most important strategies to prevent/treat chronic alcohol-induced hypertension on physiological basis. The efficacious pharmacologic treatment includes the angiotensin-converting enzyme (ACE) inhibitors or angiotensin II type 1 receptor blockers (ARBs) which have antioxidant activity and calcium channel blockers. The most effective prevention and treatment of alcohol-induced hypertension is physical exercise and the use of ACE inhibitors or ARBs in the clinic

[Alcohol and acute respiratory distress syndrome: casuality or causality?]

Alcohol has been considered an important risk factor for the development of pneumonia since the last century. Nevertheless, it was not thought that it had relevant effects on lung structure and functions until recently. Recent studies have shown that the risk for acute respiratory distress syndrome (ARDS) is 2-4 times higher among alcoholic patients with sepsis or trauma, and that alcoholism can play a roll in more than 50% of cases in the pathogenesis of this syndrome. Although alcoholism per se does not cause acute lung injury it predisposes to pulmonary dysfunction after inflammatory stress, that is present in clinical situations that cause ARDS leading to its development and complicating its outcome. Recent investigations in animals and humans with alcohol abuse have uncovered several alterations currently known as the "alcoholic lung". This revision discusses the association between alcohol abuse and lung injury/ARDS and tries to explain the physiopathology along with possible treatments.

Deletion of angiotensin II type 1 receptor gene attenuates chronic alcohol-induced retinal ganglion cell death with preservation of VEGF expression

PURPOSE

To investigate how chronic alcohol consumption affects adult visual nervous system and whether renin-angiotensin system (RAS) is involved in this pathogenic process.

METHODS

Male transgenic mice with angiotensin II (Ang II) type 1 (AT1) receptor gene knockout (AT1-KO) and age-matched wild-type (WT) mice were pair-fed a modified Lieber-DeCarli alcohol or isocaloric maltose dextrin control liquid diet for 2 months. At the end of the study, retinas were harvested and subjected to histopathological and immunohistochemical examination.

RESULTS

We found that chronic alcohol consumption significantly increased retinal ganglion cell (RGC) apoptosis in the retina of WT mice, but not AT1-KO mice, detected by terminal deoxynucleotidyl-transferase-mediated dUTP-nick-end labeling staining and caspase 3 activation, along with an up-regulation of AT1 expression in RGC. At the same time, the phosphorylation of P53 in RGCs was significantly increased for both WT and AT1-KO mice exposed to alcohol, which could be significantly, although partially, prevented by AT1 gene deletion. We further examined the expression of vascular endothelial growth factor (VEGF) and CD31, and found that alcohol treatment significantly decreased the expression of VEGF and CD31 in RGCs of WT mice, but not AT1-KO mice.

CONCLUSION

Taken together, our study demonstrates that the induction of RGC apoptosis by chronic alcohol exposure may be related to p53-activation and VEGF depression, all which are partially dependent of AT1 receptor activation.

Low doses of ethanol decrease the activity of the angiotensin-converting enzyme in the aorta of aging rats and rats treated with a nitric oxide synthase inhibitor and dexamethasone

In the present study, the activity of ACE (angiotensin-converting enzyme) in the aorta of senescent rats and rats treated with the NOS (NO synthase) inhibitor L-NAME (NG-nitro-L-arginine methyl ester) or dexamethasone and the effect of low doses of ethanol (0.2-1.2 g/kg of body weight, daily for 8-12 days) on this activity were studied. We found that ACE activity increased with age and in response to L-NAME and dexamethasone treatment. Ethanol at a dose of 0.4 g/kg of body weight per day decreased ACE activity in the aorta of aged rats and of rats treated with L-NAME or dexamethasone to the level of activity in young control rats. The optimal ethanol dose (the dose inducing a maximum decrease in ACE activity) increased with increasing doses of dexamethasone: 0.4 g/kg of body weight per day at 30 μg of dexamethasone/kg of body weight and 0.8 g/kg of body weight per day at 100 μg of dexamethasone/kg of body weight. It was also found that optimal doses of ethanol increased the number of cells in the thymus of rats treated with dexamethasone. The optimal dose of ethanol of 0.4 g/kg of body weight per day, which induced a maximum decrease in ACE activity in rat aorta, corresponded to a dose of 30 g of ethanol/day, which, according to epidemiological data, produces a maximum decrease in the incidence of cardiovascular disease in humans. In conclusion, the decrease in ACE activity in vessels may be one of the main mechanisms of the beneficial effects of low doses of ethanol on human health.

PPARγ ligands regulate NADPH oxidase, eNOS, and barrier function in the lung following chronic alcohol ingestion

BACKGROUND

Chronic alcohol ingestion increases the incidence and severity of the acute respiratory distress syndrome (ARDS), where reactive species contribute to alveolar-capillary barrier dysfunction and noncardiogenic pulmonary edema. Previous studies demonstrated that chronic alcohol ingestion increased lung NADPH oxidase and endothelial nitric oxide synthase (eNOS) expression and that ligands for the peroxisome proliferator-activated receptor gamma (PPARγ) reduced NADPH oxidase expression. Therefore, we hypothesized that the PPARγ ligand, rosiglitazone, would attenuate alcohol-induced NADPH oxidase expression and pulmonary barrier dysfunction.

METHODS

C57Bl/6 mice were treated ± alcohol in drinking water (20% w/v) for 12 weeks. During the final week of alcohol treatment, mice were gavaged with rosiglitazone (10 mg/kg/d) or vehicle. Selected animals were treated twice with lipopolysaccharide (LPS, 2 mg/kg IP) prior to sacrifice. Pulmonary barrier dysfunction was estimated from protein content of bronchoalveolar lavage (BAL) fluid.

RESULTS

LPS treatment increased BAL protein in alcohol-fed but not control mice, and rosiglitazone attenuated LPS and alcohol-induced pulmonary barrier dysfunction. Alcohol- and LPS-induced increases in lung eNOS, Nox1, and Nox4 expression were attenuated by rosiglitazone. In vitro, alcohol (0.10% w/v) increased H(2)O(2) production, barrier dysfunction, eNOS, Nox1, and Nox4 expression in human umbilical vein endothelial cell (HUVEC) monolayers, effects also attenuated by rosiglitazone (10 μM). Alcohol-induced HUVEC barrier dysfunction was attenuated by inhibition of NOS or addition of the eNOS cofactor, tetrahydrobiopterin.

CONCLUSIONS

These results indicate that PPARγ activation reduced expression of eNOS, Nox1, Nox4, the production of reactive species, and barrier dysfunction caused by chronic alcohol ingestion and suggest that PPARγ represents a novel therapeutic target for strategies designed to reduce the risk of lung injury in patients with a history of chronic alcohol ingestion.

Bradykinin B2 receptor-dependent enhancement of enalapril-evoked hypotension in ethanol-fed female rats

Our previous studies showed that chronic ethanol feeding attenuates centrally (clonidine) evoked and potentiates peripherally (hydralazine) evoked hypotension in female rats. In this study, we investigated whether chronic ethanol (8 weeks, 5% wt/vol) alters hemodynamic responses elicited by angiotensin-converting enzyme (ACE) inhibition (enalapril) in telemetered female rats. Given the intimate interaction between ACE and bradykinin, studies were extended to investigate the role of bradykinin receptor (B2R) in ethanol-enalapril interaction. Compared with pair-fed controls, ethanol-fed female rats exhibited (1) higher renal expressions of ACE and B2R proteins and angiotensin II levels and (2) lower blood pressure. Pharmacological inhibition of ACE and B2R supports functional role for the higher levels of these 2 proteins in ethanol-fed rats because enalapril (10 mg/kg, intraperitoneally) caused significantly greater hypotensive response in ethanol-fed rats than in control rats. Further, blockade of B2R with bradyzide (2 mg/kg, intraperitoneally) abrogated the enhanced hypotensive effect of enalapril in ethanol-fed rats but had no effect on enalapril-evoked hypotension in control rats. Finally, enalapril enhancement of spontaneous baroreflex sensitivity (BRS) in control was absent in ethanol-fed rats. These findings demonstrate that chronic ethanol produces B2R-dependent enhancement of the hypotensive response elicited by enalapril and abrogates enalapril-evoked enhancement of spontaneous baroreflex response in female rats.

Alcohol-induced exacerbation of ischemic brain injury: role of NAD(P)H oxidase

BACKGROUND

 Chronic alcohol consumption increases ischemic stroke and exacerbates ischemic brain injury. We determined the role of NAD(P)H oxidase in exacerbated ischemic brain injury during chronic alcohol consumption.

METHODS

 Sprague Dawley rats were fed a liquid diet with or without alcohol (6.4% v/v) for 8 weeks. We measured the effect of apocynin on 2-hour middle cerebral artery occlusion (MCAO)/24-hour reperfusion-induced brain injury. In addition, superoxide production and expression of NAD(P)H oxidase subunit, gp91phox, in the peri-infarct area were assessed.

RESULTS

Chronic alcohol consumption produced a larger infarct volume, worse neurological score, and higher superoxide production. Acute (5 mg/kg, ip, 30 minutes before MCAO) and chronic treatment with apocynin (7.5 mg/kg/d in the diet, 4 weeks prior to MCAO) reduced infarct volume, improved neurological outcome, and attenuated superoxide production in alcohol-fed rats. Expression of gp91phox at basal conditions and following ischemia/reperfusion was greater in alcohol-fed rats compared to non-alcohol-fed rats. In addition, neurons are partially responsible for upregulated gp91phox during alcohol consumption.

CONCLUSIONS

Our findings suggest that NAD(P)H oxidase may play an important role in exacerbated ischemic brain injury during chronic alcohol consumption.

Alcohol abuse and acute lung injury: can we target therapy?

Recent studies have revealed an important but previously unrecognized association between alcohol abuse and the risk of acute respiratory distress syndrome (ARDS). This devastating form of lung injury strikes individuals of any age following insults, such as major trauma or sepsis, and even with state-of-the-art medical care it has a mortality as high as 50%. Although the precise incidence is unknown, it is estimated that 200,000 individuals develop ARDS each year in the USA alone. Alcohol abuse independently increases the risk approximately two- to fourfold and, therefore, causes tens of thousands of excess deaths annually. When one couples these grim estimates with the well-recognized association between alcohol abuse and severe lung infections, such as bacterial pneumonia and tuberculosis, it is apparent that alcohol-related lung diseases are a major public health problem. Exciting new studies reveal that the alcoholic lung is characterized by discrete changes in cellular function within the lower airways, mediated via oxidant stress and altered signaling pathways and, in experimental models, is highly amenable to targeted therapies. Furthermore, these therapies are already used clinically for other conditions and could readily be tested in clinical studies of alcoholics at high risk for ARDS and/or with severe lung infections. This article focuses on the epidemiology and pathophysiology of alcohol-induced lung dysfunction and discusses potential new treatments that are suggested by recent experimental findings.

Alcohol abuse and pulmonary disease

ARDS is a severe form of lung injury characterized by increased permeability of the alveolar capillary membrane, diffuse alveolar damage, the accumulation of proteinaceous interstitial and intra-alveolar edema, and the presence of hyaline membranes. These pathological changes are accompanied by physiological alterations, including severe hypoxemia, an increase in pulmonary dead space, and decreased pulmonary compliance. Approximately 200,000 individuals develop ARDS in the United States each year, and nearly 50% of these patients have a history of alcohol abuse. We have identified alcohol abuse as an independent risk factor for the development of ARDS, and more recent studies have validated these findings in patients following lung resection and blood transfusion. In ARDS survivors, alcohol abuse is also associated with an increased duration of mechanical ventilation and prolonged ICU length of stay. Despite studies aimed at improving outcomes in patients with ARDS, the mortality remains high at > 40%]. For those who abuse alcohol, the mortality is even higher, at 65%. In this review, we will discuss the relationship between alcohol abuse and ARDS, the effects of alcohol abuse on pulmonary function, and future directions and potential therapeutic targets for patients at risk for ARDS as a result of alcohol abuse, which impairs immune function, decreases pulmonary antioxidant capacity, decreases alveolar epithelial cell function, alters activation of the renin angiotensin system, and impairs GM-CSF signaling. These pathways represent potential therapeutic targets for patients at risk for ARDS as a result of alcohol abuse.

Influence of chronic alcohol consumption on inward rectifier potassium channels in cerebral arterioles

Inward rectifier potassium (K(IR)) channels appear to play an important role in the regulation of cerebral blood flow. Our goal was to examine the influence of chronic alcohol exposure on K(IR) channels in cerebral arterioles. Sprague-Dawley rats were fed liquid diets with or without alcohol for 8-12 weeks. Using intravital microscope, we measured diameter of pial arterioles in response to an inhibitor, BaCl(2), and an activator, KCl, of K(IR) channels in the absence and presence of a scavenger of reactive oxygen species, tempol, or an inhibitor of NAD(P)H oxidase, apocynin. Application of BaCl(2) (30 and 100 microM) produced dose-related vasoconstriction in non-alcohol-fed, but not in alcohol-fed rats. In addition, application of KCl (3, 10, and 30 mM) produced dose-related dilation in non-alcohol-fed and alcohol-fed rats, but the magnitude of vasodilatation was less in alcohol-fed rats. In contrast, nitroglycerin-induced vasodilation was similar in non-alcohol-fed and alcohol-fed rats. Superfusion of cranial window with tempol (0.1 mM) or apocynin (1 mM) did not alter baseline diameter and nitroglycerin-induced dilation of pial arterioles in non-alcohol-fed and alcohol-fed rats but significantly improved impaired KCl-induced dilation in alcohol-fed rats. Our findings suggest that chronic alcohol consumption impairs the role of K(IR) channels in basal tone and KCl-induced dilation of cerebral arterioles. In addition, impaired KCl-induced dilation of cerebral arterioles during alcohol consumption may be related to enhanced release of oxygen-derived free radicals via NAD(P)H oxidase.

Central Overexpression of Angiotensin AT1AReceptors Prevents Dopamine D2Receptor Regulation of Alcohol Consumption in Mice

BACKGROUND

While angiotensin receptors are found on the soma and terminals of dopaminergic neurons, controversy surrounds the potential role of angiotensin in alcohol consumption.

METHODS

Using a transgenic mouse with a brain-specific overexpression of angiotensin AT(1A) receptors (NSE-AT(1A) mice), we have examined the role of angiotensin in alcohol consumption and alcohol-induced regulation of the dopaminergic system.

RESULTS

The functional relevance of the overexpressed AT(1A) receptors was confirmed by an exaggerated rehydration response following 24-hour dehydration. NSE-AT(1A) mice showed a high preference for alcohol (similar to wild-type mice); yet, raclopride treatment had no effect on alcohol consumption in NSE-AT(1A) mice, while significantly reducing consumption in wild-type mice. In contrast, NSE-AT(1A) mice showed enhanced sensitivity to raclopride compared with wild types in terms of D(2) receptor up-regulation within the ventral mesencephalon. In addition, striatal D(2) receptors in NSE-AT(1A) mice were sensitive to up-regulation by chronic alcohol consumption.

CONCLUSIONS

Collectively, these data imply that while expression of angiotensin AT(1A) receptors on striatal neurons has no impact upon basal alcohol consumption or preference, AT(1A) receptors do modulate the sensitivity of dopamine D(2) receptors to regulation by alcohol and the ability of a D(2) receptor antagonist to reduce consumption.

Ethanol inhibitory effect on rat kidney brush border aminopeptidases

BACKGROUND/AIM

Confusing data have been reported about the effect of ethanol or its metabolic products on blood pressure. The pressor agent, angiotensin II (Ang II), is found to be susceptible to degradation by different enzymes known as angiotensinases. We have studied the effects of ethanol and L-NAME, an inhibitor of nitric oxide synthase, consumption on rat serum and kidney ectoenzymes: aminopeptidase N (APN) and aminopeptidase A (APA).

METHODS

Enzymatic activity of both enzymes was determined spectrophotometrically in serum and 10% homogenates of the rat kidney cortex using appropriate chromogenic substrates.

RESULTS

After 2 weeks of treatment with ethanol and L-NAME, blood urea and creatinine levels were significantly increased. The activities of APN (EC 3.4.11.2) and APA (EC 3.4.11.7) were reduced in serum as well as in kidney tissue during this period. L-NAME significantly attenuated activities of both enyzmes. Ethanol and L-NAME given simultaneously did not have an additional effect on the activity of investigated enzymes.

CONCLUSION

Hypertension caused by chronic ethanol treatment as well as L-NAME administration could be associated with the reduction of APN and APA activity. Possible ethanol- and L-NAME-mediated inhibition of angiotensins degrading aminopeptidases could potentiate their effects on blood pressure.

The alcoholic lung: epidemiology, pathophysiology, and potential therapies

Epidemiological evidence gathered only in the past decade reveals that alcohol abuse independently increases the risk of developing the acute respiratory distress syndrome by as much as three- to fourfold. Experimental models and clinical studies are beginning to elucidate the mechanisms underlying this previously unrecognized association and are revealing for the first time that chronic alcohol abuse causes discrete changes, particularly within the alveolar epithelium, that render the lung susceptible to acute edematous injury in response to sepsis, trauma, and other inflammatory insults. Recent studies in relevant animal models as well as in human subjects are identifying common mechanisms by which alcohol abuse targets both the alveolar epithelium and the alveolar macrophage, such that the risks for acute lung injury and pulmonary infections are inextricably linked. Specifically, chronic alcohol ingestion decreases the levels of the antioxidant glutathione within the alveolar space by as much as 80-90%, and, as a consequence, impairs alveolar epithelial surfactant production and barrier integrity, decreases alveolar macrophage function, and renders the lung susceptible to oxidant-mediated injury. These changes are often subclinical and may not manifest as detectable lung impairment until challenged by an acute insult such as sepsis or trauma. However, even otherwise healthy alcoholics have evidence of severe oxidant stress in the alveolar space that correlates with alveolar epithelial and macrophage dysfunction. This review focuses on the epidemiology and the pathophysiology of alcohol-induced lung dysfunction and discusses potential new treatments suggested by recent experimental findings.

Angiotensin II type 1 receptor blockade prevents alcoholic cardiomyopathy

BACKGROUND

Activation of the renin-angiotensin system (RAS) may contribute to the development of alcoholic cardiomyopathy. We evaluated the effect of angiotensin II (Ang II) type 1 receptor (AT1) blockade on the development of alcoholic cardiomyopathy.

METHODS AND RESULTS

We serially evaluated left ventricular (LV) and cardiomyocyte function and the RAS over 6 months in 3 groups of instrumented dogs. Eight animals received alcohol (once per day orally, providing 33% of total daily caloric intake); 6 received alcohol and irbesartan (5 mg.kg(-1).d(-1) PO); and 8 were controls. Compared with controls, alcohol ingestion caused sustained RAS activation with progressive increases in plasma levels of Ang II, renin activity, LV angiotensin-converting enzyme activity, and LV myocyte Ang II AT(1) receptor expression. The RAS activation was followed by a progressive fall in LV contractility (E(ES), alcohol-fed dogs 3.9+/-0.8 versus control dogs 8.1+/-1.0 mm Hg/mL); reductions in the peak velocity of myocyte shortening (78.9+/-5.1 versus 153.9+/-6.2 microm/s) and relengthening; and decreased peak systolic Ca2+ transient ([Ca2+]iT) and L-type Ca2+ current (I(Ca,L); P<0.05). Irbesartan prevented the alcohol-induced decreases in LV and myocyte contraction, relaxation, peak [Ca2+]iT, and I(Ca,L). With alcohol plus irbesartan, plasma Ang II, cardiac angiotensin-converting enzyme activity, and AT1 remained close to control values.

CONCLUSIONS

Chronic alcohol consumption produces RAS activation followed by progressive cardiac dysfunction. The cardiac dysfunction is prevented by AT1 receptor blockade.

Role of NAD(P)H oxidase in alcohol-induced impairment of endothelial nitric oxide synthase-dependent dilation of cerebral arterioles

BACKGROUND AND PURPOSE

Our goal was to determine whether NAD(P)H oxidase is involved in impaired endothelial nitric oxide synthase (eNOS)-dependent reactivity of cerebral arterioles during chronic alcohol consumption.

METHODS

Sprague-Dawley rats were fed with an alcohol diet for 2 to 3 months. We determined the effects of acute and chronic treatment with an NAD(P)H oxidase inhibitor, apocynin, on responses of pial arterioles to eNOS-dependent agonists (acetylcholine and ADP) and an eNOS-independent agonist (nitroglycerin). Expression of NAD(P)H oxidase in pial arterioles was measured with the use of real-time polymerase chain reaction and Western blot analysis, and superoxide production was measured with the use of lucigenin-enhanced chemiluminescence.

RESULTS

Vasodilation in response to acetylcholine and ADP, but not nitroglycerin, was significantly less in alcohol-fed rats. Treatment with apocynin did not alter vasodilation in non-alcohol-fed rats but significantly improved impaired vasodilation in alcohol-fed rats. In addition, an upregulation of p47phox in pial arterioles was found in alcohol-fed rats. Furthermore, alcohol consumption increased superoxide production under basal conditions and in the presence of ADP and NAD(P)H.

CONCLUSIONS

Our findings suggest that NAD(P)H oxidase plays a role in chronic alcohol consumption-induced impairment of eNOS-dependent dilation of cerebral arterioles.

Chronic ethanol ingestion increases superoxide production and NADPH oxidase expression in the lung

Alcohol abuse increases the incidence of acute respiratory distress syndrome and causes oxidative stress and cellular dysfunction in the lung. The mechanisms of ethanol (EtOH)-induced oxidative stress in the lung remain to be defined. Chronic alcohol ingestion has been associated with increased renin-angiotensin system (RAS) activity. Therefore, the current study investigated the ability of lisinopril, an angiotensin-converting enzyme (ACE) inhibitor, to modulate oxidative stress in the lung after chronic EtOH ingestion in a well-established rat model. Male Sprague-Dawley rats were fed liquid diets containing EtOH (36% of calories) or maltose-dextrin as an isocaloric substitution for EtOH (Control) for 6 wk. Selected animals were also treated with lisinopril (3 mg/liter) for 6 wk. Chronic EtOH ingestion increased bronchoalveolar lavage fluid glutathione disulfide levels and superoxide formation in lung parenchyma. These effects of EtOH were attenuated by lisinopril treatment. Chronic EtOH ingestion failed to increase ACE expression or angiotensin II levels in lung homogenates, but increased angiotensinogen, angiotensin II type 1 and type 2 receptor levels, and ACE activity. Chronic EtOH ingestion also increased the levels of the NADPH oxidase subunit, gp91phox, an effect that was attenuated by lisinopril, but had no effect on lung p22phox or p47phox levels. These findings suggest that EtOH-mediated RAS activation plays an important role in pulmonary oxidative stress and provide new insights into mechanisms by which EtOH causes oxidative stress in the lung and potential strategies of lung protection through ACE inhibition.

Alcohol abuse and acute lung injury: epidemiology and pathophysiology of a recently recognized association

Alcohol is the most commonly used and abused drug in the United States. The deleterious health effects of alcohol can be attributed both to its acute intoxicating effects, which result in temporary impairment of judgment and motor skills, and to its more chronic and toxic effects on the liver, pancreas, heart, and brain, all of which may result in irreversible organ damage. Although recognized for more than a century as a major risk factor for pneumonia, alcohol abuse was until recently perceived to have no significant effects on lung structure and/or function. However, within the past decade, epidemiologic studies have revealed that alcohol abuse independently increases the risk of acute respiratory distress syndrome (ARDS) two- to fourfold in patients with sepsis or trauma and may play a role in ARDS pathogenesis in as many as half of all patients with the syndrome. Although alcohol abuse alone does not cause acute lung injury, it renders the lung susceptible to dysfunction in response to the inflammatory stresses of sepsis, trauma, and other clinical conditions recognized to cause ARDS. Recent investigations in both animal models of chronic ethanol ingestion and in human subjects with a history of alcohol abuse have explored this previously unrecognized connection between alcohol and acute lung injury and have uncovered multiple derangements, which we now characterize as the "alcoholic lung." This review summarizes the epidemiologic association between alcohol abuse and acute lung injury and the recent experimental findings that are unraveling the underlying pathophysiology.

Angiotensin II mediates glutathione depletion, transforming growth factor-beta1 expression, and epithelial barrier dysfunction in the alcoholic rat lung

Alcohol abuse markedly increases the risk of sepsis-mediated acute lung injury. In a rat model, ethanol ingestion alone (in the absence of any other stress) causes pulmonary glutathione depletion, increased expression of transforming growth factor-beta1 (TGF-beta1), and alveolar epithelial barrier dysfunction, even though the lung appears grossly normal. However, during endotoxemia, ethanol-fed rats release more activated TGF-beta1 into the alveolar space where it can exacerbate epithelial barrier dysfunction and lung edema. Ethanol ingestion activates the renin-angiotensin system, and angiotensin II is capable of inducing oxidative stress and TGF-beta1 expression. We determined that lisinopril, an angiotensin-converting enzyme inhibitor that decreases angiotensin II formation, limited lung glutathione depletion, and treatment with either lisinopril or losartan, a selective angiotensin II type 1 receptor blocker, normalized TGF-beta1 expression. The glutathione precursor procysteine also prevented TGF-beta1 expression, suggesting that TGF-beta1 may be induced indirectly by angiotensin II-mediated oxidative stress and glutathione depletion. Importantly, lisinopril treatment normalized barrier function in alveolar epithelial cell monolayers from ethanol-fed rats, and treatment with either lisinopril or losartan normalized alveolar epithelial barrier function in ethanol-fed rats in vivo, as reflected by lung liquid clearance of an intratracheal saline challenge, even during endotoxemia. In parallel, lisinopril treatment limited TGF-beta1 protein release into the alveolar space during endotoxemia. Together, these results suggest that angiotensin II mediates oxidative stress and the consequent TGF-beta1 expression and alveolar epithelial barrier dysfunction that characterize the alcoholic lung.

Chronic ethanol intake modifies renin-angiotensin system-regulating aminopeptidase activities in mouse cerebellum

In developing cerebellum, where critical periods of vulnerability have been established for several basic substances, it has been extensively studied the wide array of abnormalities induced by exposure to ethanol (EtOH). However, little is known about the effects of EtOH consumption on cerebellar functions in adult individuals. Several studies show participation in cognitive activities to be concentrated in the lateral cerebellum (hemispheres), whereas basic motor functions such as balance and coordination are represented in the medial parts of the cerebellum (vermis and paravermis). In addition to the circulating renin angiotensin system (RAS), a local system has been postulated in brain. The effector peptides of the RAS are formed via the activity of several aminopeptidases (AP). The present work analyses the effect of chronic EtOH intake on the RAS-regulating AP activities in the soluble and membrane-bound fractions of two cerebellar locations: the hemispheres and the vermis. We hypothesize that cerebellar RAS is involved in basic motor functions rather than in cognitive activities.

MAP kinase signaling in diverse effects of ethanol

Chronic ethanol abuse is associated with liver injury, neurotoxicity, hypertension, cardiomyopathy, modulation of immune responses and increased risk for cancer, whereas moderate alcohol consumption exerts protective effect on coronary heart disease. However, the signal transduction mechanisms underlying these processes are not well understood. Emerging evidences highlight a central role for mitogen activated protein kinase (MAPK) family in several of these effects of ethanol. MAPK signaling cascade plays an essential role in the initiation of cellular processes such as proliferation, differentiation, development, apoptosis, stress and inflammatory responses. Modulation of MAPK signaling pathway by ethanol is distinctive, depending on the cell type; acute or chronic; normal or transformed cell phenotype and on the type of agonist stimulating the MAPK. Acute exposure to ethanol results in modest activation of p42/44 MAPK in hepatocytes, astrocytes, and vascular smooth muscle cells. Acute ethanol exposure also results in potentiation or prolonged activation of p42/44MAPK in an agonist selective manner. Acute ethanol treatment also inhibits serum stimulated p42/44 MAPK activation and DNA synthesis in vascular smooth muscle cells. Chronic ethanol treatment causes decreased activation of p42/44 MAPK and inhibition of growth factor stimulated p42/44 MAPK activation and these effects of ethanol are correlated to suppression of DNA synthesis, impaired synaptic plasticity and neurotoxicity. In contrast, chronic ethanol treatment causes potentiation of endotoxin stimulated p42/44 MAPK and p38 MAPK signaling in Kupffer cells leading to increased synthesis of tumor necrosis factor. Acute exposure to ethanol activates pro-apoptotic JNK pathway and anti-apoptotic p42/44 MAPK pathway. Apoptosis caused by chronic ethanol treatment may be due to ethanol potentiation of TNF induced activation of p38 MAPK. Ethanol induced activation of MAPK signaling is also involved in collagen expression in stellate cells. Ethanol did not potentiate serum stimulated or Gi-protein dependent activation of p42/44 MAPK in normal hepatocytes but did so in embryonic liver cells and transformed hepatocytes leading to enhanced DNA synthesis. Ethanol has a 'triangular effect' on MAPK that involve direct effects of ethanol, its metabolically derived mediators and oxidative stress. Acetaldehyde, phosphatidylethanol, fatty acid ethyl ester and oxidative stress, mediate some of the effects seen after ethanol alone whereas ethanol modulation of agonist stimulated MAPK signaling appears to be mediated by phosphatidylethanol. Nuclear MAPKs are also affected by ethanol. Ethanol modulation of nuclear p42/44 MAPK occurs by both nuclear translocation of p42/44 MAPK and its activation in the nucleus. Of interest is the observation that ethanol caused selective acetylation of Lys 9 of histone 3 in the hepatocyte nucleus. It is plausible that ethanol modulation of cross talk between phosphorylation and acetylations of histone may regulate chromatin remodeling. Taken together, these recent developments place MAPK in a pivotal position in relation to cellular actions of ethanol. Furthermore, they offer promising insights into the specificity of ethanol effects and pharmacological modulation of MAPK signaling. Such molecular signaling approaches have the potential to provide mechanism-based therapy for the management of deleterious effects of ethanol or for exploiting its beneficial effects.

Chronic ethanol ingestion increases expression of the angiotensin II type 2 (AT2) receptor and enhances tumor necrosis factor-alpha- and angiotensin II-induced cytotoxicity via AT2 signaling in rat alveolar epithelial cells

BACKGROUND

Alcohol abuse increases the risk of acute lung injury in critically ill patients. We have shown that alveolar epithelial cell (AEC) apoptosis in response to inflammatory mediators, including tumor necrosis factor-alpha (TNF-alpha), parallels endotoxin-mediated acute lung injury in ethanol-fed rats. Although angiotensin II mediates TNF-alpha-induced apoptosis of AECs in vitro, its role in ethanol-mediated susceptibility to AEC apoptosis is unknown.

METHODS

Adult male rats were fed the Lieber-DeCarli diet for 6 weeks. AECs were isolated, and TNF-alpha- and angiotensin II-induced cytotoxicity (by terminal transferase-mediated dUTP nick end labeling staining) was determined with or without the addition of the angiotensin-converting enzyme inhibitor (lisinopril) or a selective blocker of the angiotensin II type 1 receptor (AT(1)) or type 2 receptor (AT(2)). Finally, the relative expression of the AT(1) and AT(2) receptors in AECs was determined by Western blot analysis.

RESULTS

TNF-alpha-induced cytotoxicity, but not angiotensin II-induced cytotoxicity, was prevented by lisinopril, indicating that de novo angiotensin II synthesis is required for TNF-alpha-induced apoptosis in these cells. Both TNF-alpha- and angiotensin II-induced cytotoxicity in AECs from control-fed and ethanol-fed rats were inhibited by the selective AT(2) blocker, PD123319, but not by the selective AT(1) blocker, losartan. In parallel, ethanol ingestion doubled AT(2) expression in AECs (by Western blot) but had no significant effect on AT(1) receptor expression.

CONCLUSIONS

Chronic ethanol ingestion increases AT(2) expression in the alveolar epithelium and enhances TNF-alpha- and angiotensin II-induced cytotoxicity, both of which act via AT(2). Together, these findings suggest that selective AT(2) receptor inhibition could limit the development of acute lung injury in alcoholic patients.

Bicuculline sensitive depressor response to ethanol infusion into the lateral hypothalamus

Decreased GABA function in the hypothalamus increases mean arterial pressure (MAP) and heart rate (HR). Since ethanol acts on GABA-A receptors, blocking GABA-A receptors can prevent a decrease of MAP and HR by ethanol in the lateral hypothalamus (LH). Ethanol at 5-30 mM, with or without 25 ng/microl bicuculline, was infused into the LH, and the activity of the site was validated with 100 nmoles of serotonin. Male rats were anesthetized with pentobarbital, and the femoral artery was catheterized to measure MAP and HR. Microinfusion was performed with a 28-gauge cannula placed into the LH. Serotonin increased MAP and HR within 15 sec. Ethanol decreased the MAP by -21.15 +/- 3.92 mmHg and HR by -53.61 +/- 14.95 BPM, at 15 min, which recovered by 15 min after the infusion was terminated. These maximum decreases were produced by 20 mM ethanol giving a U-shaped dose response. The aCSF vehicle had no effect. Bicuculline prevented ethanol-induced changes and had no effect when administered alone. Both serotonin and ethanol have direct effects on LH neurons with cardiovascular function. Ethanol produces this effect through GABA-A receptors.

Changes in angiotensin II receptors in dopamine-rich regions of the mouse brain with age and ethanol consumption

The density of angiotensin II (Ang II) receptors was determined in three dopaminergic nerve terminal-rich brain regions (caudate putamen, nucleus accumbens, and ventral pallidum) of mice that were given either water (control) or 20% w/v ethanol (EtOH) to drink for either 2-8 weeks (young) or 46 weeks (old). The receptors were labeled with 125I-sarcosine1, isoleucine8 angiotensin II (125I-SI Ang II) and measured by quantitative densitometric image analysis (receptor autoradiography) or by saturation binding assays on homogenates of these brain regions. The selective AT2 receptor subtype antagonist PD 123319 (10 microM) was used to inhibit 125I-SI Ang II binding to AT2 receptors to determine AT1 receptor density in brain sections. In young control mice the density of Ang II receptor binding sites in the caudate putamen was 407+/-26 fmol/g, in the nucleus accumbens the density was 346+/-27 fmol/g, and in the ventral pallidum the density was 317+/-27 fmol/g. Less than 5% of specific 125I-SI Ang II binding was displaced by PD 123319, suggesting that nearly all of the Ang II receptors in these brain regions were the AT1 subtype. The Bmax in homogenates of these three regions in young control mice was 11.0+/-2.1 fmol/mg protein. The KD was 0.49+/-0.13. Ang II receptors in old mouse brains were decreased, respectively, by 32%, 35% and 30% in the caudate putamen, nucleus accumbens and ventral pallidum (p<0.001). Ang II receptors were slightly, but not significantly increased in both young and old EtOH-consuming mice.

Effects of daily alcohol intake on the blood pressure differ depending on an individual's sensitivity to alcohol: oriental flushing as a sign to stop drinking for health reasons

OBJECTIVE

To determine whether flushing of the facial skin in response to alcohol consumption (alcohol flushing) is a warning sign of hypertension. We also sought the relationship between alcohol flushing and other risk factors that may contribute to the development of hypertension.

METHODS

We first investigated the relationship of the aldehyde dehydrogenase 2 (ALDH2) genotype to alcohol flushing for 53 normal volunteers. We evaluated the relationships among hypertension, alcohol consumption, and facial flushing for 1011 middle-aged Japanese men (aged 40-68 years; mean 51.6 +/- 5.5 years), on the basis of their responses to questionnaires and health records.

RESULTS

The first examination of 53 normal volunteers showed that there were differences in the degree of alcohol flushing between the ALDH2 genotypes (P < 0.01). Hypertension was observed in 27.4% of the study population (277 of 1011), and was correlated positively to alcohol consumption (P < 0.01). The prevalence of hypertension differed significantly among these four groups: there was a 22.4% prevalence (70 of 312) among subjects with no flushing, a 33.8% prevalence (113 of 334) among those with slight flushing, a 27% prevalence (84 of 311) among those with visible flushing, and an 18.5% prevalence (10 of 54) among subjects who were almost completely intolerant to alcohol (P < 0.05). In particular, heavy drinkers who consumed > or = 1.5 Go (a traditional Japanese unit equivalent to 27 g ethanol) a day had a high prevalence of hypertension with slight and visible skin flushing [42% (63 of 150) and 40.7% (24 of 59), respectively]. That a family history of hypertension, greater age, heavy alcohol consumption, obesity, and symptoms of intoxication including flushing were correlated significantly to the prevalence of hypertension for all groups was demonstrated by multiple logistic regression analysis (P < 0.05).

CONCLUSIONS

A repeated heavy alcohol intake could increase the risk of hypertension for Japanese subjects who exhibit skin flushing in response to alcohol consumption. Chronic alcohol intake by subjects with alcohol flushing might bring about a significant increase in blood acetaldehyde levels and cause an additional rise in the blood pressure.

A vasoactive serum component and reactivity of isolated rat aorta after chronic alcohol administration

Norepinephrine-induced contractility and relaxation to acetylcholine of isolated aortas taken from normal and chronic alcoholic rats were measured. Similar experiments were performed adding serum from normal (NS) or alcoholic rats (AS), with or without norepinephrine and acetylcholine. Responses of normal and alcoholic aortas to agonists were comparable. NS and AS induced contractions on normal aorta, but the responses of alcoholic aortas were lower; contractions induced by AS on both aortas were larger than those induced by NS. AS decreased verapamil-induced relaxation more than NS. A pressor circulating factor might be responsible.

Interaction of acetaldehyde with plasma proteins of the renin-angiotensin system

Chronic alcohol abuse may lead to hypertension by stimulating the activity of the renin angiotensin system (RAS). While there are reports on the alcohol associated increase of angiotensin II in rats and increases of plasma renin activity in rats and human alcoholics, the exact mechanisms of stimulation of the RAS activity is not clear. This study provides evidence for a biochemical interaction of acetaldehyde, the primary oxidative metabolite of ethanol, upon bilaterally nephrectomized (NEPEX) rat plasma that contains significant quantities of angiotensinogen and lacks active renin. Rat plasma served as the source of renin in this study. Preincubation of NEPEX plasma with 0.2 M acetaldehyde at 4 degrees C for 2 h resulted in a 21% increase in the angiotensin I (A I) formation by the rat plasma renin and 27% increase in the A I formation by the trypsinized rat plasma renin. When the rat plasma which contains modest quantities of endogenous angiotensinogen in addition to renin was preincubated with 0.2 M acetaldehyde at 4 degrees C for 2 h, the rate of A I formation was increased by 10%. Equivalent amounts of ethanol did not modify the rate of A I generation when added to NEPEX plasma or rat plasma. These results suggest the possibility of a biochemical interaction of acetaldehyde with the renin substrate which may enhance the activity of the RAS cascade, thereby contributing to hypertension in chronic alcoholics.

Dietary salt and voluntary ethanol consumption in golden hamsters

Adult male golden hamsters were maintained on powdered Purina chow and tap water, and were permitted continuous access to either a 15% or a 30% ethanol solution (v/v); after an initial 4-5 weeks of ethanol availability, hamsters had stabilized their intakes and were deriving an average of 1.25 and 1.96 g/day of absolute ethanol from the 15% and 30% solutions, respectively. When salt was added to the diet in increasing concentrations ranging from 4% to 10% over a period of 40 days, hamsters reduced chow-derived calories by up to 35%, increased tap water consumption by up to 50%, and increased consumption of ethanol solutions by up to 100%; when unadulterated Purina chow was reinstated, intakes of chow-derived calories, tap water, and ethanol solutions returned to baseline levels. Hamsters that were continuously maintained on unadulterated Purina chow, but with chow-derived calories matched to that of animals on the salt-adulterated diet, significantly increased their ethanol intake, but not their tap water intake; the increase in their ethanol intake was only about half as large as that of hamsters that had salt added to the diet, but the increase persisted even after ad lib feeding was reinstated. The results indicate that the addition of salt to the diet of hamsters produces large increases in ethanol consumption; furthermore, the increased ethanol intake is not simply the result either of a nonselective increase in fluid consumption or of the reduction in food intake that accompanies the addition of salt to the diet. Results are related to the possible role of the renin-angiotensin system in the control of ethanol consumption in the golden hamster.

Brain angiotensin receptor subtypes in the control of physiological and behavioral responses

This review summarizes emerging evidence that supports the notion of a separate brain renin-angiotensin system (RAS) complete with the necessary precursors and enzymes for the formation and degradation of biologically active forms of angiotensins, and several binding subtypes that may mediate their diverse functions. Of these subtypes the most is known about the AT1 site which preferentially binds angiotensin II (AII) and angiotensin III (AIII). The AT1 site appears to mediate the classic angiotensin responses concerned with body water balance and the maintenance of blood pressure. Less is known about the AT2 site which also binds AII and AIII and may play a role in vascular growth. Recently, an AT3 site was discovered in cultured neoblastoma cells, and an AT4 site which preferentially binds AII(3-8), a fragment of AII now referred to as angiotensin IV (AIV). The AT4 site has been implicated in memory acquisition and retrieval, and the regulation of blood flow. In addition to the more well-studied functions of the brain RAS, we review additional less well investigated responses including regulation of cellular function, the modulation of sensory and motor systems, long term potentiation, and stress related mechanisms. Although the receptor subtypes responsible for mediating these physiologies and behaviors have not been definitively identified research efforts are ongoing. We also suggest potential contributions by the RAS to clinically relevant syndromes such as dysfunctions in the regulation of blood flow and ischemia, changes in cognitive affect and memory in clinical depressed and Alzheimer's patients, and angiotensin's contribution to alcohol consumption.

Reduction of voluntary alcohol consumption in the rat by transplantation of hypothalamic grafts

Stimulation of the peripheral renin-angiotensin system has been shown previously to decrease the voluntary intake of ethanol in the rat. The existence of a separate brain renin-angiotensin system, independent from that of the periphery, has been widely demonstrated. The brain renin-angiotensin system plays an important role in the regulation of water and electrolyte balance and neuroendocrine function. However, the role played by this system in the regulation of voluntary alcohol consumption has not yet been studied. The goal of the present work was to assess the feasibility of decreasing the voluntary alcohol intake in a strain of rats (Rapp SS/Jr rats) that have a genetic deficiency responsible for a low activity of the renin-angiotensin system and elevated alcohol intake. Adult Rapp SS/Jr rats received intraventricular transplants of fetal hypothalamic grafts (from normal donors), known to contain angiotensin-immunoreactive cell bodies. Our studies revealed that angiotensin-immunoreactivity in the cell bodies and fibres in the paraventricular, supraoptic and suprachiasmatic nuclei of the hypothalamus in Rapp SS/Jr rats was markedly reduced. Animals that had surviving grafts containing angiotensin-immunoreactive cell bodies in the dorsal third ventricle--but not in the ventral third ventricle, in the lateral ventricles, or sham operated animals--had a 40% decrease of their voluntary alcohol intake, when compared to their intake before surgery, or to the control group. However, water consumption was not reduced in both the sham and transplanted animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Neuroendocrine, fluid balance, and thirst responses to alcohol in alcoholics

This study simultaneously evaluated multiple circulating neurohormones, osmolality, thirst, and fluid balance in eight actively drinking, alcoholic males and seven controls before and 12 hr after an ethanol challenge. Basal levels of serum osmolality and thirst were significantly higher in alcoholics compared with controls, yet actively drinking alcoholics at the start of the study had normal vasopressin (AVP) levels, plasma angiotensin II (Ang II), plasma renin activity, plasma aldosterone (Aldo), and plasma catecholamines. In response to ethanol, serum osmolalities rose significantly higher while plasma AVP levels became significantly suppressed in alcoholics. After the ethanol stimulus, plasma Ang II levels of alcoholics were significantly higher than those of controls at 11 AM (12.15 +/- 4.49 vs. 1.83 +/- 0.6 pg/ml, p less than 0.02) and 12 noon (14.93 +/- 6.81 vs. 1.37 +/- 0.17 pg/ml, p less than 0.04). Neither plasma renin activity nor Aldo changed in accordance with the elevated plasma Ang II in alcoholics. Diuresis in the alcoholics, assessed by the sum of urine output following the challenge dose, was significantly less than that of controls. Thirst scores and fluid intakes after the ethanol challenge did not differ between alcoholics and controls. The lack of an Ang II-mediated increase in plasma Aldo or thirst response suggests that ethanol may have a specific blunting effect on Ang II receptors. This study demonstrates that ethanol can be used as a provocative test in chronic alcoholics to uncover aberrant hormonal responses for two systems, namely, Ang II and AVP.(ABSTRACT TRUNCATED AT 250 WORDS)

The amino acid composition of angiotensin alters its ability to reduce alcohol consumption in rats

The voluntary consumption of alcohol has been shown to be reduced by a variety of manipulations which enhance activity in the renin-angiotensin system, including the administration of the bovine form of angiotensin II-[Val5]-ANG II. The present study investigated the relationship between the amino acid composition of angiotensin II and its ability to reduce alcohol intake by administering a number of different forms or fragments of the parent peptide. [Ile5]-Angiotensin II ([Ile5]-ANG II), two endogenous fragments of angiotensin II [( Des-Asp1]-ANG II and [Des-Phe8]-ANG II) were administered subcutaneously in rats across a range of doses. [Ile5]-ANG II reduced alcohol intake at all doses tested between 20 and 400 micrograms/kg while [Des-Asp1]-ANG II reduced alcohol intake only at the 400 micrograms/kg dose. [Des-Phe8]-ANG II had no effect on alcohol intake at any dose tested. Administration of the antagonist [Sar1-Thr8]-ANG II by itself did not enhance alcohol intake. While the pressor and dipsogenic properties of these fragments sometimes correlated with the reduction in alcohol intake they were not a causal factor in decreasing the intake. These results indicate that variations in the peptide composition of angiotensin can significantly alter its ability to reduce the consumption of alcohol.

Regulation of alcohol consumption by the renin-angiotensin system: a review of recent findings and a possible mechanism of action

The renin-angiotensin system has traditionally been associated with the regulation of fluid and electrolyte balance. In this review we summarize the data which ascribes a completely new function to this system, i.e., the regulation of alcohol consumption. In addition, we suggest a possible mechanism for this effect based on the concept of a satiety or stop process. The approach taken was to examine the effect on alcohol intake of a wide variety of drug, genetic, dietary, surgical and neurosurgical manipulations, each of which has a range of biological effects characteristic of that manipulation, but all of which share the common property of altering activity in the renin-angiotensin system. The effect of these manipulations on alcohol intake was most parsimoniously explained by reference to their ability to raise or lower activity in the renin-angiotensin system. Any intervention which modulates activity in this system, either directly or indirectly, is likely to have consequences for alcohol consumption.

Effects of the novel compound Hoe 065, a central enhancer of cholinergic activity, on voluntary alcohol consumption in rats

Hoe 065 is a compound structurally related to the angiotensin converting enzyme inhibitors and capable of increasing central cholinergic activity. The effects of this compound were studied on alcohol intake and on the reduction in alcohol intake produced by abutapril, an angiotensin converting enzyme inhibitor. Hoe 065 failed to alter alcohol intake or to modify the reduction in alcohol intake produced by abutapril. These findings suggest that enhanced cholinergic activity may not play a role in the control of alcohol consumption and may not be part of the mechanism by which the angiotensin converting enzyme inhibitors reduce alcohol intake.