Alcohol-induced blood?brain barrier dysfunction is mediated via inositol 1,4,5-triphosphate receptor (IP3R)-gated intracellular calcium release

Alcohol diminishes barrier integrity in human stem cell-derived brain microvascular endothelial cells: Role of reactive oxygen species

The World Health Organization has linked alcohol consumption to over 200 diseases including neurodegenerative diseases. A dysfunctional blood-brain barrier (BBB) has been found to be influential in a number of brain disorders. The BBB is critical in maintaining homeostasis between the brain vasculature and parenchyma and a loss in barrier integrity would enable otherwise impermeable immune cells, molecules, and inflammatory mediators to reach the brain parenchyma. A subset of studies demonstrated that alcohol could diminish BBB integrity, but it is unclear if this effect translates clinically. In this study, we utilize a human stem cell-derived BBB model with near in vivo properties to investigate the effects of alcohol on critical barrier properties. Barrier forming brain-like microvascular endothelial cells (BMECs) were derived from human induced pluripotent stem cells (iPSCs) and exposed to several alcohol concentrations. Alcohol decreased barrier integrity observed by a loss in trans-endothelial electrical resistance and an increase in sodium fluorescein permeability. Alcohol decreased expression and junctional localization of tight junction proteins, a critical component to barrier integrity. Additionally, alcohol did not affect efflux transporter activity or cell viability in BMECs. The detrimental effects of alcohol on BBB properties were due to in part elevated reactive oxygen species (ROS); as scavenging ROS improved barrier properties, including the restoration of tight junction expression and localization. These data suggest that excessive alcohol consumption could diminish the BBB and contribute to the development or exacerbation of brain disorders. CLINICAL TRIAL NUMBER AND REGISTRY URL: Not applicable.

Structural and Functional Dysregulation of the Brain Endothelium in HIV Infection and Substance Abuse

Blood-brain barrier (BBB) injury and dysfunction following infection with the human immunodeficiency virus (HIV) enables viral entry into the brain, infection of resident brain cells, neuronal injury and subsequent neurodegeneration leading to HIV-associated neurocognitive disorders (HAND). Although combination antiretroviral therapy has significantly reduced the incidence and prevalence of acquired immunodeficiency syndrome and increased the life expectancy of people living with HIV, the prevalence of HAND remains high. With aging of people living with HIV associated with increased comorbidities, the prevalence of HIV-related central nervous system (CNS) complications is expected to remain high. Considering the principal role of the brain endothelium in HIV infection of the CNS and HAND, the purpose of this manuscript is to review the current literature on the pathobiology of the brain endothelium structural and functional dysregulation in HIV infection, including in the presence of HIV-1 and viral proteins (gp120, Tat, Nef, and Vpr). We summarize evidence from human and animal studies, in vitro studies, and associated mechanisms. We further summarize evidence of synergy or lack thereof between commonly abused substances (cocaine, methamphetamine, alcohol, tobacco, opioids, and cannabinoids) and HIV- or viral protein-induced BBB injury and dysfunction.

The Influence of Arsenic Co-Exposure in a Model of Alcohol-Induced Neurodegeneration in C57BL/6J Mice

Both excessive alcohol consumption and exposure to high levels of arsenic can lead to neurodegeneration, especially in the hippocampus. Co-exposure to arsenic and alcohol can occur because an individual with an Alcohol Use Disorder (AUD) is exposed to arsenic in their drinking water or food or because of arsenic found directly in alcoholic beverages. This study aims to determine if co-exposure to alcohol and arsenic leads to worse outcomes in neurodegeneration and associated mechanisms that could lead to cell death. To study this, mice were exposed to a 10-day gavage model of alcohol-induced neurodegeneration with varying doses of arsenic (0, 0.005, 2.5, or 10 mg/kg). The following were examined after the last dose of ethanol: (1) microglia activation assessed via immunohistochemical detection of Iba-1, (2) reactive oxygen and nitrogen species (ROS/RNS) using a colorimetric assay, (3) neurodegeneration using Fluoro-Jade® C staining (FJC), and 4) arsenic absorption using ICP-MS. After exposure, there was an additive effect of the highest dose of arsenic (10 mg/kg) in the dentate gyrus of alcohol-induced FJC+ cells. This additional cell loss may have been due to the observed increase in microglial reactivity or increased arsenic absorption following co-exposure to ethanol and arsenic. The data also showed that arsenic caused an increase in CYP2E1 expression and ROS/RNS production in the hippocampus which could have independently contributed to increased neurodegeneration. Altogether, these findings suggest a potential cyclical impact of co-exposure to arsenic and ethanol as ethanol increases arsenic absorption but arsenic also enhances alcohol's deleterious effects in the CNS.

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.

Therapeutic strategies of small molecules in the microbiota-gut-brain axis for alcohol use disorder

The microbiota-gut-brain axis (MGBA) is important in maintaining the structure and function of the central nervous system (CNS) and is regulated by the CNS environment and signals from the peripheral tissues. However, the mechanism and function of the MGBA in alcohol use disorder (AUD) are still not completely understood. In this review, we investigate the underlying mechanisms involved in the onset of AUD and/or associated neuronal deficits and create a foundation for better treatment (and prevention) strategies. We summarize recent reports focusing on the alteration of the MGBA in AUD. Importantly, we highlight the properties of small-molecule short-chain fatty acids (SCFAs), neurotransmitters, hormones, and peptides in the MGBA and discusses their usage as therapeutic agents against AUD.

Hsp90 protected chicken primary myocardial cells from heat-stress injury by inhibiting oxidative stress and calcium overload in mitochondria

Severe heat stress can cause human and animal heart failure and sudden death, which is an important issue of public health worldwide. Our previous studies in animals showed that myocardial cells injury was critical in the above process, and Hsp90 induction has a definite anti-myocardial injury effect, especially through aspirin (ASA). But the mechanism has not been fully clarified. In this study, an in vitro heat stress model of chicken primary myocardial cells (CPMCs) most sensitive to heat stress was used to explore the cell injuries and corresponding molecular resistance mechanism. We found that heat stress resulted in serious oxidation stress and calcium overload in mitochondria, which destroyed the mitochondrial structure and function and then triggered the cell death mechanism of CPMCs. Hsp90 was proven to be a central regulator for resisting heat-stress injury in CPMCs mitochondria using its inhibitor and inducer (geldanamycin and ASA), respectively. The mechanism involved that Hsp90 could activate Akt and PKM2 signals to promote Bcl-2 translocation into mitochondria and its phosphorylation, thereby preventing ROS production and subsequent cell apoptosis. In addition, Hsp90 inhibited mitochondrial calcium overload to overcome MPTP opening and MMP suppression through the inhibitory effect of Raf-1-ERK activation on the CREB-IP3R pathway. This study is the first to reveal a pivotal reason for heat-stressed damage in chicken myocardial cells at subcellular level and identify an effective regulator, Hsp90, and its protective mechanisms responsible for maintaining mitochondrial homeostasis.

Involvement of TRPM7 in Alcohol-Induced Damage of the Blood-Brain Barrier in the Presence of HIV Viral Proteins

Ethanol (EtOH) exerts its effects through various protein targets, including transient receptor potential melastatin 7 (TRPM7) channels, which play an essential role in cellular homeostasis. We demonstrated that TRPM7 is expressed in rat brain microvascular endothelial cells (rBMVECs), the major cellular component of the blood-brain barrier (BBB). Heavy alcohol drinking is often associated with HIV infection, however mechanisms underlying alcohol-induced BBB damage and HIV proteins, are not fully understood. We utilized the HIV-1 transgenic (HIV-1Tg) rat to mimic HIV-1 patients on combination anti-retroviral therapy (cART) and demonstrated TRPM7 expression in rBMVECs wass lower in adolescent HIV-1Tg rats compared to control animals, however control and HIV-1Tg rats expressed similar levels at 9 weeks, indicating persistent presence of HIV-1 proteins delayed TRPM7 expression. Binge exposure to EtOH (binge EtOH) decreased TRPM7 expression in control rBMVECs in a concentration-dependent manner, and abolished TRPM7 expression in HIV-1Tg rats. In human BMVECs (hBMVECs), TRPM7 expression was downregulated after treatment with EtOH, HIV-1 proteins, and in combination. Next, we constructed in vitro BBB models using BMVECs and found TRPM7 antagonists enhanced EtOH-mediated BBB integrity changes. Our study demonstrated alcohol decreased TRPM7 expression, whereby TRPM7 could be involved in the mechanisms underlying BBB alcohol-induced damage in HIV-1 patients on cART.

Innate immune activation: Parallels in alcohol use disorder and Alzheimer’s disease

Alcohol use disorder is associated with systemic inflammation and organ dysfunction especially in the liver and the brain. For more than a decade, studies have highlighted alcohol abuse-mediated impairment of brain function and acceleration of neurodegeneration through inflammatory mechanisms that directly involve innate immune cells. Furthermore, recent studies indicate overlapping genetic risk factors between alcohol use and neurodegenerative disorders, specifically regarding the role of innate immunity in the pathomechanisms of both areas. Considering the pressing need for a better understanding of the relevance of alcohol abuse in dementia progression, here we summarize the molecular mechanisms of neuroinflammation observed in alcohol abuse and Alzheimer’s disease, the most common cause of dementia. In addition, we highlight mechanisms that are already established in the field of Alzheimer’s disease that may be relevant to explore in alcoholism to better understand alcohol mediated neurodegeneration and dementia, including the relevance of the liver-brain axis.

High-Dose Acetaminophen Alters the Integrity of the Blood-Brain Barrier and Leads to Increased CNS Uptake of Codeine in Rats

The consumption of acetaminophen (APAP) can induce neurological changes in human subjects; however, effects of APAP on blood-brain barrier (BBB) integrity are unknown. BBB changes by APAP can have profound consequences for brain delivery of co-administered drugs. To study APAP effects, female Sprague-Dawley rats (12-16 weeks old) were administered vehicle (i.e., 100% dimethyl sulfoxide (DMSO), intraperitoneally (i.p.)) or APAP (80 mg/kg or 500 mg/kg in DMSO, i.p.; equivalent to a 900 mg or 5600 mg daily dose for a 70 kg human subject). BBB permeability was measured via in situ brain perfusion using [¹⁴C]sucrose and [³H]codeine, an opioid analgesic drug that is co-administered with APAP (i.e., Tylenol #3). Localization and protein expression of tight junction proteins (i.e., claudin-5, occludin, ZO-1) were studied in rat brain microvessels using Western blot analysis and confocal microscopy, respectively. Paracellular [¹⁴C]sucrose "leak" and brain [³H]codeine accumulation were significantly enhanced in rats treated with 500 mg/kg APAP only. Additionally, claudin-5 localization and protein expression were altered in brain microvessels isolated from rats administered 500 mg/kg APAP. Our novel and translational data show that BBB integrity is altered following a single high APAP dose, results that are relevant to patients abusing or misusing APAP and/or APAP/opioid combination products.

Prevention and mitigation of alcohol-induced neuroinflammation by Lactobacillus plantarum by an EGF receptor-dependent mechanism

Neuroinflammation is implicated in the pathogenesis of alcohol use disorders. We investigated the role of Gut-Brain interactions in alcohol-induced neuroinflammation by probiotic-mediated manipulation of intestinal dysbiosis in mice. Chronic ethanol feeding induced dysbiosis, as evidenced by an increase in Firmicutes/Bacteroidetes ratio and depletion of Lactobacillus species in the colon. Ethanol increased the levels of IL-1β, IL-6, and TNFα in plasma and the mRNA for IL-1β, IL-6, TNFα, and MCP1 genes in the cerebral cortex and hippocampus. Ethanol feeding increased inulin flux from the circulation into different brain regions, accompanied by the increase in TLR4 mRNA levels in the cerebral cortex and hippocampus. The immunofluorescence confocal microscopy showed that ethanol elevates the expression of microglial activation marker TMEM119 in the cerebral cortex. Feeding L. plantarum suppressed the ethanol-induced dysbiosis to some extent, as evidenced by attenuation of ethanol effects on Firmicutes/Bacteroidetes ratio and abundance of Lactobacillus spp. L. plantarum blocked ethanol-induced elevation of plasma cytokines, inulin permeability to the brain, mRNA for TLR4, IL-1β, IL-6, TNFα, and MCP1 in brain regions, and the expression of TMEM119 in the cerebral cortex. The L. plantarum effect was absent in mice that express a dominant-negative EGFR, suggesting that the EGFR receptor plays an essential role in the protective effect of L. plantarum against ethanol-induced neuroinflammation. L. plantarum, when administered after chronic ethanol-induced injury, rescued the ethanol-induced systemic inflammation and neuroinflammation. This study demonstrates that L. plantarum in the gut prevents and mitigates ethanol-induced neuroinflammation by an EGFR-dependent mechanism.

New insights into the role of melatonin in diabetic cardiomyopathy

Diabetic cardiovascular complications and impaired cardiac function are considered to be the main causes of death in diabetic patients worldwide, especially patients with type 2 diabetes mellitus (T2DM). An increasing number of studies have shown that melatonin, as the main product secreted by the pineal gland, plays a vital role in the occurrence and development of diabetes. Melatonin improves myocardial cell metabolism, reduces vascular endothelial cell death, reverses microcirculation disorders, reduces myocardial fibrosis, reduces oxidative and endoplasmic reticulum stress, regulates cell autophagy and apoptosis, and improves mitochondrial function, all of which are the characteristics of diabetic cardiomyopathy (DCM). This review focuses on the role of melatonin in DCM. We also discuss new molecular findings that might facilitate a better understanding of the underlying mechanism. Finally, we propose potential new therapeutic strategies for patients with T2DM.

Combined and sequential effects of alcohol and methamphetamine in animal models

Comorbid drug use, often alcohol with other drugs, poses significant health and societal concerns. Methamphetamine is among the illicit drugs most often co-used with alcohol. The current review examines the animal literature for impacts of comorbid alcohol and methamphetamine exposure. We found evidence for additive or synergistic effects of combined or sequential exposure on behavior and physiology. Dopaminergic, serotonergic, and glutamatergic systems are all impacted by combined exposure to alcohol and methamphetamine and cyclooxygenase-2 activity plays an important role in their combined neurotoxic effects. Adverse consequences of comorbid exposure include altered brain development with prenatal exposure, impaired learning and memory, motor deficits, gastrotoxicity, hepatotoxicity, and augmented intake under some conditions. Given high susceptibility to drug experimentation in adolescence, studies of co-exposure during the adolescent period and of how adolescent exposure to one drug impacts later use or sensitivity to the other drug should be a priority. Further, to gain traction on prevention and treatment, additional research to identify motivational and neurobiological drivers and consequences of comorbid use is needed.

Sexually dimorphic prelimbic cortex mechanisms play a role in alcohol dependence: protection by endostatin

Angiogenesis or proliferation of endothelial cells plays a role in brain microenvironment homeostasis. Previously we have shown enhanced expression of markers of angiogenesis in the medial prefrontal cortex during abstinence in an animal model of ethanol dependence induced by chronic intermittent ethanol vapor (CIE) and ethanol drinking (ED) procedure. Here we report that systemic injections of the angiogenesis inhibitor endostatin reduced relapse to drinking behavior in female CIE-ED rats without affecting relapse to drinking in male CIE-ED rats, and female and male nondependent ED rats. Endostatin did not alter relapse to sucrose drinking in both sexes. Endostatin reduced expression of platelet endothelial cell adhesion molecule-1 (PECAM-1) in all groups; however, rescued expression of tight junction protein claudin-5 in the prelimbic cortex (PLC) of female CIE-ED rats. In both sexes, CIE-ED enhanced microglial activation in the PLC and this was selectively prevented by endostatin in female CIE-ED rats. Endostatin prevented CIE-ED-induced enhanced NF-kB activity and expression and Fos expression in females and did not alter reduced Fos expression in males. Analysis of synaptic processes within the PLC revealed sexually dimorphic adaptations, with CIE-ED reducing synaptic transmission and altering synaptic plasticity in the PLC in females, and increasing synaptic transmission in males. Endostatin prevented the neuroadaptations in the PLC in females via enhancing phosphorylation of CaMKII, without affecting the neuroadaptations in males. Our multifaceted approach is the first to link PLC endothelial cell damage to the behavioral, neuroimmune, and synaptic changes associated with relapse to ethanol drinking in female subjects, and provides a new therapeutic strategy to reduce relapse in dependent subjects.

Possible mechanisms of HIV neuro-infection in alcohol use: Interplay of oxidative stress, inflammation, and energy interruption

Alcohol use and HIV-1 infection have a pervasive impact on brain function, which extends to the requirement, distribution, and utilization of energy within the central nervous system. This effect on neuroenergetics may explain, in part, the exacerbation of HIV-1 disease under the influence of alcohol, particularly the persistence of HIV-associated neurological complications. The objective of this review article is to highlight the possible mechanisms of HIV/AIDS progression in alcohol users from the perspective of oxidative stress, neuroinflammation, and interruption of energy metabolism. These include the hallmark of sustained immune cell activation and high metabolic energy demand by HIV-1-infected cells in the central nervous system, with at-risk alcohol use. Here, we discussed the point that the increase in energy supply requirement by HIV-1-infected neuroimmune cells as well as the deterrence of nutrient uptake across the blood-brain barrier significantly depletes the energy source and neuro-environment homeostasis in the CNS. We also described the mechanistic idea that comorbidity of HIV-1 infection and alcohol use can cause a metabolic shift and redistribution of energy usage toward HIV-1-infected neuroimmune cells, as shown in neuropathological evidence. Under such an imbalanced neuro-environment, meaningless energy waste is expected in infected cells, along with unnecessary malnutrition in non-infected neuronal cells, which is likely to accelerate HIV neuro-infection progression in alcohol use. Thus, it will be important to consider the factor of nutrients/energy imbalance in formulating treatment strategies to help impede the progression of HIV-1 disease and associated neurological disorders in alcohol use.

Blood-brain barrier integrity is the primary target of alcohol abuse

The effects of long-term alcohol consumptions on cognitive function remain elusive with contradictory results. Whilst it is widely accepted that long-term intoxication can cause cognitive impairment, moderate drinking can improve cognitive function. In reality, many older people and those with chronic medical conditions are long-term alcohol consumers in Asian countries. Our previous studies have suggested that long-term alcohol consumption can damage blood-brain barrier (BBB) integrity and aggravate cognitive deficit in APPswe/PS1De9 mice, but little is known about the underlying mechanisms, especially whether this consumption can cause cognitive decline via aggravating BBB damage in people who are exposed to the risk factors for cognitive disorders such as aging or inflammation. These questions were addressed in this study. The mouse models of cognitive deficit induced by d-galactose or lipopolysaccharide, the important risk conditions in human on cognitive function, were used to evaluate the effects of long-term alcohol consumption on the BBB integrity. After alcohol administration for 30 days in these models the BBB integrity was significantly destroyed with remarkably increased permeability and down-regulated protein expression of zonula occludens-1, VE-cadherin, occludin, low-density lipoprotein receptor-related protein-1, receptor for advanced glycation end products, major facilitator superfamily domain-containing protein-2a and aquaporin-4, which is the most closely related with the structure and function of BBB integrity. Meanwhile, the level of oxidative stress in d-galactose mice or inflammatory factors in cortex and serum in lipopolysaccharide mice, which might be involved in the cognitive dysfunctions, was significantly amplified. Furthermore, the impaired memory and hippocampal neuron damage induced by d-galactose and lipopolysaccharide were concurrently aggravated. Collectively, our study provided novel and compelling evidence that the structural and functional proteins for BBB integrity may be the primary targets for the detrimental effects of alcohol abuse that lead to cognitive dysfunction and neurological deficits in high risk populations.

Neuroinflammatory processes are augmented in mice overexpressing human heat-shock protein B1 following ethanol-induced brain injury

Background

Heat-shock protein B1 (HSPB1) is among the most well-known and versatile member of the evolutionarily conserved family of small heat-shock proteins. It has been implicated to serve a neuroprotective role against various neurological disorders via its modulatory activity on inflammation, yet its exact role in neuroinflammation is poorly understood. In order to shed light on the exact mechanism of inflammation modulation by HSPB1, we investigated the effect of HSPB1 on neuroinflammatory processes in an in vivo and in vitro model of acute brain injury.

Methods

In this study, we used a transgenic mouse strain overexpressing the human HSPB1 protein. In the in vivo experiments, 7-day-old transgenic and wild-type mice were treated with ethanol. Apoptotic cells were detected using TUNEL assay. The mRNA and protein levels of cytokines and glial cell markers were examined using RT-PCR and immunohistochemistry in the brain. We also established primary neuronal, astrocyte, and microglial cultures which were subjected to cytokine and ethanol treatments. TNFα and hHSPB1 levels were measured from the supernates by ELISA, and intracellular hHSPB1 expression was analyzed using fluorescent immunohistochemistry.

Results

Following ethanol treatment, the brains of hHSPB1-overexpressing mice showed a significantly higher mRNA level of pro-inflammatory cytokines (Tnf, Il1b), microglia (Cd68, Arg1), and astrocyte (Gfap) markers compared to wild-type brains. Microglial activation, and 1 week later, reactive astrogliosis was higher in certain brain areas of ethanol-treated transgenic mice compared to those of wild-types. Despite the remarkably high expression of pro-apoptotic Tnf, hHSPB1-overexpressing mice did not exhibit higher level of apoptosis. Our data suggest that intracellular hHSPB1, showing the highest level in primary astrocytes, was responsible for the inflammation-regulating effects. Microglia cells were the main source of TNFα in our model. Microglia isolated from hHSPB1-overexpressing mice showed a significantly higher release of TNFα compared to wild-type cells under inflammatory conditions.

Conclusions

Our work provides novel in vivo evidence that hHSPB1 overexpression has a regulating effect on acute neuroinflammation by intensifying the expression of pro-inflammatory cytokines and enhancing glial cell activation, but not increasing neuronal apoptosis. These results suggest that hHSPB1 may play a complex role in the modulation of the ethanol-induced neuroinflammatory response.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-020-02070-2.

Gallic Acid Reverses Neurochemical Changes Induced by Prolonged Ethanol Exposure in the Zebrafish Brain

Gallic acid (GA) is a polyphenolic compound that has attracted significant interest due to its antioxidant action through free radical elimination and metal chelation. Ethanol is a highly soluble psychoactive substance, and its toxicity is associated with oxidative stress. In this context, the purpose of the present study was to investigate the effect of GA on neurochemical changes in zebrafish brains exposed to ethanol. GA was first analyzed in isolation by treating the animals at concentrations of 5, 10, and 20 mg/L for 24 h and 48 h. The results revealed that the group exposed to 20 mg/L over a 24/48 h period exhibited increases in thiobarbituric acid reactive substance (TBA-RS) levels and 2',7'-dichlorofluorescein (DCFH) oxidation, demonstrating a pro-oxidant profile. Moreover, decrease in acetylcholinesterase (AChE) enzyme activity was observed. To investigate the effects of GA after ethanol exposure, the animals were divided into four groups: control; those exposed to 0.5% ethanol for 7 days; those exposed to 0.5% ethanol for 7 days and treated with GA at 5 and 10 mg/L on day 8. Treatment with GA at 5 and 10 mg/L reversed impairment of choline acetyltransferase activity and the damage to TBA-RS levels, DCFH oxidation, and superoxide dismutase activity induced by ethanol. Results of the present study suggest that GA treatment (20 mg/L) appeared to disrupt oxidative parameters in the zebrafish brain. GA treatment at 5 and 10 mg/L reversed alterations to the cholinergic system induced by prolonged exposure to ethanol in the zebrafish brain, probably through an antioxidant mechanism.

Alcohol induces programmed death receptor-1 and programmed death-ligand-1 differentially in neuroimmune cells

Engagement of programmed death-1 (PD-1) receptor by its ligands (PD-L1/PD-L2) in activated immune cells is known to be involved in inflammatory neurological disease via a co-inhibitory signal pathway. Interaction of PD-1/PD-L1 is believed to occur only in activated neuroimmune cells because there are undetectable levels of PD-1/PD-L1 in normal physiological conditions. Here, we evaluated whether activation of neuroimmune cells such as human macrophage, brain endothelial cells (hBECs), astrocytes, microglia, and neurons by non-toxic concentrations of ethanol (EtOH) exposure can alter PD-1/PD-L1 expression. Thus, the present study is limited to the screening of PD-1/PD-L1 alterations in neuroimmune cells following ethanol exposure. We found that exposure of human macrophage or microglia to EtOH in primary culture immediately increased the levels of PD-L1 and gradually up-regulated PD-1 levels (beginning at 1-2 h). Similarly, ethanol exposure was able to induce PD-1/PD-L1 levels in hBECs and neuronal culture in a delayed process (occurring at 24 h). Astrocyte culture was the only cell type that showed endogenous levels of PD-1/PD-L1 that was decreased by EtOH exposure time-dependently. We concluded that ethanol (alcohol) mediated the induction of PD-1/PD-L1 differentially in neuroimmune cells. Taken together, our findings suggest that up-regulation of PD-1/PD-L1 by chronic alcohol use may dampen the innate immune response of neuroimmune cells, thereby contributing to neuroinflammation and neurodegeneration.

Calcium signaling in brain microvascular endothelial cells and its roles in the function of the blood-brain barrier

The blood-brain barrier (BBB) plays critical roles in maintaining the stability of the brain's internal milieu, providing nutrients for the brain, and preventing toxic materials from the blood from entering the brain. The cellular structure of the BBB is mainly composed of brain microvascular endothelial cells (BMVECs), which are surrounded by astrocytic endfeet that are connected by tight junction proteins, pericytes and astrocytes. Recently, several studies have shown that aberrant increase in intracellular calcium levels in BMVECs lead to cellular metabolic disturbances and subsequent impairment of BBB integrity. Although multiple stresses can lead to intracellular calcium accumulation, inherent protective mechanisms in affected cells are subsequently activated to maintain calcium homeostasis. However, once the increase in intracellular calcium goes beyond a certain threshold, disturbances in cellular structures, protein expression, and the BBB permeability are inevitable. Here, we review recent research on the different factors regulating intracellular calcium concentrations and the mechanisms related to how calcium signaling cascades protect the BMVECs from outside injury. We also consider the potential of calcium signaling regulators as therapeutic targets for modulating intracellular calcium homeostasis and ameliorating BBB disruption in patients with calcium-related pathologies.

Substance Use Disorder in the COVID-19 Pandemic: A Systematic Review of Vulnerabilities and Complications

As the world endures the coronavirus disease 2019 (COVID-19) pandemic, the conditions of 35 million vulnerable individuals struggling with substance use disorders (SUDs) worldwide have not received sufficient attention for their special health and medical needs. Many of these individuals are complicated by underlying health conditions, such as cardiovascular and lung diseases and undermined immune systems. During the pandemic, access to the healthcare systems and support groups is greatly diminished. Current research on COVID-19 has not addressed the unique challenges facing individuals with SUDs, including the heightened vulnerability and susceptibility to the disease. In this systematic review, we will discuss the pathogenesis and pathology of COVID-19, and highlight potential risk factors and complications to these individuals. We will also provide insights and considerations for COVID-19 treatment and prevention in patients with SUDs.

Effects of Drugs of Abuse on the Blood-Brain Barrier: A Brief Overview

The use of psychostimulants and alcohol disrupts blood-brain barrier (BBB) integrity, resulting in alterations to cellular function, and contributes to neurotoxicity. The BBB is the critical boundary of the central nervous system (CNS) where it maintains intracellular homeostasis and facilitates communication with the peripheral circulation. The BBB is regulated by tight junction (TJ) proteins that closely interact with endothelial cells (EC). The complex TJ protein network consists of transmembrane proteins, including claudins, occludins, and junction adhesion molecules (JAM), as well as cytoskeleton connected scaffolding proteins, zonula occludentes (ZO-1, 2, and 3). The use of psychostimulants and alcohol is known to affect the CNS and is implicated in various neurological disorders through neurotoxicity that partly results from increased BBB permeability. The present mini review primarily focuses on BBB structure and permeability. Moreover, we assess TJ protein and cytoskeletal changes induced by cocaine, methamphetamine, morphine, heroin, nicotine, and alcohol. These changes promote glial activation, enzyme potentiation, and BBB remodeling, which affect neuroinflammatory pathways. Although the effect of drugs of abuse on BBB integrity and the underlying mechanisms are well studied, the present review enhances the understanding of the underlying mechanisms through which substance abuse disorders cause BBB dysfunction.

Ethanol consumption following mild traumatic brain injury is related to blood-brain barrier permeability

Several preclinical and clinical studies that deal with the neuropathological consequences of mild traumatic brain injury (mTBI) have focused on unraveling its effect on ethanol drinking behavior. Previous reports describe changes in ethanol consumption, both in animal models of mTBI as well as in patients, after concussive brain injury. However, the neurobiological mechanisms underlying this phenomenon are still poorly understood. In the present study, we used a unique model of mouse lines divergently selected for high (HA) or low (LA) swim stress-induced analgesia to examine the effect of mTBI on ethanol drinking behavior. In comparison with LA mice, their HA counterparts exhibited increased blood-brain barrier (BBB) permeability, lower basal alcohol preference, and lower level of stress-induced ethanol intake. Here, we showed that mTBI attenuates voluntary ethanol intake in LA, but not in HA mice. Interestingly, BBB disruption after mannitol infusion also decreases the level of ethanol drinking behavior in this line. We conclude that in alcohol-preferring LA mice, BBB disruption as a consequence of mTBI attenuates ethanol consumption. Our results suggest that the innate level of BBB integrity plays a pivotal role in regulation of ethanol consumption in mice showing differential endogenous opioid system activity.

Reciprocality Between Estrogen Biology and Calcium Signaling in the Cardiovascular System

17β-Estradiol (E₂) is the main estrogenic hormone in the body and exerts many cardiovascular protective effects. Via three receptors known to date, including estrogen receptors α (ERα) and β (ERβ) and the G protein-coupled estrogen receptor 1 (GPER, aka GPR30), E₂ regulates numerous calcium-dependent activities in cardiovascular tissues. Nevertheless, effects of E₂ and its receptors on components of the calcium signaling machinery (CSM), the underlying mechanisms, and the linked functional impact are only beginning to be elucidated. A picture is emerging of the reciprocality between estrogen biology and Ca²⁺ signaling. Therein, E₂ and GPER, via both E₂-dependent and E₂-independent actions, moderate Ca²⁺-dependent activities; in turn, ERα and GPER are regulated by Ca²⁺ at the receptor level and downstream signaling via a feedforward loop. This article reviews current understanding of the effects of E₂ and its receptors on the cardiovascular CSM and vice versa with a focus on mechanisms and combined functional impact. An overview of the main CSM components in cardiovascular tissues will be first provided, followed by a brief review of estrogen receptors and their Ca²⁺-dependent regulation. The effects of estrogenic agonists to stimulate acute Ca²⁺ signals will then be reviewed. Subsequently, E₂-dependent and E₂-independent effects of GPER on components of the Ca²⁺ signals triggered by other stimuli will be discussed. Finally, a case study will illustrate how the many mechanisms are coordinated to moderate Ca²⁺-dependent activities in the cardiovascular system.

Alcohol promotes waste clearance in the CNS via brain vascular reactivity

The efficient clearance of the interstitial waste metabolites is essential for the normal maintenance of brain homeostasis. The brain lacks the lymphatic clearance system. Thus, the drainage of waste metabolites in the brain is dependent on a slow flow of cerebrospinal fluid (CSF) system. Glymphatic system claims the direct bulk flow transport of small size water-soluble waste metabolites into to the perivenous space by aquaporin-4 water channels of the astrocyte end-feet, but it did not address the diffusive clearance of large size waste metabolites. Here, we addressed the clearance mechanisms of large size waste metabolites from interstitial fluid to perivascular space as well as from CSF subarachnoid into perivascular space via the paravascular drainage. A low dose ethanol acting as a potent vasodilator promotes the dynamic clearance of waste metabolites through this perivascular-perivenous drainage path. We observed that ethanol-induced increased in vascular endothelial and smooth muscle cell reactivity regulated the enhanced clearance of metabolites. Here, activation of endothelial specific nitric oxide synthase (eNOS) by ethanol and generation of vasodilator nitric oxide mediates the interactive reactivity of endothelial-smooth muscle cells and subsequent diffusion of the CNS waste metabolites towards perivascular space. Detection of tracer dye (waste metabolite) in the perivenous space and in the blood samples further confirmed the improved clearance of waste metabolites through this unraveled interstitial-perivascular-perivenous clearance path. Our results suggest that alcohol intake at low-dose levels may promote clearance of neurological disease associated entangled proteins.

Effects of different routes of endotoxin injury on barrier function in alcoholic lung syndrome

In the lung, chronic alcohol consumption is a risk factor for acute respiratory distress syndrome (ARDS), a disorder that can be fatal due to airspace flooding. The severity of pulmonary edema is controlled by multiple barriers, and in particular the alveolar epithelial barrier and pulmonary microvasculature. However, to date, the effects of chronic alcohol ingestion on both of these barriers in the lung has not been directly and simultaneously measured. In addition the effects of alcohol on systemic, indirect lung injury versus direct injury have not been compared. In this study, we used tissue morphometry and Evans Blue permeability assays to assess the effects of alcohol and endotoxemia injury on pulmonary barrier function comparing intraperitoneal (IP) administration of lipopolysaccharide (LPS) to intratracheal (IT) administration. Consistent with previous reports, we found that in alcohol-fed mice, the alveolar barrier was impaired, allowing Evans Blue to permeate into the airspaces. Moreover, IT administered LPS caused a significant breach of both the alveolar epithelial and vascular barriers in alcohol-fed mice, whereas the endothelial barrier was less affected in response to IP administered LPS. The alveolar barrier of control mice remained intact for both IP and IT administered LPS. However, both injuries caused significant interstitial edema, independently of whether the mice were fed alcohol or not. These data suggest that in order to properly target pulmonary edema due to alcoholic lung syndrome, both the alveolar and endothelial barriers need to be considered as well as the nature of the "second hit" that initiates ARDS.

Pathomechanisms of Blood-Brain Barrier Disruption in ALS

The blood-brain barrier (BBB) and the blood-spinal cord barrier (BSCB) are responsible for controlling the microenvironment within neural tissues in humans. These barriers are fundamental to all neurological processes as they provide the extreme nutritional demands of neural tissue, remove wastes, and maintain immune privileged status. Being a semipermeable membrane, both the BBB and BSCB allow the diffusion of certain molecules, whilst restricting others. In amyotrophic lateral sclerosis (ALS) and other neurodegenerative diseases, these barriers become hyperpermeable, allowing a wider variety of molecules to pass through leading to more severe and more rapidly progressing disease. The intention of this review is to discuss evidence that BBB hyperpermeability is potentially a disease driving feature in ALS and other neurodegenerative diseases. The various biochemical, physiological, and genomic factors that can influence BBB permeability in ALS and other neurodegenerative diseases are also discussed, in addition to novel therapeutic strategies centred upon the BBB.

PCSK9 is Increased in Cerebrospinal Fluid of Individuals With Alcohol Use Disorder

BACKGROUND

Recent studies have shown that alcohol use affects the regulation and expression of proprotein convertase subtilisin/kexin 9 (PCSK9). While a major role of PCSK9 in hepatic function and lipid regulation has been clearly established, other pleiotropic effects remain poorly understood. Existing research suggests a positive association between PCSK9 expression in the brain and psychopathology, with increased levels of PCSK9 in the cerebrospinal fluid (CSF) of individuals with dementia and epigenetic modifications of PCSK9 associated with alcohol use disorder (AUD). In this study, we hypothesized that chronic alcohol use would increase PCSK9 expression in CSF.

METHODS

PCSK9 levels in CSF were measured in individuals with AUD (n = 42) admitted to an inpatient rehabilitation program and controls (n = 25). CSF samples in AUD were assessed at 2 time points, at day 5 and day 21 after admission. Furthermore, plasma samples were collected and measured from the individuals with AUD.

RESULTS

PCSK9 in CSF was significantly increased in the AUD group at day 5 and day 21 compared to the controls (p < 0.0001). Plasma PCSK9 levels were correlated positively with CSF PCSK9 levels in AUD (p = 0.0493).

CONCLUSIONS

Our data suggest that PCSK9 is elevated in the CSF of individuals with AUD, which may indicate a potential role of PCSK9 in AUD. Additional studies are necessary to further elucidate the functions of PCSK9 in the brain.

A comparison of hippocampal microglial responses in aged and young rodents following dependent and non-dependent binge drinking

Alcoholism is a highly visible and prevalent issue in the United States. Although binge-drinking is assumed to be a college-age problem, older adults (ages 65+) consume binge amounts of alcohol and have alcohol use disorders (AUDs). Moreover, individuals with alcohol dependence in their youth often continue to drink as they age. As such, this study tested the hypothesis that the effects of alcohol on hippocampal microglia are exacerbated in aged versus younger rodents in two AUD models. Briefly, adult (2-3 months) and aged (15+ months) Sprague-Dawley rats were administered alcohol or control diet using the Majchrowicz model to study alcohol-induced neurodegeneration. To study the effects of non-dependent binge consumption on microglia, adolescent (6-8 weeks) and aged (18+ months) C57/BL6N were subjected to the Drinking in the Dark paradigm. Microglia number and densitometry were assessed using immunohistochemistry. Hippocampal subregional and model/species-specific effects of alcohol were observed, but overall, aging did not appear to increase the alcohol-induced microglia reactivity as measured by Iba-1 densitometry. However, analysis of microglial counts revealed a significant decrease in the number microglia cells in both the alcohol-induced neurodegeneration and DID model across age groups. In the dentate gyrus, the loss of microglia was exacerbated by aging, particularly in mice after DID, non-dependent model. Using qRT-PCR, the persistence of alcohol and aging effects was assessed following the DID model. Allograft Inflammatory Factor 1 mRNA was increased in both young and aged mice by alcohol exposure; however, only in the aged mice did the alcohol effect persist. Overall, these data imply that the microglial response to alcohol is complex with evidence of depressed numbers of microglia but also increased reactivity with advanced age.

Serum inflammatory molecules and markers of neuronal damage in alcohol-dependent subjects after withdrawal

OBJECTIVES

Our aim is to describe changes in serum concentration for the pro-inflammatory factors TNF-α, IFN-γ, IL-1β, IL-8, IL-6, IL-10, IL-12 and MCP-1, for the satiety factor leptin and for factors associated with neuronal changes, neuron-specific enolase (NSE) and glial activation S100-beta protein (S100-β), and explore their association with abstinence in alcohol-dependent subjects after withdrawal.

METHODS

Serum sampling and clinical assessments from 115 alcohol-dependent subjects admitted to a psychiatric hospital for alcohol were repeated during the first 48 h of withdrawal (M0) and 1, 2, 4 and 6 months (M1, M2, M4 and M6) thereafter. Serum factors were determined with Luminex technology or by ELISA.

RESULTS

The levels of TNF-α, IL-1β, IL-8, IL-6, IL-12, MCP-1, and leptin decreased after withdrawal and remained low until M6, regardless of alcohol consumption. IFN-γ levels remained constant and IL-10 levels changed only slightly. NSE levels were not modified, whereas serum S100-β concentration increased significantly on M1 and then plateaued, regardless of abstinence status at 6 months.

CONCLUSIONS

Alcohol-dependent subjects present an inflammatory condition that is not dependent on alcohol consumption. An understanding of the changes in concentration of the various proteins considered here would provide insight into the physiology of withdrawal or dependence.

Ethanol's Effects on Transient Receptor Potential Channel Expression in Brain Microvascular Endothelial Cells

Ethanol (EtOH), the main ingredient in alcoholic beverages, is well known for its behavioral, physiological, and immunosuppressive effects. There is evidence that EtOH acts through protein targets to exert its physiological effects; however, the mechanisms underlying EtOH's effects on inflammatory processes, particularly at the blood-brain barrier (BBB), are still poorly understood. Transient receptor potential (TRP) channels, the vanguards of human sensory systems, are novel molecular receptors significantly affected by EtOH, and are heavily expressed in brain microvascular endothelial cells (BMVECs), one of the cellular constituents of the BBB. EtOH's actions on endothelial TRP channels could affect intracellular Ca²⁺ and Mg²⁺ dynamics, which mediate leukocyte adhesion to endothelial cells and endothelial permeability at the BBB, thus altering immune and inflammatory responses. We examined the basal expression profiles of all 29 known mammalian TRP channels in mouse BMVECs and determined both EtOH concentration- and time-dependent effects on TRP expression using a PCR array. We also generated an in vitro BBB model to examine the involvement of a chosen TRP channel, TRP melastatin 7 (TRPM7), in EtOH-mediated alteration of BBB permeability. With the exception of the akyrin subfamily, members of five TRP subfamilies were expressed in mouse BMVECs, and their expression levels were modulated by EtOH in a concentration-dependent manner. In the in vitro BBB model, TRPM7 antagonists further enhanced EtOH-mediated alteration of BBB permeability. Because of the diversity of TRP channels in BMVECs that regulate cellular processes, EtOH can affect Ca²⁺/Mg²⁺ signaling, immune responses, lysosomal functions as well as BBB integrity.

The Role of Endothelial Ca2+ Signaling in Neurovascular Coupling: A View from the Lumen

BACKGROUND

Neurovascular coupling (NVC) is the mechanism whereby an increase in neuronal activity (NA) leads to local elevation in cerebral blood flow (CBF) to match the metabolic requirements of firing neurons. Following synaptic activity, an increase in neuronal and/or astrocyte Ca2+ concentration leads to the synthesis of multiple vasoactive messengers. Curiously, the role of endothelial Ca2+ signaling in NVC has been rather neglected, although endothelial cells are known to control the vascular tone in a Ca2+-dependent manner throughout peripheral vasculature.

METHODS

We analyzed the literature in search of the most recent updates on the potential role of endothelial Ca2+ signaling in NVC.

RESULTS

We found that several neurotransmitters (i.e., glutamate and acetylcholine) and neuromodulators (e.g., ATP) can induce dilation of cerebral vessels by inducing an increase in endothelial Ca2+ concentration. This, in turn, results in nitric oxide or prostaglandin E2 release or activate intermediate and small-conductance Ca2+-activated K⁺ channels, which are responsible for endothelial-dependent hyperpolarization (EDH). In addition, brain endothelial cells express multiple transient receptor potential (TRP) channels (i.e., TRPC3, TRPV3, TRPV4, TRPA1), which induce vasodilation by activating EDH.

CONCLUSIONS

It is possible to conclude that endothelial Ca2+ signaling is an emerging pathway in the control of NVC.

Melatonin protected cardiac microvascular endothelial cells against oxidative stress injury via suppression of IP3R-[Ca2+]c/VDAC-[Ca2+]m axis by activation of MAPK/ERK signaling pathway

The cardiac microvascular reperfusion injury is characterized by the microvascular endothelial cells (CMECs) oxidative damage which is responsible for the progression of cardiac dysfunction. However, few strategies are available to reverse such pathologies. This study aimed to explore the mechanism by which oxidative stress induced CMECs death and the beneficial actions of melatonin on CMECs survival, with a special focused on IP3R-[Ca2+]c/VDAC-[Ca2+]m damage axis and the MAPK/ERK survival signaling. We found that oxidative stress induced by H2O2 significantly activated cAMP response element binding protein (CREB) that enhanced IP3R and VDAC transcription and expression, leading to [Ca2+]c and [Ca2+]m overload. High concentration of [Ca2+]m suppressed ΔΨm, opened mPTP, and released cyt-c into cytoplasm where it activated mitochondria-dependent death pathway. However, melatonin could protect CMECs against oxidative stress injury via stimulation of MAPK/ERK that inactivated CREB and therefore blocked IP3R/VDAC upregulation and [Ca2+]c/[Ca2+]m overload, sustaining mitochondrial structural and function integrity and ultimately blockading mitochondrial-mediated cellular death. In summary, these findings confirmed the mechanisms by which oxidative injury induced CMECs mitochondrial-involved death and provided an attractive and effective way to enhance CMECs survival.

Long-term exposure to ethanol downregulates tight junction proteins through the protein kinase Cα signaling pathway in human cerebral microvascular endothelial cells

Brain microvascular endothelial cells (BMECs) are the primary component of the blood-brain barrier (BBB). Tight junction (TJ) proteins, including claudin, occludin and zonula occludens (ZO)-1, ZO-2 and ZO-3, maintain the structural integrity of BMECs. Ethanol activates the assembly and disassembly of TJs, which is a process that is regulated by protein kinase C (PKC). In addition, ethanol treatment leads to the loss of structural integrity, which damages the permeability of the BBB and subsequently affects central nervous system homeostasis, thus allowing additional substances to enter the brain. However, the mechanisms underlying ethanol-induced loss of BBB structure remain unknown. It has been hypothesized that long-term exposure to ethanol reduces the expression of claudin-5, occludin and ZO-1 via the PKC signaling pathway, thereby affecting BBB structural integrity. In the current study, the human cerebral microvascular endothelial cell line, HCMEC/D3, was treated with 50, 100, 200 and 400 mM ethanol for 24, 48 and 72 h. Cell viability was determined using an MTS assay. The expression of claudin-5, occludin and ZO-1 protein and mRNA was measured using western blot analysis and reverse transcription-quantitative polymerase chain reaction, respectively. Following the pretreatment of HCMEC/D3 cells with the PKCα-specific inhibitor, safingol (10 µmol/l), the expression of claudin-5, occludin, ZO-1 and phosphorylated (p)-PKCα was measured using western blot analysis, and PKCα localization was determined by immunofluorescence. With increasing concentrations of ethanol, the expression of claudin-5, occludin and ZO-1 protein decreased, while the expression of claudin-5, occludin and ZO-1 mRNA increased. Exposure to ethanol significantly increased the expression of p-PKCα, whereas no significant effect on the expression of PKCα was observed. Following 48 h treatment with 200 mM ethanol, the expression of claudin-5, occludin and ZO-1 protein was significantly decreased when compared with the control. By contrast, the expression of p-PKCα was increased, and increased translocation of PKCα from the cytoplasm to the nuclear membrane and nucleus was observed. In addition, the results demonstrated that safingol significantly reversed these effects of ethanol. In conclusion, long-term exposure to ethanol downregulates the expression of claudin-5, occludin and ZO-1 protein in HCMEC/D3 s, and this effect may be mediated via activation of PKCα.

Age-dependent redox status in the brain stem of NO-deficient hypertensive rats

BACKGROUND

The brain stem contains important nuclei that control cardiovascular function via the sympathetic nervous system (SNS), which is strongly influenced by nitric oxide. Its biological activity is also largely determined by oxygen free radicals. Despite many experimental studies, the role of AT1R-NAD(P)H oxidase-superoxide pathway in NO-deficiency is not yet sufficiently clarified. We determined changes in free radical signaling and antioxidant and detoxification response in the brain stem of young and adult Wistar rats during chronic administration of exogenous NO inhibitors.

METHODS

Young (4 weeks) and adult (10 weeks) Wistar rats were treated with 7-nitroindazole (7-NI group, 10 mg/kg/day), a specific nNOS inhibitor, with N^G-nitro-L-arginine-methyl ester (L-NAME group, 50 mg/kg/day), a nonspecific NOS inhibitor, and with drinking water (Control group) during 6 weeks. Systolic blood pressure was measured by non-invasive plethysmography. Expression of genes (AT1R, AT2R, p22phox, SOD and NOS isoforms, HO-1, MDR1a, housekeeper GAPDH) was identified by real-time PCR. NOS activity was detected by conversion of [3H]-L-arginine to [3H]-L-citrulline and SOD activity was measured using UV VIS spectroscopy.

RESULTS

We observed a blood pressure elevation and decrease in NOS activity only after L-NAME application in both age groups. Gene expression of nNOS (youngs) and eNOS (adults) in the brain stem decreased after both inhibitors. The radical signaling pathway triggered by AT1R and p22phox was elevated in L-NAME adults, but not in young rats. Moreover, L-NAME-induced NOS inhibition increased antioxidant response, as indicated by the observed elevation of mRNA SOD3, HO-1, AT2R and MDR1a in adult rats. 7-NI did not have a significant effect on AT1R-NADPH oxidase-superoxide pathway, yet it affected antioxidant response of mRNA expression of SOD1 and stimulated total activity of SOD in young rats and mRNA expression of AT2R in adult rats.

CONCLUSION

Our results show that chronic NOS inhibition by two different NOS inhibitors has age-dependent effect on radical signaling and antioxidant/detoxificant response in Wistar rats. While 7-NI had neuroprotective effect in the brain stem of young Wistar rats, L-NAME- induced NOS inhibition evoked activation of AT1R-NAD(P)H oxidase pathway in adult Wistar rats. Triggering of the radical pathway was followed by activation of protective compensation mechanism at the gene expression level.

Hyper-oligodendrogenesis at the vascular niche and reduced blood-brain barrier integrity in the prefrontal cortex during protracted abstinence

Alcoholism is a relapsing disorder with limited treatment options, in part due to our limited understanding of the disease etiology. We have recently shown that increased ethanol-seeking in a behavioral model of relapse in a rat model of alcoholism was associated with increased oligodendrogenesis which was positively correlated with platelet/endothelial cell adhesion molecule (PECAM-1) expression in the medial prefrontal cortex (mPFC). The current study investigated whether newly born oligodendrocytes form close physical associations with endothelial cells expressing PECAM-1 and whether these changes were accompanied by altered blood-brain barrier (BBB) integrity. Colableling and confocal analysis demonstrate that newly born oligodendroglia were always located in close physical proximity to PECAM-1 in the mPFC of rats that were ethanol dependent and demonstrated high propensity for relapse. Notably, the endothelial proximity of new oligodendrocytes was associated with reduced expression of endothelial barrier antigen (SMI-71), a marker for BBB integrity. Furthermore, voluntary wheel running during abstinence enhanced SMI-71 expression in endothelial cells, indicating protection against abstinence-induced reduction in BBB integrity. Taken together, these results suggest that ethanol experience and abstinence disrupts homeostasis in the oligo-vascular niche in the mPFC. Reversing these mechanisms may hold the key to reducing propensity for relapse in individuals with moderate to severe alcohol use disorder.

IP3 receptor signaling and endothelial barrier function

The endothelium, a monolayer of endothelial cells lining vessel walls, maintains tissue-fluid homeostasis by restricting the passage of the plasma proteins and blood cells into the interstitium. The ion Ca²⁺, a ubiquitous secondary messenger, initiates signal transduction events in endothelial cells that is critical to control of vascular tone and endothelial permeability. The ion Ca²⁺ is stored inside the intracellular organelles and released into the cytosol in response to environmental cues. The inositol 1,4,5-trisphosphate (IP₃) messenger facilitates Ca²⁺ release through IP₃ receptors which are Ca²⁺-selective intracellular channels located within the membrane of the endoplasmic reticulum. Binding of IP₃ to the IP₃Rs initiates assembly of IP₃R clusters, a key event responsible for amplification of Ca²⁺ signals in endothelial cells. This review discusses emerging concepts related to architecture and dynamics of IP₃R clusters, and their specific role in propagation of Ca²⁺ signals in endothelial cells.

Activation of NLRP3 inflammasome by cholesterol crystals in alcohol consumption induces atherosclerotic lesions

Epidemiological studies showed a strong association between alcoholism and incidence of stroke, for which the underlying causative mechanisms remain to be understood. Here we found that infiltration of immune cells and deposition of cholesterol at the site of brain artery/capillary injury induced atherosclerosis in chronic alcohol (ethanol) consumption in the presence or absence of high-fat diet. Conversion of cholesterol into sharp edges of cholesterol crystals (CCs) in alcohol intake was key to activation of NLRP3 inflammasome, induction of cerebral atherosclerosis, and development of neuropathy around the atherosclerotic lesions. The presence of alcohol was critical for the formation of CCs and development of the neuropathology. Thus, we observed that alcohol consumption elevated the level of plasma cholesterol, deposition and crystallization of cholesterol, as well as activation of NLRP3 inflammasome. This led to arteriole or capillary walls thickening and increase intracranial blood pressure. Distinct neuropathy around the atherosclerotic lesions indicated vascular inflammation as an initial cause of neuronal degeneration. We demonstrated the molecular mechanisms of NLRP3 activation and downstream signaling cascade event in primary culture of human brain arterial/capillary endothelial cells in the setting of dose-/time-dependent effects of alcohol/CCs using NLRP3 gene silencing technique. We also detected CCs in blood samples from alcohol users, which validated the clinical importance of the findings. Finally, combined therapy of acetyl-l-carnitine and Lipitor® prevented deposition of cholesterol, formation of CCs, activation of NLRP3, thickening of vessel walls, and elevation of intracranial blood pressure. We conclude that alcohol-induced accumulation and crystallization of cholesterol activates NLRP3/caspase-1 in the cerebral vessel that leads to early development of atherosclerosis.

Deep grey matter iron accumulation in alcohol use disorder

PURPOSE

Evaluate brain iron accumulation in alcohol use disorder (AUD) patients compared to controls using quantitative susceptibility mapping (QSM).

METHODS

QSM was performed retrospectively by using phase images from resting state functional magnetic resonance imaging (fMRI). 20 male AUD patients and 15 matched healthy controls were examined. Susceptibility values were manually traced in deep grey matter regions including caudate nucleus, combined putamen and globus pallidus, combined substantia nigra and red nucleus, dentate nucleus, and a reference white matter region in the internal capsule. Average susceptibility values from each region were compared between the patients and controls. The relationship between age and susceptibility was also explored.

RESULTS

The AUD group exhibited increased susceptibility in caudate nucleus (+8.5%, p=0.034), combined putamen and globus pallidus (+10.8%, p=0.006), and dentate nucleus (+14.9%, p=0.022). Susceptibility increased with age in two of the four measured regions - combined putamen and globus pallidus (p=0.013) and combined substantia nigra and red nucleus (p=0.041). AUD did not significantly modulate the rate of susceptibility increase with age in our data.

CONCLUSION

Retrospective QSM computed from standard fMRI datasets provides new opportunities for brain iron studies in psychiatry. Substantially elevated brain iron was found in AUD subjects in the basal ganglia and dentate nucleus. This was the first human AUD brain iron study and the first retrospective clinical fMRI QSM study.

Effects of Ethanol on Brain Extracellular Matrix: Implications for Alcohol Use Disorder

The brain extracellular matrix (ECM) occupies the space between cells and is involved in cell-matrix and cell-cell adhesion. However, in addition to providing structural support to brain tissue, the ECM activates cell signaling and controls synaptic transmission. The expression and activity of brain ECM components are regulated by alcohol exposure. This review will discuss what is currently known about the effects of alcohol on the activity and expression of brain ECM components. An interpretation of how these changes might promote alcohol use disorder (AUD) will be also provided. Ethanol (EtOH) exposure decreases levels of structural proteins involved in the interstitial matrix and basement membrane, with a concomitant increase in proteolytic enzymes that degrade these components. In contrast, EtOH exposure generally increases perineuronal net components. Because the ECM has been shown to regulate both synaptic plasticity and behavioral responses to drugs of abuse, regulation of the brain ECM by alcohol may be relevant to the development of alcoholism. Although investigation of the function of brain ECM in alcohol abuse is still in early stages, a greater understanding of the interplay between ECM and alcohol might lead to novel therapeutic strategies for treating AUD.

Liraglutide protects cardiac microvascular endothelial cells against hypoxia/reoxygenation injury through the suppression of the SR-Ca(2+)-XO-ROS axis via activation of the GLP-1R/PI3K/Akt/survivin pathways

Microvascular endothelial cells (CMECs) oxidative damage resulting from hypoxia/reoxygenation (H/R) injury is responsible for microcirculation perfusion disturbances and the progression of cardiac dysfunction. However, few strategies are available to reverse such pathologies. Here, we studied the effects and mechanisms of liraglutide on CEMCs oxidative damage, focusing in particular on calcium overload-triggered free radical injury signals and the GLP-1R/PI3K/Akt/survivin survival pathways. The results indicate that H/R increased IP3R expression but reduced SERCA2a expression, which rapidly raised intracellular Ca(2+) levels, subsequently leading to Ca(2+)-dependent xanthine oxidase (XO) activation, reactive oxygen species (ROS) production and the cellular apoptosis of CMECs. However, liraglutide pretreatment abrogated Ca(2+)-mediated oxidative apoptosis. Furthermore, liraglutide regulated the rate of IP3R/SERCA2a gene transcription and conserved SERCA2a-ATPase activity via the maintenance of ATP production under H/R, which drove excessive Ca(2+) reflux to the sarcoplasmic reticulum (SR) and inhibited Ca(2+) release from the SR, ultimately restoring Ca(2+) homeostasis. Furthermore, the regulatory role of liraglutide on Ca(2+) balance in conjunction with its up-regulation of superoxide dismutase, glutathione and glutathione peroxidase collectively scavenged the excess ROS under H/R. Moreover, we showed that liraglutide strengthened Akt phosphorylation and subsequently survivin expression. In addition, both the blockade of the GLP-1R/PI3K/Akt pathways and the siRNA-mediated knockdown of survivin abolished the protective effects of liraglutide on SR-Ca(2+) function and CMECs oxidative apoptosis. In summary, this study confirmed that H/R induced CMECs oxidative damage through the SR-Ca(2+)-XO-ROS injury signals and that liraglutide pretreatment may suppress such CMECs damage through the PI3K/Akt/survivin pathways.

Effects of 20 Selected Fruits on Ethanol Metabolism: Potential Health Benefits and Harmful Impacts

The consumption of alcohol is often accompanied by other foods, such as fruits and vegetables. This study is aimed to investigate the effects of 20 selected fruits on ethanol metabolism to find out their potential health benefits and harmful impacts. The effects of the fruits on ethanol metabolism were characterized by the concentrations of ethanol and acetaldehyde in blood, as well as activities of alcohol dehydrogenase and acetaldehyde dehydrogenase in liver of mice. Furthermore, potential health benefits and harmful impacts of the fruits were evaluated by biochemical parameters including aspartate transaminase (AST), alanine transferase (ALT), malondialdehyde, and superoxide dismutase. Generally, effects of these fruits on ethanol metabolism were very different. Some fruits (such as Citrus limon (yellow), Averrhoa carambola, Pyrus spp., and Syzygium samarangense) could decrease the concentration of ethanol in blood. In addition, several fruits (such as Cucumis melo) showed hepatoprotective effects by significantly decreasing AST or ALT level in blood, while some fruits (such as Averrhoa carambola) showed adverse effects. The results suggested that the consumption of alcohol should not be accompanied by some fruits, and several fruits could be developed as functional foods for the prevention and treatment of hangover and alcohol use disorder.

Third trimester-equivalent ethanol exposure causes micro-hemorrhages in the rat brain

Exposure to ethanol during fetal development produces long-lasting neurobehavioral deficits caused by functional alterations in neuronal circuits across multiple brain regions. Therapeutic interventions currently used to treat these deficits are only partially efficacious, which is a consequence of limited understanding of the mechanism of action of ethanol. Here, we describe a novel effect of ethanol in the developing brain. Specifically, we show that exposure of rats to ethanol in vapor chambers during the equivalent to the third trimester of human pregnancy causes brain micro-hemorrhages. This effect was observed both at low and high doses of ethanol vapor exposure, and was not specific to this exposure paradigm as it was also observed when ethanol was administered via intra-esophageal gavage. The vast majority of the micro-hemorrhages were located in the cerebral cortex but were also observed in the hypothalamus, midbrain, olfactory tubercle, and striatum. The auditory, cingulate, insular, motor, orbital, retrosplenial, somatosensory, and visual cortices were primarily affected. Immunohistochemical experiments showed that the micro-hemorrhages caused neuronal loss, as well as reactive astrogliosis and microglial activation. Analysis with the Catwalk test revealed subtle deficits in motor function during adolescence/young adulthood. In conclusion, our study provides additional evidence linking developmental ethanol exposure with alterations in the fetal cerebral vasculature. Given that this effect was observed at moderate levels of ethanol exposure, our findings lend additional support to the recommendation that women abstain from consuming alcoholic beverages during pregnancy.

Ethanol-Induced TLR4/NLRP3 Neuroinflammatory Response in Microglial Cells Promotes Leukocyte Infiltration Across the BBB

We reported that the ethanol-induced innate immune response by activating TLR4 signaling triggers gliosis and neuroinflammation. Ethanol also activates other immune receptors, such as NOD-like-receptors, and specifically NLRP3-inflammasome in astroglial cells, to stimulate caspase-1 cleavage and IL-1β and IL-18 cytokines production. Yet, whether microglia NLRs are also sensitive to the ethanol effects that contribute to neuroinflammation is uncertain. Using cerebral cortexes of the chronic alcohol-fed WT and TLR4(-/-) mice, we demonstrated that chronic ethanol treatment enhanced TLR4 mediated-NLRP3/Caspase-1 complex activation, and up-regulated pro-inflammatory cytokines and chemokines levels. Ethanol-induced NLRP3-inflammasome activation and mitochondria-ROS generation were also observed in cultured microglial cells. The up-regulation of CD45(high)/CD11b(+) cell populations and matrix metalloproteinase-9 levels was also noted in the cortexes of the ethanol-treated WT mice. Notably, elimination of the TLR4 function abolished most ethanol-induced neuroinflammatory effects. Thus, our results demonstrate that ethanol triggers TLR4-mediated NLRP3-inflammasome activation in glial cells, and suggest that microglia stimulation may compromise the permeability of blood-brain barrier events to contribute to ethanol-induced neuroinflammation and brain damage.

Concentrations of MDPV in rat striatum correlate with the psychostimulant effect

3,4-methylenedioxypyrovalerone or MDPV is a synthetic cathinone with psychostimulant properties more potent than cocaine. We quantified this drug in the striatum after subcutaneous administration to rats. MDPV reached the brain around 5 min after its administration and peaked at 20-25 min later. The elimination half-life in the striatum (61 min) correlates with the decrease in the psychostimulant effect after 60 min. Around 11% of the administered dose reached the striatum and, considering a homogeneous brain distribution, we determined that around 86% of the plasma MDPV is distributed to the brain. MDPV induced a dose-dependent increase in locomotor activity, rearing behaviour and stereotypies, all prevented by haloperidol. A plot of locomotor activity or stereotypies versus MDPV striatal concentrations over time showed a direct relationship between factors. No free MDPV metabolites were detected in plasma, at any time, but hydrolysis with glucuronidase allowed us to identify mainly three metabolites, one of them for the first time in rat plasma. The present results contribute to evidence that MDPV induces hyperlocomotion mainly through a dopamine-dependent mechanism. Good correlation between behavioural effects and striatal levels of MDPV leads us to conclude that its psychostimulant effect is mainly due to a striatal distribution of the substance. The present research provides useful information on the pharmacokinetics of MDPV, and can help design new experiments with kinetics data as well as provide a better understanding of the effects of MDPV in humans and its potential interactions.

Variation des taux sériques de marqueurs d’intégrité neuronale et de l’inflammation de sujets alcoolo-dépendants après sevrage

La recherche d’indices biologiques de dépendance à l’alcool est nécessaire pour le développement de nouvelles thérapeutiques et de marqueurs de suivi. Elle implique d’explorer les mécanismes physiopathologiques qui peuvent être modifiés, de préférence au niveau périphérique, afin d’en faciliter la mesure. Les phénomènes inflammatoires, la possible altération de la barrière hémato-méningée et des soutiens gliaux, et les dommages au niveau neuronal, semblent contribuer à l’expression pathologique générale. Toutefois, la façon dont les facteurs sériques qui y sont liés évoluent après sevrage reste inconnue. Nous avons mesuré, au moment du sevrage, les taux sériques des facteurs pro-inflammatoires (TNF-alpha, IFN-gamma, Il-1bêta, Il-8, Il-6, Il-10, Il-12, MCP-1) et de la satiété (leptine) (technique de Luminex) et de témoins d’altérations neuronales Neuron Specific Enolase (NSE) ou d’une activation gliale (S100-B) (Elisa) chez 115 sujets (27 femmes et 88 hommes) dépendants à l’alcool et hospitalisés. Ces mesures ont été répétées à 28 jours (j28), 2, 4 et 6 mois (m2, m4, m6). L’objectif était d’en décrire les variations, et de rechercher leur lien avec l’abstinence. Certains marqueurs pro-inflammatoires ne sont pas détectables, d’autres varient après sevrage en augmentant jusqu’à j28 avant de baisser. Les taux de NSE ne varient pas significativement après sevrage, au contraire des taux sériques de S100 bêta qui augmentent significativement à j28 puis baissent, indépendamment de l’abstinence à 6 mois. La compréhension de l’évolution de la synthèse de ces différentes protéines peut être importante pour comprendre la physiologie du sevrage ou de la dépendance, ou encore caractériser l’état neuronal des sujets dépendants à l’alcool.

Shear-dependent attenuation of cellular ROS levels can suppress proinflammatory cytokine injury to human brain microvascular endothelial barrier properties

The regulatory interplay between laminar shear stress and proinflammatory cytokines during homeostatic maintenance of the brain microvascular endothelium is largely undefined. We hypothesized that laminar shear could counteract the injurious actions of proinflammatory cytokines on human brain microvascular endothelial cell (HBMvEC) barrier properties, in-part through suppression of cellular redox signaling. For these investigations, HBMvECs were exposed to either shear stress (8 dynes/cm(2), 24 hours) or cytokines (tumor necrosis factor-α (TNF-α) or interleukin-6 (IL-6), 0 to 100 ng/mL, 6 or 18 hours). Human brain microvascular endothelial cell 'preshearing'±cytokine exposure was also performed. Either cytokine dose-dependently decreased expression and increased phosphorylation (pTyr/pThr) of interendothelial occludin, claudin-5, and vascular endothelial-cadherin; observations directly correlating to endothelial barrier reduction, and in precise contrast to effects seen with shear. We further observed that, relative to unsheared cells, HBMvECs presheared for 24 hours exhibited significantly reduced reactive oxygen species production and barrier permeabilization in response to either TNF-α or IL-6 treatment. Shear also downregulated NADPH oxidase (nicotinamide adenine dinucleotide phosphate-oxidase) activation in HBMvECs, as manifested in the reduced expression and coassociation of gp91phox and p47phox. These findings lead us to conclude that physiologic shear can protect the brain microvascular endothelium from injurious cytokine effects on interendothelial junctions and barrier function by regulating the cellular redox state in-part through NADPH oxidase inhibition.

Acute alcohol intoxication-induced microvascular leakage

BACKGROUND

Alcohol intoxication can increase inflammation and worsen injury, yet the mechanisms involved are not clear. We investigated whether acute alcohol intoxication increases microvascular permeability and investigated potential signaling mechanisms in endothelial cells that may be involved.

METHODS

Conscious rats received a 2.5 g/kg alcohol bolus via gastric catheters to produce acute intoxication. Microvascular leakage of intravenously administered fluorescein isothiocyanate (FITC)-conjugated albumin (FITC-albumin) from the mesenteric microcirculation was assessed by intravital microscopy. Endothelial-specific mechanisms were studied using cultured endothelial cell monolayers. Transendothelial electrical resistance (TER) served as an index of barrier function, before and after treatment with alcohol or its metabolite acetaldehyde. Pharmacologic agents were used to test the roles of alcohol metabolism, oxidative stress, p38 mitogen-activated protein kinase (MAPK), myosin light-chain kinase (MLCK), rho kinase (ROCK), and exchange protein activated by cAMP (Epac). VE-cadherin localization was investigated to assess junctional integrity. Rac1 and RhoA activation was assessed by ELISA assays.

RESULTS

Alcohol significantly increased FITC-albumin extravasation from the mesenteric microcirculation. Alcohol also significantly decreased TER and disrupted VE-cadherin organization at junctions. Acetaldehyde significantly decreased TER, but inhibition of alcohol dehydrogenase or application of a superoxide dismutase mimetic failed to prevent alcohol-induced decreases in TER. Inhibition of p38 MAPK, but not MLCK or ROCK, significantly attenuated the alcohol-induced barrier dysfunction. Alcohol rapidly decreased GTP-bound Rac1 but not RhoA during the drop in TER. Activation of Epac increased TER, but did not prevent alcohol from decreasing TER. However, activation of Epac after initiation of alcohol-induced barrier dysfunction quickly resolved TER to baseline levels.

CONCLUSIONS

Our results suggest that alcohol intoxication increases microvascular permeability to plasma proteins. The data also suggest the endothelial-specific mechanism involves the p38 MAPK, Rac1, and reorganization of VE-cadherin at junctions. Last, activation of Epac can quickly resolve alcohol-induced endothelial barrier dysfunction.