N-acetyl cysteine mitigates the acute effects of cocaine-induced toxicity in astroglia-like cells

Astrocytic transcriptional and epigenetic mechanisms of drug addiction

Addiction is a leading cause of disease burden worldwide and remains a challenge in current neuroscience research. Drug-induced lasting changes in gene expression are mediated by transcriptional and epigenetic regulation in the brain and are thought to underlie behavioral adaptations. Emerging evidence implicates astrocytes in regulating drug-seeking behaviors and demonstrates robust transcriptional response to several substances of abuse. This review focuses on the astrocytic transcriptional and epigenetic mechanisms of drug action.

Acute Cocaine Intoxication: An Approach to Severe Hepatic and Renal Dysfunctions

Cocaine is a highly addictive substance. Its poisoning can lead to potentially fatal multi-organ dysfunction. We report a case of cocaine overdose with severe multi-organ dysfunction. A healthy 51-year-old man was admitted to the emergency room due to behaviour changes and seizure after inhaling crack. Multiple dysfunctions were developed, with emphasis on liver and kidney dysfunction, due to their severity. The patient had marked hepatic cytolysis with a peak on the third day with alanine aminotransferase (ALT) and aspartate aminotransferase (AST): 7941 and 4453 IU/L, respectively with mild coagulopathy and hyperbilirubinemia. Underwent empirical treatment with acetylcysteine ​​with good clinical response. Also developed anuric AKIN3 acute kidney injury secondary to rhabdomyolysis, requiring treatment with intermittent haemodialysis. The approach to a case with severe multiorgan dysfunction is described, with special emphasis on the use of acetylcysteine. The good evolution of the patient can corroborate the use of this drug as a potential modifier of prognosis.

Platelet Lysate Therapy Attenuates Hypoxia Induced Apoptosis in Human Uroepithelial SV-HUC-1 Cells through Regulating the Oxidative Stress and Mitochondrial-Mediated Intrinsic Apoptotic Pathway

(1) Background: Ischemia/hypoxia plays an important role in interstitial cystitis/bladder pain syndrome (IC/BPS). Platelet-rich plasma (PRP) has been shown to relieve symptoms of IC/BPS by regulating new inflammatory processes and promoting tissue repair. However, the mechanism of action of PRP on the IC/BPS bladder remains unclear. We hypothesize that PRP might protect the urothelium during ischemia/hypoxia by decreasing apoptosis. (2) Methods: SV-HUC-1 cells were cultured under hypoxia for 3 h and treated with or without 2% PLTGold^® human platelet lysate (PL). Cell viability assays using trypan blue cell counts were examined. Molecules involved in the mitochondrial-mediated intrinsic apoptosis pathway, HIF1α, and PCNA were assessed by Western blot analysis. The detection of apoptotic cells and CM-H2DCFDA, an indicator of reactive oxygen species (ROS) in cells, was analyzed by flow cytometry. (3) Results: After 3 h of hypoxia, the viability of SV-HUC-1 cells and expression of PCNA were significantly decreased, and the expression of ROS, HIF1α, Bax, cytochrome c, caspase 3, and early apoptosis rate were significantly increased, all of which were attenuated by PL treatment. The addition of the antioxidant N-acetyl-L-cysteine (NAC) suppressed the levels of ROS induced by hypoxia, leading to inhibition of late apoptosis. (4) Conclusions: PL treatment could potentially protect the urothelium from apoptosis during ischemia/hypoxia by a mechanism that modulates the expression of HIF1α, the mitochondria-mediated intrinsic apoptotic pathway, and reduces ROS.

Additive cortical gray matter deficits in people living with HIV who use cocaine

Cocaine use, which is disproportionately common in people living with HIV (PWH), is known to have neurotoxic effects that may exacerbate HIV neuropathogenesis. While both cocaine use and HIV disease are independently associated with deficits in gray matter (GM) volume, the additive effect of cocaine use to HIV disease on GM volume has not been explored. Here, we investigated subcortical and cortical brain volume differences between four groups of individuals with and without HIV disease and/or cocaine use. Participants also completed a comprehensive neuropsychological testing battery, and HIV disease characteristics were recorded. Within subcortical regions, cocaine use was independently associated with higher volume in the dorsal striatum and pallidum, while HIV disease was associated with lower volume in the nucleus accumbens and thalamus. For cortical regions, there was an additive effect of cocaine use on HIV disease in parietal and occipital lobe volume with PWH who used cocaine displaying the lowest GM volume. Within regions that differed between groups, higher neurocognitive function was positively associated with thalamic, nucleus accumbens, dorsal striatum, and occipital lobe volume. For regions that showed a significant main effect of HIV disease, lower nadir CD4 + T cell count was associated with lower nucleus accumbens and occipital lobe volume. Lower current CD4 + T cell count was associated with lower occipital lobe volume. These results suggest that PWH who use cocaine are at greater risk for cortical atrophy than cocaine use or HIV disease alone.

N-acetyl cysteine prevents arecoline-inhibited C2C12 myoblast differentiation through ERK1/2 phosphorylation

Arecoline is known to induce reactive oxygen species (ROS). Our previous studies showed that arecoline inhibited myogenic differentiation and acetylcholine receptor cluster formation of C2C12 myoblasts. N-acetyl-cysteine (NAC) is a known ROS scavenger. We hypothesize that NAC scavenges the excess ROS caused by arecoline. In this article we examined the effect of NAC on the inhibited myoblast differentiation by arecoline and related mechanisms. We found that NAC less than 2 mM is non-cytotoxic to C2C12 by viability analysis. We further demonstrated that NAC attenuated the decreased number of myotubes and nuclei in each myotube compared to arecoline treatment by H & E staining. We also showed that NAC prevented the decreased expression level of the myogenic markers, myogenin and MYH caused by arecoline, using immunocytochemistry and western blotting. Finally, we found that NAC restored the decreased expression level of p-ERK1/2 by arecoline. In conclusion, our results indicate that NAC attenuates the damage of the arecoline-inhibited C2C12 myoblast differentiation by the activation/phosphorylation of ERK. This is the first report to demonstrate that NAC has beneficial effects on skeletal muscle myogenesis through ERK1/2 upon arecoline treatment. Since defects of skeletal muscle associates with several diseases, NAC can be a potent drug candidate in diseases related to defects in skeletal muscle myogenesis.

Metabolites of Cannabis Induce Cardiac Toxicity and Morphological Alterations in Cardiac Myocytes

Cannabis is one of the most commonly used recreational drugs worldwide. Rrecent epidemiology studies have linked increased cardiac complications to cannabis use. However, this literature is predominantly based on case incidents and post-mortem investigations. This study elucidates the molecular mechanism of Δ9-tetrahydrocannabinol (THC), and its primary metabolites 11-Hydroxy-Δ9-THC (THC-OH) and 11-nor-9-carboxy-Δ⁹-tetrahydrocannabinol (THC-COOH). Treatment of cardiac myocytes with THC-OH and THC-COOH increased cell migration and proliferation (p < 0.05), with no effect on cell adhesion, with higher doses (250–100 ng/mL) resulting in increased cell death and significant deterioration in cellular architecture. Conversely, no changes in cell morphology or viability were observed in response to THC. Expression of key ECM proteins α-SMA and collagen were up-regulated in response to THC-OH and THC-COOH treatments with concomitant modulation of PI3K and MAPK signalling. Investigations in the planarian animal model Polycelis nigra demonstrated that treatments with cannabinoid metabolites resulted in increased protein deposition at transection sites while higher doses resulted in significant lethality and decline in regeneration. These results highlight that the key metabolites of cannabis elicit toxic effects independent of the parent and psychoactive compound, with implications for cardiotoxicity relating to hypertrophy and fibrogenesis.

The Drosophila brain on cocaine at single-cell resolution

Whereas the neurological effects of cocaine have been well documented, effects of acute cocaine consumption on genome-wide gene expression across the brain remain largely unexplored. This question cannot be readily addressed in humans but can be approached using the Drosophila melanogaster model, where gene expression in the entire brain can be surveyed at once. Flies exposed to cocaine show impaired locomotor activity, including climbing behavior and startle response (a measure of sensorimotor integration), and increased incidence of seizures and compulsive grooming. To identify specific cell populations that respond to acute cocaine exposure, we analyzed single-cell transcriptional responses in duplicate samples of flies that consumed fixed amounts of sucrose or sucrose supplemented with cocaine, in both sexes. Unsupervised clustering of the transcriptional profiles of a total of 86,224 cells yielded 36 distinct clusters. Annotation of clusters based on gene markers revealed that all major cell types (neuronal and glial) as well as neurotransmitter types from most brain regions were represented. The brain transcriptional responses to cocaine showed profound sexual dimorphism and were considerably more pronounced in males than females. Differential expression analysis within individual clusters indicated cluster-specific responses to cocaine. Clusters corresponding to Kenyon cells of the mushroom bodies and glia showed especially large transcriptional responses following cocaine exposure. Cluster specific coexpression networks and global interaction networks revealed a diverse array of cellular processes affected by acute cocaine exposure. These results provide an atlas of sexually dimorphic cocaine-modulated gene expression in a model brain.

The role of mitochondria in cocaine addiction

The incidence of cocaine abuse is increasing especially in the U.K. where the rates are among the highest in Europe. In addition to its role as a psychostimulant, cocaine has profound effect on brain metabolism, impacting glycolysis and impairing oxidative phosphorylation. Cocaine exposure alters metabolic gene expression and protein networks in brain regions including the prefrontal cortex, the ventral tegmental area and the nucleus accumbens, the principal nuclei of the brain reward system. Here, we focus on how cocaine impacts mitochondrial function, in particular through alterations in electron transport chain function, reactive oxygen species (ROS) production and oxidative stress (OS), mitochondrial dynamics and mitophagy. Finally, we describe the impact of cocaine on brain energy metabolism in the developing brain following prenatal exposure. The plethora of mitochondrial functions altered following cocaine exposure suggest that therapies maintaining mitochondrial functional integrity may hold promise in mitigating cocaine pathology and addiction.

Optimization of PhysicoChemical Parameters for Production of Cytotoxic Secondary Metabolites and Apoptosis Induction Activities in the Culture Extract of a Marine Algal-Derived Endophytic Fungus Aspergillus sp

The endophytic fungal community in the marine ecosystem has been demonstrated to be relevant source of novel and pharmacologically active secondary metabolites. The current study focused on the evaluation of cytotoxic and apoptosis induction potential in the culture extracts of endophytic fungi associated with Sargassum muticum, a marine brown alga. The cytotoxicity of the four marine endophytes, Aspergillus sp., Nigrospora sphaerica, Talaromyces purpureogenus, and Talaromyces stipitatus, was evaluated by the MTT assay on HeLa cells. Further, several physicochemical parameters, including growth curve, culture media, and organic solvents, were optimized for enhanced cytotoxic activity of the selected extract. The Aspergillus sp. ethyl acetate extract (ASE) showed maximum cytotoxicity on multiple cancer cell lines. Chemical investigation of the metabolites by gas chromatography–mass spectroscopy (GC-MS) showed the presence of several compounds, including quinoline, indole, 2,4-bis(1,1-dimethylethyl) phenol, and hexadecenoic acid, known to be cytotoxic in ASE. The ASE was then tested for cytotoxicity in vitro on a panel of six human cancer cell lines, namely, HeLa (cervical adenocarcinoma), MCF-7 (breast adenocarcinoma), Hep G2 (hepatocellular carcinoma), A-549 (lung carcinoma), A-431 (skin/epidermis carcinoma), and LN-229 (glioblastoma). HeLa cells were most vulnerable to ASE treatment with an IC₅₀ value of 24 ± 2 μg/ml. The mechanism of cytotoxicity exhibited by the ASE was further investigated on Hela cells. The results showed that the ASE was capable of inducing apoptosis in HeLa cells through production of reactive oxygen species, depolarization of mitochondrial membrane, and activation of the caspase-3 pathway, which shows a possible activation of the intrinsic apoptosis pathway. It also arrested the HeLa cells at the G2/M phase of the cell cycle, eventually leading to apoptosis. Through this study, we add to the knowledge about the marine algae associated with fungal endophytes and report its potential for purifying specific compounds responsible for cytotoxicity.

Cocaine potentiates an inflammatory response in C6 astroglia-like cells

Cocaine is a highly addictive drug that mediates its effect through altering dopamine metabolism in the central nervous system (CNS), resulting in a feeling of euphoria. Owing to its high lipophilicity, cocaine easily crosses the blood brain barrier of the CNS and reaches various domains of the brain, where it can trigger cellular damage. Cocaine-induced CNS damage may arise due to increased levels of free radicals and nitric oxide (NO) in immunecompetent astroglial cells. In the present study, the potential ability of cocaine to exacerbate the production of inflammatory products, primarily superoxide free radicals (O₂^-), hydrogen peroxide (H₂O₂) and NO/nitrite (NO₂^-) was examined in rat C6 astroglia-like cells challenged with lipopolysaccharide (LPS), a bacterial endotoxin, and interferon gamma (IFNγ), a pro-inflammatory cytokine. Furthermore, the role of cocaine in increasing the expression of hypoxia inducible factor-1 (HIF-1α) and vascular endothelial growth factor (VEGF) in cells was also determined. First, the viability of the cells was assessed when treated with cocaine (0.5-7 mM) for 24 and 48 h. The results showed that cocaine toxicity was both time and dose-dependent. In subsequent studies, cells were challenged with or without LPS and IFNγ, followed by co-treatment with cocaine (1-4 mM) for 24 h. Cocaine treatment did not increase O₂^- or H₂O₂ production in the challenged or unchallenged cells. Similarly, cocaine treatment did not increase NO/NO₂^- production in the unchallenged cells; however, NO/NO₂^- levels in the challenged cells was increased 40-50-fold upon cocaine treatment compared with the corresponding unchallenged group. The HIF-1α and VEGF levels were significantly increased in the challenged cells at higher cocaine doses compared with the unchallenged cells. Since high concentrations of NO are associated with inflammation, the high levels of NO production observed in the present study suggested that cocaine may have potentiated the inflammatory response in the challenged C6 astroglia-like cells.

Cocaine Induces Cytoskeletal Changes in Cardiac Myocytes: Implications for Cardiac Morphology

Cocaine is one of the most widely abused illicit drugs worldwide and has long been recognised as an agent of cardiac dysfunction in numerous cases of drug overdose. Cocaine has previously been shown to up-regulate cytoskeletal rearrangements and morphological changes in numerous tissues; however, previous literature observes such changes primarily in clinical case reports and addiction studies. An investigation into the fundamental cytoskeletal parameters of migration, adhesion and proliferation were studied to determine the cytoskeletal and cytotoxic basis of cocaine in cardiac cells. Treatment of cardiac myocytes with cocaine increased cell migration and adhesion (p < 0.05), with no effect on cell proliferation, except with higher doses eliciting (1–10 μg/mL) its diminution and increase in cell death. Cocaine downregulated phosphorylation of cofilin, decreased expression of adhesion modulators (integrin-β3) and increased expression of ezirin within three hours of 1 μg/mL treatments. These functional responses were associated with changes in cellular morphology, including alterations in membrane stability and a stellate-like phenotype with less compaction between cells. Higher dose treatments of cocaine (5–10 μg/mL) were associated with significant cardiomyocyte cell death (p < 0.05) and loss of cellular architecture. These results highlight the importance of cocaine in mediating cardiomyocyte function and cytotoxicity associated with the possible loss of intercellular contacts required to maintain normal cell viability, with implications for cardiotoxicity relating to hypertrophy and fibrogenesis.

HIV-Tat and Cocaine Impact Brain Energy Metabolism: Redox Modification and Mitochondrial Biogenesis Influence NRF Transcription-Mediated Neurodegeneration

HIV infection and drugs of abuse induce oxidative stress and redox imbalance, which cause neurodegeneration. The mechanisms by which HIV infection and cocaine consumption affect astrocyte energy metabolism, and how this leads to neurodegenerative dysfunction, remain poorly understood. Presently, we investigated how oxidative injury causes the depletion of energy resources and glutathione synthetase (GSS), which in turn activates 5' AMP-activated protein kinase (AMPK), glycolytic enzymes, and mitochondrial biogenesis, finally resulting in nuclear factor erythroid (NRF) transcription in astrocytes. Both human primary astrocytes incubated with HIV-1 Tat protein in vitro and HIV-inducible Tat (iTat) mice exposed to cocaine showed decreased levels of GSS and increased superoxide dismutase (SOD) levels. These changes, in turn, significantly activated AMPK and raised the concentrations of several glycolytic enzymes, along with oxidative phosphorylation, the mitochondrial biogenesis of peroxisome proliferator-activated receptor-γ coactivator (PGC-1α) and mitochondrial transcription factor (TFAM), and Nrf1 and Nrf2 gene transcription and protein expression. Moreover, neurons exposed to HIV-1Tat/cocaine-conditioned media showed reductions in dendritic formation, spine density, and neuroplasticity compared with control neurons. These results suggest that redox inhibition of GSS altered AMPK activation and mitochondrial biogenesis to influence Nrf transcription. These processes are important components of the astrocyte signaling network regulating brain energy metabolism in HIV-positive cocaine users. In conclusion, HIV-1 Tat alters redox inhibition, thus increasing glycolytic metabolic profiles and mitochondrial biogenesis, leading to Nrf transcription, and ultimately impacting astrocyte energy resource and metabolism. Cocaine exacerbated these effects, leading to a worsening of neurodegeneration.

The impact of substance abuse on HIV-mediated neuropathogenesis in the current ART era

Approximately 37 million people worldwide are infected with human immunodeficiency virus (HIV). One highly significant complication of HIV infection is the development of HIV-associated neurocognitive disorders (HAND) in 15-55% of people living with HIV (PLWH), that persists even in the antiretroviral therapy (ART) era. The entry of HIV into the central nervous system (CNS) occurs within 4-8 days after peripheral infection. This establishes viral reservoirs that may persist even in the presence of ART. Once in the CNS, HIV infects resident macrophages, microglia, and at low levels, astrocytes. In response to chronic infection and cell activation within the CNS, viral proteins, inflammatory mediators, and host and viral neurotoxic factors produced over extended periods of time result in neuronal injury and loss, cognitive deficits and HAND. Substance abuse is a common comorbidity in PLWH and has been shown to increase neuroinflammation and cognitive disorders. Additionally, it has been associated with poor ART adherence, and increased viral load in the cerebrospinal fluid (CSF), that may also contribute to increased neuroinflammation and neuronal injury. Studies have examined mechanisms that contribute to neuroinflammation and neuronal damage in PLWH, and how substances of abuse exacerbate these effects. This review will focus on how substances of abuse, with an emphasis on methamphetamine (meth), cocaine, and opioids, impact blood brain barrier (BBB) integrity and transmigration of HIV-infected and uninfected monocytes across the BBB, as well as their effects on monocytes/macrophages, microglia, and astrocytes within the CNS. We will also address how these substances of abuse may contribute to HIV-mediated neuropathogenesis in the context of suppressive ART. Additionally, we will review the effects of extracellular dopamine, a neurotransmitter that is increased in the CNS by substances of abuse, on HIV neuropathogenesis and how this may contribute to neuroinflammation, neuronal insult, and HAND in PLWH with active substance use. Lastly, we will discuss some potential therapies to limit CNS inflammation and damage in HIV-infected substance abusers.

Identification of cytotoxic markers in methamphetamine treated rat C6 astroglia-like cells

Methamphetamine (METH) is a powerfully addictive psychostimulant that has a pronounced effect on the central nervous system (CNS). The present study aimed to assess METH toxicity in differentiated C6 astroglia-like cells through biochemical and toxicity markers with acute (1 h) and chronic (48 h) treatments. In the absence of external stimulants, cellular differentiation of neuronal morphology was achieved through reduced serum (2.5%) in the medium. The cells displayed branched neurite-like processes with extensive intercellular connections. Results indicated that acute METH treatment neither altered the cell morphology nor killed the cells, which echoed with lack of consequence on reactive oxygen species (ROS), nitric oxide (NO) or inhibition of any cell cycle phases except induction of cytoplasmic vacuoles. On the other hand, chronic treatment at 1 mM or above destroyed the neurite-like processors and decreased the cell viability that paralleled with increased levels of ROS, lipid peroxidation and lactate, depletion in glutathione (GSH) level and inhibition at G0/G1 phase of cell cycle, leading to apoptosis. Pre-treatment of cells with N-acetyl cysteine (NAC, 2.5 mM for 1 h) followed by METH co-treatment for 48 h rescued the cells completely from toxicity by decreasing ROS through increased GSH. Our results provide evidence that increased ROS and GSH depletion underlie the cytotoxic effects of METH in the cells. Since loss in neurite connections and intracellular changes can lead to psychiatric illnesses in drug users, the evidence that we show in our study suggests that these are also contributing factors for psychiatric-illnesses in METH addicts.

Cocaine addicted to cytoskeletal change and a fibrosis high

Cocaine is one of the most widely abused illicit drugs due to its euphoric and addictive properties. Cocaine-mediated cognitive impairments are the result of dynamic cytoskeletal rearrangements involved in mediating structural and behavioural plasticity. Cytoskeletal changes initiated following cocaine abuse are regulated by the Rho family of GTPases with significant downstream activity in key actin binding proteins. Moreover, signalling via the endoplasmic reticulum chaperone protein, sigma-1 receptor has highlighted the possibility of cocaine regulated pathology in other organ systems. However, the question of whether upstream stimulation of such a high affinity binding receptor is directly involved in cocaine-mediated cytoskeletal changes at present remains unknown. In this review, we describe the functional role of key cytoskeletal regulators in response to cocaine-induced signalling cues. In addition, we ascertain the extent of whether global cytoskeletal modulators involved in cocaine-induced neurological stimulation can be used as a platform for future studies into elucidating its fibrotic potential within the hepatic microenvironment. A focus on aspects still poorly understood relating to the nonneuronal pathological impact of cocaine is discussed in the sphere of hepatic dysregulation. Lastly, we suggest that cocaine may mediate its pathological capacity via the sigma1 receptor in regulating hepatoxicity, hepatic stellate cells activity, cytoskeletal dynamics, and the transcriptional regulation of key hepato-fibrogenic modulators.

Targeting redox regulation to treat substance use disorder using N‐acetylcysteine

Substance use disorder (SUD) is a chronic relapsing disorder characterized by transitioning from acute drug reward to compulsive drug use. Despite the heavy personal and societal burden of SUDs, current treatments are limited and unsatisfactory. For this reason, a deeper understanding of the mechanisms underlying addiction is required. Altered redox status, primarily due to drug-induced increases in dopamine metabolism, is a unifying feature of abused substances. In recent years, knowledge of the effects of oxidative stress in the nervous system has evolved from strictly neurotoxic to include a more nuanced role in redox-sensitive signaling. More specifically, S-glutathionylation, a redox-sensitive post-translational modification, has been suggested to influence the response to drugs of abuse. In this review we will examine the evidence for redox-mediating drugs as therapeutic tools focusing on N-acetylcysteine as a treatment for cocaine addiction. We will conclude by suggesting future research directions that may further advance this field.

Cellular and molecular responses to acute cocaine treatment in neuronal-like N2a cells: potential mechanism for its resistance in cell death

Cocaine is a highly abused drug that causes psychiatric and neurological problems. Its entry into neurons could alter cell-biochemistry and contribute in the manifestation of early pathological symptoms. We have previously shown the acute cocaine effects in rat C6 astroglia-like cells and found that these cells were highly sensitive to cocaine in terms of manifesting certain pathologies known to underlie psychological disorders. The present study was aimed to discern acute cocaine effects on the early onset of various changes in Neuro-2a (N2a) cells. Whole-cell patch-clamp recording of differentiated cells displayed the functional voltage-gated Na⁺ and K⁺ channels, which demonstrated the neuronal characteristics of the cells. Treatment of these cells with acute cocaine (1 h) at in vivo (nM to μM) and in vitro (mM) concentrations revealed that the cells remained almost 100% viable. Cocaine administration at 6.25 μM or 4 mM doses significantly reduced the inward currents but had no significant effect on outward currents, indicating the Na⁺ channel-blocking activity of cocaine. While no morphological change was observed at in vivo doses, treatment at in vitro doses altered the morphology, damaged the neurites, and induced cytoplasmic vacuoles; furthermore, general mitochondrial activity and membrane potential were significantly decreased. Mitochondrial dysfunction enabled the cells switch to anaerobic glycolysis, evidenced by dose-dependent increases in lactate and H₂S, resulting unaltered ATP level in the cells. Further investigation on the mechanism of action unfolded that the cell's resistance to cocaine was through the activation of nuclear factor E2-related factor-2 (Nrf-2) gene and subsequent increase of antioxidants (glutathione [GSH], catalase and GSH peroxidase [GPx]). The data clearly indicate that the cells employed a detoxifying strategy against cocaine. On a broader perspective, we envision that extrapolating the knowledge of neuronal resistance to central nervous system (CNS) diseases could delay their onset or progression.

Identification of biochemical and cytotoxic markers in cocaine treated PC12 cells

Cocaine is one of the powerful addictive drugs, widely abused in most Western countries. Because of high lipophilic nature, cocaine easily reaches various domains of the central nervous system (CNS) and triggers different levels of cellular toxicity. The aim of this investigation was to reproduce cocaine toxicity in differentiated PC12 cells through quantitative knowledge on biochemical and cytotoxicity markers. We differentiated the cells with 0.1 μg/ml nerve growth factor (NGF) for 5 days, followed by treatment with cocaine for 48 h at in vivo and in vitro concentrations. Results indicated that cocaine at in vivo concentrations neither killed the cells nor altered the morphology, but decreased the mitochondrial membrane potential that paralleled with increased lactate and glutathione (GSH) levels. On the other hand, cocaine at in vitro concentrations damaged the neurites and caused cell death, which corresponded with increased reactive oxygen species (ROS) generation, plasma membrane damage, and GSH depletion with no detectable nitric oxide (NO) level. While direct understanding of cocaine and cell interaction under in vivo animal models is impeded due to high complexity, our present in vitro results assisted in understanding the onset of some key events of neurodegenerative diseases in cocaine treated neuronal cells.

Involvement of the NADPH Oxidase NOX2-Derived Brain Oxidative Stress in an Unusual Fatal Case of Cocaine-Related Neurotoxicity Associated With Excited Delirium Syndrome

Here, we investigated the possible role of the Nicotinamide Adenine Dinucleotide Phosphate oxidase NOX2-derived brain oxidative stress in a fatal case of cocaine-related neurotoxicity, associated to excited delirium syndrome. We detected a strong NOX2 immunoreactivity, mainly in cortical GABAergic neurons and astrocytes, with a minor presence in microglia, glutamatergic and dopaminergic neurons as well as a significant immunostaining for other markers of oxidative stress (8OhDG, HSP70, HSP90, and NF-κB) and apoptotic phenomena. These results support a crucial role of NOX2-derived brain oxidative stress in cocaine-induced brain dysfunctions and neurotoxicity.

Drugs of abuse and blood-brain barrier endothelial dysfunction: A focus on the role of oxidative stress

Psychostimulants and nicotine are the most widely abused drugs with a detrimental impact on public health globally. While the long-term neurobehavioral deficits and synaptic perturbations are well documented with chronic use of methamphetamine, cocaine, and nicotine, emerging human and experimental studies also suggest an increasing incidence of neurovascular complications associated with drug abuse. Short- or long-term administration of psychostimulants or nicotine is known to disrupt blood-brain barrier (BBB) integrity/function, thus leading to an increased risk of brain edema and neuroinflammation. Various pathophysiological mechanisms have been proposed to underlie drug abuse-induced BBB dysfunction suggesting a central and unifying role for oxidative stress in BBB endothelium and perivascular cells. This review discusses drug-specific effects of methamphetamine, cocaine, and tobacco smoking on brain microvascular crisis and provides critical assessment of oxidative stress-dependent molecular pathways focal to the global compromise of BBB. Additionally, given the increased risk of human immunodeficiency virus (HIV) encephalitis in drug abusers, we have summarized the synergistic pathological impact of psychostimulants and HIV infection on BBB integrity with an emphasis on unifying role of endothelial oxidative stress. This mechanistic framework would guide further investigations on specific molecular pathways to accelerate therapeutic approaches for the prevention of neurovascular deficits by drugs of abuse.

S-Glutathionylation and Redox Protein Signaling in Drug Addiction

Drug addiction is a chronic relapsing disorder that comes at a high cost to individuals and society. Therefore understanding the mechanisms by which drugs exert their effects is of prime importance. Drugs of abuse increase the production of reactive oxygen and nitrogen species resulting in oxidative stress. This change in redox homeostasis increases the conjugation of glutathione to protein cysteine residues; a process called S-glutathionylation. Although traditionally regarded as a protective mechanism against irreversible protein oxidation, accumulated evidence suggests a more nuanced role for S-glutathionylation, namely as a mediator in redox-sensitive protein signaling. The reversible modification of protein thiols leading to alteration in function under different physiologic/pathologic conditions provides a mechanism whereby change in redox status can be translated into a functional response. As such, S-glutathionylation represents an understudied means of post-translational protein modification that may be important in the mechanisms underlying drug addiction. This review will discuss the evidence for S-glutathionylation as a redox-sensing mechanism and how this may be involved in the response to drug-induced oxidative stress. The function of S-glutathionylated proteins involved in neurotransmission, dendritic spine structure, and drug-induced behavioral outputs will be reviewed with specific reference to alcohol, cocaine, and heroin.

Lipoic acid and N-acetylcysteine prevent ammonia-induced inflammatory response in C6 astroglial cells: The putative role of ERK and HO1 signaling pathways

Hyperammonemia induces significant changes in the central nervous system (CNS) in direct association with astroglial functions, such as oxidative damage, glutamatergic excitotoxicity, and impaired glutamine synthetase (GS) activity and pro-inflammatory cytokine release. Classically, lipoic acid (LA) and N-acetylcysteine (NAC) exhibit antioxidant and anti-inflammatory activities by increasing glutathione (GSH) biosynthesis and decreasing pro-inflammatory mediator levels in glial cells. Thus, we evaluated the protective effects of LA and NAC against ammonia cytotoxicity in C6 astroglial cells. Ammonia decreased GSH levels and increased cytokine release and NFκB transcriptional activation. LA and NAC prevented these effects by the modulation of ERK and HO1 pathways. Taken together, these observations show that LA and NAC prevent the ammonia-induced inflammatory response.