Immunosuppression and oxidative stress induced by acute and chronic exposure to cocaine in rat

Comparisons of physicochemical features and hepatoprotective potentials of unprocessed and processed polysaccharides from Polygonum multiflorum Thunb

The raw and processed Polygonum multiflorum Thunb (PM) are used to treat different diseases, and PM has also been reported to have hepatotoxic effects. Moreover, mounting evidence indicates that processed PM is less toxic than raw PM. The changes in efficacy and toxicity of PM during the processing are closely related to the changes in chemical composition. Previous studies have mainly focused on the changes of anthraquinone and stilbene glycosides during process. Polysaccharides, as main components of PM, showed many pharmacological effects, but its changes in the processing has been neglected for a long time. In this study, the polysaccharides of PM in the raw (RPMPs) and processed products (PPMPs) were determined and the liver injury model induced by acetaminophen was utilized to evaluate the impact of polysaccharides on the liver. Results showed that the heteropolysaccharides RPMPs and PPMPs both comprised Man, Rha, GlcA, GalA, Glc, Ara and Xyl, but markedly differed in polysaccharide yield, molar ratio of monosaccharide composition and M_w. In vivo analysis, results showed that demonstrated that RPMPs and PPMPs both exerted hepatoprotective effects by upregulating antioxidant enzymes and repressing lipid peroxidation. It is noteworthy that the polysaccharide yield of processed PM was seven-fold higher than that of raw PM, so it is speculated that processed PM has better hepatoprotective effects at the same dose of decoction. The present work provides an important foundation for studying the polysaccharide activity of PM and further revealing the processing mechanism of PM. This study also proposed a new hypothesis that the significant increase of polysaccharide content in processed PM may be another reason that the product PM causes less liver injury.

Repeated cocaine administration upregulates CB2 receptor expression in striatal medium-spiny neurons that express dopamine D1 receptors in mice

Cannabinoid CB₂ receptors (CB₂R) are importantly involved in drug reward and addiction. However, the cellular mechanisms underlying CB₂R action remain unclear. We have previously reported that cocaine self-administration upregulates CB₂R expression in midbrain dopamine (DA) neurons. In the present study, we investigated whether cocaine or heroin also alters CB₂R expression in striatal medium-spiny neurons that express dopamine D₁ or D₂ receptors (D₁-MSNs, D₂-MSNs) and microglia. Due to the concern of CB₂R antibody specificity, we developed three mouse CB₂-specific probes to detect CB₂R mRNA using quantitative RT-PCR and RNAscope in situ hybridization (ISH) assays. We found that a single injection of cocaine failed to alter, while repeated cocaine injections or self-administration dose-dependently upregulated CB₂R gene expression in both brain (cortex and striatum) and periphery (spleen). In contrast, repeated administration of heroin produced a dose-dependent reduction in striatal CB₂ mRNA expression. RNAscope ISH assays detected CB₂R mRNA in striatal D₁- and D₂-MSNs, not in microglia. We then used transgenic CX3CR1^eGFP/+ microglia reporter mice and D₁- or D₂-Cre-RiboTag mice to purify striatal microglia or ribosome-associated mRNAs from CX3CR1^eGFP/+, D₁-MSNs, or D₂-MSNs, respectively. We found that CB₂R upregulation occurred mainly in D₁-MSNs, not in D₂-MSNs or microglia, in the nucleus accumbens rather than the dorsal striatum. These findings indicate that repeated cocaine exposure may upregulate CB₂R expression in both brain and spleen, with regional and cell type-specific profiles. In the striatum, CB₂R upregulation occurs mainly in D₁-MSNs in the nucleus accumbens. Given the important role of D₁-MSNs in brain reward function, the present findings provide new insight into mechanisms by which brain CB₂Rs modulate cocaine action.

Huganbuzure Granule Attenuates Concanavalin-A-Induced Immune Liver Injury in Mice via Regulating the Balance of Th1/Th2/Th17/Treg Cells and Inhibiting Apoptosis

In Uygur medicine, Huganbuzure granule (HBG) is one of the classical prescriptions for liver protection. However, its role in immune liver injury remains unknown. This study evaluates the effect of HBG on concanavalin-A- (ConA-) induced immune liver injury and investigates its protective underlying mechanism. BALB/c mice were randomly divided into five groups (n = 24 mice per group): control, ConA, 1.6 g/kg HBG + ConA, 3.2 g/kg HBG + ConA, and 6 mg/kg prednisolone + ConA. HBG was intragastrically administrated once daily for ten consecutive days, prior to ConA (20 mg/kg) injection. The levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), total bilirubin (TBIL), superoxide dismutase (SOD), and malondialdehyde (MDA) in mouse serum were measured after ConA injection. Moreover, liver-related mRNA levels were evaluated by qPCR. The detection of liver-related proteins was assessed by immunohistochemistry and western blot analysis. Compared with the ConA group, HBG reduced the mRNA expression of IL-17A and IFN-γ and the protein expression of T-bet and ROR-γt. In addition, HBG increased the mRNA expression of IL-4 and TGF-β and protein expression of GATA3 and Foxp3, indicating that HBG regulated the balance of Th1/Th2 and Th17/Treg. Furthermore, HBG alleviated immune liver injury by reducing oxidative stress, inhibiting apoptosis, and decreasing the expression of p-JNK, p-ERK, p-p38, p-JAK1, p-STAT1, p-STAT3, and IRF1. Our data suggested that HBG attenuated ConA-induced immune liver injury by regulating the immune balance and inhibiting JAK1/STATs/IRF1 signaling, thereby reducing apoptosis induced by JNK activation. The findings indicate that HBG may be a promising drug for immune liver injury.

Chronic opipramol treatment extinguishes cocaine craving through Rac1 in responders: A rat model study

Ras-related C3 botulinum toxin substrate 1 (Rac1), of the Rho small GTPase family, is a key regulator of actin cytoskeleton rearrangement and plays an important role in dendritic morphogenesis. Cocaine produces neuronal alterations, including structural changes in dendritic number and morphology. Emerging data indicate sigma-1 receptors (σ-1Rs) as a promising candidate for the prevention of cocaine craving. Opipramol is a σ-1R agonist approved in some European countries for depression and anxiety. Here we report that opipramol, mediated by Rac1, attenuates cocaine-seeking behavior in a rat model of self-administration. The opipramol effect was shown in two phases. It decreased cocaine-seeking behavior throughout the withdrawal phase and, interestingly, showed a significant reduction of cocaine-primed reinstatement in 75% of the opipramol-treated group (termed 'responders'). All opipramol-treated rats showed a decrease in σ-1R mRNA expression levels in the nucleus accumbens (NAc) versus controls. Responders also exhibited significantly decreased NAc Rac1 mRNA expression levels, compared with non-responder rats. Hence, Rac1 differentiated responders from non-responders. Rac1 correlated positively with σ-1R mRNA levels in opipramol responders. In another experiment, Rac1 inhibitor injected directly into the NAc core decreased active lever presses on the first day of extinction, indicating the critical role of Rac1 in the opipramol effect on drug seeking. We postulate that chronic activation of σ-1R, through a dynamic interaction with Rac1, may suggest a new approach to treat substance use disorder (SUD). Rac1 inhibition is a prerequisite for decreasing drug seeking and rehabilitation, and this can be achieved by opipramol, a medication that can be given during detoxification.

Sex Differences, Cocaine Use, and Liver Fibrosis Among African Americans in the Miami Adult Studies on HIV Cohort

Background: HIV infection disproportionally affects African Americans. Liver disease is a major cause of non-HIV morbidity and mortality in this population. Substance abuse accelerates HIV disease and may facilitate progression of liver disease. This study investigated the relationship between sex differences and cocaine use with liver injury, characterized as hepatic fibrosis. Materials and Methods: A cross-sectional study was conducted on 544 African Americans [369 people living with HIV (PLWH) and 175 HIV seronegative] from the Miami Adult Studies on HIV (MASH) cohort. Cocaine use was determined with a validated self-reported questionnaire and confirmed with urine screen. Fasting blood was used to estimate liver fibrosis using the noninvasive fibrosis-4 (FIB-4) index. Results: Men living with HIV had 1.79 times higher odds for liver fibrosis than women living with HIV (p = 0.038). African American women had higher CD4 count (p = 0.001) and lower HIV viral load (p = 0.011) compared to African American men. Fewer women (PLWH and HIV seronegative) smoked cigarettes (p = 0.002), and fewer had hazardous or harmful alcohol use (p < 0.001) than men. Women also had higher body mass index (kg/m²) (p < 0.001) compared to men. No significant association was noted among HIV seronegative participants for liver fibrosis by sex differences or cocaine use. Among African Americans living with HIV, cocaine users were 1.68 times more likely to have liver fibrosis than cocaine nonusers (p = 0.044). Conclusions: Sex differences and cocaine use appear to affect liver disease among African Americans living with HIV pointing to the importance of identifying at-risk individuals to improve outcomes of liver disease.

Cardiovascular Mitochondrial Dysfunction Induced by Cocaine: Biomarkers and Possible Beneficial Effects of Modulators of Oxidative Stress

Cocaine abuse has long been known to cause morbidity and mortality due to its cardiovascular toxic effects. The pathogenesis of the cardiovascular toxicity of cocaine use has been largely reviewed, and the most recent data indicate a fundamental role of oxidative stress in cocaine-induced cardiovascular toxicity, indicating that mitochondrial dysfunction is involved in the mechanisms of oxidative stress. The comprehension of the mechanisms involving mitochondrial dysfunction could help in selecting the most appropriate mitochondria injury biological marker, such as superoxide dismutase-2 activity and glutathionylated hemoglobin. The potential use of modulators of oxidative stress (mitoubiquinone, the short-chain quinone idebenone, and allopurinol) in the treatment of cocaine cardiotoxic effects is also suggested to promote further investigations on these potential mitochondria-targeted antioxidant strategies.

Myocardial oxidative damage is induced by cardiac Fas-dependent and mitochondria-dependent apoptotic pathways in human cocaine-related overdose

The aim of this study is to analyse cardiac specimens from human cocaine-related overdose, to verify the hypothesis that cardiac toxicity by acute exposure to high dosage of cocaine could be mediated by unbalanced myocardial oxidative stress, and to evaluate the apoptotic response. To address these issues, biochemical and immunohistological markers of oxidative/nitrosative stress were evaluated. We found that i-NOS, NOX2 and nitrotyrosine expression were significantly higher in the hearts of subjects who had died from high doses of cocaine, compared to the control group. Increase of these markers was associated with a dramatic increase in 8-OHdG, another marker of oxidative stress. A high number of TUNEL-positive apoptotic myocells was observed in the study group compared to the control group. The immunoexpression of TNF-α was significantly higher in the cocaine group compared to the control group. Furthermore, we detected a significantly stronger immunoresponse to anti-SMAC/DIABLO in our study group compared to control cases. Both cardiac Fas-dependent and mitochondria-dependent apoptotic pathways appeared to be activated to a greater extent in the cocaine group than in the control group. Our results highlight the central role of oxidative stress in cocaine toxicity. High levels of NOS can promote the oxidation process and lead to apoptosis.

Cocaine Use and Liver Disease are Associated with All-Cause Mortality in the Miami Adult Studies in HIV (MASH) Cohort

OBJECTIVE

Liver disease is a frequent cause of morbidity and mortality in HIV infection. We examined the relationship of cocaine use, liver disease progression and mortality in an HIV-infected cohort.

METHODS

Consent was obtained from 487 HIV+ participants, a subset of the Miami Adult Studies on HIV (MASH) cohort. Participants were eligible if they were followed for at least two years, completed questionnaires on demographics and illicit drug use and had complete metabolic panels, CD4 cell counts and HIV-viral loads. FIB-4 was calculated and cut-off points were used for staging liver fibrosis. Death certificates were obtained.

RESULTS

Participants were 65% men, 69% Black and 81% were on ART at recruitment. Cocaine was used by 32% of participants and 29% were HIV/HCV co-infected. Mean age was 46.9 ± 7.7 years, mean CD4 cell count was 501.9 ± 346.7 cells/μL and mean viral load was 2.75 ± 1.3 log10 copies/mL at baseline. During the follow-up, 27 patients died, with a mortality rate of 28.2/1000 person-year. Cocaine was used by 48% of those who died (specific mortality rate was 13/1000 person-year). Those who died were more likely to use cocaine (HR=3.8, P=0.006) and have more advanced liver fibrosis (HR=1.34, P<0.0001), adjusting for age, gender, CD4 cell count and HIV-viral load at baseline and over time. Among the HIV mono-infected participants, cocaine users were 5 times more likely to die (OR=5.09, P=0.006) than participants who did not use cocaine.

CONCLUSION

Cocaine use and liver fibrosis are strong and independent predictors of mortality in HIV infected and HIV/HCV co-infected adults. Effective interventions to reduce cocaine use among people living with HIV (PHLW) are needed.

Pathophysiological mechanisms of catecholamine and cocaine-mediated cardiotoxicity

Overactivation of the sympatho-adrenergic system is an essential mechanism providing short-term adaptation to the stressful conditions of critical illnesses. In the same way, the administration of exogenous catecholamines is mandatory to support the failing circulation in acutely ill patients. In contrast to these short-term benefits, prolonged adrenergic stress is detrimental to the cardiovascular system by initiating a series of adverse effects triggering significant cardiotoxicity, whose pathophysiological mechanisms are complex and only partially elucidated. In addition to the development of myocardial oxygen supply/demand imbalance induced by the sustained activation of adrenergic receptors, catecholamines can damage cardiomyocytes by fostering mitochondrial dysfunction, via two main mechanisms. The first one is calcium overload, consecutive to β-adrenergic receptor-mediated activation of protein kinase A and subsequent phosphorylation of multiple Ca(2+)-cycling proteins. The second one is oxidative stress, primarily related to the transformation of catecholamines into "aminochromes," which undergo redox cycling in mitochondria to generate copious amounts of oxygen-derived free radicals. In turn, calcium overload and oxidative stress promote mitochondrial permeability transition and cardiomyocyte cell death, both via the apoptotic and necrotic pathways. Comparable mechanisms of myocardial toxicity, including marked oxidative stress and mitochondrial dysfunction, have been reported with the use of cocaine, a common recreational drug with potent sympathomimetic activity. The aim of the current review is to present in detail the pathophysiological processes underlying the development of catecholamine and cocaine-induced cardiomyopathy, as such conditions may be frequently encountered in the clinical practice of cardiologists and ICU specialists.

Early abstinence of crack-cocaine is effective to attenuate oxidative stress and to improve antioxidant defences

RATIONALE

Preclinical studies have shown that cocaine exposure and withdrawal are associated with cellular oxidative stress damage. However, the impact of crack-cocaine dependence on oxidative stress biomarkers remains unclear. Here, we assessed peripheral oxidative stress and antioxidant defences during two periods of crack-cocaine detoxification treatment and associated these changes with psychological morbidity.

METHODS

Thirty female inpatients were recruited, and plasma samples were collected at the 4th and 18th days of abstinence; 30 healthy controls were also recruited. Plasma levels of protein carbonyl, protein thiol content, superoxide dismutase (SOD), glutathione peroxidase (GPx), reduced reduced (GSH) and total reactive antioxidant potential (TRAP) were measured by standard methods; the questionnaires Cocaine Selective Severity Assessment, Beck Depressive Inventory and the Addiction Severity Index were applied.

RESULTS

We report higher oxidative stress damage after 4 days of detoxification, as shown by increased total thiol content and protein carbonylation when compared with control group and after 18 days of detoxification. After 18 days of treatment, we observed a recovery of the oxidative stress damage and increase of the antioxidant defences, as shown by higher levels of SOD, GPx, GSH and TRAP. There was a positive correlation between protein carbonylation and psychological variables; in contrast, there was a negative correlation between TRAP levels and clinical assessments.

CONCLUSIONS

Taken together, these results suggest that drug rehabilitation treatment was effective in decreasing oxidative damage represented by the reduction in biological markers, which are closely related to the severity of withdrawal symptoms.

Cocaine alters cytokine profiles in HIV-1-infected African American individuals in the DrexelMed HIV/AIDS genetic analysis cohort

BACKGROUND

This study evaluated the relationship between illicit drug use and HIV-1 disease severity in HIV-1-infected patients enrolled in the DREXELMED HIV/AIDS Genetic Analysis Cohort. Because cocaine is known to have immunomodulatory effects, the cytokine profiles of preferential nonusers, cocaine users, and multidrug users were analyzed to understand the effects of cocaine on cytokine modulation and HIV-1 disease severity.

METHODS

Patients within the cohort were assessed approximately every 6 months for HIV-1 clinical markers and for history of illicit drug, alcohol, and tobacco use. The Luminex human cytokine 30-plex panel was used for cytokine quantitation. Analysis was performed using a newly developed biostatistical model.

RESULTS

Substance abuse was common within the cohort. Using the drug screens at the time of each visit, the subjects in the cohort were categorized as preferential nonusers, cocaine users, or multidrug users. The overall health of the nonuser population was better than that of the cocaine users, with peak and current viral loads in nonusers substantially lower than those in cocaine and multidrug users. Among the 30 cytokines investigated, differential levels were established within the 3 populations. The T-helper 2 cytokines, interleukin-4 and -10, known to play a critical role during HIV-1 infection, were positively associated with increasing cocaine use. Clinical parameters such as latest viral load, CD4 T-cell counts, and CD4:CD8 ratio were also significantly associated with cocaine use, depending on the statistical model used.

CONCLUSIONS

Based on these assessments, cocaine use seems to be associated with more severe HIV-1 disease.

Cocaine exposure alters H2S tissue concentrations in peripheral mouse organs

BACKGROUND

Hydrogen sulfide (H2S) is well-known as a physiological mediator in the mammalian brain and peripheral tissues. Among several factors that change the concentration of H2S, oxidative stress and generation of reactive oxygen species, which accompany neurochemical actions of drugs of abuse, are of recent interest.

OBJECTIVE

Limited data on the connection of cocaine and H2S levels prompted us to investigate the effect of this psychostimulant on the H2S concentration in the mouse brain and peripheral organs.

METHODS

Male BALB/C mice were given several cocaine dosage and treatment regimens, and the free and acid-labile H2S tissue concentrations were determined with a modified spectrophotometric method of Siegel.

RESULTS

We demonstrated the dose- and treatment-dependent decreases in the H2S level in the heart (83% of control level), and in the liver and kidney (17-34% of control levels) homogenates, but no changes were seen in the mouse brain. The strongest effect occurred after repeated administration of cocaine (20mg/kg) in all peripheral tissues.

CONCLUSION

A reduction in the peripheral tissue H2S level in the heart, liver and kidney homogenates after repeated injections of cocaine may be the result of a strong toxic effect of the drug.

Glutathione and redox signaling in substance abuse

Throughout the last couple decades, the cause and consequences of substance abuse has expanded to identify the underlying neurobiological signaling mechanisms associated with addictive behavior. Chronic use of drugs, such as cocaine, methamphetamine and alcohol leads to the formation of oxidative or nitrosative stress (ROS/RNS) and changes in glutathione and redox homeostasis. Of importance, redox-sensitive post-translational modifications on cysteine residues, such as S-glutathionylation and S-nitrosylation could impact on the structure and function of addiction related signaling proteins. In this commentary, we evaluate the role of glutathione and redox signaling in cocaine-, methamphetamine- and alcohol addiction and conclude by discussing the possibility of targeting redox pathways for the therapeutic intervention of these substance abuse disorders.

Varicella zoster virus (VZV) in cerebral arteries of subjects at high risk for VZV reactivation

With a decline in varicella zoster virus (VZV)-specific cell-mediated immunity, VZV can reactivate, infect cerebral arteries and cause stroke. Previous studies of cerebral arteries from subjects without a history of transient ischemic attacks or stroke revealed no VZV DNA or VZV antigen; however, VZV DNA and VZV antigen were found in the cerebral arteries of a subject with diabetes, a known risk factor for VZV reactivation and zoster. The present study analyzed an additional 55 cerebral arteries from 18 subjects with co-morbidities that may increase risk of VZV reactivation: a history of alcohol abuse, tricyclic antidepressant intoxication, cocaine abuse, HIV or being over age 70 years. VZV antigen was detected in 24 (44%) cerebral arteries from 14 (78%) subjects.

Oxidative stress biomarkers in some rat brain structures and peripheral organs underwent cocaine

Oxidative stress (OS) generates or intensifies cocaine-evoked toxicity in the brain and peripheral organs. The aim of this study was to examine superoxide dismutase (SOD) activity and lipid peroxidation [measured by malondialdehyde (MDA) levels] in rats during maintenance of cocaine self-administration and after withdrawal by a yoked-triad procedure. Our results indicate that repeated cocaine self-administration provoked an elevation of SOD activity in the hippocampus, frontal cortex, dorsal striatum, and liver. MDA levels were reduced in the brain, increased in the liver, kidney, and heart during maintenance of self-administration, and increased in the kidney in cocaine-yoked rats. In addition, following extinction training, we found enhanced MDA levels and SOD activity in the rat hippocampus, while changes in the activity of OS biomarkers in other brain structures and peripheral tissues were reminiscent of the changes seen during cocaine self-administration. These findings highlight the association between OS biomarkers in motivational processes related to voluntary cocaine intake in rats. OS participates in memory and learning impairments that could be involved in drug toxicity and addiction mechanisms. Therefore, further studies are necessary to address protective mechanisms against cocaine-induced brain and peripheral tissue damage.

The H2O2 scavenger ebselen decreases ethanol-induced locomotor stimulation in mice

BACKGROUND

In the brain, the enzyme catalase by reacting with H(2)O(2) forms Compound I (catalase-H(2)O(2) system), which is the main system of central ethanol metabolism to acetaldehyde. Previous research has demonstrated that acetaldehyde derived from central-ethanol metabolism mediates some of the psychopharmacological effects produced by ethanol. Manipulations that modulate central catalase activity or sequester acetaldehyde after ethanol administration modify the stimulant effects induced by ethanol in mice. However, the role of H(2)O(2) in the behavioral effects caused by ethanol has not been clearly addressed. The present study investigated the effects of ebselen, an H(2)O(2) scavenger, on ethanol-induced locomotion.

METHODS

Swiss RjOrl mice were pre-treated with ebselen (0-50mg/kg) intraperitoneally (IP) prior to administration of ethanol (0-3.75g/kg; IP). In another experiment, animals were pre-treated with ebselen (0 or 25mg/kg; IP) before caffeine (15mg/kg; IP), amphetamine (2mg/kg; IP) or cocaine (10mg/kg; IP) administration. Following these treatments, animals were placed in an open field to measure their locomotor activity. Additionally, we evaluated the effect of ebselen on the H(2)O(2)-mediated inactivation of brain catalase activity by 3-amino-1,2,4-triazole (AT).

RESULTS

Ebselen selectively prevented ethanol-induced locomotor stimulation without altering the baseline activity or the locomotor stimulating effects caused by caffeine, amphetamine and cocaine. Ebselen reduced the ability of AT to inhibit brain catalase activity.

CONCLUSIONS

Taken together, these data suggest that a decline in H(2)O(2) levels might result in a reduction of the ethanol locomotor-stimulating effects, indicating a possible role for H(2)O(2) in some of the psychopharmacological effects produced by ethanol.

α-Lipoic acid, a scavenging agent for H₂O₂, reduces ethanol-stimulated locomotion in mice

RATIONALE

The main system of central ethanol oxidation is mediated by the enzyme catalase. By reacting with H(2)O(2), brain catalase forms compound I (the catalase-H(2)O(2) system), which is able to oxidize ethanol to acetaldehyde in the brain. Previous studies have demonstrated that pharmacological manipulations of brain catalase activity modulate the stimulant effects of ethanol in mice. However, the role of H(2)O(2) in the behavioral effects of ethanol has not yet been clearly addressed.

OBJECTIVES

In the present study, we investigated the effects of alpha-lipoic acid (LA), a scavenging agent for H(2)O(2), on ethanol-induced locomotor stimulation.

METHODS

CD-1 mice were pretreated with LA [0-100 mg/kg, intraperitoneally (IP)] 0-60 min prior to administration of ethanol (0-3.75 g/kg, IP). In another experiment, animals were pretreated with LA (0, 25, or 50 mg/kg, IP) 30 min before cocaine (10 mg/kg, IP), amphetamine (2 mg/kg, IP), or caffeine (25 mg/kg, IP). After these treatments the animals were placed in an open-field chamber and their locomotor activity was measured for 20 min.

RESULTS

LA 25, 50, and 100 mg/kg IP prevented ethanol-induced locomotor stimulation. LA did not affect the locomotor-stimulating effects of cocaine, amphetamine, and caffeine. Additionally, we demonstrated that LA prevents the inactivation of brain catalase by 3-amino-1,2,4-triazole, thus indicating that H(2)O(2) levels are reduced by LA.

CONCLUSIONS

These data support the idea that a decrease in cerebral H(2)O(2) production by LA administration inhibits ethanol-stimulated locomotion. This study suggests that the brain catalase-H(2)O(2) system, and by implication centrally formed acetaldehyde, plays a key role in the psychopharmacological effects of ethanol.

Cocaine-induced adaptations in cellular redox balance contributes to enduring behavioral plasticity

Impaired glutamate homeostasis in the nucleus accumbens has been linked to cocaine relapse in animal models, and results in part from cocaine-induced downregulation of the cystine-glutamate exchanger. In addition to regulating extracellular glutamate, the uptake of cystine by the exchanger is a rate-limiting step in the synthesis of glutathione (GSH). GSH is critical for balancing cellular redox in response to oxidative stress. Cocaine administration induces oxidative stress, and we first determined if downregulated cystine-glutamate exchange alters redox homeostasis in rats withdrawn from daily cocaine injections and then challenged with acute cocaine. Among the daily cocaine-induced changes in redox homeostasis were an increase in protein S-glutathionylation and a decrease in expression of GSH-S-transferase pi (GSTpi). To mimic reduced GSTpi, a genetic mouse model of GSTpi deletion or pharmacological inhibition of GSTpi by administering ketoprofen during daily cocaine administration was used. The capacity of cocaine to induce conditioned place preference or locomotor sensitization was augmented, indicating that reducing GSTpi may contribute to cocaine-induced behavioral neuroplasticity. Conversely, an acute cocaine challenge after withdrawal from daily cocaine elicited a marked increase in accumbens GSTpi, and the expression of behavioral sensitization to a cocaine challenge injection was inhibited by ketoprofen pretreatment; supporting a protective effect by the acute cocaine-induced rise in GSTpi. Together, these data indicate that cocaine-induced oxidative stress induces changes in GSTpi that contribute to cocaine-induced behavioral plasticity.

Clinical physiology and mechanism of dizocilpine (MK-801): electron transfer, radicals, redox metabolites and bioactivity

Dizocilpine (MK-801), an extensively investigated drug possessing secondary amine and benzenoid functions, displays a wide array of biological properties, including anticonvulsant and anesthetic. There is scant discussion of biomechanism. A relevant, important finding is formation of oxidative metabolites in the hydroxylamine and phenolic categories. Analogy to cocaine metabolites suggests participation of redox entities, such as, hydroxylamine, nitroxide and nitrosonium, which can lead to electron transfer and radical formation. There is also similarity to metabolism by 3,3′-iminodipropionitrile and phencyclidine. Alternatively, the phenolic metabolites are well-known precursors of ET quinones. The review documents various physiological effects, mainly involving the central nervous system. Also of interest are the pro- and anti-oxidant properties. Considerable attention has been paid to MK-801 as an antagonist of the N-methyl-D-aspartate receptor in the glutamate category. This aspect is often associated with effects on the central nervous system. The review also provides recent literature dealing with MK-801/NMDA receptor in various areas of bioactivity. Studies were made of MK-801 involvement in working memory processing. Deficits in behavior were noted after administration of the drug. Treatment of mice with dizocilpine induced learning impairment. The influence of MK-801 on fear has been investigated. The substance is known to exert an analgesic effect in pain control. A number of reports deal with anesthetic properties.

Sleep loss and acute drug abuse can induce DNA damage in multiple organs of mice

The purpose of the present study was to characterize the genetic damage induced by paradoxical sleep deprivation (PSD) in combination with cocaine or ecstasy (3,4-methylenedioxymethamphetamine; MDMA) in multiple organs of male mice using the single cell gel (comet) assay. C57BL/6J mice were submitted to PSD by the platform technique for 72 hours, followed by drug administration and evaluation of DNA damage in peripheral blood, liver and brain tissues. Cocaine was able to induce genetic damage in the blood, brain and liver cells of sleep-deprived mice at the majority of the doses evaluated. Ecstasy also induced increased DNA migration in peripheral blood cells for all concentrations tested. Analysis of damaged cells by the tail moment data suggests that ecstasy is a genotoxic chemical at the highest concentrations tested, inducing damage in liver or brain cells after sleep deprivation in mice. Taken together, our results suggest that cocaine and ecstasy/MDMA act as potent genotoxins in multiple organs of mice when associated with sleep loss.

Cocaine administration increases CD4/CD8 lymphocyte ratio in peripheral blood despite lymphopenia and elevated corticosterone

The CD4/CD8 lymphocyte ratio in peripheral blood is used in the diagnosis of HIV infection, autoimmune disorders or susceptibility to infections. The present experiment aimed to evaluate the lymphocyte subsets, their distribution and CD4/CD8 ratio in blood after repeated, intravenous administration of cocaine. Adult male Wistar rats received three daily, in 30 min intervals, intravenous infusions of cocaine hydrochloride (5 mg/kg) or saline for 14 consecutive days. After each infusion the locomotor-activating effects of cocaine were assessed. Blood samples were collected 30 min after the last daily infusion on the 1st, 7th and 14th day of treatment. Total leukocyte numbers, percentages of leukocyte subpopulations, and T, B, NK, T CD4+, and T CD8+ lymphocyte subsets, IFN-γ, and plasma corticosterone were determined. Repeated cocaine treatment resulted in an increase in neutrophil numbers and a significant decrease in total leukocyte and lymphocyte numbers involving a significant reduction in numbers of T, B, and NK lymphocyte subsets. T CD4+ and T CD8+ lymphocyte numbers were reduced but with a considerably smaller decrease in T CD4+ number. Cocaine treatment altered proportions between the lymphocyte subsets by decreasing the percentages of T CD8+, B, and NK cells but increasing a percentage of T CD4+ cells. Destabilization in proportions between T CD4+ and T CD8+ was manifested as an elevated CD4/CD8 ratio that occurred despite increased plasma corticosterone and the lymphocytopenia. Cocaine did not affect the concentration of IFN-γ. The results suggest that although cocaine induced lymphopenia, it did not suppress the overall immune activity in terms of the CD4/CD8 ratio.

Integrated approach to immunotoxicity: electron transfer, reactive oxygen species, antioxidants, cell signaling, and receptors

As with all body organs, the immune system is subjected to attack by a variety of toxins. Serious consequences can result because the immune organs serve as a defense against infective agents. The toxins, both organic and inorganic, fall into a large variety of classes, such as metals, therapeutic drugs, industrial chemicals, pollutants, pesticides, fuels, herbicides and abused drugs. Although the mode of action is multifaceted, our focus is on electron transfer (ET), reactive oxygen species (ROS), antioxidants (AOs), cell signaling, and receptors. It is significant that the toxins or their metabolites incorporate ET functionalities capable of redox cycling with resultant generation of ROS and accompanying oxidative stress.

Chronic cocaine-induced cardiac oxidative stress and mitogen-activated protein kinase activation: the role of Nox2 oxidase

Chronic cocaine exposure is associated with severe cardiac complications, but the mechanisms of cocaine cardiotoxicity remain unclear, and current therapies are unsatisfactory. We investigated the hypothesis of oxidative stress-mediated cardiotoxicity and the role of NADPH oxidase in this process in a mouse model of chronic escalating "binge" cocaine administration (milligrams per kilogram): days 1 to 4 at 3 x 15 mg, days 5 to 8 at 3 x 20 mg, days 9 to 12 at 3 x 25 mg, and days 13 to 14 at 3 x 30 mg. Compared with vehicle controls, chronic binge cocaine administration significantly increased the cardiac NADPH-dependent O(2)(.) production (1.96- +/- 0.4-fold) as detected by tiron (an O(2)(.) scavenger)-inhibitable lucigenin chemiluminescence and dihydroethidium fluorescence. Cocaine-induced reactive oxygen species (ROS) production was associated with significant increases ( approximately 2-fold) in the protein expressions of Nox2 (an isoform of NADPH oxidase) and its regulatory subunits: p22(phox), p67(phox), p47(phox), p40(phox), and Rac1, and in p47(phox) phosphorylation as detected by immunoblotting (all p < 0.03). Increased Nox2 activity was accompanied by the activation of extracellular signal-regulated kinase 1/2, p38 mitogen-activated protein kinase (MAPK), and c-Jun NH(2)-terminal kinase, notably in the cardiomyocytes. Cell culture experiments revealed that cocaine-induced ROS production was primarily a direct action of cocaine on cardiac myocytes, which caused severe oxidative damage to myocytes and cell death as detected by terminal deoxynucleotidyl transferase dUTP nick-end labeling assay. These could be inhibited by inhibitors to protein kinase C (bisindolymaleimide) or by depletion of Nox2 using small interfering RNA. In conclusion, chronic cocaine administration directly causes severe myocardial oxidative stress through the activation of Nox2 oxidase. Increased ROS production contributes to MAPK activation and the subsequent myocyte damage. Inhibitors to NADPH oxidase or antioxidants may have therapeutic potential in the treatment of cocaine cardiotoxicity.

A mechanism for the inhibition of neural progenitor cell proliferation by cocaine

BACKGROUND

Prenatal exposure of the developing brain to cocaine causes morphological and behavioral abnormalities. Recent studies indicate that cocaine-induced proliferation inhibition and/or apoptosis in neural progenitor cells may play a pivotal role in causing these abnormalities. To understand the molecular mechanism through which cocaine inhibits cell proliferation in neural progenitors, we sought to identify the molecules that are responsible for mediating the effect of cocaine on cell cycle regulation.

METHODS AND FINDINGS

Microarray analysis followed by quantitative real-time reverse transcription PCR was used to screen cocaine-responsive and cell cycle-related genes in a neural progenitor cell line where cocaine exposure caused a robust anti-proliferative effect by interfering with the G1-to-S transition. Cyclin A2, among genes related to the G1-to-S cell cycle transition, was most strongly down-regulated by cocaine. Down-regulation of cyclin A was also found in cocaine-treated human primary neural and A2B5+ progenitor cells, as well as in rat fetal brains exposed to cocaine in utero. Reversing cyclin A down-regulation by gene transfer counteracted the proliferation inhibition caused by cocaine. Further, we found that cocaine-induced accumulation of reactive oxygen species, which involves N-oxidation of cocaine via cytochrome P450, promotes cyclin A down-regulation by causing an endoplasmic reticulum (ER) stress response, as indicated by increased phosphorylation of eIF2alpha and expression of ATF4. In the developing rat brain, the P450 inhibitor cimetidine counteracted cocaine-induced inhibition of neural progenitor cell proliferation as well as down-regulation of cyclin A.

CONCLUSIONS

Our results demonstrate that down-regulation of cyclin A underlies cocaine-induced proliferation inhibition in neural progenitors. The down-regulation of cyclin A is initiated by N-oxidative metabolism of cocaine and consequent ER stress. Inhibition of cocaine N-oxidative metabolism by P450 inhibitors may provide a preventive strategy for counteracting the adverse effects of cocaine on fetal brain development.

Cocaine-induced oxidative stress precedes cell death in human neuronal progenitor cells

By 2003, an estimated 34 million Americans had used cocaine according to the National Survey on Drug Use & Health. About 5.9 million of those had used in the past 12 months. Chronic cocaine users often develop addiction, dependency and tolerance to the drug. The psychological and physical effects of cocaine are due to the disruption of the limbic system in the central nervous system (CNS). Increased oxidative stress reported in the frontal cortex and the striatum of rats exposed to cocaine suggests that oxidative damage plays a significant role in cocaine-induced disruption of the CNS. Although it is evident that cocaine induces oxidative stress in the CNS, little has been learned about whether such increased oxidative stress is also relevant to apoptosis in cocaine-exposed models. To gain insight into the role of cocaine-induced oxidative stress in apoptosis, we hypothesized that oxidative stress precedes cell death when cocaine is administrated. To test this hypothesis, we have monitored the oxidative stress and apoptotic effects of acute cocaine exposure in human neuronal progenitor cells (HNPC). We found that oxidative stress was significantly increased at 48h after a 30min cocaine exposure compared to control cells, and that this was followed by cell death at 72h. Using the same experimental paradigm we have previously shown that pro-inflammatory genes are up-regulated in cocaine-exposed HNPC at 24h. Therefore, we suggest that the increased oxidative stress (possibly mediated by inflammatory responses) precedes cell death in cocaine-exposed HNPC. This may have implications for the consequences of cocaine abuse in situations where antioxidant capacity is compromised, as in the aging brain.

Drugs of abuse, immune modulation, and AIDS

Illicit drugs such as amphetamines, cocaine, marijuana, and opiates alter immune function and decrease host resistance to microbes in vitro and in experimental animal models. Effects on the immune system may be mediated indirectly as a result of drug interactions in the central nervous system (CNS) or directly through activation of cognate receptors on various immune cell types. For marijuana and opioids, seven-transmembranal G protein-coupled receptors have been identified in the CNS and in the immune system that may play a functionally relevant role in immune modulation. There is accumulating evidence that sigma(1) receptors play a comparable role in cocaine-mediated alteration of immune responses. A mode by which these exogenously introduced substances affects immunity and host resistance may be by perturbing the balance of Th(1) proinflammatory versus Th(2) anti-inflammatory cytokines and lipid bioeffectors. However, while illicit drugs have been documented to alter immune functions in vitro and in animal models, there is a paucity of controlled longitudinal epidemiological studies that definitively correlate immunosuppressive effects with increased incidence of infections or immune disorders in humans, including infection with the human immunodeficiency virus (HIV) or disease progression to AIDS.

Mitochondrial dysfunction and caspase activation in rat cortical neurons treated with cocaine or amphetamine

Drug abuse is associated with brain dysfunction and neurodegeneration, and various recreational drugs induce apoptotic cell death. This study examined the role of the mitochondrial apoptotic pathway in psychostimulant-induced neuronal dysfunction. Using primary neuronal cultures, we observed that amphetamine (IC50=1.40 mM) was more potent than cocaine (IC50=4.30 mM) in inducing cell toxicity. Apoptotic cell death was further evaluated using cocaine and amphetamine concentrations that moderately decreased cell reduction capacity but did not affect plasma membrane integrity. Compared to cocaine, amphetamine highly decreased the mitochondrial membrane potential, as determined using the fluorescent probe rhodamine-123, whereas both drugs decreased mitochondrial cytochrome c. In contrast to amphetamine, cocaine cytotoxicity was partly mediated through effects on the electron transport chain, since cocaine toxicity was ameliorated in mitochondrial DNA-depleted cells lacking mitochondrially encoded electron transport chain subunits. Cocaine and amphetamine induced activation of caspases-2, -3 and -9 but did not affect activity of caspases-6 or -8. In addition, amphetamine, but not cocaine, was associated with the appearance of evident nuclear apoptotic morphology. These events were not accompanied by differences in the release of the apoptosis-inducing factor (AIF) from mitochondria. Our results demonstrate that although both amphetamine and cocaine activate the mitochondrial apoptotic pathway in cortical neurons, amphetamine is more likely to promote apoptosis.

Cocaine induced inflammatory response in human neuronal progenitor cells

We have employed a genomic approach in homogenous cell culture to investigate the fundamental transcriptional responses which occur in neurons over time as a consequence of a single 30-min exposure to cocaine. Data from 24 Affymetrix microarrays, representing eight treatment groups, were analyzed by GeneChip Operating Software and then further mined by hierarchical clustering, anova, and Ingenuity Pathway Analysis software to examine known molecular pathways impacted by the observed transcriptional changes. For each time point under investigation, the data sets of genes exhibiting altered expression in treated cells compared with control were interrogated with a specific focus on differential expression of genes involved in immunomodulation and inflammation. The existing literature on the effects of cocaine in a diverse array of experimental paradigms demonstrates a significant modulation of inflammation and immune mechanisms, but these have typically been studies of chronic exposure in immune-competent cells. Our data show a time-dependent up-regulation of genes associated with pro-inflammatory and immune responses, peaking at 24 h as confirmed by all methods of analysis, suggesting a specific neuronal immunomodulatory response to acute cocaine exposure.

Suppression of natural killer cell activity by morphine is mediated by the nucleus accumbens shell

Despite a wealth of data indicating that morphine modulates immune status by acting at mu-opioid receptors in the brain, there is little known about how the opioid system interacts with other neurotransmitter systems to modulate specific immune parameters. The aim of the present study was to investigate whether dopaminergic projections to the nucleus accumbens are involved in morphine-induced suppression of splenic natural killer (NK) cell activity. The results indicate that administration of the dopamine D1 antagonist SCH-23390 into the nucleus accumbens shell, but not core, blocked morphine's suppressive effect on NK activity in male Lewis rats. In support of these findings, the effect of morphine was also prevented by intra-accumbens microinfusions of the dopaminergic immunotoxin anti-DAT-saporin. Additionally, administration of the D1 agonist SKF-38393 into the nucleus accumbens shell produced reductions in splenic NK activity comparable to morphine, suggesting a critical role for D1 receptors in the modulation of NK activity. Collectively, these findings demonstrate that dopaminergic inputs to the nucleus accumbens are critically involved in opioid-induced immunosuppression and suggest that opioid-induced increases in D1 receptor activation may have adverse consequences on immune status.

Chronic Exposure to Cocaine Binging Predisposes to an Accelerated Course of Dilated Cardiomyopathy in Conscious Dogs following Rapid Ventricular Pacing

Despite extensive study, the extent to which cocaine use predisposes to cardiac injury remains unknown. We hypothesized that chronic cocaine binging would increase susceptibility to a subsequent cardiac insult, even in the absence of demonstrable effects on baseline hemodynamics. We studied progression of dilated cardiomyopathy (DCM) induced by rapid ventricular pacing (240 beats per minute) in five conscious, chronically instrumented dogs, after exposure to repetitive cocaine binging (COC) in the form of four consecutive 1 mg/kg i.v. boluses daily for 8 days, to simulate human cocaine abuse. We compared the results with nine control dogs (CON) undergoing the exact pacing protocol, without prior cocaine exposure. Baseline hemodynamics were not significantly altered by chronic cocaine exposure. Following 2 weeks of pacing, COC dogs exhibited accelerated progression to DCM, depressed plasma nitric oxide levels (CON, 17 +/- 2 microM; COC, 10 +/- 2 microM, p < 0.05), and a significantly greater increase in plasma epinephrine (CON, 33 +/- 6 pg/ml; COC, 104 +/- 24 pg/ml). After only 2 weeks of pacing, COC dogs demonstrated progressive DCM of a magnitude comparable with end-stage pacing-induced DCM. Chronic cocaine binging increases susceptibility to a subsequent myocardial insult and accelerates progression of DCM in conscious dogs following rapid pacing. These data suggest that although chronic cocaine use alone may not affect myocardial function, it predisposes to greater susceptibility to a superimposed insult.

Role of oxidative metabolites of cocaine in toxicity and addiction: oxidative stress and electron transfer

Cocaine is one of the principal drugs of abuse. Although impressive advances have been made, unanswered questions remain concerning mechanism of toxicity and addiction. Discussion of action mode usually centers on receptor binding and enzyme inhibition, with limited attention to events at the molecular level. This review provides extensive evidence in support of the hypothesis that oxidative metabolites play important roles comprising oxidative stress (OS), reactive oxygen species (ROS), and electron transfer (ET). The metabolites include norcocaine and norcocaine derivatives: nitroxide radical, N-hydroxy, nitrosonium, plus cocaine iminium and formaldehyde. Observed formation of ROS is rationalized by redox cycling involving several possible ET agents. Three potential ones are present in the form of oxidative metabolites, namely, nitroxide, nitrosonium, and iminium. Most attention has been devoted to the nitroxide-hydroxylamine couple which has been designated by various investigators as the principal source of ROS. The proximate ester substituent is deemed important for intramolecular stabilization of reactive intermediates. Reduction potential of nitroxide is in accord with plausibility of ET in the biological milieu. Toxicity by cocaine, with evidence for participation of OS, is demonstrated for many body components, including liver, central nervous system, cardiovascular system, reproductive system, kidney, mitochondria, urine, and immune system. Other adverse effects associated with ROS comprise teratogenesis and apoptosis. Examples of ROS generated are lipid peroxides and hydroxyl radical. Often observed were depletion of antioxidant defenses, and protection by added antioxidants, such as, thiol, salicylate, and deferoxamine. Considerable evidence supports the contention that oxidative ET metabolites of cocaine are responsible for much of the observed OS. Quite significantly, the pro-oxidant, toxic effects, including generation of superoxide and lipid peroxyl radicals, plus depletion of glutathione, elicited by nitroxide or the hydroxylamine derivative, were greater than for the parent drug. The formaldehyde metabolite also appears to play a role. Mechanistic similarity to the action of neurotoxin 3,3'-iminodipropionitrile is pointed out. A number of literature strategies for treatment of addiction are addressed. However, no effective interventions are currently available. An hypothesis for addiction is offered based on ET and ROS at low concentrations. Radicals may aid in cell signaling entailing redox processes which influence ion transport, neuromodulation, and transcription. Ideas are suggested for future work dealing with health promotion. These include use of AOs, both dietary and supplemental, trapping of the norcocaine metabolite by non-toxic complexing agents, and use of nitrones for capturing harmful radical species.

Gender and sodium-ascorbate transporter isoforms determine ascorbate concentrations in mice

We evaluated the hypothesis that sodium-dependent vitamin C (ascorbate) transporters SVCT1 and SVCT2 (encoded by genes Slc23a1 and Slc23a2) regulate ascorbate concentrations in tissues of adult mice. Slc23a2+/- and Slc23a2+/+ mice were fed an ascorbate-free diet for 10-12 wk, and then segregated according to gender and genome, and were placed in groups of 3-4 in metabolic cages for 24-h urine collection. RT-PCR analysis showed that liver and kidney expressed mainly SVCT1, and brain, skeletal muscle, and spleen expressed predominantly SVCT2. Slc23a2+/- mice had low SVCT2 but normal SVCT1 messenger RNA (mRNA) levels, which did not differ between genders. Ascorbate concentrations were lower in Slc23a2+/- than Slc23a2+/+ mice in tissues where SVCT2 was the main isoform. Compared with males, females had lower ascorbate excretion and ascorbate:creatinine ratio in urine and had higher ascorbate concentrations in plasma and SVCT1-predominant tissues. SVCT2 contributed to a gender effect in spleen because males had higher spleen ascorbate concentration than females in wild-type but not in Slc23a2+/- mice. Hepatic gulonolactone oxidase mRNA and activity levels did not differ with genotype or gender, indicating no differences in ascorbate synthesis. We concluded that SVCT2 is a major determinant of ascorbate accumulation in tissues lacking SVCT1. The SVCT isoforms appear to function independently of one another because SVCT1 expression and ascorbate concentrations in SVCT1-predominant organs were not affected by SVCT2 deficiency. Additionally, lower ascorbate excretion in females may elevate the vitamin's concentrations in plasma and tissues expressing SVCT1 that, unlike SVCT2, is not saturated by plasma ascorbate concentrations.