Oxidized soluble guanylyl cyclase causes erectile dysfunction in alcoholic mice.

BACKGROUND AND PURPOSE: Alcohol abuse has been associated with erectile dysfunction (ED), but the implicated molecular mechanisms are unresolved. This study analyses the role of alterations in soluble guanylyl cyclase (sGC) in ED. EXPERIMENTAL APPROACH: ED was analysed in adult male C57BL/6J mice subjected to the Chronic Intermittent Ethanol (CIE) paradigm. Erectile function was assessed in anaesthetised mice in vivo by evaluating intracavernosal pressure (ICP) and in vitro in isolated mice corpora cavernosa (CC) mounted in a myograph. Protein expression and reactive oxygen species were analysed by western blot and dihydroethidium staining, respectively. KEY RESULTS: In CIE mice, we observed a significant decrease in the relaxant response of the CC to stimulation of NO release from nitrergic nerves by electrical field stimulation, to NO release from endothelial cells by acetylcholine, to the PDE5 inhibitor sildenafil, and to the sGC stimulator riociguat. Conversely, the response to the sGC activator cinaciguat, whose action is independent of the oxidation state of sGC, was significantly enhanced in these CC. The responses to adenylyl cyclase stimulation with forskolin were unchanged. We found an increase in reactive oxygen species in the CC from CIE mice as well as an increase in CYP2E1 and NOX2 protein expression. In vivo pre-treatment with tempol prevented alcohol-induced erectile dysfunction. CONCLUSIONS AND IMPLICATIONS: Our results demonstrate that alcoholic mice show ED in vitro and in vivo due to an alteration in the redox state of sGC and suggest that sGC activators may be effective in ED associated with alcoholism.

Influx of kynurenine into the brain is involved in the reduction of ethanol consumption induced by Ro 61-8048 after chronic intermittent ethanol in mice.

BACKGROUND AND PURPOSE: The kynurenine pathway has been proposed as a target for modulating drug abuse. We previously demonstrated that inhibition of kynurenine 3-monooxygenase (KMO), using Ro 61-8048, reduces ethanol consumption in a binge drinking model. Here, we investigate the effect of the kynurenine pathway modulation in ethanol-dependent mice. EXPERIMENTAL APPROACH: Adult male and female mice were subjected to a Chronic Intermittent Ethanol (CIE) paradigm. On the last day of CIE, mice were treated with Ro 61-8048, Ro 61-8048 + PNU-120596, a positive allosteric modulator of α7nAChR, and Ro 61-8048 + L-leucine or probenecid, which blocks the influx or efflux of kynurenine from the brain, respectively. Ethanol, water consumption and preference were measured and kynurenine levels in plasma and limbic forebrain were determined. KEY RESULTS: Ro 61-8048 decreases consumption and preference for ethanol in both sexes exposed to the CIE model, an effect that was prevented by PNU-120596. The Ro 61-8048-induced decrease in ethanol consumption depends on the influx of kynurenine into the brain. CONCLUSION AND IMPLICATIONS: Inhibition of KMO reduces ethanol consumption and preference in both male and female mice subjected to CIE model by a mechanism involving α7nAChR. Moreover, this centrally-mediated effect depends on the influx of peripheral kynurenine to the brain and can be prolonged by blocking the efflux of kynurenine from the brain. Here, for the first time, we demonstrate that the modulation of the kynurenine pathway is an effective strategy for the treatment of ethanol dependence in both sexes.

Decreased kynurenine pathway potentiate resilience to social defeat effect on cocaine reward.

The kynurenine (KYN) pathway of tryptophan (TRP) degradation is activated by stress and inflammatory factors. It is now well established that social stress induces the activation of the immune system, with central inflammation and KYN metabolism being two of the main factors linking stress with depression. The aim of the present study was to evaluate the long-lasting changes in the KYN pathway induced by social defeat (SD) associated with the resilience or susceptibility to an increase in the conditioned rewarding effects of cocaine. Mice were exposed to repeated SD and 3 weeks later, a conditioned place preference (CPP) induced by a subthreshold dose of cocaine (1.5 mg/kg) was developed. KYN levels in plasma, cerebellum, hippocampus, striatum and limbic forebrain were studied at the end of the CPP procedure. Changes in the KYN pathway after exposure to pharmacological (oxytocin and indomethacin) and environmental interventions (environmental enrichment) were also evaluated. Our results showed that defeated susceptible (SD-S) mice had higher conditioning scores than resilient mice (SD-R). In addition, although KYN concentration was elevated in all defeated mice, SD-R mice showed smaller increases in KYN concentration in the cerebellum than SD-S mice. Oxytocin or Indomethacin treatment before SD normalized cocaine-induced CPP, although the increase in the KYN pathway was maintained. However, environmental enrichment before SD normalized cocaine-induced CPP and prevented the increase in the KYN pathway. The present study highlights the role of the KYN pathway and anti-inflammatory drugs acting on TRP metabolism as pharmacological targets to potentiate resilience to social stress effects.

Addiction and the kynurenine pathway: A new dancing couple?

Drug use poses a serious threat to health systems throughout the world and the number of consumers rises relentlessly every year. The kynurenine pathway, main pathway of tryptophan degradation, has drawn interest in this field due to its relationship with addictive behaviour. Recently it has been confirmed that modulation of kynurenine metabolism at certain stages of the pathway can reduce, prevent or abolish drug seeking-like behaviours in studies with several different drugs. In this review, we present an up-to-date summary of the evidences of a relationship between drug use and the kynurenine pathway, both the alterations of the pathway due to drug use as well as modulation of the pathway as a potential approach to treat drug addiction. The review discusses ethanol, nicotine, cannabis, amphetamines, cocaine and opioids and new prospects in the drug research field are proposed.

Plasma tryptophan and kynurenine pathway metabolites in abstinent patients with alcohol use disorder and high prevalence of psychiatric comorbidity.

BACKGROUND: Alterations in tryptophan (TRP) metabolism has been linked to drug exposure and mental disorders. However, most of studies have been performed without considering the co-occurrence of both disorders in the context of addiction. This cross-sectional study examines TRP metabolism through the serotonin (5-HT) and kynurenine (KYN) pathways in subjects with alcohol use disorders (AUD) and high prevalence of psychiatric comorbidity. METHODS: For this purpose, male and female abstinent AUD patients (N = 130) and healthy controls (N = 80) were clinically evaluated for substance use and mental disorders, and blood samples were collected to determine plasma concentrations of TRP, 5-HT, KYN and kynurenic acid (KA) using high performance liquid chromatography. Clinical and biochemical variables were analyzed for potential associations considering AUD, psychiatric comorbidity and sex. RESULTS: TRP concentrations were significantly associated with an interaction effect between AUD diagnosis and sex (p < .01): TRP concentrations were lower in male AUD patients but higher in female AUD patients compared with their controls. KYN and KA concentrations were significantly associated with AUD diagnosis (p < .01 and p < .05, respectively). Thus, AUD patients showed significantly higher KYN concentrations and lower KA concentrations than controls. Regarding 5-HT concentrations, there were sex differences in the alcohol group (p < .05) and female AUD patients showed lower 5-HT concentrations than male AUD patients. Moreover, there was a significant interaction effect between psychiatric comorbidity and sex on TRP concentrations in the alcohol group (p < .01). Whereas male patients with both comorbid substance use and mental disorders showed lower TRP concentrations than male non-comorbid patients, female patients with comorbid mental disorders showed higher TRP concentrations than female non-comorbid patients. CONCLUSION: While alterations in the KYN pathway appear to be directly associated with a history of AUD, altered TRP concentrations are associated with the presence of comorbid psychiatric disorders. Finally, sex differences in TRP metabolism must be considered in future studies.

Serotonin is the main tryptophan metabolite associated with psychiatric comorbidity in abstinent cocaine-addicted patients.

The lack of effective treatments and a high rate of relapse in cocaine addiction constitute a major health problem. The present study was conducted to examine the expression of tryptophan-derived metabolites in the context of cocaine addiction and psychiatric comorbidity, which is common in addicted subjects. Abstinent patients with cocaine use disorder (CUD) and control subjects were recruited for a cross-sectional study. Participants were assessed with a semi-structured diagnostic interview (PRISM) based on DSM-IV-TR for substance and mental disorders. Plasma concentrations of tryptophan metabolites and their association with relevant CUD-related variables and psychiatric comorbidity were explored. We observed decreased plasma kynurenic acid concentrations in the cocaine group, however no associations between CUD-related variables and tryptophan-derived metabolites were found. In contrast, 5-HT concentrations were increased in CUD-patients and the diagnosis of different psychiatric disorders in the cocaine group was related to higher plasma 5-HT concentrations compared with non-comorbid patients. Therefore, while changes in plasma kynurenic acid concentrations appear to be directly associated with lifetime CUD, changes in 5-HT concentrations are associated with psychiatric comorbidity. These results emphasize the need to find potential biomarkers for a better stratification of cocaine-addicted patients in order to develop therapeutic approaches to prevent cocaine relapse.

Changes in brain kynurenine levels via gut microbiota and gut-barrier disruption induced by chronic ethanol exposure in mice.

Inflammatory processes have been shown to modify tryptophan (Trp) metabolism. Gut microbiota appears to play a significant role in the induction of peripheral and central inflammation. Ethanol (EtOH) exposure alters gut permeability, but its effects on Trp metabolism and the involvement of gut microbiota have not been studied. We analyzed several parameters of gut-barrier and of peripheral and central Trp metabolism following 2 different EtOH consumption patterns in mice, the binge model, drinking in the dark (DID), and the chronic intermittent (CI) consumption paradigm. Antibiotic treatment was used to evaluate gut microbiota involvement in the CI model. Mice exposed to CI EtOH intake, but not DID, show bacterial translocation and increased plasma LPS immediately after EtOH removal. Gut-barrier permeability to FITC-dextran is increased by CI, and, furthermore, intestinal epithelial tight-junction (TJ) disruption is observed (decreased expression of zonula occludens 1 and occludin) associated with increased matrix metalloproteinase (MMP)-9 activity and iNOS expression. CI EtOH, but not DID, increases kynurenine (Kyn) levels in plasma and limbic forebrain. Intestinal bacterial decontamination prevents the LPS increase but not the permeability to FITC-dextran, TJ disruption, or the increase in MMP-9 activity and iNOS expression. Although plasma Kyn levels are not affected by antibiotic treatment, the elevation of Kyn in brain is prevented, pointing to an involvement of microbiota in CI EtOH-induced changes in brain Trp metabolism. Additionally, CI EtOH produces depressive-like symptoms of anhedonia, which are prevented by the antibiotic treatment thus pointing to an association between anhedonia and the increase in brain Kyn and to the involvement of gut microbiota.-Giménez-Gómez, P., Pérez-Hernández, M., O'Shea, E., Caso, J. R., Martín-Hernández, D., Cervera, L. A., Centelles. M. L. G.-L., Gutiérrez-Lopez, M. D., Colado, M. I. Changes in brain kynurenine levels via gut microbiota and gut-barrier disruption induced by chronic ethanol exposure in mice.

Increasing kynurenine brain levels reduces ethanol consumption in mice by inhibiting dopamine release in nucleus accumbens.

Recent research suggests that ethanol (EtOH) consumption behaviour can be regulated by modifying the kynurenine (KYN) pathway, although the mechanisms involved have not yet been well elucidated. To further explore the implication of the kynurenine pathway in EtOH consumption we inhibited kynurenine 3-monooxygenase (KMO) activity with Ro 61-8048 (100 mg/kg, i.p.), which shifts the KYN metabolic pathway towards kynurenic acid (KYNA) production. KMO inhibition decreases voluntary binge EtOH consumption and EtOH preference in mice subjected to "drinking in the dark" (DID) and "two-bottle choice" paradigms, respectively. This effect seems to be a consequence of increased KYN concentration, since systemic KYN administration (100 mg/kg, i.p.) similarly deters binge EtOH consumption in the DID model. Despite KYN and KYNA being well-established ligands of the aryl hydrocarbon receptor (AhR), administration of AhR antagonists (TMF 5 mg/kg and CH-223191 20 mg/kg, i.p.) and of an agonist (TCDD 50 µg/kg, intragastric) demonstrates that signalling through this receptor is not involved in EtOH consumption behaviour. Ro 61-8048 did not alter plasma acetaldehyde concentration, but prevented EtOH-induced dopamine release in the nucleus accumbens shell. These results point to a critical involvement of the reward circuitry in the reduction of EtOH consumption induced by KYN and KYNA increments. PNU-120596 (3 mg/kg, i.p.), a positive allosteric modulator of α7-nicotinic acetylcholine receptors, partially prevented the Ro 61-8048-induced decrease in EtOH consumption. Overall, our results highlight the usefulness of manipulating the KYN pathway as a pharmacological tool for modifying EtOH consumption and point to a possible modulator of alcohol drinking behaviour.

3,4-Methylenedioxymethamphetamine (MDMA, ecstasy) produces edema due to BBB disruption induced by MMP-9 activation in rat hippocampus.

The recreational drug of abuse, 3,4-methylenedioxymethamphetamine (MDMA, ecstasy) disrupts blood-brain barrier (BBB) integrity in rats through an early P2X7 receptor-mediated event which induces MMP-9 activity. Increased BBB permeability often causes plasma proteins and water to access cerebral tissue leading to vasogenic edema formation. The current study was performed to examine the effect of a single neurotoxic dose of MDMA (12.5 mg/kg, i.p.) on in vivo edema development associated with changes in the expression of the perivascular astrocytic water channel, AQP4, as well as in the expression of the tight-junction (TJ) protein, claudin-5 and Evans Blue dye extravasation in the hippocampus of adult male Dark Agouti rats. We also evaluated the ability of the MMP-9 inhibitor, SB-3CT (25 mg/kg, i.p.), to prevent these changes in order to validate the involvement of MMP-9 activation in MDMA-induced BBB disruption. The results show that MDMA produces edema of short duration temporally associated with changes in AQP4 expression and a reduction in claudin-5 expression, changes which are prevented by SB-3CT. In addition, MDMA induces a short-term increase in both tPA activity and expression, a serine-protease which is involved in BBB disruption and upregulation of MMP-9 expression. In conclusion, this study provides evidence enough to conclude that MDMA induces edema of short duration due to BBB disruption mediated by MMP-9 activation.

Disruption of blood-brain barrier integrity in postmortem alcoholic brain: preclinical evidence of TLR4 involvement from a binge-like drinking model.

Inflammatory cytokines and reactive oxygen species are reported to be involved in blood-brain barrier (BBB) disruption. Because there is evidence that ethanol (EtOH) induces release of free radicals, cytokines and inflammatory mediators we examined BBB integrity and matrix metalloproteinase (MMP) activity in postmortem human alcoholic brain and investigated the role of TLR4 signaling in BBB permeability in TLR4-knockout mice under a binge-like EtOH drinking protocol. Immunohistochemical studies showed reduced immunoreactivity of the basal lamina protein, collagen-IV and of the tight junction protein, claudin-5 in dorsolateral prefrontal cortex of alcoholics. There was also increased MMP-9 activity and expression of phosphorylated ERK1/2 and p-38. Greater number of CD45+ IR cells were observed associated with an enhanced neuroinflammatory response reflected by increased GFAP and Iba-1 immunostaining. To further explore effects of high EtOH consumption on BBB integrity we studied TLR4-knockout mice exposed to the drinking in the dark paradigm. Repetitive EtOH exposure in wild-type mice decreased hippocampal expression of laminin and collagen-IV and increased IgG immunoreactivity, indicating IgG extravasation. Western blot analysis also revealed increased MyD88 and p-ERK1/2 levels. None of these changes was observed in TLR4-knockout mice. Collectively, these findings indicate that chronic EtOH increases degradation of tight junctions and extracellular matrix in postmortem human brain and induces a neuroinflammatory response associated with activation of ERK1/2 and p-38 and greater MMP-9 activity. The EtOH-induced effects on BBB impairment are not evident in the hippocampus of TLR4-knockout mice, suggesting the involvement of TLR4 signaling in the underlying mechanism leading to BBB disruption in mice.

3,4-Methylenedioxymethamphetamine (MDMA, ecstasy) disrupts blood-brain barrier integrity through a mechanism involving P2X7 receptors.

The recreational drug 3,4-methylenedioxymethamphetamine (MDMA; 'ecstasy') produces a neuro-inflammatory response in rats characterized by an increase in microglial activation and IL-1ß levels. The integrity of the blood-brain barrier (BBB) is important in preserving the homeostasis of the brain and has been shown to be affected by neuro-inflammatory processes. We aimed to study the effect of a single dose of MDMA on the activity of metalloproteinases (MMPs), expression of extracellular matrix proteins, BBB leakage and the role of the ionotropic purinergic receptor P2X7 (P2X7R) in the changes induced by the drug. Adult male Dark Agouti rats were treated with MDMA (10 mg/kg, i.p.) and killed at several time-points in order to evaluate MMP-9 and MMP-3 activity in the hippocampus and laminin and collagen-IV expression and IgG extravasation in the dentate gyrus. Microglial activation, P2X7R expression and localization were also determined in the dentate gyrus. Separate groups were treated with MDMA and the P2X7R antagonists Brilliant Blue G (BBG; 50 mg/kg, i.p.) or A-438079 (30 mg/kg, i.p.). MDMA increased MMP-3 and MMP-9 activity, reduced laminin and collagen-IV expression and increased IgG immunoreactivity. In addition, MDMA increased microglial activation and P2X7R immunoreactivity in these cells. BBG suppressed the increase in MMP-9 and MMP-3 activity, prevented basal lamina degradation and IgG extravasation into the brain parenchyma. A-438079 also prevented the MDMA-induced reduction in laminin and collagen-IV immunoreactivity. These results indicate that MDMA alters BBB permeability through an early P2X7R-mediated event, which in turn leads to enhancement of MMP-9 and MMP-3 activity and degradation of extracellular matrix.

Current preclinical studies on neuroinflammation and changes in blood-brain barrier integrity by MDMA and methamphetamine.

The blood-brain barrier (BBB) is essential in the maintenance of brain homeostasis both by preserving normal brain functioning and also by protecting the brain from exposure to a range of potentially harmful substances. This review presents some of the evidence of BBB disruption following exposure to the substituted amphetamines 3,4-methylenedioxymethamphetamine (MDMA, 'ecstasy') and methamphetamine (METH), two drugs of abuse which are widely consumed recreationally by younger sectors of the population. Both MDMA and METH have been shown to produce disruption of the BBB as reflected by IgG extravasation and Evans Blue leakage. In particular, METH decreases the expression of basal lamina proteins associated with an increase in matrix metalloproteinase activity. These changes in BBB integrity appear to be related to MDMA-induced activation of the mitogen-activated protein kinase (MAPK) JNK1/2. The consequences of the disruption in the BBB by these two drugs remain to be established, but there is evidence in the literature that, at least in the case of METH, increased matrix metalloproteinase (MMP) activity may be related to increased behavioural sensitization and reward perhaps because of the modification of the passage of the drug into the CNS. In addition, the high incidence of AIDS-related neurologic disease in METH users may also be related to increased entry into the brain of virally derived neurotoxic products. This article is part of the Special Issue entitled 'CNS Stimulants'.

The JNK inhibitor, SP600125, potentiates the glial response and cell death induced by methamphetamine in the mouse striatum.

This study investigates the effect of the selective Jun NH2-terminal kinase 1/2 (JNK1/2) inhibitor, (SP600125) on the striatal dopamine nerve terminal loss and on the increased interleukin-15 (IL-15) expression and glial response induced by methamphetamine (METH). Mice were given repeated low doses of METH (4 mg/kg, i.p., three times separated by 3 h) and killed 24 h or 7 d after the last dose. SP600125 (30 mg/kg, i.p) was administered 30 min before the last METH injection. Results indicate that METH produced dopaminergic axonal neurotoxicity reflected as a marked decrease in the striatal density of tyrosine hydroxylase-immunoreactive (TH-ir) fibres and dopamine transporter-immunoreactivity (DAT-ir) 24 h after dosing. These effects were not modified by SP600125. This compound also failed to prevent the long-term loss of dopamine levels and DAT observed 7 d following METH injection. Nevertheless, SP600125 potentiated METH-induced striatal cell loss reflected by an increase in Fluoro-Jade immunostaining, cleaved capase-3 immunoreactivity and the number of terminal deoxyncleotidyl transferase-mediated dUTP nick end labelling (TUNEL) positive cells. In line with a deleterious effect of JNK1/2 inhibition, SP600125 increased the astroglial and microglial response induced by METH and interfered with drug-induced IL-15 expression. Together these data indicate that, not only does SP600125 fail to protect against the dopaminergic damage induced by METH but also, in fact, it potentiates the glial response and the non-dopaminergic striatal cell loss caused by the drug.

Cocaine potentiates MDMA-induced oxidative stress but not dopaminergic neurotoxicity in mice: implications for the pathogenesis of free radical-induced neurodegenerative disorders.

RATIONALE: The drugs of abuse 3,4-methylenedioxymethamphetamine (MDMA; "ecstasy") and cocaine both increase the generation of free radicals, and in the case of MDMA, this increase in oxidative stress is involved in the dopaminergic neurotoxicity produced by the drug in mice. Oxidative stress processes are also involved in the pathogenesis of several neurodegenerative diseases. OBJECTIVES: We aimed to determine the consequences of the combined administration of MDMA and cocaine on oxidative stress and dopaminergic neurotoxicity. METHODS: Mice received MDMA (20 mg/kg, i.p.; two doses separated by 3 h) followed by cocaine 1, 3, 6, or 24 h after the second MDMA dose. Mice were killed between 1 h and 7 days after cocaine injection. RESULTS: MDMA decreased dopamine transporter density and dopamine concentration 7 days later. Cocaine did not alter this neurotoxicity. MDMA produced an increase in the concentration of 2,3-dihydroxybenzoic acid in striatal microdialysis samples and an increase in lipid peroxidation in the striatum which were potentiated by cocaine. MDMA and cocaine given together also increased nitrate and 3-nitrotyrosine levels compared with either drug given alone. On the other hand, MDMA increased superoxide dismutase activity and decreased catalase activity, changes which were prevented by cocaine administration. In addition, cocaine administration produced an increase in glutathione peroxidase (GPx) activity in both saline-treated and MDMA-treated mice. CONCLUSIONS: Cocaine potentiates MDMA-induced oxidative stress but does not produce an increase in the neurotoxicity produced by MDMA, and this lack of potentiation may involve an increase in GPx activity.

A study on the effect of JNK inhibitor, SP600125, on the disruption of blood-brain barrier induced by methamphetamine.

Methamphetamine (METH) is a widely consumed drug with high abuse potential. Studies in animals have shown that the drug produces dopaminergic neurotoxicity following both single high-dose and repeated low-dose administration. In addition, METH produces an increase in matrix metalloproteinase expression and loss of BBB integrity. We have examined the effect of repeated low-dose METH on MMP-9/2 expression and activity and laminin expression and the role of MMPs and JNK 1/2 phosphorylation on the changes induced by the drug in BBB integrity. Mice were given METH (4 mg/kg, i.p., three times separated by 3 h) and killed at different times after the last dose. Striatal MMP-9/2 activity was determined by zymography and expression of MMPs, laminin and phosphorylated JNK 1/2 was determined by western blot. BBB integrity was determined by IgG immunoreactivity. SP600125 and BB-94 were used to inhibit JNK and MMPs respectively. METH increased striatal MMP-9 expression and activity, IgG immunoreactivity and p-JNK 1/2 expression and decreased laminin expression. Increased IgG immunoreactivity colocalized with areas of greater MMP-9 activity. JNK inhibition prevented METH-induced changes in MMP-9 activity, laminin degradation and BBB leakage. BB-94 also prevented laminin degradation and BBB leakage. The decrease in BBB integrity induced by METH is mediated by the JNK pathway which activates MMP-9 causing degradation of laminin and BBB leakage.

Increased interleukin-1ß levels following low dose MDMA induces tolerance against the 5-HT neurotoxicity produced by challenge MDMA.

BACKGROUND: Preconditioning is a phenomenon by which tolerance develops to injury by previous exposure to a stressor of mild severity. Previous studies have shown that single or repeated low dose MDMA can attenuate 5-HT transporter loss produced by a subsequent neurotoxic dose of the drug. We have explored the mechanism of delayed preconditioning by low dose MDMA. METHODS: Male Dark Agouti rats were given low dose MDMA (3 mg/kg, i.p.) 96 h before receiving neurotoxic MDMA (12.5 mg/kg, i.p.). IL-1ß and IL1ra levels and 5-HT transporter density in frontal cortex were quantified at 1 h, 3 h or 7 days. IL-1ß, IL-1ra and IL-1RI were determined between 3 h and 96 h after low dose MDMA. sIL-1RI combined with low dose MDMA or IL-1ß were given 96 h before neurotoxic MDMA and toxicity assessed 7 days later. RESULTS: Pretreatment with low dose MDMA attenuated both the 5-HT transporter loss and elevated IL-1ß levels induced by neurotoxic MDMA while producing an increase in IL-1ra levels. Low dose MDMA produced an increase in IL-1ß at 3 h and in IL-1ra at 96 h. sIL-1RI expression was also increased after low dose MDMA. Coadministration of sIL-1RI (3 µg, i.c.v.) prevented the protection against neurotoxic MDMA provided by low dose MDMA. Furthermore, IL-1ß (2.5 pg, intracortical) given 96 h before neurotoxic MDMA protected against the 5-HT neurotoxicity produced by the drug, thus mimicking preconditioning. CONCLUSIONS: These results suggest that IL-1ß plays an important role in the development of delayed preconditioning by low dose MDMA.

Changes in interleukin-1 signal modulators induced by 3,4-methylenedioxymethamphetamine (MDMA): regulation by CB2 receptors and implications for neurotoxicity.

BACKGROUND: 3,4-Methylenedioxymethamphetamine (MDMA) produces a neuroinflammatory reaction in rat brain characterized by an increase in interleukin-1 beta (IL-1ß) and microglial activation. The CB2 receptor agonist JWH-015 reduces both these changes and partially protects against MDMA-induced neurotoxicity. We have examined MDMA-induced changes in IL-1 receptor antagonist (IL-1ra) levels and IL-1 receptor type I (IL-1RI) expression and the effects of JWH-015. The cellular location of IL-1ß and IL-1RI was also examined. MDMA-treated animals were given the soluble form of IL-1RI (sIL-1RI) and neurotoxic effects examined. METHODS: Dark Agouti rats received MDMA (12.5 mg/kg, i.p.) and levels of IL-1ra and expression of IL-1RI measured 1 h, 3 h or 6 h later. JWH-015 (2.4 mg/kg, i.p.) was injected 48 h, 24 h and 0.5 h before MDMA and IL-1ra and IL-1RI measured. For localization studies, animals were sacrificed 1 h or 3 h following MDMA and stained for IL-1ß or IL-1RI in combination with neuronal and microglial markers. sIL-1RI (3 µg/animal; i.c.v.) was administered 5 min before MDMA and 3 h later. 5-HT transporter density was determined 7 days after MDMA injection. RESULTS: MDMA produced an increase in IL-ra levels and a decrease in IL-1RI expression in hypothalamus which was prevented by CB2 receptor activation. IL-1RI expression was localized on neuronal cell bodies while IL-1ß expression was observed in microglial cells following MDMA. sIL-1RI potentiated MDMA-induced neurotoxicity. MDMA also increased IgG immunostaining indicating that blood brain-barrier permeability was compromised. CONCLUSIONS: In summary, MDMA produces changes in IL-1 signal modulators which are modified by CB2 receptor activation. These results indicate that IL-1ß may play a partial role in MDMA-induced neurotoxicity.

Dopamine D2-receptor knockout mice are protected against dopaminergic neurotoxicity induced by methamphetamine or MDMA.

Methamphetamine (METH) and 3,4-methylenedioxymethamphetamine (MDMA), amphetamine derivatives widely used as recreational drugs, induce similar neurotoxic effects in mice, including a marked loss of tyrosine hydroxylase (TH) and dopamine transporter (DAT) in the striatum. Although the role of dopamine in these neurotoxic effects is well established and pharmacological studies suggest involvement of a dopamine D2-like receptor, the specific dopamine receptor subtype involved has not been determined. In this study, we used dopamine D2 receptor knock-out mice (D2R(-/-)) to determine whether D2R is involved in METH- and MDMA-induced hyperthermia and neurotoxicity. In wild type animals, both drugs induced marked hyperthermia, decreased striatal dopamine content and TH- and DAT-immunoreactivity and increased striatal GFAP and Mac-1 expression as well as iNOS and interleukin 15 at 1 and 7days after drug exposure. They also caused dopaminergic cell loss in the SNpc. Inactivation of D2R blocked all these effects. Remarkably, D2R inactivation prevented METH-induced loss of dopaminergic neurons in the SNpc. In addition, striatal dopamine overflow, measured by fast scan cyclic voltammetry in the presence of METH, was significantly reduced in D2R(-/-) mice. Pre-treatment with reserpine indicated that the neuroprotective effect of D2R inactivation cannot be explained solely by its ability to prevent METH-induced hyperthermia: reserpine lowered body temperature in both genotypes, and potentiated METH toxicity in WT, but not D2R(-/-) mice. Our results demonstrate that the D2R is necessary for METH and MDMA neurotoxicity and that the neuroprotective effect of D2R inactivation is independent of its effect on body temperature.

Sex-dependent maternal deprivation effects on brain monoamine content in adolescent rats.

Rats subjected to a single prolonged episode of maternal deprivation (MD) [24h, postnatal days 9-10] show, later in life, behavioural alterations that resemble specific signs of schizophrenia and other neuropsychiatric signs including increased levels of impulsivity and an apparent difficulty to cope with stressful situations. Some of these behavioural modifications are observable in the periadolescent period. However there is no previous information regarding the possible underlying neurochemical correlates at this critical developmental period. In this study we have addressed the effects of MD on the levels of serotonin (5-HT), dopamine (DA) and their respective metabolites in prefrontal cortex, hippocampus, striatum, midbrain and cerebellum of male and female periadolescent Wistar rats. MD rats showed significantly increased levels of 5-HT in all regions studied with the exception of cerebellum. In addition, MD animals showed increased levels of DA in PFC as well as increased levels of DA and a decrease of DOPAC/DA and HVA/DA ratios in striatum. The effect of MD on the monoaminergic systems was in several cases sex-dependent.

Evidence that MDMA ('ecstasy') increases cannabinoid CB2 receptor expression in microglial cells: role in the neuroinflammatory response in rat brain.

3,4-Methylenedioxymethamphetamine (MDMA, 'ecstasy') produces selective long-lasting serotonergic neurotoxicity in rats. The drug also produces acute hyperthermia which modulates the severity of the neurotoxic response. In addition, MDMA produces signs of neuroinflammation reflected as microglial activation and an increase in the release of interleukin-1beta, the latter of which appears to be a consequence of the hyperthermic response and to be implicated in the neurotoxicity induced by the drug. Over-expression of the cannabinoid CB2 receptor in microglia during non-immune and immune pathological conditions is thought to be aimed at controlling the production of neurotoxic factors such as proinflammatory cytokines. Our objective was to study the pattern of CB2 receptor expression following MDMA and to examine the effect of JWH-015 (a CB2 agonist) on the MDMA-induced neuroinflammatory response as well as 5-hydroxytryptamine (5-HT) neurotoxicity. Adult Dark Agouti rats were given MDMA (12.5 mg/kg, i.p.) and killed 3 h or 24 h later for the determination of CB2 receptor expression. JWH-015 was given 48 h, 24 h and 0.5 h before MDMA and 1 h and/or 6 h later and animals were killed for the determination of microglial activation (3 h and 24 h) and 5-HT neurotoxicity (7 days). MDMA increased CB2 receptor expression shortly after administration and these receptors were found in microglia. JWH-015 decreased MDMA-induced microglial activation and interleukin-1beta release and slightly decreased MDMA-induced 5-HT neurotoxicity. In conclusion, CB2 receptor activation reduces the neuroinflammatory response following MDMA and provides partial neuroprotection against the drug.