Drug-induced neurotoxicity in addiction medicine: From prevention to harm reduction

Relationship between the cGAS-STING and NF-κB pathways-role in neurotoxicity

Neurotoxicity can cause a range of symptoms and disorders in humans, including neurodegenerative diseases, neurodevelopmental disorders, nerve conduction abnormalities, neuroinflammation, autoimmune disorders, and cognitive deficits. The cyclic guanosine-adenosine synthase (cGAS)-stimulator of interferon genes (STING) pathway and NF-κB pathway are two important signaling pathways involved in the innate immune response. The cGAS-STING pathway is activated by the recognition of intracellular DNA, which triggers the production of type I interferons and pro-inflammatory cytokines, such as tumor necrosis factor, IL-1β, and IL-6. These cytokines play a role in oxidative stress and mitochondrial dysfunction in neurons. The NF-κB pathway is activated by various stimuli, such as bacterial lipopolysaccharide, viral particle components, and neurotoxins. NF-κB activation may lead to the production of pro-inflammatory cytokines, which promote neuroinflammation and cause neuronal damage. A potential interaction exists between the cGAS-STING and NF-κB pathways, and NF-κB activation blocks STING degradation by inhibiting microtubule-mediated STING transport. This review examines the progress of research on the roles of these pathways in neurotoxicity and their interrelationships. Understanding the mechanisms of these pathways will provide valuable therapeutic insights for preventing and controlling neurotoxicity.

Mercury chloride causes cognitive impairment, oxidative stress and neuroinflammation in male Wistar rats: The potential protective effect of 6-gingerol-rich fraction of Zingiber officinale via regulation of antioxidant defence system and reversal of pro-inflammatory markers increase

This study investigated the effects of 6-gingerol-rich fraction of Zingiber officinale (6-GIRIFZO) on mercury chloride (HgCl2)-induced neurotoxicity in Wistar rats. Thirty -five male Wistar rats weighing between (150-200 g) were divided randomly into five groups (n = 7): group 1: control, received 0.5 mL of normal saline, group 2: received HgCl2 (5 mg/kg), group 3: received N-acetylcysteine (NAC) (50 mg/kg) as well as HgCl2 (5 mg/kg), group 4: received 6-GIRIFZO (100 mg/kg) and HgCl2 (5 mg/kg), group 5: had 6-GIRIFZO (200 mg/kg) and HgCl2 (5 mg/kg), consecutively for 14 days. On the day14, the rats were subjected to behavioural tests using a Morris water maze and novel object recognition tests. The rats were then euthanized to obtain brain samples for the determination of biochemical parameters (acetylcholinesterase (AchE), nitric oxide (NO), malondialdehyde (MDA), superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase (CAT), glutathione (GSH), tumor necrosis factor- alpha (TNF-α), nuclear factor kappa-B (NF-κB), interleukin-1β (IL-1β) and interleukin-6 (IL-6)) using standard methods. The result revealed a significant increase in escape latency and a significant decrease in recognition ratio in the rats that were exposed to HgCl2 only. However, 6-GIRIFZO produced a significant reduction in the escape latency and (p < 0.05) increase in the recognition ratio. Similarly, HgCl2 exposure caused a significant (p < 0.05) decrease in the brain SOD, GPx, CAT, GSH with increased brain levels of MDA, NO, AchE, TNF-α, NF-κB, IL-1β and IL-6. Similarly to the standard drug, NAC, 6-GIRIFZO (100 and 200 mg/kg) significantly (p < 0.05) increased brain SOD, GPx, CAT, and GSH levels with decreased concentrations of MDA, NO, AchE, TNF-α, NF-κB, IL-1β and IL-6. Also, pre-treatment with 6-GIRIFZO prevented the HgCl2-induced morphological aberrations in the rats. This study concludes that 6-GIRIFZO prevents HgCl2-induced cognitive deficit via reduction of brain inflammation as well as oxidative stress in rats.

Metabolic and functional substrates of impulsive decision-making in individuals with heroin addiction after prolonged methadone maintenance treatment

Elevated impulsivity has been frequently reported in individuals with opioid addiction receiving methadone maintenance therapy (MMT), but the underlying neural mechanisms and cognitive subprocesses are not fully understood. We acquired functional magnetic resonance imaging (fMRI) data from 37 subjects with heroin addiction receiving long-term MMT and 33 healthy controls who performed a probabilistic reversal learning task, and measured their resting-state brain glucose using fluorine-18-fluorodeoxyglucose positron emission tomography (18F-FDG PET). Subjects receiving MMT exhibited significantly elevated self-reported impulsivity, and computational modeling revealed a marked impulsive decision bias manifested as switching more frequently without available evidence. Moreover, this impulsive decision bias was associated with the dose and duration of methadone use, irrelevant to the duration of heroin use. During the task, the switch-related hypoactivation in the left rostral middle frontal gyrus was correlated with the impulsive decision bias while the function of reward sensitivity was intact in subjects receiving MMT. Using prior brain-wide receptor density data, we found that the highest variance of regional metabolic abnormalities was explained by the spatial distribution of μ-opioid receptors among 10 types of neurotransmitter receptors. Heightened impulsivity in individuals receiving prolonged MMT is manifested as atypical choice bias and noise in decision-making processes, which is further driven by deficits in top-down cognitive control, other than reward sensitivity. Our findings uncover multifaceted mechanisms underlying elevated impulsivity in subjects receiving MMT, which might provide insights for developing complementary therapies to improve retention during MMT.

Modulating cyclic nucleotides pathways by bioactive compounds in combatting anxiety and depression disorders

Anxiety and depression disorders are highly prevalent neurological disorders (NDs) that impact up to one in three individuals during their lifetime. Addressing these disorders requires reducing their frequency and impact, understanding molecular causes, implementing prevention strategies, and improving treatments. Cyclic nucleotide monophosphates (cNMPs) like cyclic adenosine monophosphate (cAMP), cyclic guanosine monophosphate (cGMP), cyclic uridine monophosphate (cUMP), and cyclic cytidine monophosphate (cCMP) regulate the transcription of genes involved in neurotransmitters and neurological functions. Evidence suggests that cNMP pathways, including cAMP/cGMP, cAMP response element binding protein (CREB), and Protein kinase A (PKA), play a role in the physiopathology of anxiety and depression disorders. Plant and mushroom-based compounds have been used in traditional and modern medicine due to their beneficial properties. Bioactive compound metabolism can activate key pathways and yield pharmacological outcomes. This review focuses on the molecular mechanisms of bioactive compounds from plants and mushrooms in modulating cNMP pathways. Understanding these processes will support current treatments and aid in the development of novel approaches to reduce the prevalence of anxiety and depression disorders, contributing to improved outcomes and the prevention of associated complications.

Functional and structural brain abnormalities in substance use disorder: A multimodal meta-analysis of neuroimaging studies

INTRODUCTION

Numerous neuroimaging studies of resting-state functional imaging and voxel-based morphometry (VBM) have revealed that patients with substance use disorder (SUD) may present brain abnormalities, but their results were inconsistent. This multimodal neuroimaging meta-analysis aimed to estimate common and specific alterations in SUD patients by combining information from all available studies of spontaneous functional activity and gray matter volume (GMV).

METHODS

A whole-brain meta-analysis on resting-state functional imaging and VBM studies was conducted using the Seed-based d Mapping with Permutation of Subject Images (SDM-PSI) software, followed by multimodal overlapping to comprehensively investigate function and structure of the brain in SUD.

RESULTS

In this meta-analysis, 39 independent studies with 47 datasets related to resting-state functional brain activity (1444 SUD patients; 1446 healthy controls [HCs]) were included, as well as 77 studies with 89 datasets for GMV (3457 SUD patients; 3774 HCs). Patients with SUD showed the decreased resting-state functional brain activity in the bilateral anterior cingulate cortex/medial prefrontal cortex (ACC/mPFC). For the VBM meta-analysis, patients with SUD showed the reduced GMV in the bilateral ACC/mPFC, insula, thalamus extending to striatum, and left sensorimotor cortex.

CONCLUSIONS

This multimodal meta-analysis exhibited that SUD shows common impairment in both function and structure in the ACC/mPFC, suggesting that the deficits in functional and structural domains could be correlated together. In addition, a few regions exhibited only structural impairment in SUD, including the insula, thalamus, striatum, and sensorimotor areas.

Functional brain abnormalities in major depressive disorder using a multiscale community detection approach

Major depressive disorder (MDD) is a serious disease associated with abnormal brain regions, however, the interconnection between specific brain regions related to depression has not been fully explored. To solve this problem, the paper proposes a novel multiscale community detection method to compare the differences in brain regions between normal controls (NC) and MDD patients. This study adopted the Brainnetome Atlas to divide the brain into 246 regions and extract the time series of each region. The Pearson correlation was used to measure the similarity among different brain regions to conduct the brain functional network and to perform multiscale community detection. The optimal brain community structure of each group was further explored based on the modularized Qcut algorithm, normalized mutual information (NMI), and variation of information (VI). The Jaccard index was then applied to compare the abnormalities of each brain region from different community environments between the brain function networks of NC and MDD patients. The experiments revealed several abnormal brain regions between NC and MDD, including the superior frontal gyrus, middle frontal gyrus, inferior frontal gyrus, orbital gyrus, superior temporal gyrus, middle temporal gyrus, inferior temporal gyrus, posterior superior temporal sulcus, inferior parietal gyrus, precuneus, postcentral gyrus, insular gyrus, cingulate gyrus, hippocampus and basal ganglia. Finally, a new subnetwork related to cognitive function was discovered, which was composed of the island gyrus and inferior frontal gyrus. All experiments indicated that the proposed method is useful in detecting functional brain abnormalities in MDD, and it can provide valuable insights into the diagnosis and treatment of MDD.

The Therapeutic Potential of Carnosine as an Antidote against Drug-Induced Cardiotoxicity and Neurotoxicity: Focus on Nrf2 Pathway

Different drug classes such as antineoplastic drugs (anthracyclines, cyclophosphamide, 5-fluorouracil, taxanes, tyrosine kinase inhibitors), antiretroviral drugs, antipsychotic, and immunosuppressant drugs are known to induce cardiotoxic and neurotoxic effects. Recent studies have demonstrated that the impairment of the nuclear factor erythroid 2–related factor 2 (Nrf2) pathway is a primary event in the pathophysiology of drug-induced cardiotoxicity and neurotoxicity. The Nrf2 pathway regulates the expression of different genes whose products are involved in antioxidant and inflammatory responses and the detoxification of toxic species. Cardiotoxic drugs, such as the anthracycline doxorubicin, or neurotoxic drugs, such as paclitaxel, suppress or impair the Nrf2 pathway, whereas the rescue of this pathway counteracts both the oxidative stress and inflammation that are related to drug-induced cardiotoxicity and neurotoxicity. Therefore Nrf2 represents a novel pharmacological target to develop new antidotes in the field of clinical toxicology. Interestingly, carnosine (β-alanyl-l-histidine), an endogenous dipeptide that is characterized by strong antioxidant, anti-inflammatory, and neuroprotective properties is able to rescue/activate the Nrf2 pathway, as demonstrated by different preclinical studies and preliminary clinical evidence. Starting from these new data, in the present review, we examined the evidence on the therapeutic potential of carnosine as an endogenous antidote that is able to rescue the Nrf2 pathway and then counteract drug-induced cardiotoxicity and neurotoxicity.

Increased Inflammatory Markers at AMPH-Addicts Are Related to Neurodegenerative Conditions: Alzheimer’s Disease

Amphetamine addiction is widespread worldwide despite causing severe physical and mental problems, including neurodegeneration. One of the most common neurodegenerative disorders is Alzheimer’s disease (AD). Several inflammatory markers have been linked to AD. Previous studies have also found these biomarkers in amphetamine-addicts (AMPH-add). This study thus seeks to understand how AD and AMPH-addiction are related. A case–control observational study was conducted. Seventeen AMPH-adds ranging in age from 23 to 40 were recruited from Al Amal Psychiatric Hospital. In addition, 19 healthy subjects matching their age and gender were also recruited. The Luminex technique was used to measure serum alpha 1 antichymotrypsin (ACT), pigment epithelium-derived factor (PEDF), and macrophage inflammatory protein-4 (MIP-4), after complying with ethical guidelines and obtaining informed consent. In addition, liver function enzymes were correlated to AD’s predictive biomarkers in AMPH-adds. AMPH-adds had significantly higher serum levels of ACT, PEDF, and MIP-4 when compared to healthy controls (p = 0.03, p = 0.001, and p = 0.012, respectively). Furthermore, there is a significant correlation between lower ALT levels and elevated AST to ALT ratios in AMPH-adds (r = 0.618, 0.651, and p = 0.0001). These changes in inflammatory biomarkers may be linked to the onset of AD at a young age in amphetamine-drug addicts.

Sporadic Alzheimer's Disease- and Neurotoxicity-Related microRNAs Affecting Key Events of Tau-Driven Adverse Outcome Pathway Toward Memory Loss

BACKGROUND

A complex network of aging-related homeostatic pathways that are sensitive to further deterioration in the presence of genetic, systemic, and environmental risk factors, and lifestyle, is implicated in the pathogenesis of progressive neurodegenerative diseases, such as sporadic (late-onset) Alzheimer's disease (sAD).

OBJECTIVE

Since sAD pathology and neurotoxicity share microRNAs (miRs) regulating common as well as overlapping pathological processes, environmental neurotoxic compounds are hypothesized to exert a risk for sAD initiation and progression.

METHODS

Literature search for miRs associated with human sAD and environmental neurotoxic compounds was conducted. Functional miR analysis using PathDip was performed to create miR-target interaction networks.

RESULTS

The identified miRs were successfully linked to the hypothetical starting point and key events of the earlier proposed tau-driven adverse outcome pathway toward memory loss. Functional miR analysis confirmed most of the findings retrieved from literature and revealed some interesting findings. The analysis identified 40 miRs involved in both sAD and neurotoxicity that dysregulated processes governing the plausible adverse outcome pathway for memory loss.

CONCLUSION

Creating miR-target interaction networks related to pathological processes involved in sAD initiation and progression, and environmental chemical-induced neurotoxicity, respectively, provided overlapping miR-target interaction networks. This overlap offered an opportunity to create an alternative picture of the mechanisms underlying sAD initiation and early progression. Looking at initiation and progression of sAD from this new angle may open for new biomarkers and novel drug targets for sAD before the appearance of the first clinical symptoms.

Crossroads of Drug Abuse and HIV Infection: Neurotoxicity and CNS Reservoir

Drug abuse is a common comorbidity in people infected with HIV. HIV-infected individuals who abuse drugs are a key population who frequently experience suboptimal outcomes along the HIV continuum of care. A modest proportion of HIV-infected individuals develop HIV-associated neurocognitive issues, the severity of which further increases with drug abuse. Moreover, the tendency of the virus to go into latency in certain cellular reservoirs again complicates the elimination of HIV and HIV-associated illnesses. Antiretroviral therapy (ART) successfully decreased the overall viral load in infected people, yet it does not effectively eliminate the virus from all latent reservoirs. Although ART increased the life expectancy of infected individuals, it showed inconsistent improvement in CNS functioning, thus decreasing the quality of life. Research efforts have been dedicated to identifying common mechanisms through which HIV and drug abuse lead to neurotoxicity and CNS dysfunction. Therefore, in order to develop an effective treatment regimen to treat neurocognitive and related symptoms in HIV-infected patients, it is crucial to understand the involved mechanisms of neurotoxicity. Eventually, those mechanisms could lead the way to design and develop novel therapeutic strategies addressing both CNS HIV reservoir and illicit drug use by HIV patients.

Antibiotics and the Nervous System-Which Face of Antibiotic Therapy Is Real, Dr. Jekyll (Neurotoxicity) or Mr. Hyde (Neuroprotection)?

Antibiotics as antibacterial drugs have saved many lives, but have also become a victim of their own success. Their widespread abuse reduces their anti-infective effectiveness and causes the development of bacterial resistance. Moreover, irrational antibiotic therapy contributes to gastrointestinal dysbiosis, that increases the risk of the development of many diseases, including neurological and psychiatric. One of the potential options for restoring homeostasis is the use of oral antibiotics that are poorly absorbed from the gastrointestinal tract (e.g., rifaximin alfa). Thus, antibiotic therapy may exert neurological or psychiatric adverse drug reactions which are often considered to be overlooked and undervalued issues. Drug-induced neurotoxicity is mostly observed after beta-lactams and quinolones. Penicillin may produce a wide range of neurological dysfunctions, including encephalopathy, behavioral changes, myoclonus or seizures. Their pathomechanism results from the disturbances of gamma-aminobutyric acid-GABA transmission (due to the molecular similarities between the structure of the β-lactam ring and GABA molecule) and impairment of the functioning of benzodiazepine receptors (BZD). However, on the other hand, antibiotics have also been studied for their neuroprotective properties in the treatment of neurodegenerative and neuroinflammatory processes (e.g., Alzheimer's or Parkinson's diseases). Antibiotics may, therefore, become promising elements of multi-targeted therapy for these entities.

Development of blood brain barrier permeation prediction models for organic and inorganic biocidal active substances

Biocidal products are broadly used in homes and industries. However, the safety of biocidal active substances (BASs) is not yet fully understood. In particular, the neurotoxic action of BASs needs to be studied as diverse epidemiological studies have reported associations between exposure to BASs and neural diseases. In this study, we developed in silico models to predict the blood-brain barrier (BBB) permeation of organic and inorganic BASs. Due to a lack of BBB data for BASs, the chemical space of BASs and BBB dataset were compared in order to select BBB data that were structurally similar to BASs. In silico models to predict log-scaled BBB penetration were developed using support vector regression for organic BASs and multiple linear regression for inorganic BASs. The model for organic BASs was developed with 231 compounds (training set: 153 and test set: 78) and achieved good prediction accuracy on an external test set (R² = 0.64), and the model outperformed the model for pharmaceuticals. The model for inorganic BASs was developed with 11 compounds (R² = 0.51). Applicability domain (AD) analysis of the models clarified molecular structures reliably predicted by the models. Therefore, the models developed in this study can be used for predicting BBB permeable BASs in human. These models were developed according to the Quantitative Structure-Activity Relationship validation principles proposed by the Organization for Economic Cooperation and Development.

Polyphenols from Brown Seaweeds (Ochrophyta, Phaeophyceae): Phlorotannins in the Pursuit of Natural Alternatives to Tackle Neurodegeneration

Globally, the burden of neurodegenerative disorders continues to rise, and their multifactorial etiology has been regarded as among the most challenging medical issues. Bioprospecting for seaweed-derived multimodal acting products has earned increasing attention in the fight against neurodegenerative conditions. Phlorotannins (phloroglucinol-based polyphenols exclusively produced by brown seaweeds) are amongst the most promising nature-sourced compounds in terms of functionality, and though research on their neuroprotective properties is still in its infancy, phlorotannins have been found to modulate intricate events within the neuronal network. This review comprehensively covers the available literature on the neuroprotective potential of both isolated phlorotannins and phlorotannin-rich extracts/fractions, highlighting the main key findings and pointing to some potential directions for neuro research ramp-up processes on these marine-derived products.

Assessment of Ethanol-Induced Toxicity on iPSC-Derived Human Neurons Using a Novel High-Throughput Mitochondrial Neuronal Health (MNH) Assay

Excessive ethanol exposure can cause mitochondrial and cellular toxicity. In order to discover potential counteracting interventions, it is essential to develop assays capable of capturing the consequences of ethanol exposure in human neurons, and particularly dopaminergic neurons that are crucial for the development of alcohol use disorders (AUD). Here, we developed a novel high-throughput (HT) assay to quantify mitochondrial and neuronal toxicity in human dopaminergic neuron-containing cultures (DNs) from induced pluripotent stem cells (iPSCs). The assay, dubbed mitochondrial neuronal health (MNH) assay, combines live-cell measurement of mitochondrial membrane potential (MMP) with quantification of neuronal branching complexity post-fixation. Using the MNH assay, we demonstrated that chronic ethanol exposure in human iPSC-derived DNs decreases MMP and neuronal outgrowth in a dose-dependent manner. The toxic effect of ethanol on DNs was already detectable after 1 h of exposure, and occurred similarly in DNs derived from healthy individuals and from patients with AUD. We next used the MNH assay to carry out a proof-of-concept compound screening using FDA-approved drugs. We identified potential candidate compounds modulating acute ethanol toxicity in human DNs. We found that disulfiram and baclofen, which are used for AUD treatment, and lithium caused neurotoxicity also in the absence of ethanol, while the spasmolytic drug flavoxate positively influenced MNH. Altogether, we developed an HT assay to probe human MNH and used it to assess ethanol neurotoxicity and to identify modulating agents. The MNH assay represents an effective new tool for discovering modulators of MNH and toxicity in live human neurons.

Compulsive methamphetamine taking induces autophagic and apoptotic markers in the rat dorsal striatum

Methamphetamine (METH) use disorder (MUD) is often accompanied by psychotic symptoms, cognitive deficits, and pathological changes in the brains of users. Animals that experimenters injected with drugs also show neurodegenerative changes in their brains. Recently, we have been investigating METH-induced molecular and biochemical consequences in animals that had infused themselves with METH using the drug self-administration (SA) paradigm. In that model, footshocks administered contingently help to separate rats that had already escalated their METH intake into resilient-to-drug (shock-sensitive, SS) or compulsive (shock-resistant, SR) METH takers. Herein, we used that model to test the idea that compulsive METH takers might show evidence of drug-induced autophagic changes in their brains. There were significant increases in mRNA levels of autophagy-related genes including Atg2a, Atg5, Atg14, and Atg16L1 in the rat dorsal striatum. Levels of two autophagy biomarkers, autophagy activating kinase (ULK1) and phospho-Beclin1, were also increased. In addition, we found increased p53 but decreased Bcl-2 protein levels. Moreover, the expression of cleaved initiator caspase-9 and effector caspase-6 was higher in compulsive METH takers in comparison to shock-sensitive rats. When taken together, these results suggest that the striata of rats that had escalated and continue to take METH compulsively the presence of adverse consequences exhibit some pathological changes similar to those reported in post-mortem human striatal tissues. These results provide supporting evidence that compulsive METH taking is neurotoxic. Our observations also support the notion of developing neuro-regenerative agents to add to the therapeutic armamentarium against METH addiction.

Shared Causal Paths underlying Alzheimer's dementia and Type 2 Diabetes

Although Alzheimer's disease (AD) is a central nervous system disease and type 2 diabetes MELLITUS (T2DM) is a metabolic disorder, an increasing number of genetic epidemiological studies show clear link between AD and T2DM. The current approach to uncovering the shared pathways between AD and T2DM involves association analysis; however such analyses lack power to discover the mechanisms of the diseases. As an alternative, we developed novel causal inference methods for genetic studies of AD and T2DM and pipelines for systematic multi-omic casual analysis to infer multilevel omics causal networks for the discovery of common paths from genetic variants to AD and T2DM. The proposed pipelines were applied to 448 individuals from the ROSMAP Project. We identified 13 shared causal genes, 16 shared causal pathways between AD and T2DM, and 754 gene expression and 101 gene methylation nodes that were connected to both AD and T2DM in multi-omics causal networks.

Induced pluripotent stem cells for therapy personalization in pediatric patients: Focus on drug-induced adverse events

Adverse drug reactions (ADRs) are major clinical problems, particularly in special populations such as pediatric patients. Indeed, ADRs may be caused by a plethora of different drugs leading, in some cases, to hospitalization, disability or even death. In addition, pediatric patients may respond differently to drugs with respect to adults and may be prone to developing different kinds of ADRs, leading, in some cases, to more severe consequences. To improve the comprehension, and thus the prevention, of ADRs, the set-up of sensitive and personalized assays is urgently needed. Important progress is represented by the possibility of setting up groundbreaking patient-specific assays. This goal has been powerfully achieved using induced pluripotent stem cells (iPSCs). Due to their genetic and physiological species-specific differences and their ability to be differentiated ideally into all tissues of the human body, this model may be accurate in predicting drug toxicity, especially when this toxicity is related to individual genetic differences. This review is an up-to-date summary of the employment of iPSCs as a model to study ADRs, with particular attention to drugs used in the pediatric field. We especially focused on the intestinal, hepatic, pancreatic, renal, cardiac, and neuronal levels, also discussing progress in organoids creation. The latter are three-dimensional in vitro culture systems derived from pluripotent or adult stem cells simulating the architecture and functionality of native organs such as the intestine, liver, pancreas, kidney, heart, and brain. Based on the existing knowledge, these models are powerful and promising tools in multiple clinical applications including toxicity screening, disease modeling, personalized and regenerative medicine.

In vivo characterization of toxicity of norcocaethylene and norcocaine identified as the most toxic cocaine metabolites in male mice

BACKGROUND

Majority of cocaine users also consume alcohol, and concurrent use of cocaine and alcohol produces cocaethylene, norcocaine, norcocaethylene, and other non-toxic metabolites. It is essential to know their relative toxicity for development of a truly effective therapeutics for cocaine toxicity treatment.

METHODS

Drug (norcocaethylene or norcocaine)-induced acute toxicity was characterized by the occurrence (and the timing) of prostration, seizure, and death after intraperitoneal administration of the drug (n = 15) using the same strain (Swiss Webster) of male mice reported in previous study by Hearn et al. to determine LD₅₀ of cocaine and cocaethylene. In addition, drug (cocaine, cocaethylene, norcocaine, or norcocaethylene)-induced hyperactivity was determined by locomotor activity testing (n = 8).

RESULTS

According to the animal data, norcocaethylene (LD₅₀=∼39.4 mg/kg) and norcocaine (LD₅₀=∼49.7 mg/kg) are the most toxic metabolites, but they do not induce significant hyperactivity. In addition, the relative toxicity of drugs correlates with the time to the occurrence of prostration/seizure/death after the drug administration.

CONCLUSIONS

The relative toxicity of these toxic drugs can be ranked in this order: norcocaethylene > norcocaine > cocaethylene > cocaine. The data suggest that norcocaethylene, norcocaine, and cocaethylene are all significant contributors to acute toxicity of cocaine in concurrent use of cocaine and alcohol. Hence, future therapeutic development for cocaine toxicity treatment must account for detoxification of these more toxic metabolites. In addition, the relative toxicity of different drugs correlates with the average time to the occurrence of death, seizure, or prostration after the drug administration with a same dose close to their LD₅₀ values.

Cognitive deficits and neurotoxicity induced by synthetic cathinones: is there a role for neuroinflammation?

RATIONALE

The number of synthetic derivatives of cathinone, the primary psychoactive alkaloid found in Catha edulis (khat), has risen exponentially in the past decade. Synthetic cathinones (frequently referred to as "bath salts") produce adverse cognitive and behavioral sequelae, share similar pharmacological mechanisms of action with traditional psychostimulants, and may therefore trigger similar cellular events that give rise to neuroinflammation and neurotoxicity.

OBJECTIVES

In this review, we provide a brief overview of synthetic cathinones, followed by a summary of cognitive deficits in animals and humans that have been documented following acute or repeated exposure. We also summarize growing evidence from in vitro and in vivo studies for synthetic cathinone-induced neurotoxicity, and provide a working hypothetic model of potential cellular mechanisms.

RESULTS

Synthetic cathinones produce varying effects on markers of monoaminergic terminal function and can increase the formation of reactive oxygen and nitrogen species, induce apoptotic signaling, and cause neurodegeneration and cytotoxicity. We hypothesize that these effects result from biochemical events similar to those induced by traditional psychostimulants. However, empirical evidence for the ability of synthetic cathinones to induce neuroinflammatory processes is currently lacking.

CONCLUSIONS

Like their traditional psychostimulant counterparts, synthetic cathinones appear to induce neurocognitive dysfunction and cytotoxicity, which are dependent on drug type, dose, frequency, and time following exposure. However, additional studies on synthetic cathinone-induced neuroinflammation are clearly needed, as are investigations into the neurochemical and neuroimmune mechanisms underlying their neurotoxic effects. Such endeavors may lead to novel therapeutic avenues to promote recovery in habitual synthetic cathinone users.

Measures of possible allostatic load in comorbid cocaine and alcohol use disorder: Brain white matter integrity, telomere length, and anti-saccade performance

Chronic cocaine and alcohol use impart significant stress on biological and cognitive systems, resulting in changes consistent with an allostatic load model of neurocognitive impairment. The present study measured potential markers of allostatic load in individuals with comorbid cocaine/alcohol use disorders (CUD/AUD) and control subjects. Measures of brain white matter (WM), telomere length, and impulsivity/attentional bias were obtained. WM (CUD/AUD only) was indexed by diffusion tensor imaging metrics, including radial diffusivity (RD) and fractional anisotropy (FA). Telomere length was indexed by the telomere to single copy gene (T/S) ratio. Impulsivity and attentional bias to drug cues were measured via eye-tracking, and were also modeled using the Hierarchical Diffusion Drift Model (HDDM). Average whole-brain RD and FA were associated with years of cocaine use (R2 = 0.56 and 0.51, both p < .005) but not years of alcohol use. CUD/AUD subjects showed more anti-saccade errors (p < .01), greater attentional bias scores (p < .001), and higher HDDM drift rates on cocaine-cue trials (Bayesian probability CUD/AUD > control = p > 0.99). Telomere length was shorter in CUD/AUD, but the difference was not statistically significant. Within the CUD/AUD group, exploratory regression using an elastic-net model determined that more years of cocaine use, older age, larger HDDM drift rate differences and shorter telomere length were all predictive of WM as measured by RD (model R2 = 0.79). Collectively, the results provide modest support linking CUD/AUD to putative markers of allostatic load.

Neurocognitive dysfunction following repeated binge-like self-administration of the synthetic cathinone 3,4-methylenedioxypyrovalerone (MDPV)

Synthetic cathinones, frequently referred to as "bath salts", have significant abuse potential, and recent evidence suggests that these novel psychoactive substances can also produce cognitive deficits as well as cytotoxic effects. However, most of these latter findings have been obtained either using high concentrations in vitro or following non-contingent high dose administration in vivo. The present study utilized a model of long-term voluntary binge-like self-administration to determine potential detrimental effects of synthetic cathinones on cognitive function and their known underlying neural circuits, collectively referred to as neurocognitive dysfunction. Male Sprague-Dawley rats were allowed to self-administer the cocaine-like synthetic cathinone 3,4-methylenedioxypyrovalerone (MDPV, 0.03 mg/kg/infusion i.v.) in 96-hr sessions, or saline as a control. A total of five 96-hr sessions were conducted, each separated by 3 days of abstinence in the home cage. Three weeks following the last 96-hr session, animals underwent assessment of cognitive function using spatial object recognition (SOR) and novel object recognition (NOR) tasks, after which brains were harvested and assessed for neurodegeneration using FluoroJade C (FJC). Compared to animals self-administering saline, animals self-administering MDPV demonstrated (1) robust drug intake that escalated over time, (2) deficits in NOR but not SOR, and (3) neurodegeneration in the perirhinal and entorhinal cortices. These results indicate that repeated binge-like intake of MDPV can induce neurocognitive dysfunction. In addition, utilization of rodent models of extended binge-like intake may provide insight into potential mechanisms and/or approaches to prevent or reverse the detrimental effects of abused substances on cognitive and neurobiological functioning. This article is part of the Special Issue entitled 'Designer Drugs and Legal Highs.'

Clinical Potential of an Enzyme-based Novel Therapy for Cocaine Overdose

It is a grand challenge to develop a truly effective medication for treatment of cocaine overdose. The current available, practical emergence treatment for cocaine overdose includes administration of a benzodiazepine anticonvulsant agent (e.g. diazepam) and/or physical cooling with an aim to relieve the symptoms. The inherent difficulties of antagonizing physiological effects of drugs in the central nervous system have led to exploring protein-based pharmacokinetic approaches using biologics like vaccines, monoclonal antibodies, and enzymes. However, none of the pharmacokinetic agents has demonstrated convincing preclinical evidence of clinical potential for drug overdose treatment without a question mark on the timing used in the animal models. Here we report the use of animal models, including locomotor activity, protection, and rescue experiments in rats, of drug toxicity treatment with clinically relevant timing for the first time. It has been demonstrated that an efficient cocaine-metabolizing enzyme developed in our previous studies can rapidly reverse the cocaine toxicity whenever the enzyme is given to a living rat, demonstrating promising clinical potential of an enzyme-based novel therapy for cocaine overdose as a successful example in comparison with the commonly used diazepam.

Differential effects of MDMA and cocaine on inhibitory avoidance and object recognition tests in rodents

INTRODUCTION

Drug addiction continues being a major public problem faced by modern societies with different social, health and legal consequences for the consumers. Consumption of psychostimulants, like cocaine or MDMA (known as ecstasy) are highly prevalent and cognitive and memory impairments have been related with the abuse of these drugs.

AIM

The aim of this work was to review the most important data of the literature in the last 10 years about the effects of cocaine and MDMA on inhibitory avoidance and object recognition tests in rodents.

DEVELOPMENT

The object recognition and the inhibitory avoidance tests are popular procedures used to assess different types of memory. We compare the effects of cocaine and MDMA administration in these tests, taking in consideration different factors such as the period of life development of the animals (prenatal, adolescence and adult age), the presence of polydrug consumption or the role of environmental variables. Brain structures involved in the effects of cocaine and MDMA on memory are also described.

CONCLUSIONS

Cocaine and MDMA induced similar impairing effects on the object recognition test during critical periods of lifetime or after abstinence of prolonged consumption in adulthood. Deficits of inhibitory avoidance memory are observed only in adult rodents exposed to MDMA. Psychostimulant abuse is a potential factor to induce memory impairments and could facilitate the development of future neurodegenerative disorders.

Neuroscience-informed psychoeducation for addiction medicine: A neurocognitive perspective

Psychoeducation (PE) is defined as an intervention with systematic, structured, and didactic knowledge transfer for an illness and its treatment, integrating emotional and motivational aspects to enable patients to cope with the illness and to improve its treatment adherence and efficacy. PE is considered an important component of treatment in both medical and psychiatric disorders, especially for mental health disorders associated with lack of insight, such as alcohol and substance use disorders (ASUDs). New advancements in neuroscience have shed light on how various aspects of ASUDs may relate to neural processes. However, the actual impact of neuroscience in the real-life clinical practice of addiction medicine is minimal. In this chapter, we provide a perspective on how PE in addiction medicine can be informed by neuroscience in two dimensions: content (knowledge we transfer in PE) and structure (methods we use to deliver PE). The content of conventional PE targets knowledge about etiology of illness, treatment process, adverse effects of prescribed medications, coping strategies, family education, and life skill training. Adding neuroscience evidence to the content of PE could be helpful in communicating not only the impact of drug use but also the beneficial impact of various treatments (i.e., on brain function), thus enhancing motivation for compliance and further destigmatizing their symptoms. PE can also be optimized in its "structure" by implicitly and explicitly engaging different neurocognitive processes, including salience/attention, memory, and self-awareness. There are many interactions between these two dimensions, structure and content, in the delivery of neuroscience-informed psychoeducation (NIPE). We explore these interactions in the development of a cartoon-based NIPE to promote brain recovery during addiction treatment as a part of the brain awareness for addiction recovery initiative.

Neuro-protective effect of rutin against Cisplatin-induced neurotoxic rat model

Background

Cisplatin is widely used chemotherapeutic agent for cancer treatment with limited uses due to its neurotoxic side effect. The aim of this study was to determine the potential preventive effects of rutin on the brain of cisplatin- neurotoxic rat model.

Methods

Forty rats were divided into four groups. Group-1 (control group) was intra-peritoneal (IP) injected with 2.5 ml/kg saline. Group-2 (rutin group) was orally administrated 30 mg/kg rutin dissolved in water for 14 days. Group-3 (cisplatin group) was IP received 5 mg/kg cisplatin single dose. Group-4 (rutin and cisplatin group) was orally administrated 30 mg/kg rutin dissolved in water for 14 days with a single dose of 5 mg/kg cisplatin IP on day ten. Brain tissues from frontal cortex was used to extract RNA, the gene expression levels of paraoxonase-1 (PON-1), PON-2, PON-3, peroxisome proliferator-activated receptor delta (PPAR-δ), and glutathione peroxidase (GPx) was investigated by Real-time PCR.

Results

Cisplatin significantly decreased the expression levels of PON-1, PON-3, PPAR-δ and GPX whereas significantly increased PON-2 expression levels. Co-administration of Rutin prevented the cisplatin-induced toxicity by restoring the alteration in the studied genes to normal values as in the control group.

Conclusion

This study showed that Rutin has neuroprotective effect and reduces cisplatin- neurotoxicity with possible mechanism via the antioxidant pathway.

Emerging various environmental threats to brain and overview of surveillance system with zebrafish model

Pathologies related to neurotoxicity represent an important percentage of the diseases that determine the global burden of diseases. Neurotoxicity may be related to the increasing levels of potentially neurotoxic agents that pollute the environment, which generates concern, since agents that affect children may increase the incidence of neurodevelopmental disorders, affecting the quality of life of future citizens. Many environmental contaminants have been detected, and many of them derive from several human activities, including the mining, agriculture, manufacturing, pharmaceutical, beverage and food industries. These problems are more acute in third world countries, where environmental regulations are lax or non-existent. An additional major emerging problem is drug contamination. Periodic monitoring should be performed to identify potential neurotoxic substances using biological tests capable of identifying the risk. In this sense the fish embryo test (FET), which is performed on zebrafish embryos, is a useful, reliable and economical alternative that can be implemented in developing countries.