Methamphetamine accelerates cellular senescence through stimulation of de novo ceramide biosynthesis

Sphingolipid biosynthetic inhibitor L-Cycloserine prevents oxidative-stress-mediated death in an in vitro model of photoreceptor-derived 661W cells

Oxidative stress plays a pivotal role in the pathogenesis of several neurodegenerative diseases. Retinal degeneration causes irreversible death of photoreceptor cells, ultimately leading to vision loss. Under oxidative stress, the synthesis of bioactive sphingolipid ceramide increases, triggering apoptosis in photoreceptor cells and leading to their death. This study investigates the effect of L-Cycloserine, a small molecule inhibitor of ceramide biosynthesis, on sphingolipid metabolism and the protection of photoreceptor-derived 661W cells from oxidative stress. The results demonstrate that treatment with L-Cycloserine, an inhibitor of Serine palmitoyl transferase (SPT), markedly decreases bioactive ceramide and associated sphingolipids in 661W cells. A nontoxic dose of L-Cycloserine can provide substantial protection of 661W cells against H2O2-induced oxidative stress by reversing the increase in ceramide level observed under oxidative stress conditions. Analysis of various antioxidant, apoptotic and sphingolipid pathway genes and proteins also confirms the ability of L-Cycloserine to modulate these pathways. Our findings elucidate the generation of sphingolipid mediators of cell death in retinal cells under oxidative stress and the potential of L-Cycloserine as a therapeutic candidate for targeting ceramide-induced degenerative diseases by inhibiting SPT. The promising therapeutic prospect identified in our findings lays the groundwork for further validation in in-vivo and preclinical models of retinal degeneration.

Metabolomics and lipidomics strategies in modern drug discovery and development

Metabolomics and lipidomics have an increasingly pivotal role in drug discovery and development. In the context of drug discovery, monitoring changes in the levels or composition of metabolites and lipids relative to genetic variations yields functional insights, bolstering human genetics and (meta)genomic methodologies. This approach also sheds light on potential novel targets for therapeutic intervention. In the context of drug development, metabolite and lipid biomarkers contribute to enhanced success rates, promising a transformative impact on precision medicine. In this review, we deviate from analytical chemist-focused perspectives, offering an overview tailored to drug discovery. We provide introductory insight into state-of-the-art mass spectrometry (MS)-based metabolomics and lipidomics techniques utilized in drug discovery and development, drawing from the collective expertise of our research teams. We comprehensively outline the application of metabolomics and lipidomics in advancing drug discovery and development, spanning fundamental research, target identification, mechanisms of action, and the exploration of biomarkers.

Methamphetamine causes cardiovascular dysfunction via cystathionine gamma lyase and hydrogen sulfide depletion

Methamphetamine (METH) is an addictive illicit drug used worldwide that causes significant damage to blood vessels resulting in cardiovascular dysfunction. Recent studies highlight increased prevalence of cardiovascular disease (CVD) and associated complications including hypertension, vasospasm, left ventricular hypertrophy, and coronary artery disease in younger populations due to METH use. Here we report that METH administration in a mouse model of 'binge and crash' decreases cardiovascular function via cystathionine gamma lyase (CSE), hydrogen sulfide (H2S), nitric oxide (NO) (CSE/H2S/NO) dependent pathway. METH significantly reduced H2S and NO bioavailability in plasma and skeletal muscle tissues co-incident with a significant reduction in flow-mediated vasodilation (FMD) and blood flow velocity revealing endothelial dysfunction. METH administration also reduced cardiac ejection fraction (EF) and fractional shortening (FS) associated with increased tissue and perivascular fibrosis. Importantly, METH treatment selectively decreased CSE expression and sulfide bioavailability along with reduced eNOS phosphorylation and NO levels. Exogenous sulfide therapy or endothelial CSE transgenic overexpression corrected cardiovascular and associated pathological responses due to METH implicating a central molecular regulatory pathway for tissue pathology. These findings reveal that therapeutic intervention targeting CSE/H2S bioavailability may be useful in attenuating METH mediated cardiovascular disease.

Intraoperative delineation of p16+ oropharyngeal carcinoma of unknown primary origin with fluorescence lifetime imaging: Preliminary report

BACKGROUND

This study evaluated whether fluorescence lifetime imaging (FLIm), coupled with standard diagnostic workups, could enhance primary lesion detection in patients with p16+ head and neck squamous cell carcinoma of the unknown primary (HNSCCUP).

METHODS

FLIm was integrated into transoral robotic surgery to acquire optical data on six HNSCCUP patients' oropharyngeal tissues. An additional 55-patient FLIm dataset, comprising conventional primary tumors, trained a machine learning classifier; the output predicted the presence and location of HNSCCUP for the six patients. Validation was performed using histopathology.

RESULTS

Among the six HNSCCUP patients, p16+ occult primary was surgically identified in three patients, whereas three patients ultimately had no identifiable primary site in the oropharynx. FLIm correctly detected HNSCCUP in all three patients (ROC-AUC: 0.90 ± 0.06), and correctly predicted benign oropharyngeal tissue for the remaining three patients. The mean sensitivity was 95% ± 3.5%, and specificity 89% ± 12.7%.

CONCLUSIONS

FLIm may be a useful diagnostic adjunct for detecting HNSCCUP.

Early onset cardiovascular disease related to methamphetamine use is most striking in individuals under 30: A retrospective chart review

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Prior MA is associated with an earlier onset of cardiovascular onset which is striking in young adults.

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Both the races displayed the prior MA use associated earlier age of CVD onset with marked differences in the latency to cardiovascular onset between the Blacks and Whites.

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Hypertension emerged as the most frequently observed CVD in the MA group.

Introduction

The illicit use of methamphetamine (MA), a dangerous psychostimulant has become a global epidemic. Studies have demonstrated a link between illicit substance use and cardiovascular consequences. The objective of this study was to assess whether MA use is associated with an early onset of cardiovascular diseases (CVD).

Methods

Retrospective analysis was conducted using data collected from 1376 individuals at Louisiana State University Health Sciences Center - Shreveport between 2011 and 2020. Cardiovascular patients with and without a history of MA use were divided into the MA and Control groups. The age of CVD onset was assessed. Descriptive statistics for patient characteristics, Two Samples T-Test for continuous and Pearson's χ^2- tests for categorical variables were calculated. Hazard ratios (HR) and time ratios (TR) were calculated.

Results

The age of CVD onset in patients with prior MA use occurred on average 8 year earlier than the age of CVD onset (mean age ± SD = 44 ± 12.04) in controls (mean age ± SD = 52 ± 10.70) (unpaired t-test, p < 0.0001). The findings were noted in both the races (Time Ratio = 0.93, 95% CI = 0.89 to 0.97, p-value < 0.001), with a striking difference in the latency to CVD onset between Black and White subjects. A 12-fold increase in subjects who showed a premature onset of CVD (<30 years of age) in the MA group was observed. Our data analysis revealed that hypertension was the most frequently observed CVD.

Conclusions

MA use likely accelerates early onset of CVD and contributes to CVD complications in young adults.

Methamphetamine Induces the Release of Proadhesive Extracellular Vesicles and Promotes Syncytia Formation: A Potential Role in HIV-1 Neuropathogenesis

Despite the success of combinational antiretroviral therapy (cART), the high pervasiveness of human immunodeficiency virus-1 (HIV)-associated neurocognitive disorders (HAND) poses a significant challenge for society. Methamphetamine (meth) and related amphetamine compounds, which are potent psychostimulants, are among the most commonly used illicit drugs. Intriguingly, HIV-infected individuals who are meth users have a comparatively higher rate of neuropsychological impairment and exhibit a higher viral load in the brain than infected individuals who do not abuse meth. Effectively, all cell types secrete nano-sized lipid membrane vesicles, referred to as extracellular vesicles (EVs) that can function as intercellular communication to modulate the physiology and pathology of the cells. This study shows that meth treatments on chronically HIV-infected promonocytic U1 cells induce the release of EVs that promote cellular clustering and syncytia formation, a phenomenon that facilitates HIV pathogenesis. Our analysis also revealed that meth exposure increased intercellular adhesion molecule-1 (ICAM-1) and HIV-Nef protein expression in both large (10 K) and small (100 K) EVs. Further, when meth EVs are applied to uninfected naïve monocyte-derived macrophages (MDMs), we saw a significant increase in cell clustering and syncytia formation. Furthermore, treatment of MDMs with antibodies against ICAM-1 and its receptor, lymphocyte function-associated antigen 1 (LFA1), substantially blocked syncytia formation, and consequently reduced the number of multinucleated cells. In summary, our findings reveal that meth exacerbates HIV pathogenesis in the brain through release of proadhesive EVs, promoting syncytia formation and thereby aiding in the progression of HIV infection in uninfected cells.

A comprehensive study to delineate the role of an extracellular vesicle-associated microRNA-29a in chronic methamphetamine use disorder

Extracellular vesicles (EVs), which express a repertoire of cargo molecules (cf. proteins, microRNA, lipids, etc.), have been garnering a prominent role in the modulation of several cellular processes. Here, using both non-human primate and rodent model systems, we provide evidence that brain-derived EV (BDE) miRNA, miR-29a-3p (mir-29a), is significantly increased during chronic methamphetamine (MA) exposure. Further, miR-29a levels show significant increase both with drug-seeking and reinstatement in a rat MA self-administration model. We also show that EV-associated miR-29a is enriched in EV pool comprising of small EVs and exomeres and further plays a critical role in MA-induced inflammation and synaptodendritic damage. Furthermore, treatment with the anti-inflammatory drug ibudilast (AV411), which is known to reduce MA relapse, decreased the expression of miR-29a and subsequently attenuated inflammation and rescued synaptodendritic injury. Finally, using plasma from MUD subjects, we provide translational evidence that EV-miR29a could potentially serve as a biomarker to detect neuronal damage in humans diagnosed with MA use disorder (MUD). In summary, our work suggests that EV-associated miR-29a-3p plays a crucial role in MUD and might be used as a potential blood-based biomarker for detecting chronic inflammation and synaptic damage.

Astrocyte-derived TNF and glutamate critically modulate microglia activation by methamphetamine

Methamphetamine (Meth) is a powerful illicit psychostimulant, widely used for recreational purposes. Besides disrupting the monoaminergic system and promoting oxidative brain damage, Meth also causes neuroinflammation, contributing to synaptic dysfunction and behavioral deficits. Aberrant activation of microglia, the largest myeloid cell population in the brain, is a common feature in neurological disorders triggered by neuroinflammation. In this study, we investigated the mechanisms underlying the aberrant activation of microglia elicited by Meth in the adult mouse brain. We found that binge Meth exposure caused microgliosis and disrupted risk assessment behavior (a feature that usually occurs in individuals who abuse Meth), both of which required astrocyte-to-microglia crosstalk. Mechanistically, Meth triggered a detrimental increase of glutamate exocytosis from astrocytes (in a process dependent on TNF production and calcium mobilization), promoting microglial expansion and reactivity. Ablating TNF production, or suppressing astrocytic calcium mobilization, prevented Meth-elicited microglia reactivity and re-established risk assessment behavior as tested by elevated plus maze (EPM). Overall, our data indicate that glial crosstalk is critical to relay alterations caused by acute Meth exposure.

Shortened leukocyte telomere length in young adults who use methamphetamine

Methamphetamine (METH) use, most prevalent in young adults, has been associated with high rates of morbidity and mortality. The relationship between METH use and accelerated biological aging, which can be measured using leukocyte telomere length (LTL), remains unclear. We examined whether young adult METH users have shorter LTL and explored the relationship between characteristics of METH use and LTL by using Mendelian randomization (MR) analysis. We compared the LTL for 187 METH users and 159 healthy individuals aged between 25 and 34 years and examined the relationship of LTL with METH use variables (onset age, duration, and maximum frequency of METH use) by using regression analyses. In addition, 2-stage-least-squares (2SLS) MR was also performed to possibly avoid uncontrolled confounding between characteristics of METH use and LTL. We found METH users had significantly shorter LTL compared to controls. Multivariate regression analysis showed METH use was negatively associated with LTL (β = -0.36, P < .001). Among METH users, duration of METH use was negatively associated with LTL after adjustment (β = -0.002, P = .01). We identified a single nucleotide polymorphism (SNP) rs6585206 genome-wide associated with duration of METH use. This SNP was used as an instrumental variable to avoid uncontrolled confounding for the relationship between the use duration and LTL shortening. In conclusion, we show that young adult METH users may have shorter LTL compared with controls and longer duration of METH use was significantly associated with telomere shortening. These observations suggest that METH use may accelerate biological senescence.

Pathological methamphetamine exposure triggers the accumulation of neuropathic protein amyloid-β by inhibiting UCHL1

Methamphetamine (METH), a powerful psychoactive drug, causes damage to the nervous system and leads to degenerative changes similar to Alzheimer's disease (AD), however, the molecular mechanism between the toxicity of METH and AD-related symptoms remains poorly understood. In this study, we investigated the effect of METH exposure on the accumulation of amyloid-β by establishing the animal and cell models. The results showed that METH exposure increased amyloid precursor protein (APP) and β-secretase (BACE1), contributed to the accumulation of amyloid-β, and which was alleviated with the pretreatment of BACE1 inhibitor. In addition, METH exposure decreased ubiquitin carboxy-terminal hydrolases L1 (UCHL1) which was related to the degradation of BACE1, and therefore led to the up-regulation of BACE1. In summary, the study could provide a new insight into the molecular mechanisms of METH toxicity and new evidence for the link between METH abuse and AD.

Effect of ketamine on gene expression in zebrafish embryos

Ketamine is an N-methyl-D-aspartate (NMDA) receptor antagonist. Used as an anesthetic, potential neurotoxic and cardiotoxic effects of ketamine in animal models have been reported. The underlying mechanisms of ketamine-induced toxicity are not clear. The zebrafish is an ideal model for toxicity assays because of its predictive capability in chemical testing, which compares well with that of mammalian models. To gain insight into potential mechanisms of ketamine effects, we performed real-time quantitative polymerase chain reaction-based gene expression array analyses. Gene expression analysis was conducted for multiple genes (a total of 84) related to 10 major signaling pathways including the transforming growth factor β (TGFβ), Wingless and Int-1 (Wnt), nuclear factor κ-light-chain-enhancer of activated B cells (NF-κB), Janus kinase/signal transducers and activators of transcription (JAK/STAT), p53, Notch, Hedgehog, peroxisome proliferator-activated receptor (PPAR), oxidative stress, and hypoxia pathways. Our results show that ketamine altered the expression of specific genes related to hypoxia, p53, Wnt, Notch, TGFβ, PPAR, and oxidative stress pathways. Thus, we can further focus on these specific pathways to elucidate the mechanisms by which ketamine elicits a toxic response.

Ceramide contributes to pathogenesis and may be targeted for therapy in VCP inclusion body myopathy

Knock-in homozygote VCPR155H/R155H mutant mice are a lethal model of valosin-containing protein (VCP)-associated inclusion body myopathy associated with Paget disease of bone, frontotemporal dementia and amyotrophic lateral sclerosis. Ceramide (d18:1/16:0) levels are elevated in skeletal muscle of the mutant mice, compared to wild-type controls. Moreover, exposure to a lipid-enriched diet reverses lethality, improves myopathy and normalizes ceramide levels in these mutant mice, suggesting that dysfunctions in lipid-derived signaling are critical to disease pathogenesis. Here, we investigated the potential role of ceramide in VCP disease using pharmacological agents that manipulate the ceramide levels in myoblast cultures from VCP mutant mice and VCP patients. Myoblasts from wild-type, VCPR155H/+ and VCPR155H/R155H mice, as well as patient-induced pluripotent stem cells (iPSCs), were treated with an inhibitor of ceramide degradation to increase ceramide via acid ceramidase (ARN082) for proof of principle. Three chemically distinct inhibitors of ceramide biosynthesis via serine palmitoyl-CoA transferase (L-cycloserine, myriocin or ARN14494) were used as a therapeutic strategy to reduce ceramide in myoblasts. Acid ceramidase inhibitor, ARN082, elevated cellular ceramide levels and concomitantly enhanced pathology. Conversely, inhibitors of ceramide biosynthesis L-cycloserine, myriocin and ARN14494 reduced ceramide production. The results point to ceramide-mediated signaling as a key contributor to pathogenesis in VCP disease and suggest that manipulating this pathway by blocking ceramide biosynthesis might exert beneficial effects in patients with this condition. The ceramide pathway appears to be critical in VCP pathogenesis, and small-molecule inhibitors of ceramide biosynthesis might provide therapeutic benefits in VCP and related neurodegenerative diseases.

Role of Extracellular Vesicles in Substance Abuse and HIV-Related Neurological Pathologies

Extracellular vesicles (EVs) are a broad, heterogeneous class of membranous lipid-bilayer vesicles that facilitate intercellular communication throughout the body. As important carriers of various types of cargo, including proteins, lipids, DNA fragments, and a variety of small noncoding RNAs, including miRNAs, mRNAs, and siRNAs, EVs may play an important role in the development of addiction and other neurological pathologies, particularly those related to HIV. In this review, we summarize the findings of EV studies in the context of methamphetamine (METH), cocaine, nicotine, opioid, and alcohol use disorders, highlighting important EV cargoes that may contribute to addiction. Additionally, as HIV and substance abuse are often comorbid, we discuss the potential role of EVs in the intersection of substance abuse and HIV. Taken together, the studies presented in this comprehensive review shed light on the potential role of EVs in the exacerbation of substance use and HIV. As a subject of growing interest, EVs may continue to provide information about mechanisms and pathogenesis in substance use disorders and CNS pathologies, perhaps allowing for exploration into potential therapeutic options.

mTOR-autophagy promotes pulmonary senescence through IMP1 in chronic toxicity of methamphetamine

It is growingly concerned about methamphetamine (MA)-induced lung toxicity. IMP1 is identified as a key molecule for cell life processes, but the role of IMP1 in MA-induced senescence remains unclear. The purpose of this study was to investigate whether chronic exposure to MA can cause autophagy and senescence of the lungs, whether there are interactions between Mammalian target of rapamycin (mTOR) and IMP1 and whether IMP1 is involved in pulmonary senescence promoted by mTOR-autophagy. The rats were randomly divided into control group and MA group, following by H&E staining, immunohistochemistry staining and Western blot. The alveolar epithelial cells were proceeded by ß-galactosidase staining, cell cycle detection, transfection and co-immunoprecipitation. Long-term exposure to MA led to the thickening of alveolar septum and more compact lungs. MA promoted the conversion of LC3-I to LC3-II and inhibited the activation of mTOR to induce autophagy. Bioinformatics and co-immunoprecipitation results presented the interactions between IMP1 and mTOR. MA induced cell senescence by decreasing IMP1, up-regulating p21 and p53, arresting cell cycle and increasing SA-β-gal. Overexpression of IMP1 reduced p21 and SA-β-gal to inhibit the senescence of alveolar epithelial cells. These results demonstrated that mTOR-autophagy promotes pulmonary senescence through IMP1 in chronic toxicity of methamphetamine.

Revealing Metabolic Perturbation Following Heavy Methamphetamine Abuse by Human Hair Metabolomics and Network Analysis

Methamphetamine (MA) is a highly addictive central nervous system stimulant. Drug addiction is not a static condition but rather a chronically relapsing disorder. Hair is a valuable and stable specimen for chronic toxicological monitoring as it retains toxicants and metabolites. The primary focus of this study was to discover the metabolic effects encompassing diverse pathological symptoms of MA addiction. Therefore, metabolic alterations were investigated in human hair following heavy MA abuse using both targeted and untargeted mass spectrometry and through integrated network analysis. The statistical analyses (t-test, variable importance on projection score, and receiver-operator characteristic curve) demonstrated that 32 metabolites (in targeted metabolomics) as well as 417 and 224 ion features (in positive and negative ionization modes of untargeted metabolomics, respectively) were critically dysregulated. The network analysis showed that the biosynthesis or metabolism of lipids, such as glycosphingolipids, sphingolipids, glycerophospholipids, and ether lipids, as well as the metabolism of amino acids (glycine, serine and threonine; cysteine and methionine) is affected by heavy MA abuse. These findings reveal crucial metabolic effects caused by MA addiction, with emphasis on the value of human hair as a diagnostic specimen for determining drug addiction, and will aid in identifying robust diagnostic markers and therapeutic targets.

Neuroprotective effect of gastrodin in methamphetamine-induced apoptosis through regulating cAMP/PKA/CREB pathway in cortical neuron

OBJECTIVE

Methamphetamine (MA) abuse induces neurotoxicity and causes neuronal cell apoptosis. Gastrodin is a traditional Chinese herbal medicine used for the treatment of nerve injuries, spinal cord injuries, and some central nervous system diseases as well. The present study investigated the neuroprotective effects of gastrodin against MA-induced neurotoxicity in neuronal cells and its potential protective mechanism.

METHODS

The primary cortex neuronal culture was divided into four groups (control group, MA group, MA + gastrodin group, and MA + gastrodin + small interfering RNA group). The neurotoxicity of MA was assessed by detecting apoptotic cells by terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick-end labeling assay and cell viability by cell counting kit 8 (CCK-8) method, the Tuj1-positive cells and the average axonal length were detected by immunofluorescence, and the expressions of cyclic adenosine monophosphate (cAMP), protein kinase A (PKA), cAMP-response element-binding (CREB), and brain-derived neurotrophic factor (BDNF) proteins were detected by Western blot.

RESULTS

The results of CCK-8 assay showed that 0.5 mM MA was an optimal concentration that induced neurotoxicity (p < 0.01). Pretreatment with 25 mg/L gastrodin exerted maximum protective effects on neuronal cells. The expression levels of cAMP, PKA, phosphorylated PKA, CREB, phosphorylated CREB, and BDNF proteins were decreased in the MA group, and pretreatment with gastrodin upregulated the expression levels of these proteins (p < 0.01). The expressions of PKA and CREB proteins showed no significant changes in the control group, MA group, and gastrodin group. Compared the MA + gastrodin + small interfering RNA group with MA + gastrodin group, the Tuj1-positive cells and the average axonal length were decreased significantly, while the number of apoptotic cells was increased (p < 0.05).

CONCLUSION

Gastrodin has neuroprotective effects against MA-induced neurotoxicity, which exerts neuroprotective effects via regulation of cAMP/PKA/CREB signaling pathway and upregulates the expression of BDNF.

The multi-faceted impact of methamphetamine on Alzheimer's disease: From a triggering role to a possible therapeutic use

Although it has been initially synthesized for therapeutic purposes and currently FDA-approved and prescribed for obesity, attention-deficit/hyperactivity disorder, narcolepsy and depression, methamphetamine became a recreational drug that is nowadays massively manufactured illegally. Because it is a powerful and extremely addictive psychotropic agent, its abuse has turned out to become a major health problem worldwide. Importantly, the numerous effects triggered by this drug induce neurotoxicity in the brain ultimately leading to serious neurological impairments, tissue damage and neuropsychological disturbances that are reminiscent to most of the symptoms observed in Alzheimer's disease and other pathological manifestations in aging brain. In this context, there is a growing number of compelling evidence linking methamphetamine abuse with a higher probability of developing premature Alzheimer's disease and consequent neurodegeneration. This review proposes to establish a broad assessment of the effects that this drug can generate at the cellular and molecular levels in connection with the development of the age-related Alzheimer's disease. Altogether, the objective is to warn against the long-term effects that methamphetamine abuse may convey on young consumers and the increased risk of developing this devastating brain disorder at later stages of their lives, but also to discuss a more recently emerging concept suggesting a possible use of methamphetamine for treating this pathology under proper and strictly controlled conditions.

Interplay between Cocaine, Drug Removal, and Methylphenidate Reversal on Phospholipid Alterations in Drosophila Brain Determined by Imaging Mass Spectrometry

Cocaine dependence displays a broad impairment in cognitive performance including attention, learning, and memory. To obtain a better understanding of the action of cocaine in the nervous system, and the relation between phospholipids and memory, we have investigated whether phospholipids recover in the brain following cocaine removal using the fly model, Drosophila melanogaster. In addition, the effects of methylphenidate, a substitute medication for cocaine dependence, on fly brain lipids after cocaine abuse are also determined to see if it can rescue the lipid changes caused by cocaine. Time of flight secondary ion mass spectrometry with a (CO₂)₆₀₀₀⁺ gas cluster ion beam was used to detect intact phospholipids. We show that cocaine has persistent effects, both increasing and decreasing the levels of specific phosphatidylethanolamines and phosphatidylinositols. These changes remain after cocaine withdrawal and are not rescued by methylphenidate. Cocaine is again shown to generally increase the levels of phosphatidylcholines in the fly brain; however, after drug withdrawal, the abundance of these lipids returns to the original level and methylphenidate treatment of the flies following cocaine exposure enhances the reversal of the lipid level reducing them below the original control. The study provides insight into the molecular effects of cocaine and methylphenidate on brain lipids. We suggest that phosphatidylcholines could be a potential target for the treatment of cocaine abuse as well as be a significant hallmark of cognition and memory loss with cocaine.

Inhibition of de novo ceramide biosynthesis affects aging phenotype in an in vitro model of neuronal senescence

Although aging is considered to be an unavoidable event, recent experimental evidence suggests that the process can be counteracted. Intracellular calcium (Ca²⁺_i) dyshomeostasis, mitochondrial dysfunction, oxidative stress, and lipid dysregulation are critical factors that contribute to senescence-related processes. Ceramides, a pleiotropic class of sphingolipids, are important mediators of cellular senescence, but their role in neuronal aging is still largely unexplored. In this study, we investigated the effects of L-cycloserine (L-CS), an inhibitor of thede novoceramide biosynthesis, on the aging phenotype of cortical neurons cultured for 22 days, a setting employed as anin vitromodel of senescence. Our findings indicate that, compared to control cultures, ‘aged’ neurons display dysregulation of [Ca²⁺]_ilevels, mitochondrial dysfunction, increased generation of reactive oxygen species (ROS), altered synaptic activity as well as the activation of neuronal death-related molecules. Treatment with L-CS positively affected the senescent phenotype, a result associated with recovery of neuronal [Ca²⁺]_isignaling and reduction of mitochondrial dysfunction and ROS generation. The results suggest that thede novoceramide biosynthesis represents a critical intermediate in the molecular and functional cascade leading to neuronal senescence and identify ceramide biosynthesis inhibitors as promising pharmacological tools to decrease age-related neuronal dysfunctions.

Frailty in Comorbid HIV and Lifetime Methamphetamine Use Disorder: Associations with Neurocognitive and Everyday Functioning

HIV and methamphetamine (MA) use disorder are commonly comorbid and individually associated with adverse health consequences, including frailty; however, less is known about the combined effects of both conditions. The current cross-sectional study examined how HIV and lifetime MA use disorder relate to frailty and explored associations between frailty and relevant clinical outcomes (i.e., neurocognitive and everyday functioning). Participants were categorized into three groups based on HIV status and lifetime MA diagnosis: HIV+/MA+ (n = 43), HIV+/MA- (n = 75), and HIV-/MA- (n = 92). A frailty index score (representing proportion of accumulated multisystem deficits) was calculated from 27 medical and psychiatric deficits. Multiple regression was used to examine frailty index score by HIV/MA group. Additional multiple regression models examined the interaction between frailty and HIV/MA group on cognitive and everyday functioning. Comorbid HIV+/MA+ participants had higher frailty index scores than both HIV-/MA- (b = -0.13, p < .001) and HIV+/MA- participants (b = -0.06, p = .007). Additional models linked higher frailty index score to worse global neurocognition (b = -17.6, p = .018) and greater likelihood of everyday functioning dependence (odds ratio = 1.56, p = .021). Although these relationships did not significantly differ by HIV/MA status, group-stratified analyses showed that associations of frailty with neurocognitive and everyday functioning were strongest among the HIV+/MA+ group. Multimodal public health interventions aimed at reducing frailty may help to decrease the likelihood of neurocognitive and everyday functioning problems. Current findings additionally lay groundwork for future longitudinal research examining whether frailty predicts onset of neurocognitive and functional decline in individuals with comorbid HIV and MA use disorder.

The identification of small molecule inhibitors of the plant inositol phosphorylceramide synthase which demonstrate herbicidal activity

Resistance to 157 different herbicides and 88% of known sites of action has been observed, with many weeds resistant to two or more modes. Coupled with tighter environmental regulation, this demonstrates the need to identify new modes of action and novel herbicides. The plant sphingolipid biosynthetic enzyme, inositol phosphorylceramide synthase (IPCS), has been identified as a novel, putative herbicide target. The non-mammalian nature of this enzyme offers the potential of discovering plant specific inhibitory compounds with minimal impact on animals and humans, perhaps leading to the development of new non-toxic herbicides. The best characterised and most highly expressed isoform of the enzyme in the model-dicot Arabidopsis, AtIPCS2, was formatted into a yeast-based assay which was then utilized to screen a proprietary library of over 11,000 compounds provided by Bayer AG. Hits from this screen were validated in a secondary in vitro enzyme assay. These studies led to the identification of a potent inhibitor that showed selectivity for AtIPCS2 over the yeast orthologue, and activity against Arabidopsis seedlings. This work highlighted the use of a yeast-based screening assay to discover herbicidal compounds and the status of the plant IPCS as a novel herbicidal target.

Protective effect of gastrodin against methamphetamine-induced autophagy in human dopaminergic neuroblastoma SH-SY5Y cells via the AKT/mTOR signaling pathway

Methamphetamine (METH) has been shown to induce neuropathological dysfunction and irreversible brain cell damage. Prior studies indicated the involvement of autophagy in METH-induced neurotoxicity. However, the underlying mechanism by which autophagy contributes to METH-induced neurotoxicity remains elusive. Gastrodin, a primary bioactive constituent of Gastrodia elata-an orchid used in traditional Chinese medicine-is used widely to treat stroke, dementia, and headache. This study investigates whether METH induces autophagy in the human dopaminergic neuroblastoma cell line SH-SY5Y, then examines the neuroprotective effects of gastrodin against autophagy in METH-treated SH-SY5Y cells. The effects of METH on the protein expressions of autophagy-related genes (LC3B and Beclin-1) were evaluated with and without gastrodin. The presence of autophagosomes in the METH-induced treatment with and without gastrodin is revealed through transmission electron microscopy. Pharmacological intervention was employed to study the role of the AKT/mTOR signaling pathway in the gastrodin-mediated neuroprotection against METH-induced autophagy. The present results indicate that METH exposure elevates the protein expression levels of LC3B and Beclin-1 in a dose- and time-dependent manner. Gastrodin is observed to block the METH-induced upregulation of LC3B and Beclin-1 protein expression significantly. Gastrodin is found to exhibit an anti-autophagic effect on the inhibition of the METH-induced Beclin-1 protein expression, partly via the AKT/mTOR These findings may aid the development of a gastrodin-based therapeutic strategy for treating METH-induced neurotoxicity.

Integrative Analysis of Global Gene Expression Identifies Opposite Patterns of Reactive Astrogliosis in Aged Human Prefrontal Cortex

The prefrontal cortex (PFC) is one of the brain regions with more prominent changes in human aging. The molecular processes related to the cognitive decline and mood changes during aging are not completely understood. To improve our knowledge, we integrated transcriptomic data of four studies of human PFC from elderly people (58–80 years old) compared with younger people (20–40 years old) using a meta-analytic approximation combined with molecular signature analysis. We identified 1817 differentially expressed genes, 561 up-regulated and 1256 down-regulated. Pathway analysis revealed down-regulation of synaptic genes with conservation of gene expression of other neuronal regions. Additionally, we identified up-regulation of markers of astrogliosis with transcriptomic signature compatible with A1 neurotoxic astrocytes and A2 neuroprotective astrocytes. Response to interferon is related to A1 astrocytes and the A2 phenotype is mediated in aging by activation of sonic hedgehog (SHH) pathway and up-regulation of metallothioneins I and genes of the family ERM (ezrin, radixin, and moesin). The main conclusions of our study are the confirmation of a global dysfunction of the synapses in the aged PFC and the evidence of opposite phenotypes of astrogliosis in the aging brain, which we report for the first time in the present article.

Methamphetamine and its immune-modulating effects

The recreational use of methamphetamine (METH, or ice) is a global burden. It pervades and plagues contemporary society; it has been estimated that there are up to 35 million users worldwide. METH is a highly addictive psychotropic compound which acts on the central nervous system, and chronic use can induce psychotic behavior. METH has the capacity to modulate immune cells, giving the drug long-term effects which may manifest as neuropsychiatric disorders, and that increase susceptibility to communicable diseases, such as HIV. In addition, changes to the cytokine balance have been associated with compromise of the blood-brain barrier, resulting to alterations to brain plasticity, creating lasting neurotoxicity. Immune-related signaling pathways are key to further evaluating how METH impacts host immunity through these neurological and peripheral modifications. Combining this knowledge with current data on inflammatory responses will improve understanding of how the adaptive and innate immunity responds to METH, how this can activate premature-ageing processes and how METH exacerbates disturbances that lead to non-communicable age-related diseases, including cardiovascular disease, stroke, depression and dementia.

Complete Acid Ceramidase ablation prevents cancer-initiating cell formation in melanoma cells

Acid ceramidase (AC) is a lysosomal cysteine hydrolase that catalyzes the conversion of ceramide into fatty acid and sphingosine. This reaction lowers intracellular ceramide levels and concomitantly generates sphingosine used for sphingosine-1-phosphate (S1P) production. Since increases in ceramide and consequent decreases of S1P reduce proliferation of various cancers, AC might offer a new target for anti-tumor therapy. Here we used CrispR-Cas9-mediated gene editing to delete the gene encoding for AC, ASAH1, in human A375 melanoma cells. ASAH1-null clones show significantly greater accumulation of long-chain saturated ceramides that are substrate for AC. As seen with administration of exogenous ceramide, AC ablation blocks cell cycle progression and accelerates senescence. Importantly, ASAH1-null cells also lose the ability to form cancer-initiating cells and to undergo self-renewal, which is suggestive of a key role for AC in maintaining malignancy and self-renewal of invasive melanoma cells. The results suggest that AC inhibitors might find therapeutic use as adjuvant therapy for advanced melanoma.

Remodeling of brain lipidome in methamphetamine-sensitized mice

Lipids are predominant components of the brain and key regulators for neural structure and function. The effect of methamphetamine (METH) on behavior, cognition as well as memory has been intensively investigated; however, the impact of METH on brain lipid profiles is largely unknown. Here, we used a global lipidomic approach to investigate brain lipidome of METH-sensitized mice. We found that repeated METH significantly modified the lipidome in the hippocampus, prefrontal cortex (PFC) and striatum. Interestingly, nucleus accumbens showed no obvious alteration in lipidomic profiling. Phospholipid and sphingolipid metabolisms were profoundly modified in the hippocampus of METH-sensitized mice, exhibiting increased phosphatidic acid and ether phosphatidylcholine but decreased lysophosphatidylethanolamine, lactosylceramide and triglycerides. The fatty acyl length of phospholipids and diacylglycerol longer than 40 carbon were clearly decreased in the hippocampus, and that 36 carbon was decreased in the PFC. These results indicate METH can profoundly affect the metabolism of phospholipids, sphingolipids and glycerolipids in the brain. Our findings reveal a link between remodeled brain lipidome and neurobehavior induced by METH.

HIV-associated cellular senescence: A contributor to accelerated aging

Due to the advent of antiretroviral therapy HIV is no longer a terminal disease and the HIV infected patients are becoming increasingly older. While this is a major success, with increasing age comes an increased risk for disease. The age-related comorbidities that HIV infected patients experience suggest that they suffer from accelerated aging. One possible contributor to this accelerated aging is cellular senescence, an age-associated response that can occur prematurely in response to stress, and that is emerging as a contributor to disease and aging. HIV patients experience several stressors such as the virus itself, antiretroviral drugs and to a lesser extent, substance abuse that can induce cellular senescence. This review summarizes the current knowledge of senescence induction in response to these stressors and their relation to the comorbidities in HIV patients. Cellular senescence may be a possible therapeutic target for these comorbidities.

Dopaminergic Neuron-Specific Deletion of p53 Gene Attenuates Methamphetamine Neurotoxicity

p53 plays an essential role in the regulation of cell death in dopaminergic (DA) neurons and its activation has been implicated in the neurotoxic effects of methamphetamine (MA). However, how p53 mediates MA neurotoxicity remains largely unknown. In this study, we examined the effect of DA-specific p53 gene deletion in DAT-p53KO mice. Whereas in vivo MA binge exposure reduced locomotor activity in wild-type (WT) mice, this was significantly attenuated in DAT-p53KO mice and associated with significant differences in the levels of the p53 target genes BAX and p21 between WT and DAT-p53KO. Notably, DA-specific deletion of p53 provided protection of substantia nigra pars reticulata (SNpr) tyrosine hydroxylase (TH) positive fibers following binge MA, with DAT-p53KO mice having less decline of TH protein levels in striatum versus WT mice. Whereas DAT-p53KO mice demonstrated a consistently higher density of TH fibers in striatum compared to WT mice at 10 days after MA exposure, DA neuron counts within the substantia nigra pars compacta (SNpc) were similar. Finally, supportive of these results, administration of a p53-specific inhibitor (PFT-α) provided a similarly protective effect on MA binge-induced behavioral deficits. Neither DA specific p53 deletion nor p53 pharmacological inhibition affected hyperthermia induced by MA binge. These findings demonstrate a specific contribution of p53 activation in behavioral deficits and DA neuronal terminal loss by MA binge exposure.

Methamphetamine addiction: involvement of CREB and neuroinflammatory signaling pathways

RATIONALE AND OBJECTIVES

Addiction to psychostimulant methamphetamine (METH) remains a major public health problem in the world. Animal models that use METH self-administration incorporate many features of human drug-taking behavior and are very helpful in elucidating mechanisms underlying METH addiction. These models are also helping to decipher the neurobiological substrates of associated neuropsychiatric complications. This review summarizes our work on the influence of METH self-administration on dopamine systems, transcription and immune responses in the brain.

METHODS

We used the rat model of METH self-administration with extended access (15 h/day for eight consecutive days) to investigate the effects of voluntary METH intake on the markers of dopamine system integrity and changes in gene expression observed in the brain at 2 h-1 month after cessation of drug exposure.

RESULTS

Extended access to METH self-administration caused changes in the rat brain that are consistent with clinical findings reported in neuroimaging and postmortem studies of human METH addicts. In addition, gene expression studies using striatal tissues from METH self-administering rats revealed increased expression of genes involved in cAMP response element binding protein (CREB) signaling pathway and in the activation of neuroinflammatory response in the brain.

CONCLUSION

These data show an association of METH exposure with activation of neuroplastic and neuroinflammatory cascades in the brain. The neuroplastic changes may be involved in promoting METH addiction. Neuroinflammatory processes in the striatum may underlie cognitive deficits, depression, and parkinsonism reported in METH addicts. Therapeutic approaches that include suppression of neuroinflammation may be beneficial to addicted patients.

An animal model of differential genetic risk for methamphetamine intake

The question of whether genetic factors contribute to risk for methamphetamine (MA) use and dependence has not been intensively investigated. Compared to human populations, genetic animal models offer the advantages of control over genetic family history and drug exposure. Using selective breeding, we created lines of mice that differ in genetic risk for voluntary MA intake and identified the chromosomal addresses of contributory genes. A quantitative trait locus was identified on chromosome 10 that accounts for more than 50% of the genetic variance in MA intake in the selected mouse lines. In addition, behavioral and physiological screening identified differences corresponding with risk for MA intake that have generated hypotheses that are testable in humans. Heightened sensitivity to aversive and certain physiological effects of MA, such as MA-induced reduction in body temperature, are hallmarks of mice bred for low MA intake. Furthermore, unlike MA-avoiding mice, MA-preferring mice are sensitive to rewarding and reinforcing MA effects, and to MA-induced increases in brain extracellular dopamine levels. Gene expression analyses implicate the importance of a network enriched in transcription factor genes, some of which regulate the mu opioid receptor gene, Oprm1, in risk for MA use. Neuroimmune factors appear to play a role in differential response to MA between the mice bred for high and low intake. In addition, chromosome 10 candidate gene studies provide strong support for a trace amine-associated receptor 1 gene, Taar1, polymorphism in risk for MA intake. MA is a trace amine-associated receptor 1 (TAAR1) agonist, and a non-functional Taar1 allele segregates with high MA consumption. Thus, reduced TAAR1 function has the potential to increase risk for MA use. Overall, existing findings support the MA drinking lines as a powerful model for identifying genetic factors involved in determining risk for harmful MA use. Future directions include the development of a binge model of MA intake, examining the effect of withdrawal from chronic MA on MA intake, and studying potential Taar1 gene × gene and gene × environment interactions. These and other studies are intended to improve our genetic model with regard to its translational value to human addiction.