Autophagy Inhibition by Caffeine Increases Toxicity of Methamphetamine in SH-SY5Y Neuroblastoma Cell Line

Neuroprotective properties of a thiazolidine-2,4-dione derivative as an inhibitory agent against memory impairment and phosphorylated tau: In vitro and in vivo investigations

Alzheimer's disease (AD) is the most common form of neurodegeneration that results in memory disorders and cognitive impairment. The present study investigated the neuroprotective effects of the synthesized thiazolidine-2,4-dione derivative, (E)-5-(4-chlorobenzylidene)-3-(2-oxo-2-phenylethyl)thiazolidine-2,4-dione (TZ4C), an inhibitor of p-Tau and memory impairment, using a SH-SY5Y cell model of methamphetamine-induced tauopathy and a scopolamine-induced memory impairment model in Wistar rats. In the present study, the neuroprotective effect of TZ4C was studied in a SH-SY5Y cellular model of methamphetamine-induced (2 mM) tauopathy and a scopolamine-induced (1.5 mg/kg/day) memory impairment model in male Wistar rats (n = 48). The memory functions and learning abilities of the rats were evaluated using the Morris water maze (MWM) and passive avoidance tests. Additionally, AChE activity in the rat hippocampus was quantified, and the expression of p-Tau, HSP70, and caspase-3 in both in vitro and in vivo samples was evaluated through Western blot analysis. TZ4C (0.1-1000 µM) did not exhibit significantly toxic effects on SH-SY5Y cell viability. Western blot results indicated that TZ4C led to reduced expression of p-Tau, HSP70, and cleaved caspase-3 in SH-SY5Y cells (3 and 10 µM) and the rat hippocampus (2 and 4 mg/kg). Additionally, the findings suggested that TZ4C enhanced memory function in rats with scopolamine-induced impairment and decreased acetylcholinesterase (AChE) specific activity. The comprehensive analysis of in vitro and in vivo experiments underscores the neuroprotective potential (improved neuropathology and reduced memory impairment) of TZ4C. These findings highlight the promise of TZ4C as a candidate for drug discovery programs to identify effective therapies for AD.

Evaluating the Protective Effects of Thymoquinone on Methamphetamine-induced Toxicity in an In Vitro Model Based on Differentiated PC12 Cells

Methamphetamine (Meth) is a highly addictive stimulant. Its potential neurotoxic effects are mediated through various mechanisms, including oxidative stress and the initiation of the apoptotic process. Thymoquinone (TQ), obtained from Nigella sativa seed oil, has extensive antioxidant and anti-apoptotic properties. This study aimed to investigate the potential protective effects of TQ against Meth-induced toxicity by using an in vitro model based on nerve growth factor-differentiated PC12 cells. Cell differentiation was assessed by detecting the presence of a neuronal marker with flow cytometry. The effects of Meth exposure were evaluated in the in vitro neuronal cell-based model via the determination of cell viability (in an MTT assay) and apoptosis (by annexin/propidium iodide staining). The generation of reactive oxygen species (ROS), as well as the levels of glutathione (GSH) and dopamine, were also determined. The model was used to determine the protective effects of 0.5, 1 and 2 μM TQ against Meth-induced toxicity (at 1 mM). The results showed that TQ reduced Meth-induced neurotoxicity, possibly through the inhibition of ROS generation and apoptosis, and by helping to maintain GSH and dopamine levels. Thus, the impact of TQ treatment on Meth-induced neurotoxicity could warrant further investigation.

Caffeine Release from Magneto-Responsive Hydrogels Controlled by External Magnetic Field and Calcium Ions and Its Effect on the Viability of Neuronal Cells

Caffeine (CAF) is a psychostimulant present in many beverages and with rapid bioabsorption. For this reason, matrices that effectuate the sustained release of a low amount of CAF would help reduce the intake frequency and side effects caused by high doses of this stimulant. Thus, in this study, CAF was loaded into magnetic gelatin/alginate (Gel/Alg/MNP) hydrogels at 18.5 mg/ghydrogel. The in vitro release of CAF was evaluated in the absence and presence of an external magnetic field (EMF) and Ca2+. In all cases, the presence of Ca2+ (0.002 M) retarded the release of CAF due to favorable interactions between them. Remarkably, the release of CAF from Gel/Alg/MNP in PBS/CaCl2 (0.002 M) at 37 °C under an EMF was more sustained due to synergic effects. In PBS/CaCl2 (0.002 M) and at 37 °C, the amounts of CAF released after 45 min from Gel/Alg and Gel/Alg/MNP/EMF were 8.3 ± 0.2 mg/ghydrogel and 6.1 ± 0.8 mg/ghydrogel, respectively. The concentration of CAF released from Gel/Alg and Gel/Alg/MNP hydrogels amounted to ~0.35 mM, thereby promoting an increase in cell viability for 48 h. Gel/Alg and Gel/Alg/MNP hydrogels can be applied as reservoirs to release CAF at suitable concentrations, thus forestalling possible side effects and improving the viability of SH-SY5Y cells.

Molecular mechanisms of programmed cell death in methamphetamine-induced neuronal damage

Methamphetamine, commonly referred to as METH, is a highly addictive psychostimulant and one of the most commonly misused drugs on the planet. Using METH continuously can increase your risk for drug addiction, along with other health complications like attention deficit disorder, memory loss, and cognitive decline. Neurotoxicity caused by METH is thought to play a significant role in the onset of these neurological complications. The molecular mechanisms responsible for METH-caused neuronal damage are discussed in this review. According to our analysis, METH is closely associated with programmed cell death (PCD) in the process that causes neuronal impairment, such as apoptosis, autophagy, necroptosis, pyroptosis, and ferroptosis. In reviewing this article, some insights are gained into how METH addiction is accompanied by cell death and may help to identify potential therapeutic targets for the neurological impairment caused by METH abuse.

Mystery of methamphetamine-induced autophagosome accumulation in hippocampal neurons: loss of syntaxin 17 in defects of dynein-dynactin driving and autophagosome-late endosome/lysosome fusion

Methamphetamine (METH), a psychoactive-stimulant facilitates massive accumulation of autophagosomes and causes autophagy-associated neuronal death. However, the underlying mechanisms involving METH-induced auto-phagosome accumulation remain poorly understood. In the current study, autophagic flux was tracked by mRFP-GFP-LC3 adenovirus, 900 μM METH treatment was found to significantly disrupt autophagic flux, which was further validated by remarkable increase of co-localized of LC3 and SQSTM1/p62, enhancement of LC3-II and SQSTM1/p62 protein levels, and massive autophagosome puncta aggregation. With the cycloheximide (CHX) treatment, METH treatment was displayed a significant inhibition of SQSTM1/p62 degradation. Therefore, the mRNAs associated with vesicle degradation were screened, and syntaxin 17 (Stx17) and dynein-dynactin mRNA levels significantly decreased, an effect was proved in protein level as well. Intriguingly, METH induced autophagosome accumulation and autophagic flux disturbance was incredibly retarded by overexpression of Stx17, which was validated by the restoration of the fusion autophagosome-late endosome/lysosome fusion. Moreover, Stx17 overexpression obviously impeded the METH-induced decrease of co-localization of the retrograded motor protein dynein/dynactin and autophagosome-late endosome, though the dynein/dynactin proteins were not involved in autophagosome-late endosome/lysosome fusion. Collectively, our findings unravel the mechanism of METH-induced autophagosome accumulation involving autophagosome-late endosome/lysosome fusion deficiency and that autophagy-enhancing mechanisms such as the overexpression of Stx17 may be therapeutic strategies for the treatment of METH-induced neuronal damage.

Autophagy as a gateway for the effects of methamphetamine: From neurotransmitter release and synaptic plasticity to psychiatric and neurodegenerative disorders

As a major eukaryotic cell clearing machinery, autophagy grants cell proteostasis, which is key for neurotransmitter release, synaptic plasticity, and neuronal survival. In line with this, besides neuropathological events, autophagy dysfunctions are bound to synaptic alterations that occur in mental disorders, and early on, in neurodegenerative diseases. This is also the case of methamphetamine (METH) abuse, which leads to psychiatric disturbances and neurotoxicity. While consistently altering the autophagy machinery, METH produces behavioral and neurotoxic effects through molecular and biochemical events that can be recapitulated by autophagy blockade. These consist of altered physiological dopamine (DA) release, abnormal stimulation of DA and glutamate receptors, as well as oxidative, excitotoxic, and neuroinflammatory events. Recent molecular insights suggest that METH early impairs the autophagy machinery, though its functional significance remains to be investigated. Here we discuss evidence suggesting that alterations of DA transmission and autophagy are intermingled within a chain of events underlying behavioral alterations and neurodegenerative phenomena produced by METH. Understanding how METH alters the autophagy machinery is expected to provide novel insights into the neurobiology of METH addiction sharing some features with psychiatric disorders and parkinsonism.

An updated review on synthetic cathinones

Cathinone, the main psychoactive compound found in the plant Catha edulis Forsk. (khat), is a β-keto analogue of amphetamine, sharing not only the phenethylamine structure, but also the amphetamine-like stimulant effects. Synthetic cathinones are derivatives of the naturally occurring cathinone that largely entered the recreational drug market at the end of 2000s. The former "legal status", impressive marketing strategies and their commercial availability, either in the so-called "smartshops" or via the Internet, prompted their large spread, contributing to their increasing popularity in the following years. As their popularity increased, the risks posed for public health became clear, with several reports of intoxications and deaths involving these substances appearing both in the social media and scientific literature. The regulatory measures introduced thereafter to halt these trending drugs of abuse have proved to be of low impact, as a continuous emergence of new non-controlled derivatives keep appearing to replace those prohibited. Users resort to synthetic cathinones due to their psychostimulant properties but are often unaware of the dangers they may incur when using these substances. Therefore, studies aimed at unveiling the pharmacological and toxicological properties of these substances are imperative, as they will provide increased expertise to the clinicians that face this problem on a daily basis. The present work provides a comprehensive review on history and legal status, chemistry, pharmacokinetics, pharmacodynamics, adverse effects and lethality in humans, as well as on the current knowledge of the neurotoxic mechanisms of synthetic cathinones.

Caffeine Inhibits Growth of Temozolomide-Treated Glioma via Increasing Autophagy and Apoptosis but Not via Modulating Hypoxia, Angiogenesis, or Endoplasmic Reticulum Stress in Rats

Thirty rats with glioma were divided into control group, temozolomide (TMZ) group (TMZ 30 mg/kg once daily for 5 day), and TMZ plus Caffeine group (TMZ 30 mg/kg once daily for 5 day and caffeine 100 mg/kg once daily for 2 weeks). The relative tumor fold and expression of hypoxia-induced factor-1α (HIF-1α), vascular endothelial growth factor (VEGF), neuropilin-1 (NRP-1), CCAAT/enhancer-binding protein homologous protein (CHOP), LC-3A/B, apoptosis-inducing factor-1 (AIF-1), and cleaved caspase three were compared. The relative tumor fold of TMZ plus Caffeine group was lower significantly than that of TMZ group at day 14. HIF-1α, VEGF, NRP-1, and CHOP expressions were not significantly different in the three groups. The LC-3A/B expression of TMZ plus Caffeine group was higher significantly than that of the control group and TMZ group. The AIF expressions of TMZ group and TMZ plus Caffeine group were higher significantly than that of the control group. The caspase-3 expression of TMZ plus Caffeine group was higher significantly than that of the control group and TMZ group. In conclusions, the inhibitory effect of caffeine on TMZ-treated glioma might be associated with increasing expressions of autophagy- and apoptosis-related genes.

Caffeine and Parkinson's Disease: Multiple Benefits and Emerging Mechanisms

Parkinson’s disease (PD) is the second most common neurodegenerative disorder, characterized by dopaminergic neurodegeneration, motor impairment and non-motor symptoms. Epidemiological and experimental investigations into potential risk factors have firmly established that dietary factor caffeine, the most-widely consumed psychoactive substance, may exerts not only neuroprotective but a motor and non-motor (cognitive) benefits in PD. These multi-benefits of caffeine in PD are supported by convergence of epidemiological and animal evidence. At least six large prospective epidemiological studies have firmly established a relationship between increased caffeine consumption and decreased risk of developing PD. In addition, animal studies have also demonstrated that caffeine confers neuroprotection against dopaminergic neurodegeneration using PD models of mitochondrial toxins (MPTP, 6-OHDA, and rotenone) and expression of α-synuclein (α-Syn). While caffeine has complex pharmacological profiles, studies with genetic knockout mice have clearly revealed that caffeine’s action is largely mediated by the brain adenosine A_2A receptor (A_2AR) and confer neuroprotection by modulating neuroinflammation and excitotoxicity and mitochondrial function. Interestingly, recent studies have highlighted emerging new mechanisms including caffeine modulation of α-Syn degradation with enhanced autophagy and caffeine modulation of gut microbiota and gut-brain axis in PD models. Importantly, since the first clinical trial in 2003, United States FDA has finally approved clinical use of the A_2AR antagonist istradefylline for the treatment of PD with OFF-time in Sept. 2019. To realize therapeutic potential of caffeine in PD, genetic study of caffeine and risk genes in human population may identify useful pharmacogenetic markers for predicting individual responses to caffeine in PD clinical trials and thus offer a unique opportunity for “personalized medicine” in PD.

Occurrence, fate, persistence and remediation of caffeine: a review

Pharmaceutical and personal care products (PPCPs) have gained attention in recent years due to their continuous discharge in natural waters. Their persistence in the environment has impacted flora, fauna and human being worldwide. One of the most common PPCPs is caffeine (1, 3, 7-trimethylxanthine) which acts as a stimulant to the central nervous system in humans and is found in nature in about 60 plant species, especially in coffee, tea and cacao plants. Here we discuss the evidence with respect to caffeine occurrence, its persistence and remediation in light of increasing knowledge and the impact of caffeine on the environment. Daily intake of caffeine around the world is found to increase due to the frequent introduction of new caffeinated beverages as well as increased consumption of coffee, tea and carbonated soft drinks, which has led to increase in its concentration in water bodies including agricultural soil. The caffeine concentration in different water system, studied by various authors is also described. Diverse effects of the use of caffeine on several organisms including humans are also briefly presented. Therefore, urgent attention for the removal of caffeine and its derivatives is the need of the hour. Various methods described in literature for caffeine degradation/removal is also presented. Another widely used technique in environmental remediation is molecular imprinting (MIP); however, only few MIPs have been demonstrated for caffeine which is also discussed. Regular monitoring can be useful to control toxic effects of caffeine. Graphical abstract.

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.

Obestatin attenuated methamphetamine-induced PC12 cells neurotoxicity via inhibiting autophagy and apoptosis

Methamphetamine (METH) is an illicit dopaminergic neurotoxin and is an extremely addictive psychostimulant drug that influences monoamine neurotransmitter system of the brain and is responsible for enhancing energy and satisfaction and feelings of alertness. Long-lasting exposure to METH causes psychosis and increases the risk of Parkinson's disease. Studies have revealed that obestatin (OB) is a novel endogenous ligand, which may have neuroprotective effects. Hence, we hypothesized that OB might appropriately limit METH-induced neurotoxicity via the control of apoptotis and autophagy. In the current study, PC12 cells were exposed to both METH (0.5, 1, 2, 3, 4, and 6 mmol/L) and pretreatment OB (1, 10, 100, and 200 nmol/L) in vitro for 24 h to determine appropriate dose, and then downstream pathways were measured to investigate apoptosis and autophagy. The results have shown that OB reduced the apoptotic response post-METH exposure in PC12 cells by developing cell viability and diminishing apoptotic rates. Furthermore, the study has exhibited OB decreased gene expression of Beclin-1 by real-time polymerase chain reaction and LC3-II by Western blotting in METH-induced PC12 cells, which demonstrated that autophagy is reduced. The study is proposed that OB is useful in reducing oxidative stress, which may also play an essential role in the regulation of METH-triggered apoptotic response. So these data indicate that OB could potentially alleviate METH-induced neurotoxicity via the reduction of apoptotic and autophagy responses.

Signal Transduction of Improving Effects of Ibudilast on Methamphetamine Induced Cell Death

Objective:

Interaction of methamphetamine and sigma (σ) receptors lead to up-regulation and activation of these receptors. The σ receptors induced apoptosis in some parts of the brain by increasing calcium, dopamine, ROS, mitochondrial pores and caspase activity. Ibudilast is a phosphodiesterase inhibitor and anti-inflammatory drug, which can decrease the inflammatory cytokines. Also, it has a neuroprotective effect. It seems that ibudilast can reduce the methamphetamine-induced cell death due to inhibition of σ receptors.

Materials and Methods:

There were seven treatments including; control: culture medium, Treatment 1: 1mM methamphetamine, Treatment 2: 1mM methamphetamine and 1nM ibudilast, Treatment 3: 1mM methamphetamine and 10nM ibudilast, Treatment 4: 1mM methamphetamine and 100nM ibudilast, Treatment 5: 1mM methamphetamine and 1uM ibudilast, Treatment 6: 1mM methamphetamine and 10uM ibudilast, and Treatment 7: 1mM methamphetamine and 100uM ibudilast. Finally, for inhibition of PKA, CREB, IP3 receptor, NMDA receptor, Sigma receptor antagonist, sigma receptor agonist, cells were preincubated with adding H89 dihydrochloride, 666-15, Heparin, Ketamine, BMY 14802, and Pentazocine. MTT and LDH tests were performed for cell viability and cytotoxicity measurement, respectively. In continuing, the caspase activity colorimetric assay kit used for caspase 3 activity diagnosis. Rhodamine-123 performed to detection of mitochondrial membrane potential. TUNEL test used to DNA fragmentation and apoptosis, Fura-2 used to Measurement of (Ca²⁺) ic and (Ca²⁺) m, and fluorescence microscope used to Measurement of antioxidant enzyme activities.

Results:

Ibudilast increased the cell viability and the rhodamine-123 absorbance in methamphetamin-treated PC1₂ cells. It reduced cell cytotoxicity, caspase 3 activity, ic and m Ca²⁺ concentration, (OH) generation and DNA fragmentation in all concentrations of 1 nM t0 100 µM (p<0.05) by the optimal concentration of 100 µM, between our tested treatments.

Conclusion:

Ibudilast as a phosphodiesterase inhibitor can reduce the methamphetamine-induced cell death due to inhibition of σ receptors through cAMP production.

Apelin-13 Protects PC12 Cells Against Methamphetamine-Induced Oxidative Stress, Autophagy and Apoptosis

Methamphetamine (METH) is a potent psychomotor stimulant that has a high potential for abuse in humans. In addition, it is neurotoxic, especially in dopaminergic neurons. Long-lasting exposure to METH causes psychosis and increases the risk of Parkinson's disease. Apelin-13 is a novel endogenous ligand which studies have shown that may have a neuroprotective effect. Therefore, we hypothesized that Apelin-13 might adequately prevent METH-induced neurotoxicity via the inhibition of apoptotic, autophagy, and ROS responses. In this study, PC12 cells were exposed to both METH (0.5, 1, 2, 3, 4, 6 mmol/L) and Apelin-13 (0.5, 1.0, 2.0, 4.0, 8.0 μmol/L) in vitro for 24 h to measure determined dose, and then downstream pathways were measured to investigate apoptosis, autophagy, and ROS responses. The results have indicated that Apelin-13 decreased the apoptotic response post-METH exposure in PC12 cells by increasing cell viability, reducing apoptotic rates. In addition, the study has revealed Apelin-13 decreased gene expression of Beclin-1 by Real-Time PCR and LC3-II by western blotting in METH-induced PC12 cells, which demonstrated autophagy is reduced. In addition, this study has shown that Apelin-13 reduces intracellular ROS of METH-induced PC12 cells. These results support Apelin-13 to be investigated as a potential drug for treatment of neurodegenerative diseases. It is suggested that Apelin-13 is beneficial in reducing oxidative stress, which may also play an important role in the regulation of METH-triggered apoptotic response. Hence, these data indicate that Apelin-13 could potentially alleviate METH-induced neurotoxicity via the reduction of oxidative damages, apoptotic, and autophagy cell death.

mTOR Modulates Methamphetamine-Induced Toxicity through Cell Clearing Systems

Methamphetamine (METH) is abused worldwide, and it represents a threat for public health. METH exposure induces a variety of detrimental effects. In fact, METH produces a number of oxidative species, which lead to lipid peroxidation, protein misfolding, and nuclear damage. Cell clearing pathways such as ubiquitin-proteasome (UP) and autophagy (ATG) are involved in METH-induced oxidative damage. Although these pathways were traditionally considered to operate as separate metabolic systems, recent studies demonstrate their interconnection at the functional and biochemical level. Very recently, the convergence between UP and ATG was evidenced within a single organelle named autophagoproteasome (APP), which is suppressed by mTOR activation. In the present research study, the occurrence of APP during METH toxicity was analyzed. In fact, coimmunoprecipitation indicates a binding between LC3 and P20S particles, which also recruit p62 and alpha-synuclein. The amount of METH-induced toxicity correlates with APP levels. Specific markers for ATG and UP, such as LC3 and P20S in the cytosol, and within METH-induced vacuoles, were measured at different doses and time intervals following METH administration either alone or combined with mTOR modulators. Western blotting, coimmunoprecipitation, light microscopy, confocal microscopy, plain transmission electron microscopy, and immunogold staining were used to document the effects of mTOR modulation on METH toxicity and the merging of UP with ATG markers within APPs. METH-induced cell death is prevented by mTOR inhibition, while it is worsened by mTOR activation, which correlates with the amount of autophagoproteasomes. The present data, which apply to METH toxicity, are also relevant to provide a novel insight into cell clearing pathways to counteract several kinds of oxidative damage.

Epigenetic Effects Induced by Methamphetamine and Methamphetamine-Dependent Oxidative Stress

Methamphetamine is a widely abused drug, which possesses neurotoxic activity and powerful addictive effects. Understanding methamphetamine toxicity is key beyond the field of drug abuse since it allows getting an insight into the molecular mechanisms which operate in a variety of neuropsychiatric disorders. In fact, key alterations produced by methamphetamine involve dopamine neurotransmission in a way, which is reminiscent of spontaneous neurodegeneration and psychiatric schizophrenia. Thus, understanding the molecular mechanisms operated by methamphetamine represents a wide window to understand both the addicted brain and a variety of neuropsychiatric disorders. This overlapping, which is already present when looking at the molecular and cellular events promoted immediately after methamphetamine intake, becomes impressive when plastic changes induced in the brain of methamphetamine-addicted patients are considered. Thus, the present manuscript is an attempt to encompass all the molecular events starting at the presynaptic dopamine terminals to reach the nucleus of postsynaptic neurons to explain how specific neurotransmitters and signaling cascades produce persistent genetic modifications, which shift neuronal phenotype and induce behavioral alterations. A special emphasis is posed on disclosing those early and delayed molecular events, which translate an altered neurotransmitter function into epigenetic events, which are derived from the translation of postsynaptic noncanonical signaling into altered gene regulation. All epigenetic effects are considered in light of their persistent changes induced in the postsynaptic neurons including sensitization and desensitization, priming, and shift of neuronal phenotype.

Methamphetamine-induced toxicity: The role of autophagy?

Methamphetamine (METH) is a highly potent and addictive drug with major medical, psychiatric, cognitive, socioeconomic, and legal consequences. It is well absorbed following different routes of administration and distributed throughout the body. METH is known as psychomotor stimulant with potent physiological outcomes on peripheral and central nervous systems, resulting in physical and psychological disorders. Autophagy is a highly conserved and regulated catabolic pathway which is critical for maintaining cellular energy homeostasis and regulating cell growth. The mechanism of autophagy has attracted considerable attention in the last few years because of its recognition as a vital arbiter of death/survival decisions in cells and as a critical defense mechanism in undesirable physiological conditions. The purpose of the current article was to review available evidence to find a relationship between METH toxicity and mechanisms associated with autophagy in different organs.

In Vivo and In Vitro Genotoxic and Epigenetic Effects of Two Types of Cola Beverages and Caffeine: A Multiassay Approach

The aim of this work was to assess the biological and food safety of two different beverages: Classic Coca Cola™ (CCC) and Caffeine-Free Coca Cola (CFCC). To this end, we determined the genotoxicological and biological effects of different doses of lyophilised CCC and CFCC and Caffeine (CAF), the main distinctive constituent. Their toxic/antitoxic, genotoxic/antigenotoxic, and chronic toxicity (lifespan assay) effects were determined in vivo using the Drosophila model. Their cytotoxic activities were determined using the HL-60 in vitro cancer model. In addition, clastogenic DNA toxicity was measured using internucleosomal fragmentation and SCGE assays. Their epigenetic effects were assessed on the HL-60 methylation status using some repetitive elements. The experimental results showed a slight chemopreventive effect of the two cola beverages against HL-60 leukaemia cells, probably mediated by nonapoptotic mechanisms. Finally, CCC and CAF induced a global genome hypomethylation evaluated in LINE-1 and Alu M1 repetitive elements. Overall, we demonstrated for the first time the safety of this famous beverage in in vivo and in vitro models.

Autophagy in acute brain injury

Autophagy is an evolutionarily ancient mechanism that ensures the lysosomal degradation of old, supernumerary or ectopic cytoplasmic entities. Most eukaryotic cells, including neurons, rely on proficient autophagic responses for the maintenance of homeostasis in response to stress. Accordingly, autophagy mediates neuroprotective effects following some forms of acute brain damage, including methamphetamine intoxication, spinal cord injury and subarachnoid haemorrhage. In some other circumstances, however, the autophagic machinery precipitates a peculiar form of cell death (known as autosis) that contributes to the aetiology of other types of acute brain damage, such as neonatal asphyxia. Here, we dissect the context-specific impact of autophagy on non-infectious acute brain injury, emphasizing the possible therapeutic application of pharmacological activators and inhibitors of this catabolic process for neuroprotection.

Effects of DDIT4 in Methamphetamine-Induced Autophagy and Apoptosis in Dopaminergic Neurons

Methamphetamine (METH) is an illicit psychoactive drug that can cause a variety of detrimental effects to the nervous system, especially dopaminergic pathways. We hypothesized that DNA damage-inducible transcript 4 (DDIT4) is involved in METH-induced dopaminergic neuronal autophagy and apoptosis. To test the hypothesis, we determined changes of DDIT4 protein expression and the level of autophagy in rat catecholaminergic PC12 cells and human dopaminergic SH-SY5Y cells, and in the hippocampus, prefrontal cortex, and striatum of Sprague Dawley rats exposed to METH. We also examined the effects of silencing DDIT4 expression on METH-induced dopaminergic neuronal autophagy using fluorescence microscopy and electron microscopy. Flow cytometry and Western blot were used to determine apoptosis and the expression of apoptotic markers (cleaved caspase-3 and cleaved PARP) after blocking DDIT4 expression in PC12 cells and SH-SY5Y cells with synthetic siRNA, as well as in the striatum of rats by injecting LV-shDDIT4 lentivirus using a stereotaxic positioning system. Our results showed that METH exposure increased DDIT4 expression that was accompanied with increased autophagy and apoptosis in PC12 cells (3 mM) and SH-SY5Y cells (2 mM), and in the hippocampus, prefrontal cortex, and striatum of rats. Inhibition of DDIT4 expression reduced METH-induced autophagy and apoptosis in vitro and in vivo. However, DDIT4-related effects were not observed at a low concentration of METH (1 μM). These results suggest that DDIT4 plays an essential role in METH-induced dopaminergic neuronal autophagy and apoptosis at higher doses and may be a potential gene target for therapeutics in high-dose METH-induced neurotoxicity.

DNA damage-inducible transcript 4 (DDIT4) mediates methamphetamine-induced autophagy and apoptosis through mTOR signaling pathway in cardiomyocytes

Methamphetamine (METH) is an amphetamine-like psychostimulant that is commonly abused. Previous studies have shown that METH can induce damages to the nervous system and recent studies suggest that METH can also cause adverse and potentially lethal effects on the cardiovascular system. Recently, we demonstrated that DNA damage-inducible transcript 4 (DDIT4) regulates METH-induced neurotoxicity. However, the role of DDIT4 in METH-induced cardiotoxicity remains unknown. We hypothesized that DDIT4 may mediate METH-induced autophagy and apoptosis in cardiomyocytes. To test the hypothesis, we examined DDIT4 protein expression in cardiomyocytes and in heart tissues of rats exposed to METH with Western blotting. We also determined the effects on METH-induced autophagy and apoptosis after silencing DDIT4 expression with synthetic siRNA with or without pretreatment of a mTOR inhibitor rapamycin in cardiomyocytes using Western blot analysis, fluorescence microscopy and TUNEL staining. Our results showed that METH exposure increased DDIT4 expression and decreased phosphorylation of mTOR that was accompanied with increased autophagy and apoptosis both in vitro and in vivo. These effects were normalized after silencing DDIT4. On the other hand, rapamycin promoted METH-induced autophagy and apoptosis in DDIT4 knockdown cardiomyocytes. These results suggest that DDIT4 mediates METH-induced autophagy and apoptosis through mTOR signaling pathway in cardiomyocytes.

Potential Molecular Mechanisms on the Role of the Sigma-1 Receptor in the Action of Cocaine and Methamphetamine

The sigma-1 receptor (Sig-1R) is an endoplasmic reticulum membrane protein that involves a wide range of physiological functions. The Sig-1R has been shown to bind psychostimulants including cocaine and methamphetamine (METH) and thus has been implicated in the actions of those psychostimulants. For example, it has been demonstrated that the Sig-1R antagonists mitigate certain behavioral and cellular effects of psychostimulants including hyperactivity and neurotoxicity. Thus, the Sig-1R has become a potential therapeutic target of medication development against drug abuse that differs from traditional monoamine-related strategies. In this review, we will focus on the molecular mechanisms of the Sig-1R and discuss in such a manner with a hope to further understand or unveil unexplored relations between the Sig-1R and the actions of cocaine and METH, particularly in the context of cellular biological relevance.

The cross-talk of HIV-1 Tat and methamphetamine in HIV-associated neurocognitive disorders

Antiretroviral therapy has dramatically improved the lives of human immunodeficiency virus 1 (HIV-1) infected individuals. Nonetheless, HIV-associated neurocognitive disorders (HAND), which range from undetectable neurocognitive impairments to severe dementia, still affect approximately 50% of the infected population, hampering their quality of life. The persistence of HAND is promoted by several factors, including longer life expectancies, the residual levels of virus in the central nervous system (CNS) and the continued presence of HIV-1 regulatory proteins such as the transactivator of transcription (Tat) in the brain. Tat is a secreted viral protein that crosses the blood–brain barrier into the CNS, where it has the ability to directly act on neurons and non-neuronal cells alike. These actions result in the release of soluble factors involved in inflammation, oxidative stress and excitotoxicity, ultimately resulting in neuronal damage. The percentage of methamphetamine (MA) abusers is high among the HIV-1-positive population compared to the general population. On the other hand, MA abuse is correlated with increased viral replication, enhanced Tat-mediated neurotoxicity and neurocognitive impairments. Although several strategies have been investigated to reduce HAND and MA use, no clinically approved treatment is currently available. Here, we review the latest findings of the effects of Tat and MA in HAND and discuss a few promising potential therapeutic developments.

Amphetamine-related drugs neurotoxicity in humans and in experimental animals: Main mechanisms

Amphetamine-related drugs, such as 3,4-methylenedioxymethamphetamine (MDMA) and methamphetamine (METH), are popular recreational psychostimulants. Several preclinical studies have demonstrated that, besides having the potential for abuse, amphetamine-related drugs may also elicit neurotoxic and neuroinflammatory effects. The neurotoxic potentials of MDMA and METH to dopaminergic and serotonergic neurons have been clearly demonstrated in both rodents and non-human primates. This review summarizes the species-specific cellular and molecular mechanisms involved in MDMA and METH-mediated neurotoxic and neuroinflammatory effects, along with the most important behavioral changes elicited by these substances in experimental animals and humans. Emphasis is placed on the neuropsychological and neurological consequences associated with the neuronal damage. Moreover, we point out the gap in our knowledge and the need for developing appropriate therapeutic strategies to manage the neurological problems associated with amphetamine-related drug abuse.