Methamphetamine-induced neuronal apoptosis involves the activation of multiple death pathways. Review

Effect of methamphetamine on ultraweak photon emission and level of reactive oxygen species in male rat brain

All living cells, including neurons, generate ultra-weak photon emission (UPE) during biological activity, and in particular, in the brain, it has been shown that UPE is correlated with neuronal activity and associated metabolic processes. Various intracellular factors, as well as external factors, can reduce or increase the intensity of UPE. In this study, we have used Methamphetamine (METH) as one potentially effective external factor, which is a substance that has the property of stimulating the central nervous system. METH can impair mitochondrial function by causing toxicity via various pathways, including an increase in the number of mitochondria, hyperthermia, the increased metabolic activity of the brain, and the production of glutamate and excess calcium. In addition to mitochondrial dysfunction, METH alters cellular homeostasis, leading to cell damage and the production of excess ROS. The aim of this study is to measure and compare the UPE intensity and reactive oxygen species (ROS) levels of the prefrontal, motor, and visual cortex before and after METH administration. Twenty male rats were randomly assigned to two groups, the control, and METH groups. In the control group, 2 h after injection of normal saline and without any intervention, and in the experimental group 2 h after IP injection of 20 mg/kg METH, sections were prepared from three areas: prefrontal, motor, and V1-V2 cortex, which were used to evaluate the emission of UPE using a photomultiplier tube (PMT) device and to evaluate the amount of ROS. The results showed that the amount of ROS and UPE in the experimental group in all three areas significantly increased compared to the control group. So, METH increases UPE and ROS in the prefrontal, motor, and visual regions, and there is a direct relationship between UPE intensity and ROS production. Therefore, UPE may be used as a dynamic reading tool to monitor oxidative metabolism in physiological processes related to ROS and METH research. Also, the results of this experiment may create a new avenue to test the hypothesis that the excess in UPE generation may lead to the phenomenon of phosphene and visual hallucinations.

A novel gene therapy for methamphetamine- induced cognitive disorder with a hyper-acidified fusion variant of DnaJB1

Methamphetamine (MA) is spread worldwide and is a highly addictive psychostimulant that can induce neurodegeneration and cognitive disorder, which lacks effective treatments. We and other researchers have found that the crucial member of Hsp70 chaperone machinery, DnaJ, is liable to be co-aggregated with aberrant proteins, which has been confirmed a risk factor to promote neurodegeneration. In the current study, we demonstrated that tailing with a hyper-acidic fusion partner, tua2, human DnaJB1 could resist the formation of toxic mutant Tau aggregates both in prokaryote and eukaryote models. We found that aberrant Tau aggregates could deplete the antioxidant enzyme pool and disturb Hsp70 molecular chaperone system by co-aggregating with the principal members of these systems. Stability-enhanced DnaJB1-tua2 could stop the chain reaction of Tau aggregates as well as maintain redox balance and protein homeostasis. With an MA-induced cognitive disorder mouse model, we found that the cognitive disorder of MA mice was rescued and the overactivated inflammatory response was relieved by the expression of DnaJB1-tua2 in the hippocampus. Furthermore, the Tau neurofibrillary tangles and apoptotic neurons were diminished with the escorting of DnaJB1-tua2. These findings demonstrate that delivering DnaJB1-tua2 in hippocampus may have a therapeutic potential in the treatment of MA-induced cognitive disorder.

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.

Functional and structural alternations in the choroid plexus upon methamphetamine exposure

Choroid plexus (CP) is the principal source of cerebrospinal fluid. CP can produce and release a wide range of materials including growth factors, neurotrophic factors, etc. all of which play an important role in the maintenance and proper functioning of the brain. Methamphetamine (METH) is a CNS neurostimulant that causes brain dysfunction. Herein, we investigated the potential effects of METH exposure on CP structure and function. Stereological analysis revealed a significant alteration in CP volume, epithelial cells and capillary number upon METH treatment. Electron microscopy exhibited changes in ultrastructure. Moreover, the upregulation of neurotrophic factors such as BDNF and VEGF as well as autophagy and apoptosis gene following METH administration were observed. We also identified several signaling cascades related to autophagy. In conclusion, gene expression changes coupled with structural alterations of the CP in response to METH suggested METH-induced autophagy in CP.

Neurotoxicity of methamphetamine: Main effects and mechanisms

Methamphetamine (METH) is an illicit psychostimulant that is abused throughout the world. METH addiction is also a major public health concern and the abuse of large doses of the drug is often associated with serious neuropsychiatric consequences that may include agitation, anxiety, hallucinations, paranoia, and psychosis. Some human methamphetamine users can also suffer from attention, memory, and executive deficits. METH-associated neurological and psychiatric complications might be related, in part, to METH-induced neurotoxic effects. Those include altered dopaminergic and serotonergic functions, neuronal apoptosis, astrocytosis, and microgliosis. Here we have endeavored to discuss some of the main effects of the drug and have presented the evidence supporting certain of the molecular and cellular bases of METH neurotoxicity. The accumulated evidence suggests the involvement of transcription factors, activation of dealth pathways that emanate from mitochondria and endoplasmic reticulum (ER), and a role for neuroinflammatory mechanisms. Understanding the molecular processes involved in METH induced neurotoxicity should help in developing better therapeutic approaches that might also serve to attenuate or block the biological consequences of use of large doses of the drug by some humans who meet criteria for METH use disorder.

Pharmacological and Molecular Evidence of Neuroprotective Curcumin Effects Against Biochemical and Behavioral Sequels Caused by Methamphetamine: Possible Function of CREB-BDNF Signaling Pathway

INTRODUCTION

The neuroprotective impact of curcumin and the role of CREB (Cyclic AMP Response Element Binding protein)-BDNF (Brain-Derived Neurotrophic Factor) signaling pathway was evaluated in Methamphetamine (METH)-induced neurodegeneration in rats.

METHODS

Sixty adult male rats were randomly divided into 6 groups. While normal saline and 10 mg/kg METH were administered intraperitoneally in groups 1 and 2, groups 3, 4, 5, and 6 received METH (10 mg/kg) and curcumin (10, 20, 40, and 80 mg/kg, respectively) simultaneously. Morris water maze test was administered, and oxidative hippocampal, antioxidant, inflammatory, apoptotic, and CREB and BDNF were assessed.

RESULTS

We found that METH disturbs learning and memory. Concurrent curcumin therapy (40 and 80 mg/kg) decreased cognitive disturbance caused by METH. Multiple parameters, such as lipid peroxidation, the oxidized form of glutathione, interleukin 1 beta, tumor necrosis factor-alpha, and Bax were increased by METH therapy, while the reduced type of glutathione, Bcl-2, P-CREB, and BDNF concentrations in the hippocampus were decreased.

CONCLUSION

Different doses of curcumin adversely attenuated METH-induced apoptosis, oxidative stress, and inflammation but enhanced the concentrations of P-CREB and BDNF. The neuroprotection caused by curcumin against METH-induced neurodegeneration is mediated through P-CREB-BDNF signaling pathway activation.

Long-term effects of young-adult methamphetamine on dorsal raphe serotonin systems in mice: Role of brain-derived neurotrophic factor

To assess the long-term effects of chronic adolescent methamphetamine (METH) treatment on the serotonin system in the brain, we used serotonin-1A receptor (5-HT_1A) and serotonin transporter (SERT) autoradiography, and quantitative tryptophan-hydroxylase 2 (TPH2) immunohistochemistry in the raphe nuclei of mice. Because of the modulatory role of brain-derived neurotrophic factor (BDNF) on the serotonin system and the effects of METH, we included both BDNF heterozygous (HET) mice and wildtype (WT) controls. Male and female mice of both genotypes were treated with an escalating METH dose regimen from the age of 6-9 weeks. At least two weeks later, acute locomotor hyperactivity induced by a 5 mg/kg D-amphetamine challenge was significantly enhanced in METH-pretreated mice, showing long-term sensitisation. METH pretreatment caused a small, but significant decrease of 5-HT_1A receptor binding in the dorsal raphe nucleus (DRN) of males independent of genotype, but there were no changes in the median raphe nucleus (MRN) or in SERT binding density. METH treatment reduced the number of TPH2 positive cells in ventral subregions of the rostral and medial DRN independent of genotype. METH treatment selectively reduced DRN cell counts in BDNF HET mice compared to wildtype mice in medial and caudal ventrolateral subregions previously associated with panic-like behaviour. The data increase our understanding of the long-term and selective effects of METH on brain serotonin systems. These findings could be relevant for some of the psychosis-like symptoms associated with long-term METH use.

Psychoactive Drugs-From Chemical Structure to Oxidative Stress Related to Dopaminergic Neurotransmission. A Review

Nowadays, more and more young people want to experience illegal, psychoactive substances, without knowing the risks of exposure. Besides affecting social life, psychoactive substances also have an important effect on consumer health. We summarized and analyzed the published literature data with reference to the mechanism of free radical generation and the link between chemical structure and oxidative stress related to dopaminergic neurotransmission. This review presents data on the physicochemical properties, on the ability to cross the blood brain barrier, the chemical structure activity relationship (SAR), and possible mechanisms by which neuronal injuries occur due to oxidative stress as a result of drug abuse such as "bath salts", amphetamines, or cocaine. The mechanisms of action of ingested compounds or their metabolites involve intermediate steps in which free radicals are generated. The brain is strongly affected by the consumption of such substances, facilitating the induction of neurodegenerative diseases. It can be concluded that neurotoxicity is associated with drug abuse. Dependence and oxidative stress are linked to inhibition of neurogenesis and the onset of neuronal death. Understanding the pathological mechanisms following oxidative attack can be a starting point in the development of new therapeutic targets.

NUPR1- CHOP experssion, autophagosome formation and apoptosis in the postmortem striatum of chronic methamphetamine user

Methamphetamine (Meth) is a neuro-stimulator substrate which might lead to neural cell death and the activation of several interconnected cellular pathways as well. However, the precise molecular mechanisms underlying Meth-induced neural cell death remained unclear yet. The current study aimed to assess the specific relationship between long-term Meth exposure and several endoplasmic reticulum stress, autophagy, and apoptosis associated markers including C/EBP homologous protein (CHOP), Tribbles homolog 3(Trib3), Nuclear protein 1(NUPR1), and Beclin-1 expression in postmortem human striatum. Therefore, the effects of long-term Meth exposure on autophagy and apoptosis in the striatum of postmortem users were evaluated and molecular, immunehistochemical, and histological examinations were performed on 10 control and 10 Meth-addicted brains. The level of CHOP, Trib3, NUPR1, and Beclin-1, Microtubule-associated proteins 1A/1B light chain 3B(LC3), Caspase 3, and Autophagy protein 5 (ATG5) were measured by using qPCR and immunohistochemistry. Stereological neural cell counting, Hematoxylin and Eosin, Nissl and Tunel staining were also performed. Based on our findings, the expression level of CHOP, Trib3, NUPR1, and Beclin-1 in the striatum of Meth group were significantly higher than the control group. Besides, the neuronal cell death was substantially increased in the striatum based on data obtained from the Tunel assay and the stereological analysis. Long-term presence of Meth in the brain can induce ER stress and overexpression of NUPR1 which is associated with the upregulation of CHOP, a pro-apoptotic transcription factor. Moreover, an increase in Trib3 expression is implicated in CHOP-dependent autophagic cell death during Meth-induced ER stress accompanied by an increase in neuronal cell death in the striatum of the postmortem human brains. Beclin 1 expression was also upregulated which may due to the activation of autophagic mechanisms upon prolonged Meth exposure.

Methamphetamine-Induced Neuronal Damage: Neurotoxicity and Neuroinflammation

Methamphetamine (METH) is a highly addictive psychostimulant and one of the most widely abused drugs worldwide. The continuous use of METH eventually leads to drug addiction and causes serious health complications, including attention deficit, memory loss and cognitive decline. These neurological complications are strongly associated with METH-induced neurotoxicity and neuroinflammation, which leads to neuronal cell death. The current review investigates the molecular mechanisms underlying METH-mediated neuronal damages. Our analysis demonstrates that the process of neuronal impairment by METH is closely related to oxidative stress, transcription factor activation, DNA damage, excitatory toxicity and various apoptosis pathways. Thus, we reach the conclusion here that METH-induced neuronal damages are attributed to the neurotoxic and neuroinflammatory effect of the drug. This review provides an insight into the mechanisms of METH addiction and contributes to the discovery of therapeutic targets on neurological impairment by METH abuse.

Effects of chronic methamphetamine abuse on the retinal nerve fiber layer, ganglion cell layer and Bruch's membrane opening minimum rim width

BACKGROUND

Methamphetamine (Meth) is a highly addictive and hallucinogenic agent which is used as the second most common illicit drug globally. Meth could affect the retina and optic nerve by inducing the release of vasoconstrictive agents such as endothelin 1 and induction of severe oxidative stress with accumulation of reactive oxygen species.

AIM

To evaluate the effects of chronic Meth abuse on the retinal nerve fiber layer (RNFL), ganglion cell layer (GCL) and the Bruch's membrane opening minimum rim width (MRW).

METHOD

In this case-control study, we recruited 55 Meth abusers and 49 healthy individuals with mean age of 44.63 ± 0.97 and 43.08 ± 0.91 years, respectively. RNFL thickness, GCL thickness and MRW were evaluated using optical coherence tomography.

RESULTS

We found statistically significant decrease in RNFL, MRW thickness in Meth abusers (P: 0.002 and P: 0.006, respectively). We did not detect statistically significant difference regarding GCL thickness between the groups (P = 0.320). Our results showed a weak but statistically significant correlation of Meth dose increment and decrement of RNFL thickness ((P: 0.005, r = -0.193) and MRW (P: 0.013, r = -0.174). We found no correlation between duration of Meth consumption with RNFL and MRW thickness (P: 0.205, r= -0.124; P: 0.771, r= -0.029, respectively).

CONCLUSION

We found a statistically significant adverse association in meth abusers with RNFL thickness and MRW. These two parameters were also statistically associated with the meth dose as measured by daily dose of Meth. Although we found a decrease in the GCL thickness, it did not reach statistical significance.

Identification of the Differentially Expressed Genes Involved in the Synergistic Neurotoxicity of an HIV Protease Inhibitor and Methamphetamine

BACKGROUND

The abuse of psychostimulants such as methamphetamine (METH) is common in human immunodeficiency virus (HIV)-infected individuals. Acquired immunodeficiency syndrome (AIDS) patients taking METH and antiretroviral drugs could suffer severe neurologic damage and cognitive impairment.

OBJECTIVE

To reveal the underlying neuropathologic mechanisms of an HIV protease inhibitor (PI) combined with METH, growth-inhibition tests of dopaminergic cells and RNA sequencing were performed.

METHODS

A combination of METH and PI caused more growth inhibition of dopaminergic cells than METH alone or a PI alone. Furthermore, we identified differentially expressed gene (DEG) patterns in the METH vs. untreated cells (1161 genes), PI vs. untreated cells (16 genes), METH-PI vs. PI (3959 genes), and METH-PI vs. METH groups (14 genes).

RESULTS

The DEGs in the METH-PI co-treatment group were verified in the brains of a mouse model using quantitative polymerase chain reaction and were involved mostly in the regulatory functions of cell proliferation and inflammation.

CONCLUSION

Such identification of key regulatory genes could facilitate the study of their neuroprotective potential in the users of METH and PIs.

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.

Neuroprotective and neuro-survival properties of safinamide against methamphetamine-induced neurodegeneration: Hypothetic possible role of BDNF/TrkB/PGC-1α signaling pathway and mitochondrial uncoupling protein -2(UCP-2)

Methamphetamine is a behavioral psychostimulant that has a high potential for misuse and induction of neurotoxicity. Safinamide is a novel inhibitor of monoamine oxidase B (MAOB) with neuroprotective properties. Methamphetamine abuse causes dysfunction in the respiratory chain of the mitochondria, but the specific signaling mechanism and role of the uncoupling protein-2(UCP-2) remain unclear. As we know, some indirect evidence indicates that neurodegeneration can be caused by inhibition of the brain-derived neurotrophic factor (BDNF) receptor, TrkB and its downstream signaling pathway, such as the PGC-1α protein. Neuroprotective strategies and approaches to the management, treatment or prevention of methamphetamine-induced neurodegeneration by modulating BDNF / TrkB / PGC-1α-UCP-2 can be considered as novel therapeutic approaches to these psychostimulant neurochemical and neurobehavioral approaches. Previous studies have shown that safinamide, a monoamine oxidase-B (MAOB) inhibitor, can function as a neuroprotective agent and inhibit the neurodegenerative process especially in Parkinson's disease but its impact on other neurodegenerative processes and drug-induced neurotoxicity remain unclear. Although there is some evidence that BDNF / TrkB / PGC-1α-UCP-2 signaling pathway and mitochondrial UCP-2 mediated safinamide induced neuroprotection but it's exact and precise mechanism of action and neuroprotective effects in neurodegenerative disorder and the protective properties against methamphetamine induced neurodegeneration and the role of BDNF / TrkB / PGC-1α signaling pathway and role of mitochondrial UCP-2 in this process have not yet been clarified. Therefore, in subjects addicted to methamphetamine, we hypothesized that safinamide will provide neuroprotection against methamphetamine-prompted neurodegeneration, and it appears that BDNF / TrkB / PGC-1α signaling pathway and mitochondrial UCP-2 are likely to play a critical role.

LC3 and ATG5 overexpression and neuronal cell death in the prefrontal cortex of postmortem chronic methamphetamine users

Methamphetamine (METH) abuse is accompanied by oxidative stress, METH-induced neurotoxicity, and apoptosis. Oxidative stress has devastating effects on the structure of proteins and cells. Autophagy is an evolutionarily conserved intracellular regulated mechanism for orderly degradation of dysfunctional proteins or removing damaged organelles. The precise role of autophagy in oxidative stress-induced apoptosis of dopaminergic neuronal cells caused by METH has not clarified completely. In this study, we sought to evaluate the effects of METH abuse on autophagy in the prefrontal cortex of postmortem users, mainly focusing on the ATG5 and LC3 during neuroinflammation. Postmortem molecular and histological examination was done for two groups containing 12 non-addicted and 14 METH addicted cases. ATG5 and LC3 expression were analyzed by real-time PCR and immunohistochemistry (IHC) methods. Histopathological analysis was performed by stereological cell counting of neuronal cells using Hematoxylin and Eosin (H & E) staining technique. In order to detect DNA damage in the prefrontal lobe, Tunnel staining was performed. Real-time PCR and IHC assay showed overexpression of ATG5 and LC3 protein in the prefrontal cortex of Meth users. The cell death and neuronal degeneration were increased significantly based on Tunel assay and the stereological analysis in the Prefrontal cortex. Chronic METH exposure probably induces ATG5 and LC3 overexpression and neuronal cell death in the Prefrontal cortex of the postmortem cases.

Neuroprotective Effect of Pentoxifylline on 3,4-Methylenedioxymethamphetamine-Induced Apoptosis in CA1 Cells of Wistar Rat Hippocampus

Background:

3,4-Methylenedioxymethamphetamine is psychoactive and hallucinogenic and has been shown to produce neurotoxicity both in animals and in humans. Recently, vasodilator drugs such as pentoxifylline (PTX) have been introduced as an alternative with neuroprotective effects. There is no study about the protective effect of PTX on hippocampal apoptosis due to high-dose administration of 3,4-Methylenedioxymethamphetamine (MDMA), so in this study, the protective effect of PTX on the hippocampus of male Wistar rats following high-dose of the drug has been investigated.

Materials and Methods:

Twenty-four male Wistar rats weighing 250-300 g were randomly divided into four groups: control, sham (MDMA injection), experimental (MDMA+PTX injection), and vehicle (MDMA+saline) groups. Two weeks later, the brains were removed and prepared for TUNEL and western blot techniques. Concomitantly the hippocampus was removed to study the change in Bcl-2 and BAX mRNA expression with quantitative real-time polymerase chain reaction.

Results:

Data showed that the number of apoptotic bodies significantly decreased in the experimental group compared to the other groups, except for in control. Also, further investigation revealed that BAX reduced considerably, while Bcl-2 mRNA expression increased dramatically after PTX treatment.

Conclusions:

Our results suggest that PTX may be a neuroprotective agent, and its neuroprotective potential may contribute to reducing the severity of lesions in the hippocampus following a high dose administration of MDMA.

Methamphetamine-induced apoptosis in glial cells examined under marker-free imaging modalities

We used phase microscopy and Raman spectroscopic measurements to assess the response of in vitro rat C6 glial cells following methamphetamine treatment in real time. Digital holographic microscopy (DHM) and three-dimensional (3-D) tomographic nanoscopy allow measurements of live cell cultures, which yield information about cell volume changes. Tomographic phase imaging provides 3-D information about the refractive index distribution associated with the morphology of biological samples. DHM provides similar information, but for a larger population of cells. Morphological changes in cells are associated with alterations in cell cycle and initiation of cell death mechanisms. Raman spectroscopy measurements provide information about chemical changes within the cells. Our Raman data indicate that the chemical changes in proteins preceded morphological changes, which were seen with DHM. Our study also emphasizes that tomographic phase imaging, DHM, and Raman spectroscopy are imaging tools that can be utilized for noninvasive simultaneous monitoring of morphological and chemical changes in cells during apoptosis and can also be used to monitor other dynamic cell processes.

Maximal strength training improves musculoskeletal health in amphetamine users in clinical treatment

Amphetamine use leads to impaired skeletal health and elevated risk of osteoporosis. In the current study, we document that maximal strength training (MST), as a part of clinical treatment, works as a countermeasure, improving muscle force generating capacity, body composition, and skeletal health at sites particularly prone to osteoporotic fractures.

INTRODUCTION

Amphetamine users have attenuated musculoskeletal health. MST with heavy loads, few repetitions, and emphasis on maximal mobilization in the concentric phase may increase muscle force generating capacity and skeletal health. This study investigated if MST-induced improvements in force generating capacity improved bone mineral density (BMD), trabecular bone score, and body composition in amphetamine users participating in 3-months clinical treatment.

METHODS

Of 40 randomized patients, 23 completed the study: 11 in the supervised training group (TG; 8 men, 3 women, 34 ± 10 years) and 12 in the control group (CG; 9 men, 3 women, 32 ± 8 years). The TG performed hack-squat MST three times a week for 12 weeks with an intensity of ~90% of one repetition maximum (1RM). Both groups attended conventional clinical treatment. Pre-training and post-training, we assessed hack-squat 1RM and rate of force development (RFD), BMD, body composition and trabecular bone score by dual X-ray absorptiometry, and serum bone metabolism markers.

RESULTS

MST induced increases in 1RM (70%) and RFD (86%), and resulted in BMD improvements at lumbar spine (3.6%) and total hip (2.4%); all improvements were different from CG (p < 0.05). Both the 1RM and RFD increases were associated with BMD improvements (lumbar spine: r = 0.73 (1RM), r = 0.60 (RFD); total hip: r = 0.61 (1RM); all p < 0.05). No differences were observed in trabecular bone score or bone metabolism markers.

CONCLUSIONS

MST improved force generating capacity and skeletal health at sites prone to bone loss in amphetamine users, and advocate that MST should be implemented as a clinical strategy to restore the patients' musculoskeletal health.

Chronic oral methylphenidate treatment increases microglial activation in rats

Methylphenidate (MP) is a widely prescribed psychostimulant used to treat attention deficit hyperactivity disorder. Previously, we established a drinking paradigm to deliver MP to rats at doses that result in pharmacokinetic profiles similar to treated patients. In the present study, adolescent male rats were assigned to one of three groups: control (water), low-dose MP (LD; 4/10 mg/kg), and high dose MP (HD; 30/60 mg/kg). Following 3 months of treatment, half of the rats in each group were euthanized, and the remaining rats received only water throughout a 1-month-long abstinence phase. In vitro autoradiography using [³H] PK 11195 was performed to measure microglial activation. HD MP rats showed increased [³H] PK 11195 binding compared to control rats in several cerebral cortical areas: primary somatosensory cortex including jaw (68.6%), upper lip (80.1%), barrel field (88.9%), and trunk (78%) regions, forelimb sensorimotor area (87.3%), secondary somatosensory cortex (72.5%), motor cortices 1 (73.2%) and 2 (69.3%), insular cortex (59.9%); as well as subcortical regions including the thalamus (62.9%), globus pallidus (79.4%) and substantia nigra (22.7%). Additionally, HD MP rats showed greater binding compared to LD MP rats in the hippocampus (60.6%), thalamus (59.6%), substantia nigra (38.5%), and motor 2 cortex (55.3%). Following abstinence, HD MP rats showed no significant differences compared to water controls; however, LD MP rats showed increased binding in pre-limbic cortex (78.1%) and ventromedial caudate putamen (113.8%). These findings indicate that chronic MP results in widespread microglial activation immediately after treatment and following the cessation of treatment in some brain regions.

Methamphetamine Induces Apoptosis of Microglia via the Intrinsic Mitochondrial-Dependent Pathway

Methamphetamine (METH) is a drug of abuse, the acute and chronic use of which induces neurotoxic responses in the human brain, ultimately leading to neurocognitive disorders. Our goals were to understand the impact of METH on microglial mitochondrial respiration and to determine whether METH induces the activation of the mitochondrial-dependent intrinsic apoptosis pathway in microglia. We assessed the expression of pro- apoptosis genes using qPCR of RNA extracted from a human microglial cell line (HTHU). We examined the apoptosis-inducing effects of METH on microglial cells using digital holographic microscopy (DHM) to quantify real-time apoptotic volume decrease (AVD) in microglia in a noninvasive manner. METH treatment significantly increased AVD, activated Caspase 3/7, increased the gene expression levels of the pro- apoptosis proteins, APAF-1 and BAX, and decreased mitochondrial DNA content. Using immunofluorescence analysis, we found that METH increased the expression of the mitochondrial proteins cytochrome c and MCL-1, supporting the activation of mitochondrion-dependent (intrinsic) apoptosis pathway. Cellular bio-energetic flux analysis by Agilent Seahorse XF Analyzer revealed that METH treatment increased both oxidative and glycolytic respiration after 3 h, which was sustained for at least 24 h. Several events, such as oxidative stress, neuro-inflammatory responses, and mitochondrial dysfunction, may converge to mediate METH-induced apoptosis of microglia that may contribute to neurotoxicity of the CNS. Our study has important implications for therapeutic strategies aimed at preserving mitochondrial function in METH abusing patients.

Methamphetamine exposure triggers apoptosis and autophagy in neuronal cells by activating the C/EBPβ-related signaling pathway

Methamphetamine (Meth) is a widely abused psychoactive drug that primarily damages the nervous system, notably causing dopaminergic neuronal apoptosis. CCAAT-enhancer binding protein (C/EBPβ) is a transcription factor and an important regulator of cell apoptosis and autophagy. Insulin-like growth factor binding protein (IGFBP5) is a proapoptotic factor that mediates Meth-induced neuronal apoptosis, and Trib3 (tribbles pseudokinase 3) is an endoplasmic reticulum (ER) stress-inducible gene involved in autophagic cell death through the mammalian target of rapamycin (mTOR) signaling pathway. To test the hypothesis that C/EBPβ is involved in Meth-induced IGFBP5-mediated neuronal apoptosis and Trib3-mediated neuronal autophagy, we measured the protein expression of C/EBPβ after Meth exposure and evaluated the effects of silencing C/EBPβ, IGFBP5, or Trib3 on Meth-induced apoptosis and autophagy in neuronal cells and in the rat striatum after intrastriatal Meth injection. We found that, at relatively high doses, Meth exposure increased C/EBPβ protein expression, which was accompanied by increased neuronal apoptosis and autophagy; triggered the IGFBP5-mediated, p53-up-regulated modulator of apoptosis (PUMA)-related mitochondrial apoptotic signaling pathway; and stimulated the Trib3-mediated ER stress signaling pathway through the Akt-mTOR signaling axis. We also found that autophagy is an early response to Meth-induced stress upstream of apoptosis and plays a detrimental role in Meth-induced neuronal cell death. These results suggest that Meth exposure induces C/EBPβ expression, which plays an essential role in the neuronal apoptosis and autophagy induced by relatively high doses of Meth; however, relatively low concentrations of Meth did not change the expression of C/EBPβ in vitro. Further studies are needed to elucidate the role of C/EBPβ in low-dose Meth-induced neurotoxicity.-Xu, X., Huang, E., Luo, B., Cai, D., Zhao, X., Luo, Q., Jin, Y., Chen, L., Wang, Q., Liu, C., Lin, Z., Xie, W.-B., Wang, H. Methamphetamine exposure triggers apoptosis and autophagy in neuronal cells by activating the C/EBPβ-related signaling pathway.

Mental Health and Substance Use Disorder Comorbidity among Methamphetamine-Using Men Who have Sex with Men

Men who have sex with men (MSM) exhibit elevated rates of mental health and substance use disorder relative to their non-MSM male counterparts. Methamphetamine use in particular has been associated with both neuronal damage and mental health disorders among MSM, and this study reports on the prevalence and comorbidity of DSM-5 mental health and substance use disorders in a sample of methamphetamine-using MSM. From March 2014 through January 2015, 286 methamphetamine-using MSM enrolled in a study to reduce methamphetamine use and sexual risk behaviors. At baseline, participants demonstrated high rates of current major depressive episode (35.8%), antisocial personality disorder (23.9%), suicide risk (23.2%), obsessive-compulsive disorder (23.2%), and social phobia (20.4%), as well as methamphetamine use disorder (89.1%), marijuana use disorder (41.0%), alcohol use disorder (39.6%), cocaine use disorder (30.9%), and inhalants use disorder (15.4%). Analyses revealed significant (p < 0.05) associations between methamphetamine use disorder severity and all listed mental health disorders, as well as between alcohol use disorder and all listed mental health disorders. Mental health disorder prevalence and substance use disorder severity were both elevated, and both methamphetamine and alcohol use disorder severity were associated with increased likelihood of comorbid mental health disorder.

Ginsenoside Re protects methamphetamine-induced dopaminergic neurotoxicity in mice via upregulation of dynorphin-mediated κ-opioid receptor and downregulation of substance P-mediated neurokinin 1 receptor

BACKGROUND

We previously reported that ginsenoside Re (GRe) attenuated against methamphetamine (MA)-induced neurotoxicity via anti-inflammatory and antioxidant potentials. We also demonstrated that dynorphin possesses anti-inflammatory and antioxidant potentials against dopaminergic loss, and that balance between dynorphin and substance P is important for dopaminergic neuroprotection. Thus, we examined whether GRe positively affects interactive modulation between dynorphin and substance P against MA neurotoxicity in mice.

METHODS

We examined changes in dynorphin peptide level, prodynorphin mRNA, and substance P mRNA, substance P-immunoreactivity, homeostasis in enzymatic antioxidant system, oxidative parameter, microglial activation, and pro-apoptotic parameter after a neurotoxic dose of MA to clarify the effects of GRe, prodynorphin knockout, pharmacological inhibition of κ-opioid receptor (i.e., nor-binaltorphimine), or neurokinin 1 (NK1) receptor (i.e., L-733,060) against MA insult in mice.

RESULTS

GRe attenuated MA-induced decreases in dynorphin level, prodynorphin mRNA expression in the striatum of wild-type (WT) mice. Prodynorphin knockout potentiated MA-induced dopaminergic toxicity in mice. The imbalance of enzymatic antioxidant system, oxidative burdens, microgliosis, and pro-apoptotic changes led to the dopaminergic neurotoxicity. Neuroprotective effects of GRe were more pronounced in prodynorphin knockout than in WT mice. Nor-binaltorphimine, a κ-opioid receptor antagonist, counteracted against protective effects of GRe. In addition, we found that GRe significantly attenuated MA-induced increases in substance P-immunoreactivity and substance P mRNA expression in the substantia nigra. These increases were more evident in prodynorphin knockout than in WT mice. Although, we observed that substance P-immunoreactivity was co-localized in NeuN-immunreactive neurons, GFAP-immunoreactive astrocytes, and Iba-1-immunoreactive microglia. NK1 receptor antagonist L-733,060 or GRe selectively inhibited microgliosis induced by MA. Furthermore, L-733,060 did not show any additive effects against GRe-mediated protective activity (i.e., antioxidant, antimicroglial, and antiapoptotic effects), indicating that NK1 receptor is one of the molecular targets of GRe.

CONCLUSIONS

Our results suggest that GRe protects MA-induced dopaminergic neurotoxicity via upregulatgion of dynorphin-mediated κ-opioid receptor and downregulation of substance P-mediated NK1 R.

Asiatic acid attenuates methamphetamine-induced neuroinflammation and neurotoxicity through blocking of NF-kB/STAT3/ERK and mitochondria-mediated apoptosis pathway

Background

Methamphetamine (METH) is a commonly abused drug that may result in neurotoxic effects. Recent studies have suggested that involvement of neuroinflammatory processes in brain dysfunction is induced by misuse of this drug. However, the mechanism underlying METH-induced inflammation and neurotoxicity in neurons is still unclear. In this study, we investigated whether asiatic acid (AA) effected METH-mediated neuroinflammation and neurotoxicity in dopaminergic neuronal cells. And we further determined whether the effect involved in the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and signal transducer and activator of transcription (STAT)3 and extracellular signal-regulated kinase (ERK) pathway.

Methods

We used the human dopaminergic neuroblastoma SH-SY5Y cell line, murine microglial BV2 cell line, and primary culture of rat embryo mesencephalic neurons. Pro-inflammatory cytokine production was monitored by ELISA and RT/real-time PCR. The cell cycle distribution and mitochondrial membrane integrity was analyzed by flow cytometry. We used immunoblotting, DNA-binding activity, and immunofluorescence staining to analyze the effect of AA on activation of the NF-κB, STAT3, MAPK-ERK, and apoptosis signaling pathways.

Results

METH induced TNF receptor (TNFR) expression and led to morphological changes of cells. Additionally, this drug increased pro-inflammatory cytokine (TNFα and IL-6) expression. AA significantly suppressed METH-induced TNFR expression in concentration dependent. Increased secretion of TNFα and IL-6 was inhibited in METH-stimulated neuronal cells by AA administration. AA showed significant protection against METH-induced translocation of NF-κB/STAT3 and ERK phosphorylation. AA inhibited METH-induced proteolytic fragmentation of caspase-3 and PARP. The pro-apoptotic protein Bax was significantly decreased, while the anti-apoptotic protein Bcl-xL was increased by AA treatment in METH-stimulated cells. A similar protective effect of AA on mitochondrial membrane integrity was also confirmed by flow cytometry and immunofluorescence staining.

Conclusions

Based on the literatures and our findings, AA is a promising candidate for an anti-neurotoxic agent, and it can potentially be used for the prevention and treatment of various neurological disorders.

Electronic supplementary material

The online version of this article (10.1186/s12974-017-1009-0) contains supplementary material, which is available to authorized users.

Effects of sequential ethanol exposure and repeated high-dose methamphetamine on striatal and hippocampal dopamine, serotonin and glutamate tissue content in Wistar rats

Alcohol (ethanol) and methamphetamine (METH) co-abuse is a major public health issue. Ethanol or METH exposure has been associated with changes in neurotransmitter levels in several central brain regions. However, little is known about the effect of sequential exposure to ethanol and METH on glutamate, dopamine and serotonin tissue content in striatum and hippocampus. In this study, we investigated the effects of sequential exposure to ethanol and METH on tissue content of these neurotransmitters. Male Wistar rats were orally gavaged with either ethanol (6g/kg) or water for seven days. Rats were administered with high dose of METH (10mg/kg, i.p. every 2h×4) or saline on Day 8 and euthanized 48h of last METH or saline i.p. injection. In the striatum, sequential exposure to ethanol and METH increased glutamate tissue content while reducing dopamine and serotonin tissue content as compared to the group exposed to ethanol alone. In the hippocampus, sequential exposure to ethanol and METH decreased serotonin tissue content as compared to the group that was exposed to ethanol alone. However, this study showed that ethanol has no additive effect to METH on tissue content of dopamine and serotonin as compared to METH in the striatum and hippocampus. This study demonstrated that sequential exposure of ethanol and METH has an additive effect on tissue content of certain neurotransmitters in the brain.

The Mediating Role of A2A Adenosine Receptors in the Mitochondrial Pathway of Apoptotic Hippocampal Cell Death, Following the Administration of MDMA in Rat

Introduction:

The 3,4-methylenedioxymethamphetamine (MDMA, ecstasy) is a popular recreational drug and a major source of substance abuse, which ultimately leads to sensations of well-being, elation and euphoria, moderate derealization/depersonalization, and cognitive disruptions, as well as intense sensory awareness. The mechanisms involved in memory impairment induced by MDMA are not completely understood.

Methods:

The current study used 40 Sprague-Dawley rats, weighted 200 to 250 g. Experiments were performed in four groups, each containing 10 rats. The first group of rats was used as the control, treated with dimethyl sulfoxide (DMSO). The second group was treated with MDMA. The third group was treated with MDMA and CGS (the adenosine A_2A receptor agonist, 2-[p-(2-carboxyethyl) phenethylamino]-5′-N-ethylcarboxamidoadenosine) (CGS 21680) and the fourth group was treated with MDMA and SCH (the A_2A receptor antagonist [7-(2-phenylethyl)-5-amino-2-(2-furyl-) pyrazolo-[4, 3-e]-1, 2, 4 triazolo [1,5-] pyrimidine]) (SCH 58261). The drugs in all groups were administrated intraperitoneally (i.p.) once a day for 7 days. In 5 rats of each group, following perfusion, samples were taken from hippocampi to investigate apoptosis. Accordingly, the samples were stained using the terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay kit, and studied by light microscopy. In other rats, fresh tissue was also removed to study the expression of bax and bcl-2 by Western blotting technique.

Results:

It was observed that the coadministration of MDMA with CGS reduced bax expression and prevented apoptosis of hippocampal cells. The coadministration of MDMA and SCH increased bax expression, and also increased the frequency of hippocampal cell apoptosis.

Conclusion:

The results of the current study showed that administration of CGS with MDMA decreased the common side effects associated with MDMA.

Exposure to Amphetamines Leads to Development of Amphetamine Type Stimulants Associated Cardiomyopathy (ATSAC)

With rapidly rising prevalence of exposure to Amphetamine Type Stimulants (ATS), novel insights into cardiotoxic effects of this substance are being presented in the literature and remarkably ATS Associated Cardiomyopathy (ATSAC) is emerging as a novel cardiovascular condition with its distinctive pathogenesis, risk factors, clinical features and prognosis. A comprehensive systematic review was performed to explore and analyze the current evidence on the association between ATS exposure and development of cardiomyopathy, biological mechanisms involved in pathogenesis of ATSAC, risk factors, clinical features and course of patients with ATSAC. Several animal studies, case reports, case series and case-control studies support the association between ATS exposure and ATSAC. Oxidative stress, accelerated apoptosis, increased p53 activity, cardiomyocyte necrosis, perfusion defects, fatty acid toxicity, altered gene expression, abnormal cardiac protein synthesis and function in addition to defects in intracellular calcium hemostasis present themselves as likely mechanisms of cardiotoxicity in ATSAC. Majority of patients with ATSAC were found to be male, young and presented late with severe dilated cardiomyopathy. Female ATS users predominantly develop Takotsubo type of ATSAC and in particular its atypical basal variant. Overall, cessation of ATS exposure seems to be associated with some degree of reversibility and recovery in ATSAC sufferers.

Corticosterone and exogenous glucose alter blood glucose levels, neurotoxicity, and vascular toxicity produced by methamphetamine

Our previous studies have raised the possibility that altered blood glucose levels may influence and/or be predictive of methamphetamine (METH) neurotoxicity. This study evaluated the effects of exogenous glucose and corticosterone (CORT) pretreatment alone or in combination with METH on blood glucose levels and the neural and vascular toxicity produced. METH exposure consisted of four sequential injections of 5, 7.5, 10, and 10 mg/kg (2 h between injections) D-METH. The three groups given METH in combination with saline, glucose (METH+Glucose), or CORT (METH+CORT) had significantly higher glucose levels compared to the corresponding treatment groups without METH except at 3 h after the last injection. At this last time point, the METH and METH+Glucose groups had lower levels than the non-METH groups, while the METH+CORT group did not. CORT alone or glucose alone did not significantly increase blood glucose. Mortality rates for the METH+CORT (40%) and METH+Glucose (44%) groups were substantially higher than the METH (< 10%) group. Additionally, METH+CORT significantly increased neurodegeneration above the other three METH treatment groups (≈ 2.5-fold in the parietal cortex). Thus, maintaining elevated levels of glucose during METH exposure increases lethality and may exacerbate neurodegeneration. Neuroinflammation, specifically microglial activation, was associated with degenerating neurons in the parietal cortex and thalamus after METH exposure. The activated microglia in the parietal cortex were surrounding vasculature in most cases and the extent of microglial activation was exacerbated by CORT pretreatment. Our findings show that acute CORT exposure and elevated blood glucose levels can exacerbate METH-induced vascular damage, neuroinflammation, neurodegeneration and lethality. Cover Image for this issue: doi. 10.1111/jnc.13819.

Tp53 gene mediates distinct dopaminergic neuronal damage in different dopaminergic neurotoxicant models

Tp53, a stress response gene, is involved in diverse cell death pathways and its activation is implicated in the pathogenesis of Parkinson's disease. However, whether the neuronal Tp53 protein plays a direct role in regulating dopaminergic (DA) neuronal cell death or neuronal terminal damage in different neurotoxicant models is unknown. In our recent studies, in contrast to the global inhibition of Tp53 function by pharmacological inhibitors and in traditional Tp53 knock-out mice, we examined the effects of DA-specific Tp53 gene deletion after 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine and methamphetamine exposure. Our data suggests that the Tp53 gene might be involved in both neuronal apoptosis and neuronal terminal damage caused by different neurotoxicants. Additional results from other studies also suggest that as a master regulator of many pathways that regulate apoptosis and synaptic terminal damage, it is possible that Tp53 may function as a signaling hub to integrate different signaling pathways to mediate distinctive target pathways. Tp53 protein as a signaling hub might be able to evaluate the microenvironment of neurons, assess the forms and severities of injury incurred, and determine whether apoptotic cell death or neuronal terminal degeneration occurs. Identification of the precise mechanisms activated in distinct neuronal damage caused by different forms and severities of injuries might allow for development of specific Tp53 inhibitors or ways to modulate distinct downstream target pathways involved.

Role of Melatonin in Reducing Amphetamine-Induced Degeneration in Substantia Nigra of Rats via Calpain and Calpastatin Interaction

Excessive intracellular calcium levels induce calpain activation, thereby triggering the cell death cascade. Several lines of evidence have demonstrated the neuroprotective role of the overexpression of calpain inhibitor, calpastatin. In this study, amphetamine-induced degeneration in the substantia nigra of rats was determined by evaluating the decrease in the levels of tyrosine hydroxylase phosphorylation. Amphetamine significantly decreased calpastatin levels but increased calpain levels. An induction in calpain activity was demonstrated by an increase in the formation of calpain spectrin breakdown products. The deleterious effects of amphetamine exposure were diminished in rats by pretreatment with melatonin. In addition, the effect of melatonin on calpastatin expression was investigated in human neuroblastoma SH-SY5Y cells. Melatonin was able to increase the calpastatin levels, and this effect could be blocked by luzindole, a melatonin receptor antagonist. These results demonstrate the neuroprotective ability of melatonin and its role in inducing calpastatin expression via a receptor-dependent pathway.

PACAP Protects Adult Neural Stem Cells from the Neurotoxic Effect of Ketamine Associated with Decreased Apoptosis, ER Stress and mTOR Pathway Activation

Ketamine administration is a well-established approach to mimic experimentally some aspects of schizophrenia. Adult neurogenesis dysregulation is associated with psychiatric disorders, including schizophrenia. The potential role of neurogenesis in the ketamine-induced phenotype is largely unknown. Recent results from human genetic studies have shown the pituitary adenylate cyclase-activating polypeptide (PACAP) gene is a risk factor for schizophrenia. Its potential role on the regulation of neurogenesis in experimental model of schizophrenia remains to be investigated. We aimed to determine whether ketamine affects the viability of adult neural stem cells (NSC). We also investigated whether the detrimental effect mediated by ketamine could be counteracted by PACAP. NSCs were isolated from the subventricular zone of the mouse and exposed to ketamine with/without PACAP. After 24 hours, cell viability, potential involvement of apoptosis, endoplasmic reticulum (ER) stress, mTOR and AMPA pathway activation were assessed by quantitative RT-PCR and Western blot analysis. We show that ketamine impairs NSC viability in correlation with increased apoptosis, ER stress and mTOR activation. The results also suggest that the effect of ketamine occurs via AMPA receptor activation. Finally, we show that PACAP counteracted the decreased NSC viability induced by ketamine via the specific activation of the PAC-1 receptor subtype. Our study shows that the NSC viability may be negatively affected by ketamine with putative importance for the development of a schizophrenia phenotype in the ketamine induced animal model of schizophrenia. The neuroprotective effect via PAC-1 activation suggests a potentially novel pharmacological target for the treatment of schizophrenia, via neurogenesis normalization.

Endoplasmic reticulum stress and apoptosis via PERK-eIF2α-CHOP signaling in the methamphetamine-induced chronic pulmonary injury

Methamphetamine (MA) leads to multiple organs lesions and apoptosis. The aim of this study is to investigate if endoplasmic reticulum stress (ERS) - initiated apoptosis is involved in the chronic pulmonary injury induced by MA. In this study, rats were divided into a control group, methamphetamine 5mg/kg group and methamphetamine 10mg/kg group. This study found that the protein level of GRP78 is higher in M10 group than in control group. PERK signaling and the relevant apoptosis factors were also activated. Morphological measurements showed that protein BAX and CHOP accumulated in the alveolar epithelium and the alveolar walls with epithelium were damaged and that the number of pulmonary alveoli decreased. The findings showed that ERS and PERK pathway are activated and eventually lead to apoptosis. Severe ERS mediated the apoptosis of alveolar epithelium cells as well as decreasing numbers of pulmonary alveoli.

Inhibitory effect of melatonin on cerebral endothelial cells dysfunction induced by methamphetamine via NADPH oxidase-2

Melatonin is a hormone that mostly produced from the pineal gland, and it performs as a strong neuroprotectant to both neuron and glial cells against methamphetamine (METH)-induced neurotoxicity. Recently, it has been found that METH also damages the blood brain barrier (BBB) structure and function. However, the protective mechanism of melatonin on the BBB impairment caused by METH has not been investigated. In this study, the primary rat brain microvascular endothelium cells (BMVECs) isolated from neonatal rats was used to investigate the protective effect of melatonin on METH-induced BBB impairment and the underlying mechanism. The results demonstrated that melatonin decreased the level of reactive oxygen species (ROS), reactive nitrogen species (RNS), and apoptosis induced by METH via NADPH oxidase (NOX)-2 since apocynin, a NOX-2 inhibitor abolished those changes. In addition, melatonin was found to improve cell integrity by increasing the transendothelial electric resistance (TEER) values, and up-regulate the tight junction proteins ZO-1, occludin, and claudin-5, thereby decreasing the paracellular permeability caused by METH mediated by NOX-2. Our data suggest that METH induces BBB impairment by mediating NOX-2 activity, and then induces oxidative and nitrative stress, as well as apoptosis, which causes the impairment of cell integrity, and that melatonin reduces these negative effects of METH by mediating via MT1/2 receptors.

Melatonin Protects SH-SY5Y Neuronal Cells Against Methamphetamine-Induced Endoplasmic Reticulum Stress and Apoptotic Cell Death

Methamphetamine (METH), a psychostimulant with highly neurotoxic effects, has been known to induce neuronal apoptosis in part through an endoplasmic reticulum (ER) stress pathway. Melatonin is an endogenous antioxidant compound that exerts protective effects against several neurodegenerative conditions, including METH-induced neurotoxicity, via various mechanisms. However, the role of melatonin in ER stress is still relatively unclear. In the present study, we investigated ER stress and neuronal apoptosis following METH treatment and the role of melatonin in METH-mediated ER stress-induced cell death in the SH-SY5Y neuroblastoma cell line. We found that METH caused the overexpression of ER stress-related genes, including C/EBP homologous protein and spliced X-box binding protein 1, in dose- and time-dependent manners. Moreover, METH time-dependently activated caspase-12 and -3, leading to cellular apoptosis. Furthermore, we demonstrated that pretreatment with melatonin attenuated the overexpression of ER stress-related genes and the cleavages of caspase-12 and -3 caused by METH exposure. Flow cytometry revealed that METH-mediated neuronal apoptosis was also prevented by melatonin. These findings suggest the protective effects of melatonin against ER stress and apoptosis caused by METH and other harmful agents.

Microstructural changes to the brain of mice after methamphetamine exposure as identified with diffusion tensor imaging

Methamphetamine (METH) is an addictive psychostimulant inducing neurotoxicity. Human magnetic resonance imaging and diffusion tensor imaging (DTI) of METH-dependent participants find various structural abnormities. Animal studies demonstrate immunohistochemical changes in multiple cellular pathways after METH exposure. Here, we characterized the long-term effects of METH on brain microstructure in mice exposed to an escalating METH binge regimen using in vivo DTI, a methodology directly translatable across species. Results revealed four patterns of differential fractional anisotropy (FA) and mean diffusivity (MD) response when comparing METH-exposed (n=14) to saline-treated mice (n=13). Compared to the saline group, METH-exposed mice demonstrated: 1) decreased FA with no change in MD [corpus callosum (posterior forceps), internal capsule (left), thalamus (medial aspects), midbrain], 2) increased MD with no change in FA [posterior isocortical regions, caudate-putamen, hypothalamus, cerebral peduncle, internal capsule (right)], 3) increased FA with decreased MD [frontal isocortex, corpus callosum (genu)], and 4) increased FA with no change or increased MD [hippocampi, amygdala, lateral thalamus]. MD was negatively associated with calbindin-1 in hippocampi and positively with dopamine transporter in caudate-putamen. These findings highlight distributed and differential METH effects within the brain suggesting several distinct mechanisms. Such mechanisms likely change brain tissue differentially dependent upon neural location.

Impaired skeletal health and neuromuscular function among amphetamine users in clinical treatment

SUMMARY

This study examined musculoskeletal health in amphetamine users, compared with healthy age-matched controls. We show that amphetamine users have reduced bone mass at several skeletal sites and attenuated maximal muscle strength and force development capacity in the lower extremities.

INTRODUCTION

Amphetamine use may cause poor bone quality and elevated risk of osteoporosis. The purpose of this study was to investigate whether amphetamine users exhibit reduced regional and whole body bone mineral density (BMD), altered bone metabolism, and how muscle function may relate to the patient groups' skeletal health.

METHODS

We assessed hip, lumbar spine and whole body BMD, and trabecular bone score (TBS) by dual x-ray absorptiometry (DXA), and bone metabolism markers in serum and maximal strength and force development capacity in 36 amphetamine users (25 men, 30 ± 7 years; 11 women 35 ± 10 years) and in 37 healthy controls (23 men, 31 ± 9 years; 14 women, 35 ± 7 years).

RESULTS

Whole body BMD was lower in amphetamine users (8% in males and 7% females, p < 0.01), as were BMD at the total hip and sub-regions of the hip (9-11% in men and 10-11 % in women, p < 0.05). Male users had 4% lower TBS (p < 0.05) and higher serum level of type 1 collagen amino-terminal propeptide (p < 0.01). This coincided with reduced lower extremity maximal strength of 30% (males, p < 0.001) and 25% (females, p < 0.05) and 27% slower muscular force development in males compared to controls (p < 0.01).

CONCLUSIONS

These findings demonstrate that amphetamine users suffer from a generalized reduction in bone mass, which was associated with attenuated maximal muscle strength and force development capacity in the lower extremities.

Structural imaging for addiction medicine: From neurostructure to neuroplasticity

Quantitative morphometry and diffusion tensor imaging have provided new insights into structural brain changes associated with drugs of abuse. In this chapter, we review recent studies using these methods to investigate structural brain abnormalities associated with excessive use of marijuana, stimulants, and opiates. Although many brain regions have been associated with structural abnormalities following abuse of these drugs, brain systems underlying inhibition, mood regulation, and reward are particularly involved. Candidate pathological mechanisms underlying these structural abnormalities include the direct toxic effects of the drugs, neuroinflammation, ischemia, hemorrhage, and abnormal brain development. Returning damaged brain areas to neural health would involve enhancing neuroplasticity. Behavioral, environmental, pharmacological, and cell-based therapies have been correlated with enhanced neuroplasticity following brain injury, providing a basis for new treatments of brain changes associated with excessive drug use. When testing new treatments, structural imaging may prove useful in selecting patients, monitoring recovery, and perhaps, tailoring interventions.

Recent advances in methamphetamine neurotoxicity mechanisms and its molecular pathophysiology

Methamphetamine (METH) is a sympathomimetic amine that belongs to phenethylamine and amphetamine class of psychoactive drugs, which are widely abused for their stimulant, euphoric, empathogenic, and hallucinogenic properties. Many of these effects result from acute increases in dopamine and serotonin neurotransmission. Subsequent to these acute effects, METH produces persistent damage to dopamine and serotonin release in nerve terminals, gliosis, and apoptosis. This review summarized the numerous interdependent mechanisms including excessive dopamine, ubiquitin-proteasome system dysfunction, protein nitration, endoplasmic reticulum stress, p53 expression, inflammatory molecular, D₃ receptor, microtubule deacetylation, and HIV-1 Tat protein that have been demonstrated to contribute to this damage. In addition, the feasible therapeutic strategies according to recent studies were also summarized ranging from drug and protein to gene level.

Ginsenoside Re protects methamphetamine-induced mitochondrial burdens and proapoptosis via genetic inhibition of protein kinase C δ in human neuroblastoma dopaminergic SH-SY5Y cell lines

Recently, we have demonstrated that ginsenoside Re protects methamphetamine (MA)-induced dopaminergic toxicity in mice via genetic inhibition of PKCδ and attenuation of mitochondrial stress. In addition, we have reported that induction of mitochondrial glutathione peroxidase (GPx) is also important for neuroprotection mediated by ginsenoside Re. To extend our knowledge, we examined the effects of ginsenoside Re against MA toxicity in vitro condition using SH-SY5Y neuroblastoma cells. Treatment with ginsenoside Re resulted in significant attenuations against a decrease in the activity of GPx and an increase in the activity of superoxide dismutase (SOD) in the cytosolic and mitochondrial fraction. The changes in glutathione (GSH) paralleled those in GPx in the same experimental condition. Consistently, ginsenoside Re treatment exhibited significant protections against cytosolic and mitochondrial oxidative damage (i.e. lipid peroxidation and protein oxidation), mitochondrial translocation of PKCδ, mitochondrial dysfunction (mitochondrial transmembrane potential and intra-mitochondrial Ca(2+)), apoptotic events [i.e., cytochrome c release from mitochondria, cleavage of caspase-3 and poly(ADP-ribose)polymerase-1, nuclear condensation, terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL)-positive apoptotic cells], and a reduction in the tyrosine hydroxylase (TH) expression and TH activity induced by MA in SH-SY5Y neuroblastoma cells. These protective effects of ginsenoside Re were comparable to those of PKCδ antisense oligonucleotide (ASO). However, ginsenoside Re did not significantly provide additional protective effects mediated by genetic inhibition of PKCδ. Our results suggest that PKCδ is a specific target for ginsenoside Re-mediated protective activity against MA toxicity in SH-SY5Y neuroblastoma cells.