Methamphetamine-induced toxicity: The role of autophagy?

Effects of a virtual reality-based motivational reinforcement + desensitization intervention program on psychological craving and addiction memory in female MA-dependent young adults

OBJECTIVES

The aim of this study was to explore the effects of a virtual reality (VR)-based motivational reinforcement + desensitization intervention program on psychological craving and addiction memory in female methamphetamine (MA)-dependent young adults.

METHODS

We recruited 60 female MA-dependent young adults in a compulsory isolation drug rehabilitation facility in Sichuan Province, and randomly assigned them to intervention (mean age = 23.24 ± 2.06) and control groups (mean age = 23.33 ± 2.09). The intervention group received a VR-based motivational enhancement + desensitization intervention (total of eight sessions over a 4-week period), while the control group received regular detoxification management during the same period. Assessments were conducted before, immediately after, and 1 month after the intervention, with a visual analogue scale (VAS) being used to assess subjective craving, electronic sphygmomanometer employed to measure physiological parameters, and the Addiction Memory Intensity Scale (AMIS) applied to assess addiction memory intensity.

RESULTS

Generalized estimating equation analysis showed significant main effects of group on changes in heart rate difference, systolic blood pressure difference, VAS and AMIS scores (all p < 0.01), and a significant time main effect on changes in diastolic blood pressure difference, VAS and AMIS scores (all p < 0.01), and a significant group × time interaction effect on changes in the difference values of three physiological parameters, VAS and AMIS scores (p < 0.01 or p < 0.05). After the intervention, the differences in three physiological parameters, and the VAS and AMIS scores, were significantly lower in the intervention than in the control group (all p < 0.05), and the difference between the two groups remained significant 1 month after the end of the intervention (both p < 0.01). VAS scores, heart rate difference, and diastolic blood pressure difference in the intervention group were significantly lower than baseline scores, both at the end of the intervention and 1 month thereafter (all p < 0.01); the systolic blood pressure difference in the intervention group was significantly lower at the end of the intervention than at baseline (p < 0.05); AMIS scores in the intervention group were significantly lower than the baseline scores 1 month after the end of the intervention (p < 0.01).

CONCLUSION

Our VR-based motivational reinforcement + desensitization intervention program can effectively reduce psychological craving and physiological reactivity for drugs, and the intensity of addictive memories in female MA-dependent young adults, even after 1 month.

High-throughput sequencing to evaluate the effects of methamphetamine on the succession of the bacterial community to estimate the postmortem interval

In forensic medical examinations, estimating the postmortem interval (PMI) is an important factor. Methamphetamine (MA) is a synthetic stimulant that is commonly abused, and estimation of the PMI after MA abuse has become one of the main tasks in forensic investigation. Microorganisms play a vital role in carrion decomposition. Analysing the bacterial succession patterns can be used as a forensic tool to estimate the PMI. The present study aimed to analyse bacterial succession changes during the decomposition of MA to estimate the PMI. We analysed bacterial communities in rabbits treated with three different concentrations of MA (0, 22.5, and 90 mg/kg) under the natural conditions of 20 °C and 70% humidity by sequencing 16S rRNA gene amplicons using the Illumina MiSeq system. We obtained 2 374 209 high-quality sequences and 2 937 operational taxonomic units (OTUs). The relative abundances of the bacterial communities varied markedly in response to different MA concentrations. Interestingly, in response to the different concentrations of MA, Bacteroidetes became disparate in the rectum in the late PMI. Increased numbers of bacterial taxa were identified in the rectum and buccal cavity samples, except at the highest concentration of MA in the rectum samples when PMI was 0-h, than were present in live rabbits. Meanwhile, the PMI correlated significantly with bacterial succession at different taxonomic levels. Our results suggested that bacterial community succession could be used as a "microbial clock" to estimate the PMI in cases of MA-related death; however, further study is required to gain a deeper understanding of this concept.

The protective effects of rutin on the liver, kidneys, and heart by counteracting organ toxicity caused by synthetic and natural compounds

Rutin is a flavonoid present in many plant species. Because of its antioxidant, anti-inflammatory, and antiapoptotic properties, rutin is of interest for its potential protective effects against toxic agents. The hepatoprotective, renoprotective, and cardioprotective effects of rutin are reviewed. The antioxidant effects of rutin are elicited by enhancing antioxidant enzymes such as GST, GGT, CAT, GPx, SOD, and GR, activating the Nrf2/HO-1 pathway, elevating GSH content, and the reduction in MDA. The anti-inflammatory effects of rutin are mediated by the inhibition of IL-1β, IL-6, TGF-β1, COX-2, iNOS, TLR4, and XO. Rutin exerted its antiapoptotic effects by inhibition of free radicals, caspase-3/-7/-9, hsp70, HMGB1, and p53, and the elevation of the antiapoptotic protein Bcl-2. Rutin has potential therapeutic effectiveness against several toxicants, and its beneficial effects are more than likely mediated by its antioxidant, anti-inflammatory, and/or antiapoptotic property.

Methamphetamine Use: A Narrative Review of Adverse Effects and Related Toxicities

Methamphetamine has been labeled "America's most dangerous drug" and has received significant public health attention. Stimulant addiction and tolerance are heavily documented in the literature; increasingly larger doses maintain euphoria in short time periods to withstand stimulant tolerance. Stimulant deaths are high in the United States and abroad. Between 2013 and 2019, deaths related to methamphetamine use quadrupled from 3,616 to 16,127. Methamphetamine use increased four-fold from 2015 to 2016. Due to this increase in methamphetamine use and its associated medical complications, the mortality rate associated with methamphetamine use has doubled over the past ten years. Cardiopulmonary symptoms include chest pain, palpitations, and shortness of breath. Methamphetamine-related myocardial infarction can also occur. Central nervous system symptoms include agitation, anxiety, delusions, hallucinations, and seizures. Methamphetamine-induced psychosis may unmask underlying psychiatric disorders. It can also cause cerebral vasculitis, which elicits cortical blindness and ischemic strokes. Methamphetamine-induced neurotoxicity in serotonergic systems is more diffuse, involving the striatum, hippocampus, septum, amygdala, and hypothalamus leading to mood changes, psychosis, and memory impairment. This narrative review will aim to highlight the adverse effects as well as the toxicity that can occur with methamphetamine use.

Dopamine D1 receptors mediate methamphetamine-induced dopaminergic damage: involvement of autophagy regulation via the AMPK/FOXO3A pathway

RATIONALE

Clinical studies have revealed that methamphetamine abuse increases risk for developing Parkinson's diseases. It is thus important to elucidate the mechanisms by which methamphetamine damages dopaminergic neurons.

OBJECTIVES

The present study was designed to elucidate the role of the dopamine D1 receptor in methamphetamine-mediated dopaminergic neuronal damage and its underlying mechanisms.

METHODS

Mice were treated for 4 days with vehicle, methamphetamine, or the D1 agonist SKF38393 and then assessed for locomotion and performance in the pole and rotarod tests. Cellular indices of autophagy, LC3, P62, and Beclin-1, tyrosine hydroxylase, and the AMPK/FOXO3A pathway were analyzed in striatal tissue from treated mice, in PC12 cells, and in D1 receptor mutant mice.

RESULTS

Repeated treatment with a relatively high dose of methamphetamine for 4 days induced both loss of dopaminergic neurons and activation of autophagy in the striatum as evidenced by increased expression of LC3 and P62. However, such treatment did not induce either loss of dopaminergic neurons or activation of autophagy in D1 receptor knockout mice. D1 receptor-mediated activation of autophagy was also confirmed in vitro using dopaminergic neuronal PC12 cells. Further studies demonstrated that the AMPK/FOXO3A signaling pathway is responsible for D1 receptor-mediated activation of autophagy.

CONCLUSIONS

The present data indicate a novel mechanism for methamphetamine-induced dopaminergic neuronal damage and reveal an important role for D1 receptors in the neurotoxicity of this drug.

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.

Escalating dose-multiple binge methamphetamine treatment elicits neurotoxicity, altering gut microbiota and fecal metabolites in mice

Methamphetamine (METH) is an addictive and illegal psychostimulant drug that can cause multiple organ dysfunction, especially in the central nervous system (CNS). Gut microbiota have been implicated in development of various CNS-related diseases, via the gut-brain axis (GBA). However, effect of METH in the alteration of gut microbiota and fecal metabolites is unclear, whereas the relationship with METH-induced neurotoxicity remains unknown. In the current study, we investigated effect of METH on neurotoxicity in striatum and colonic damage by exposing BALB/c mice to an escalating dose-multiple binge regimen, and then analyzed protein expression using Western blot analysis. We further detected and sequenced the 16 S rRNA gene in fecal samples, and performed ultra-high-performance liquid chromatography-mass spectrometry (UHPLC-MS)-based metabolomics to analyze gut microbes and fecal metabolites. Exposure to METH significantly downregulated tyrosine hydroxylase (TH) proteins, but upregulated MAOA, Beclin1, Atg5, and LC3-Ⅱ. METH up-regulated inflammation-related factors, such as caspase1, TNF-α and IL-18, by activating the toll-like receptors 4 (TLR4)/myeloid differentiation factor 88 (Myd88)/nuclear factor κB (NF-κB) pathway and reduced occludin protein expression. In addition, METH exposure changed α and β diversities of gut microbiota. Specifically, METH exposure elevated relative abundances of pathogenic bacteria, but reduced those of probiotics. Metabolomics, combined with enrichment analyses revealed that METH exposure altered fecal metabolites. Our findings suggest that METH exposure induced autophagy in the CNS, elevated intestinal autophagy flora, leading to accumulation of fecal metabolites in the autophagy pathway, and causing enteritis. Moreover, METH promoted intestinal inflammation by increasing the relative abundance of the pathogenic bacteria in the intestinal tract, and reduced intestinal TJ protein expression.

Diluted concentrations of methamphetamine in surface water induce behavior disorder, transgenerational toxicity, and ecosystem-level consequences of fish

Methamphetamine (METH) has been recognized as an emerging organic contaminant as it was widely detected in the aquatic environment via wastewater effluent discharge. However, the ecological hazard posed by METH at environmentally relevant concentrations was remained unclear. In this study, adult medaka fish were exposed to METH at environmental levels (0.05, 0.2, 0.5, 5 μg L^-1) and high level (25 and 100 μg L^-1) for 90 days to investigate its effect on ecologically behavioral functions, histopathology, bioconcentration, and transgenerational toxicity. The significant increase of locomotion activity, total distance, and max velocity of adult medaka were observed at low METH levels (0.2-0.5 μg L^-1), while it markedly decreased at high levels (25-100 μg L^-1). This effect may increase the predation risk of the fish. The significant alteration on the relative expressions of the genes (cacna1c, oxtr, erk1, and c-fos), as well as the contents of the proteins (oxytocin (OXT) and protein kinase A (PKA)) involved in Voltage Dependent Calcium Channel (VDCC) and Mitogen-Activated Protein Kinase (MAPK) signaling channel induced by METH could partly elucidate the underlying mechanisms of the changes of the behavioral traits. METH could induce obvious minimal gliosis, neuronal loss, and necrotic in brain tissues. Additionally, the significant increase of hepatic-somatic index (HSI) of male medaka at 0.2-5 μg L^-1 groups, and the decrease of female medaka at 100 μg L^-1 group indicated male fish was more susceptible to METH. Nephric-somatic index (NSI) of medaka markedly declined induced by METH at 0.05-100 μg L^-1. The bioconcentration factor (BCF) (0.4-5.8) in medaka fish revealed the bioconcentration potential of METH in fish. This study for the first time demonstrated METH could induced the development defects of larvae in F1 generation at environmentally relevant concentrations, thereby resulting in a significant decrease in the capacity of fish to produce offspring. Meanwhile, the RQ values (>1) of METH in river in China, USA, and Australia showed a high teratogenic risk level, suggesting the ecosystem-levels consequence posed by METH should be concerned.

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.

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.

Curcumin Inhibited Podocyte Cell Apoptosis and Accelerated Cell Autophagy in Diabetic Nephropathy via Regulating Beclin1/UVRAG/Bcl2

INTRODUCTION

Curcumin has various biological properties including being anti-inflammatory and antidiabetic. Podocyte apoptosis and autophagy dysfunction have been found to be responsible for the development of diabetic nephropathy (DN). Thus, the aim of the study was to investigate the effects of curcumin on the podocyte apoptosis and autophagy in DN and clarify its potential mechanisms.

METHODS

The mice with DN induced by injection of streptozotocin were treated with curcumin by gavage at a dose of 200 mg/kg/day for 8 weeks. The serum lipid levels were detected by total cholesterol (TC) and triglyceride (TG) kits at different time points. Renal damage was assessed by detecting urine albumin, serum creatinine (Scr), HE staining and PAS staining. The renal impairment was detected by immunohistochemical staining and TUNEL staining. Western blot assay tested the expression of autophagy-related and apoptotic-related proteins in vivo and vitro. The viabilities and apoptosis of MPC5 cells exposed to high glucose (HG) or curcumin were respectively detected by CCK-8 assay and flow cytometry.

RESULTS

The results showed that curcumin significantly decreased the progress of DN possibly via increasing autophagy and inhibiting apoptosis of renal cell in DN mice. Besides, podocyte marker proteins (podocalyxin and nephrin) were markedly increased in DN mice by curcumin treatment. The autophagy-related proteins LC3, p62, Beclin1, UVRAG and ATG5 were significantly affected in DN mice by curcumin, along with reducing expression of pro-apoptotic protein Bax and caspase-3 and increasing anti-apoptotic protein Bcl-2. In vitro, curcumin increased the viabilities and inhibited apoptosis of MPC5 cells exposed to high glucose (HG). In addition, the podocyte autophagy was enhanced partly via regulating beclin1/UVRAG.

DISCUSSION

Together, the results showed that curcumin inhibited podocyte apoptosis and accelerated cell autophagy via regulating Beclin1/UVRAG/Bcl2. Thus, the study showed that curcumin exerted significantly protective effects in DN.

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.

Neuroinflammation & pre-mature aging in the context of chronic HIV infection and drug abuse: Role of dysregulated autophagy

In the era of combined antiretroviral therapy (cART), HIV-1 infection has transformed from adeath sentenceto a manageable, chronic disease. Although the lifeexpectancy of HIV+ individuals is comparable to that of the uninfectedsubjects paradoxically, there is increased prevalence ofage-associatedcomorbidities such asatherosclerosis, diabetes, osteoporosis & neurological deficits in the context of HIV infection. Drug abuse is a commoncomorbidityofHIV infection andis often associated withincreased neurological complications. Chronic neuroinflammation (abnormal microglial and astrocyte activation) and neuronal synaptodendritic injury are the features of CNS pathology observed inHIV (+) individualsthat are takingcART & that abuse drugs. Neuroinflammation is thedrivingforceunderlying prematureaging associated with HIV (+) infection, cART and drugs of abuse. Autophagy is a highly conserved process critical for maintaining cellular homeostasis. Dysregulated autophagyhas been shown to be linked with abnormal immune responses & aging. Recent emerging evidence implicatesthe role ofHIV/HIV proteins, cART, & abused drugsin disrupting theautophagy process in brain cells such as microglia, astrocytes, and neurons. It can thus be envisioned that co-exposure of CNS cells to HIV proteins, cART and/or abused drugs couldhavesynergistic effects on theautophagy process, thereby leading to exaggerated microglial/astrocyte activation, ultimately, promotingthe aging process. Restoration of autophagic functioncould thusprovide an alternative therapeuticstrategy formitigating neuroinflammation & ameliorating the premature aging process. The current review aims to unravel the role of dysregulated autophagy in the context of single or co-exposure of microglia, astrocytes, and neurons to HIV/HIV proteins, drugs of abuse &/or cART and will also discuss the pathways involved in dysregulated autophagy-mediated neuroinflammation.

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.

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

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

Simultaneous determination of metabolic and elemental markers in methamphetamine-induced hepatic injury to rats using LC-MS/MS and ICP-MS

Methamphetamine (METH) is one of the most highly addictive illicit drugs abused all over the world. Much evidence indicates that METH abuse leads to major toxicity, medical consequences, and even severe public health consequences. Existing studies usually focus on the pathomechanism of METH-induced toxicity; therefore, data on metabolites and elements correlating with particular toxicity remain scarce. The objective of the present study is to develop appropriate analytical procedures to identify the differential metabolic and elemental biomarkers on METH-induced hepatic injury to rats. The rats were administrated with METH (15 mg/mL/kg, two times per day) via intraperitoneal (i.p.) injections for four consecutive days. The alanine aminotransferase and aspartate aminotransferase activity levels of in the rat serum of the METH group increase significantly compared with those of the control group, suggesting obvious hepatic injury. The results are further confirmed by the histopathological microscopic observation. A total of 18 small molecular metabolites and 19 elements are selected to perform the simultaneous quantification based on the combination of liquid chromatography coupled with tandem mass spectrometry and inductively coupled plasma mass spectrometry. Sample preparation was optimized to cover all the analytes. Both methods are optimized and validated according to developed guidelines such as limits of detection, limits of quantification, linearity, precision, and recovery. All the obtained data are within the satisfactory range. The normalized data were processed according to the partial least squares discrimination analysis (PLS-DA) model. Five differential metabolic and six elemental markers are identified in rat plasma based on the variable importance in projection (VIP) (> 1) and t test results. Overall, the results obtained in this study demonstrate the developed methods are suitable for simultaneous determination of metabolic and elemental markers in the hepatic injury to rats induced by METH. Graphical abstract.

Critical Roles of the PI3K-Akt-mTOR Signaling Pathway in Apoptosis and Autophagy of Astrocytes Induced by Methamphetamine

This study aimed to reveal potential roles of the phosphatidylinositol 3 kinase (PI3K)-protein kinase B (Akt)-mammalian target of rapamycin (mTOR) signaling pathway in apoptosis and autophagy of astrocytes induced by methamphetamine (METH). A Cell Counting Kit-8 (CCK-8) was used to determine the reduction in proliferation of U-118 MG cells induced by METH. Hoechst 33258 and flow cytometry were used to observe the astrocytes. Western blot analysis was performed to evaluate protein expression and phosphorylation levels. METH inhibited the proliferation of U-118 MG cells and induced apoptosis and autophagy. Western blot analysis showed that the ratio of LC3-II/I was increased, whereas the expression of Bcl-2 was decreased. The phosphorylation cascade of kinases in the PI3K-Akt-mTOR signaling pathway was significantly inhibited by METH exposure, as were proteins downstream of mTORC1, such as p70s6k, rps6, 4EBP1 and eIF4E. METH inhibited proliferation of U-118 MG cells and induced apoptosis and autophagy. The PI3K-Akt-mTOR signaling pathway likely plays a critical role in these effects.

The therapeutic role of long non-coding RNAs in human diseases: A focus on the recent insights into autophagy

Long non-coding RNA (lncRNA) is a class of non-coding RNA with ≥200 nucleotides in length which are involved as critical regulators in various cellular processes. LncRNAs contribute to the development and progression of many human diseases. Autophagy is a key catabolic process which helps to maintain the cellular homeostasis through the decay of damaged or unwanted proteins and dysfunctional cytoplasmic organelles. The impairment of the autophagy process has been described in numerous diseases. The autophagy possess can have either a protective or a detrimental role in cells depending on its activation status and other cellular conditions. LncRNAs have been shown to have an important function in the regulation of important biological processes such as autophagy. The relationship between lncRNAs and autophagy has been shown to be involved in the progression and possibly in the prevention of many diseases. In this review, recent findings on the regulatory roles of lncRNAs in the cell autophagy pathway, as well as their relevance to different diseases such as cardiovascular disease, cerebral ischemic stroke and cancer are highlighted.

Autophagy Induction by HIV-Tat and Methamphetamine in Primary Midbrain Neuronal Cells of Tree Shrews via the mTOR Signaling and ATG5/ATG7 Pathway

Background: Addictive stimulant drugs, such as methamphetamine (METH), increase the risk of exposure to the human immunodeficiency virus-1 (HIV-1) infection and thus predispose individuals to the development of HIV-associated neurocognitive disorders (HANDs). Previous studies have indicated that HIV-Tat (the transactivator of transcription) and METH can synergistically induce autophagy in SH-SY5Y neuroblastoma cells and that autophagy plays a pivotal role in the neuronal dysfunction in HANDs. However, the underlying mechanism of METH-and HIV-Tat-induced neuronal autophagy remains unclear. Methods: We cultured primary midbrain neuronal cells of tree shrews and treated them with METH and HIV-Tat to study the role of METH and HIV-Tat in inducing autophagy. We evaluated the effects of the single or combined treatment of METH and HIV-Tat on the protein expressions of the autophagy-related genes, including Beclin-1 and LC3B, ATG5, and ATG7 in METH and HIV-Tat-induced autophagy. In addition, the presence of autophagosomes in the METH and/or HIV-Tat treatment was revealed using transmission electron microscopy. Results: The results indicated that METH increased the protein levels of LC3B and Beclin-1, and these effects were significantly enhanced by HIV-Tat. Moreover, the results suggested that ATG5 and ATG7 were involved in the METH and HIV-Tat-induced autophagy. In addition, it was found that mTOR inhibition via pharmacological intervention could trigger autophagy and promote METH and HIV-Tat-induced autophagy. Discussion: Overall, this study contributes to the knowledge of the molecular underpinnings of METH and HIV-Tat-induced autophagy in primary midbrain neuronal cells. Our findings may facilitate the development of therapeutic strategies for METH-and HIV-Tat-induced autophagy in HANDs.

The effect of fasting or calorie restriction on autophagy induction: A review of the literature

Autophagy is a lysosomal degradation process and protective housekeeping mechanism to eliminate damaged organelles, long-lived misfolded proteins and invading pathogens. Autophagy functions to recycle building blocks and energy for cellular renovation and homeostasis, allowing cells to adapt to stress. Modulation of autophagy is a potential therapeutic target for a diverse range of diseases, including metabolic conditions, neurodegenerative diseases, cancers and infectious diseases. Traditionally, food deprivation and calorie restriction (CR) have been considered to slow aging and increase longevity. Since autophagy inhibition attenuates the anti-aging effects of CR, it has been proposed that autophagy plays a substantive role in CR-mediated longevity. Among several stress stimuli inducers of autophagy, fasting and CR are the most potent non-genetic autophagy stimulators, and lack the undesirable side effects associated with alternative interventions. Despite the importance of autophagy, the evidence connecting fasting or CR with autophagy promotion has not previously been reviewed. Therefore, our objective was to weigh the evidence relating the effect of CR or fasting on autophagy promotion. We conclude that both fasting and CR have a role in the upregulation of autophagy, the evidence overwhelmingly suggesting that autophagy is induced in a wide variety of tissues and organs in response to food deprivation.

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.

Effects of insulin-like growth factor-1 on endoplasmic reticulum stress and autophagy in rat gastric smooth muscle cells cultured at different glucose concentrations in vitro

The purpose of the study was to observe changes in endoplasmic reticulum stress (ERS)- and autophagy-related proteins in gastric smooth muscle tissues of diabetic rats with gastroparesis, investigate the effect of insulin-like growth factor 1 (IGF-1) on ERS and autophagy in rat gastric smooth muscle cells cultured under different glucose concentrations, and explore the influence of IGF-1 on development of diabetic gastroparesis (DGP). After establishing a rat model of DGP, rats were divided into normal control (NC) and 6-week diabetic model (DM6W) groups. Expression of ERS-related and autophagy-related proteins was detected by western blot analysis and immunofluorescence assay in rat gastric smooth muscle tissue and in vitro-cultured rat gastric smooth muscle cells exposed to different glucose concentrations and treatment with IGF-1 for 24 or 48 h. Changes in glucose-regulated-protein-78 (GRP78), growth arrest and DNA damage-inducible gene 153 (CHOP), and microtubule-associated protein 1A/1B light chain 3B (LC3) expression levels were detected by western blot analysis, and GRP78 and LC3 expression were examined by confocal laser-scanning microscopy. In vivo expression levels of GRP78, CHOP, and LC3 were significantly higher in the DM6W group compared with the NC group (p < 0.001). Twenty-four hours after cells were cultured at different glucose concentrations in vitro, expression of GRP78, CHOP, and LC3II/I was significantly higher in the high glucose-treated group compared with the normal glucose group (p < 0.05). After IGF-1 intervention, CHOP and GRP78 expression were significantly higher in the normal glucose + IGF-1 group compared with the normal glucose group (p < 0.01), while no significant difference was found between high glucose and high glucose + IGF-1 groups. LC3II/I expression was significantly lower in the normal glucose + IGF-1 group compared with the normal glucose group, and was significantly lower in the high glucose and high glucose + IGF-1 groups (p < 0.05). After 48 h of culture, CHOP expression was significantly higher and LC3II/I expression was significantly lower in the high glucose group compared with the normal glucose group (p < 0.05), but no significant change in GRP78 expression was observed between these two groups. After IGF-1 intervention, there was no difference in CHOP or GRP78 expression between normal glucose + IGF-1 and normal glucose groups. However, CHOP and GRP78 expression were significantly lower in the high glucose + IGF-1 group compared with the high glucose group (p < 0.05). There was no significant difference in LC3II/I expression between normal glucose + IGF-1 and normal glucose groups, or high glucose + IGF-1 and high glucose groups. Results of confocal laser-scanning microscopy showed significantly lower expression of LC3II/I in the high glucose + IGF-1 group compared with the high glucose group (p < 0.05). ERS and autophagy were involved in the occurrence of DGP. IGF-1 exerted an inhibitory effect on ERS in rat gastric smooth muscle cells cultured under high glucose conditions, and this inhibitory effect increased with time. IGF-1 inhibited the level of autophagy in rat gastric smooth muscle cells cultured under high glucose conditions at early stages, which may be achieved through inhibition of ERS.

Apelin involved in progression of diabetic nephropathy by inhibiting autophagy in podocytes

Podocyte autophagy dysfunction has been reported to be responsible for the progression of diabetic nephropathy (DN), however, the factors contributed to autophagy dysfunction in type 2 diabetes are not fully understood. Among promoting factors in DN, an adipokine, apelin, had been showed to trigger podocyte dysfunction. Therefore, it is hypothesized that apelin, which is increased in plasma in type 2 diabetes, lead to podocyte apoptosis through inhibiting podocyte autophagy, which resulted in podocyte dysfunction followed by DN. KkAy mice (diabetic mice) and cultured podocytes (MPC5 cells and native podocytes) were treated with high glucose (HG) and apelin or its antagonist F13A. Renal function, podocyte autophagy, podocyte apoptosis and corresponding cell signaling pathways in podocytes were detected. The results showed that apelin aggravated the renal dysfunction and foot process injuries in kkAy mice, which is positively correlated to podocyte apoptosis and negatively correlated to podocyte autophagy. Apelin induced podocyte apoptosis and inhibited podocyte autophagy in both normal glucose and HG conditions while F13A reversed these effects. Investigations by western blot found that apelin inhibits podocyte autophagy through ERK-, Akt- and mTOR-dependent pathways. In conclusion, increased apelin concentration in plasma inhibited podocyte autophagy, which would lead to podocyte apoptosis and renal dysfunction in diabetes. These effects would contribute to the progression of DN.

Nupr1 Modulates Methamphetamine-Induced Dopaminergic Neuronal Apoptosis and Autophagy through CHOP-Trib3-Mediated Endoplasmic Reticulum Stress Signaling Pathway

Methamphetamine (METH) is an illegal and widely abused psychoactive stimulant. METH exposure causes detrimental effects on multiple organ systems, primarily the nervous system, especially dopaminergic pathways, in both laboratory animals and humans. In this study, we hypothesized that Nuclear protein 1 (Nupr1/com1/p8) is involved in METH-induced neuronal apoptosis and autophagy through endoplasmic reticulum (ER) stress signaling pathway. To test this hypothesis, we measured the expression levels of Nupr1, ER stress protein markers CHOP and Trib3, apoptosis-related protein markers cleaved-caspase3 and PARP, as well as autophagy-related protein markers LC3 and Beclin-1 in brain tissues of adult male Sprague-Dawley (SD) rats, rat primary cultured neurons and the rat adrenal pheochromocytoma cells (PC12 cells) after METH exposure. We also determined the effects of METH exposure on the expression of these proteins after silencing Nupr1, CHOP, or Trib3 expression with synthetic small hairpin RNA (shRNA) or siRNA in vitro, and after silencing Nupr1 in the striatum of rats by injecting lentivirus containing shRNA sequence targeting Nupr1 gene to rat striatum. The results showed that METH exposure increased Nupr1 expression that was accompanied with increased expression of ER stress protein markers CHOP and Trib3, and also led to apoptosis and autophagy in rat primary neurons and in PC12 cells after 24 h exposure (3.0 mM), and in the prefrontal cortex and striatum of rats after repeated intraperitoneal injections (15 mg/kg × 8 injections at 12 h intervals). Silencing of Nupr1 expression partly reduced METH-induced apoptosis and autophagy in vitro and in vivo. These results suggest that Nupr1 plays an essential role in METH-caused neuronal apoptosis and autophagy at relatively higher doses and may be a potential therapeutic target in high-dose METH-induced neurotoxicity.

Regulation of autophagy by some natural products as a potential therapeutic strategy for cardiovascular disorders

Autophagy is a lysosomal degradation process through which long-lived and misfolded proteins and organelles are sequestered, degraded by lysosomes, and recycled. Autophagy is an essential part of cardiomyocyte homeostasis and increases the survival of cells following cellular stress and starvation. Recent studies made clear that dysregulation of autophagy in the cardiovascular system leads to heart hypertrophy and failure. In this manner, autophagy seems to be an attractive target in the new treatment of cardiovascular diseases. Although limited activation of autophagy is generally considered to be cardioprotective, excessive autophagy leads to cell death and cardiac atrophy. Natural products such as resveratrol, berberine, and curcumin that are present in our diet, can trigger autophagy via canonical (Beclin-1-dependent) and non-canonical (Beclin-1-independent) pathways. The autophagy-modifying capacity of these compounds should be taken into consideration for designing novel therapeutic agents. This review focuses on the role of autophagy in the cardioprotective effects of these compounds.