Lactulose attenuates METH-induced neurotoxicity by alleviating the impaired autophagy, stabilizing the perturbed antioxidant system and suppressing apoptosis in rat striatum

NMN synbiotics intervention modulates gut microbiota and metabolism in APP/PS1 Alzheimer's disease mouse models

Alzheimer's disease (AD) is a complex neurodegenerative condition with growing evidence implicating the gut microbiota in its pathogenesis. This study aimed to investigate the effects of NMN synbiotics, a combination of β-nicotinamide mononucleotide (NMN), Lactobacillus plantarum, and lactulose, on the gut microbiota composition and metabolic profiles in APP/PS1 transgenic mice. Results demonstrated that NMN synbiotics led to a notable restructuring of the gut microbiota, with a decreased Firmicutes/Bacteroidetes ratio in the AD mice, suggesting a potential amelioration of gut dysbiosis. Alpha diversity indices indicated a reduction in microbial diversity following NMN synbiotics supplementation, while beta diversity analyses revealed a shift towards a more balanced microbial community structure. Functional predictions based on the 16S rRNA data highlighted alterations in metabolic pathways, particularly those related to amino acid and energy metabolism, which are crucial for neuronal health. The metabolomic analysis uncovered a significant impact of NMN synbiotics on the gut metabolome, with normalization of metabolic composition in AD mice. Differential metabolite functions were enriched in pathways associated with neurotransmitter synthesis and energy metabolism, pointing to the potential therapeutic effects of NMN synbiotics in modulating the gut-brain axis and synaptic function in AD. Immunohistochemical staining observed a significant reduction of amyloid plaques formed by Aβ deposition in the brain of AD mice after NMN synbiotics intervention. The findings underscore the potential of using synbiotics to ameliorate the neurodegenerative processes associated with Alzheimer's disease, opening new avenues for therapeutic interventions.

Methamphetamine Increases Tubulo-Vesicular Areas While Dissipating Proteins from Vesicles Involved in Cell Clearance

Cytopathology induced by methamphetamine (METH) is reminiscent of degenerative disorders such as Parkinson's disease, and it is characterized by membrane organelles arranged in tubulo-vesicular structures. These areas, appearing as clusters of vesicles, have never been defined concerning the presence of specific organelles. Therefore, the present study aimed to identify the relative and absolute area of specific membrane-bound organelles following a moderate dose (100 µM) of METH administered to catecholamine-containing PC12 cells. Organelles and antigens were detected by immunofluorescence, and they were further quantified by plain electron microscopy and in situ stoichiometry. This analysis indicated an increase in autophagosomes and damaged mitochondria along with a decrease in lysosomes and healthy mitochondria. Following METH, a severe dissipation of hallmark proteins from their own vesicles was measured. In fact, the amounts of LC3 and p62 were reduced within autophagy vacuoles compared with the whole cytosol. Similarly, LAMP1 and Cathepsin-D within lysosomes were reduced. These findings suggest a loss of compartmentalization and confirm a decrease in the competence of cell clearing organelles during catecholamine degeneration. Such cell entropy is consistent with a loss of energy stores, which routinely govern appropriate subcellular compartmentalization.

Cinnamaldehyde/lactulose combination therapy alleviates thioacetamide-induced hepatic encephalopathy via targeting P2X7R-mediated NLRP3 inflammasome signaling

AIMS

Cinnamaldehyde (CA), the main active constituent of cinnamon oil, is reported to have neuroprotective effects. However, the potential benefits of CA for brain protection in hepatic encephalopathy (HE) are still not understood. Thus, the present study investigates the possible ameliorative effect of CA (70 mg/kg/day, I.P.) either alone or in combination with lactulose (Lac) (5.3 g/kg/day, oral) against thioacetamide (TAA)-induced hepatic encephalopathy in rats.

MATERIALS AND METHODS

For induction of HE, TAA (200 mg/kg) was intraperitoneally administered for 1 week at alternative days. CA, Lac and Lac+CA were administered for 14 days prior to and for further 7 days together with TAA injection.

KEY FINDINGS

CA, Lac and Lac+CA combination effectively attenuated TAA-induced HE; as indicated by the improvement in behavioral tests, mitigation of pathological abnormalities in both liver and brain, the significant reduction in serum hyperammonemia and amelioration in liver function biomarkers; ALT and AST. This was accompanied with a substantial restoration of redox state in liver and brain; MDA and GSH levels. Moreover, CA, Lac and Lac+CA combination reduced neuroinflammation as demonstrated by the notable attenuation of P2X7R, NLRP3, caspase-1, IL-1β, GFAP and Iba1 brain levels, as well as the amelioration of brain edema as manifested by reduction in AQP4 levels in brain.

SIGNIFICANCE

Our study has demonstrated that CA in combination with Lac possesses a superior neuroprotective effect over Lac alone against TAA-induced HE by attenuation of P2X7R/NLRP3 mediated neuroinflammation and relieving brain edema.

Long-term exposure to polystyrene microplastics induces hepatotoxicity by altering lipid signatures in C57BL/6J mice

It is estimated that the life of plastics is hundreds to thousands of years, their lasting properties making plastic debris absorbing toxic chemicals and degrading into microplastics (MPs). The purpose of this study was to explore the effects of exposure to different size (0.08 and 0.5 μm) polystyrene (PS) in mice. After 16 weeks of exposure, it was found that PS-MPs could be identified in the liver. No effect of PS-MPs treatment on body weight was observed. PS-MPs exposure disturbed lipids and lipid-like molecule metabolisms and perturbed the citrate cycle and oxidative phosphorylation. Meanwhile, isocitrate dehydrogenase (ICDHc), nicotinamide adenine dinucleotide -malate dehydrogenase (NAD-MDH), succinate dehydrogenase (SDH), α ketoglutarate dehydrogenase (α-KGDH) activities and adenosine triphosphate (ATP) level were obviously affected by PS-MPs treatment. In addition, significant differences were recorded in catalase (CAT) and malondialdehyde (MDA) levels, indicating that PS-MPs exposure induced an oxidative stress in the liver. In conclusion, our present study provided the first evidence of: (a) long-term exposure to PS-MPs lead to PS-MPs accumulated in the liver and results in liver injury; (b) long-term exposure to PS-MPs disturbs lipids and lipid-like molecule metabolisms; (c) long-term exposure to PS-MPs perturbs citrate cycle and oxidative phosphorylation and leads to oxidative stress in the liver.

Gut microbiota-derived short-chain fatty acids ameliorate methamphetamine-induced depression- and anxiety-like behaviors in a Sigmar-1 receptor-dependent manner

Methamphetamine (Meth) abuse can cause serious mental disorders, including anxiety and depression. The gut microbiota is a crucial contributor to maintaining host mental health. Here, we aim to investigate if microbiota participate in Meth-induced mental disorders, and the potential mechanisms involved. Here, 15 mg/kg Meth resulted in anxiety- and depression-like behaviors of mice successfully and suppressed the Sigma-1 receptor (SIGMAR1)/BDNF/TRKB pathway in the hippocampus. Meanwhile, Meth impaired gut homeostasis by arousing the Toll-like receptor 4 (TLR4)-related colonic inflammation, disturbing the gut microbiome and reducing the microbiota-derived short-chain fatty acids (SCFAs). Moreover, fecal microbiota from Meth-administrated mice mediated the colonic inflammation and reproduced anxiety- and depression-like behaviors in recipients. Further, SCFAs supplementation optimized Meth-induced microbial dysbiosis, ameliorated colonic inflammation, and repressed anxiety- and depression-like behaviors. Finally, Sigmar1 knockout (Sigmar1-/-) repressed the BDNF/TRKB pathway and produced similar behavioral phenotypes with Meth exposure, and eliminated the anti-anxiety and -depression effects of SCFAs. The activation of SIGMAR1 with fluvoxamine attenuated Meth-induced anxiety- and depression-like behaviors. Our findings indicated that gut microbiota-derived SCFAs could optimize gut homeostasis, and ameliorate Meth-induced mental disorders in a SIGMAR1-dependent manner. This study confirms the crucial role of microbiota in Meth-related mental disorders and provides a potential preemptive therapy.

p-Nrf2/HO-1 Pathway Involved in Methamphetamine-induced Executive Dysfunction through Endoplasmic Reticulum Stress and Apoptosis in the Dorsal Striatum

Methamphetamine (METH) abuse is known to cause executive dysfunction. However, the molecular mechanism underlying METH induced executive dysfunction remains unclear. Go/NoGo experiment was performed in mice to evaluate METH-induced executive dysfunction. Immunoblot analysis of Nuclear factor-E2-related factor 2 (Nrf2), phosphorylated Nrf2 (p-Nrf2), heme-oxygenase-1 (HO-1), Glucose Regulated Protein 78(GRP78), C/EBP homologous protein (CHOP), Bcl-2, Bax and Caspase3 was performed to evaluate the levels of oxidative stress, endoplasmic reticulum (ER) stress and apoptosis in the dorsal striatum (Dstr). Malondialdehyde (MDA) levels and glutathione peroxidase (GSH-Px) activity was conducted to evaluate the level of oxidative stress. TUNEL staining was conducted to detect apoptotic neurons. The animal Go/NoGo testing confirmed that METH abuse impaired the inhibitory control ability of executive function. Meanwhile, METH down-regulated the expression of p-Nrf2, HO-1 and GSH-Px and activated ER stress and apoptosis in the Dstr. Microinjection of Tert-butylhydroxyquinone (TBHQ), an Nrf2 agonist, into the Dstr increased the expression of p-Nrf2, HO-1, and GSH-Px, ameliorated ER stress, apoptosis and executive dysfunction caused by METH. Our results indicated that the p-Nrf2/HO-1 pathway was potentially involved in mediating methamphetamine-induced executive dysfunction by inducing endoplasmic reticulum stress and apoptosis in the dorsal striatum.

The synbiotic mixture of lactulose and Bacillus coagulans protects intestinal barrier dysfunction and apoptosis in weaned piglets challenged with lipopolysaccharide

BACKGROUND

Lactulose as an effective prebiotic protects intestinal mucosal injury. Bacillus coagulans is widely used in feed additives because of its ability to promote intestinal health. Our previous study suggests that the combination of lactulose and Bacillus coagulans may be a good candidate as alternative for antibiotic growth promoters. However, the in vivo effects of lactulose and Bacillus coagulans on growth and intestinal health under immune challenge in piglets remains unclear. The objective of this study is to explore the protective effects of synbiotic containing lactulose and Bacillus coagulans on the intestinal mucosal injury and barrier dysfunction under immune challenge in weaned piglets.

METHODS

Twenty four weaned piglets were assigned to 4 groups. Piglets in the CON_-saline and LPS_-LPS group were fed the basal diet, while others were fed either with chlortetracycline (CTC) or synbiotic mixture of lactulose and Bacillus coagulans for 32 d before injection of saline or lipopolysaccharide (LPS). Piglets were sacrificed 4 h after LPS injection to collect samples to determine intestinal morphology, integrity and barrier functions as well as relative genes and proteins.

RESULTS

Our data showed that no differences were observed in the growth performance of the four test groups. LPS injection induced higher serum diamine oxidase activities, D-lactic acid levels, and endotoxin status, lower villus height and ratio of villus height to crypt depth, greater mRNA and lower protein expression related tight junction in both jejunum and ileum. In addition, a higher apoptosis index, and protein expression of Bax and caspase-3 were also observed in the LPS challenge group. Interestingly, dietary synbiotic mixture with lactulose and Bacillus coagulans protected against LPS-induced intestinal damage, barrier dysfunction and higher apoptosis as well as CTC.

CONCLUSIONS

Our data suggest that dietary supplementation of synbiotic mixture with lactulose and Bacillus coagulans showed resilience to LPS-induced intestinal morphological damage, barrier dysfunction and aggressive apoptosis in piglets as well as the protective effects of CTC. These results indicate that synbiotic mixture of lactulose and Bacillus coagulans showed beneficial effects on performance and resilience to acute immune stress in weaned piglets.

Gut microbiota contribute to Methamphetamine-induced cardiotoxicity in mouse model

Methamphetamine (METH) is a psychotropic drug known to cause cardiotoxicity. The gut-heart axis is emerging as an important pathway linking gut microbiota to cardiovascular disease, but the precise association between METH-induced cardiotoxicity and gut microbiota has yet to be elucidated. In this study, we established an escalating dose-multiple METH administration model in male BALB/c mice, examined cardiac injury and gut microbiota, and investigated the contribution of gut microbiota to cardiotoxicity induced by METH. Additionally, we treated mice with antibiotics and fecal microbiota transplantation (FMT) to assess the impact of gut microbiota on cardiotoxicity. Our results showed that METH exposure altered the p53 and PI3K/Akt signaling pathways and modulated the apoptosis pathway in heart tissue, accompanied by elevated levels of Bax/BCL-2 expression and cleaved caspase-3 proteins. METH exposure increased the diversity and richness of gut microbiota, and significantly changed the microbial community composition, accompanied by elevated abundance of Lactobacillus, Bifidobacterium, and decreased abundance of Bacteroides, norank_f_Muribaculaceae and Alistipes. Eliminating gut microbiota by antibiotics treatment alleviated METH-induced cardiotoxicity, while FMT treatment transferred similar cardiac injury manifestations from METH-exposed mice to healthy recipient mice. Our study unveils the crucial involvement of gut microbiota in the development of cardiotoxicity induced by METH and provides potential strategies for treating cardiac complications caused by METH.

Microbial community succession in the intestine of mice with deep partial-thickness burns

Introduction

Burn injury has been shown to lead to changes in the composition of the gut microbiome and cause other damage in patients. However, little is known about how the gut microbial community evolves in individuals who have recovered from burn injury.

Methods

In this study, we established a model of deep partial-thickness burn in mice and collected fecal samples at eight time points (pre-burn, 1, 3, 5, 7, 14, 21, and 28 days post-burn) for 16S rRNA amplification and high-throughput sequencing.

Results

The results of the sequencing were analyzed using measures of alpha diversity, and beta diversity and taxonomy. We observed that the richness of the gut microbiome declined from day 7 post-burn and that the principal component and microbial community structure varied over time. On day 28 after the burn, the microbiome composition largely returned to the pre-burn level, although day 5 was a turning point for change. Some probiotics, such as the Lachnospiraceae_NK4A136_group, decreased in composition after the burn but were restored in the later recovery period. In contrast, Proteobacteria showed an opposite trend, which is known to include potential pathogenic bacteria.

Conclusion

These findings demonstrate gut microbial dysbiosis after burn injury and provide new insights into the burn-related dysbiosis of the gut microbiome and strategies for improving the treatment of burn injury from the perspective of the microbiota.

Effects of Rifaximin on Circulating Albumin Structures and Serum Ammonia Levels in Patients with Liver Cirrhosis: A Preliminary Study

Circulating albumin structures, including their oxidized and reduced forms, are involved in hepatic encephalopathy (HE) development. However, the effects of rifaximin, a key drug in HE treatment, on the circulating albumin structure in patients with liver cirrhosis remain unclear. In this multicenter prospective study, eight patients with hyperammonemia (≥80 μg/dL) were enrolled. The circulating albumin structure was evaluated using the ratio of oxidized albumin (human nonmercaptalbumin, HNA). Patients were administered 400 mg rifaximin 3 times/day for 3 months, and laboratory data were assessed at baseline and during observation. Among the eight patients, three were men; the median age and body mass index were 70 years and 26.4 kg/m², respectively. The median HNA and serum ammonia levels at baseline were 41% and 143 μg/dL, respectively. After rifaximin therapy, HNA showed a decreasing tendency (median; from 41% to 36%, p = 0.321), but serum albumin levels showed no significant change (from 3.5 g/dL to 3.5 g/dL, p = 1.00); serum ammonia levels significantly reduced (median: 143 μg/dL to 76 μg/dL, p = 0.015). Thus, rifaximin reduces serum ammonia levels and may improve circulating albumin structure in patients with cirrhosis. Further large-scale studies are required to confirm these preliminary results.

Cannabidiol prevents methamphetamine-induced neurotoxicity by modulating dopamine receptor D1-mediated calcium-dependent phosphorylation of methyl-CpG-binding protein 2

In the past decade, methamphetamine (METH) abuse has sharply increased in the United States, East Asia, and Southeast Asia. METH abuse not only leads to serious drug dependence, but also produces irreversible neurotoxicity. Currently, there are no approved pharmacotherapies for the treatment of METH use disorders. Cannabidiol (CBD), a major non-psychoactive (and non-addictive) cannabinoid from the cannabis plant, shows neuroprotective, antioxidative, and anti-inflammatory properties under METH exposure. At present, however, the mechanisms underlying these properties remain unclear, which continues to hinder research on its therapeutic potential. In the current study, computational simulations showed that CBD and METH may directly bind to the dopamine receptor D1 (DRD1) via two overlapping binding sites. Moreover, CBD may compete with METH for the PHE-313 binding site. We also found that METH robustly induced apoptosis with activation of the caspase-8/caspase-3 cascade in-vitro and in-vivo, while CBD pretreatment prevented these changes. Furthermore, METH increased the expression of DRD1, phosphorylation of Methyl-CpG-binding protein 2 (MeCP2) at serine 421 (Ser421), and level of intracellular Ca2+in-vitro and in-vivo, but these effects were blocked by CBD pretreatment. The DRD1 antagonist SCH23390 significantly prevented METH-induced apoptosis, MeCP2 phosphorylation, and Ca2+ overload in-vitro. In contrast, the DRD1 agonist SKF81297 markedly increased apoptosis, MeCP2 phosphorylation, and Ca2+ overload, which were blocked by CBD pretreatment in-vitro. These results indicate that CBD prevents METH-induced neurotoxicity by modulating DRD1-mediated phosphorylation of MeCP2 and Ca2+ signaling. This study suggests that CBD pretreatment may resist the effects of METH on DRD1 by competitive binding.

A review of basic to clinical studies of the association between hyperammonemia, methamphetamine

Methamphetamine (METH), an addictive psychostimulant drug, is the second most widely used type of drug all around the world. METH abusers are more likely to develop a psycho-neurological complication. Hyperammonemia (HAM) causes neuropsychiatric illnesses such as mental state changes and episodes of acute encephalopathy. Recently, there are some shreds of evidence about the relationship between METH complication and HAM. Both METH intoxication and HAM could induce psychosis, agitation, memory impairment, and psycho-neuronal disorders. They also have similar mechanisms of neuronal damages, such as excitotoxicity, oxidative stress, mitochondrial impairments, and inflammation responses, which can subsequently increase the glutamate level of the brain. Hence, the basic to clinical studies of the association between HAM and METH are reviewed by monitoring six case studies and a good body of animal studies literature. All instances of METH-associated HAM had changes in mental state and some level of confusion that were improved when the ammonia serum level returned to the normal level. Furthermore, most of them had typical vital signs. Several studies suggested some sources for METH-associated HAM, including METH-induced liver and renal damages, muscular hyperactivity, gut bacterial overgrowth, co-abuse of other substances, and using some forms of NH3 in METH cooking. In conclusion, it seems that mental status changes in METH abusers may be related to ammonia intoxication or HAM; therefore, it is important to assess the serum level of ammonia in METH intoxicated patients and resolve it.

Potential Effects of Nrf2 in Exercise Intervention of Neurotoxicity Caused by Methamphetamine Oxidative Stress

Methamphetamine can cause oxidative stress-centered lipid peroxidation, endoplasmic reticulum stress, mitochondrial dysfunction, excitatory neurotoxicity, and neuroinflammation and ultimately lead to nerve cell apoptosis, abnormal glial cell activation, and dysfunction of blood-brain barrier. Protecting nerve cells from oxidative destroy is a hopeful strategy for treating METH use disorder. Nrf2 is a major transcriptional regulator that activates the antioxidant, anti-inflammatory, and cell-protective gene expression through endogenous pathways that maintains cell REDOX homeostasis and is conducive to the survival of neurons. The Nrf2-mediated endogenous antioxidant pathway can also prevent neurodegenerative effects and functional defects caused by METH oxidative stress. Moderate exercise activates this endogenous antioxidant system, which involves in many diseases, including neurodegenerative diseases. Based on evidence from existing literature, we argue that appropriate exercise can play an endogenous antioxidant regulatory role in the Nrf2 signaling pathway to reduce a number of issues caused by METH-induced oxidative stress. However, more experimental evidence is needed to support this idea. In addition, further exploration is necessary about the different effects of various parameters of exercise intervention (such as exercise mode, time, and intensity) on the Nrf2 signaling pathway intervention. Whether there are synergistic effects between exercise and plant-derived Nrf2 activators is worth further investigation.

Icariside II Attenuates Methamphetamine-Induced Neurotoxicity and Behavioral Impairments via Activating the Keap1-Nrf2 Pathway

Chronic and long-term methamphetamine (METH) abuse is bound to cause damages to multiple organs and systems, especially the central nervous system (CNS). Icariside II (ICS), a type of flavonoid and one of the main active ingredients of the traditional Chinese medicine Epimedium, exhibits a variety of biological and pharmacological properties such as anti-inflammatory, antioxidant, and anticancer activities. However, whether ICS could protect against METH-induced neurotoxicity remains unknown. Based on a chronic METH abuse mouse model, we detected the neurotoxicity after METH exposure and determined the intervention effect of ICS and the potential mechanism of action. Here, we found that METH could trigger neurotoxicity, which was characterized by loss of dopaminergic neurons, depletion of dopamine (DA), activation of glial cells, upregulation of α-synuclein (α-syn), abnormal dendritic spine plasticity, and dysfunction of motor coordination and balance. ICS treatment, however, alleviated the above-mentioned neurotoxicity elicited by METH. Our data also indicated that when ICS combated METH-induced neurotoxicity, it was accompanied by partial correction of the abnormal Kelch 2 like ECH2 associated protein 1 (Keap1)-nuclear factor erythroid-2-related factor 2 (Nrf2) pathway and oxidative stress response. In the presence of ML385, an inhibitor of Nrf2, ICS failed to activate the Nrf2-related protein expression and reduce the oxidative stress response. More importantly, ICS could not attenuate METH-induced dopaminergic neurotoxicity and behavioral damage when the Nrf2 was inhibited, suggesting that the neuroprotective effect of ICS on METH-induced neurotoxicity was dependent on activating the Keap1-Nrf2 pathway. Although further research is needed to dig deeper into the actual molecular targets of ICS, it is undeniable that the current results imply the potential value of ICS to reduce the neurotoxicity of METH abusers.

The Role of Hyperthermia in Methamphetamine-Induced Depression-Like Behaviors: Protective Effects of Coral Calcium Hydride

Methamphetamine (METH) abuse causes irreversible damage to the central nervous system and leads to psychiatric symptoms including depression. Notably, METH-induced hyperthermia is a crucial factor in the development of these symptoms, as it aggravates METH-induced neurotoxicity. However, the role of hyperthermia in METH-induced depression-like behaviors needs to be clarified. In the present study, we treated mice with different doses of METH under normal (NAT) or high ambient temperatures (HAT). We found that HAT promoted hyperthermia after METH treatment and played a key role in METH-induced depression-like behaviors in mice. Intriguingly, chronic METH exposure (10 mg/kg, 7 or 14 days) or administration of an escalating-dose (2 ∼ 15 mg/kg, 3 days) of METH under NAT failed to induce depression-like behaviors. However, HAT aggravated METH-induced damage of hippocampal synaptic plasticity, reaction to oxidative stress, and neuroinflammation. Molecular hydrogen acts as an antioxidant and anti-inflammatory agent and has been shown to have preventive and therapeutic applicability in a wide range of diseases. Coral calcium hydride (CCH) is a newly identified hydrogen-rich powder which produces hydrogen gas gradually when exposed to water. Herein, we found that CCH pretreatment significantly attenuated METH-induced hyperthermia, and administration of CCH after METH exposure also inhibited METH-induced depression-like behaviors and reduced the hippocampal synaptic plasticity damage. Moreover, CCH effectively reduced the activity of lactate dehydrogenase and decreased malondialdehyde, TNF-α and IL-6 generation in hippocampus. These results suggest that CCH is an efficient hydrogen-rich agent, which has a potential therapeutic applicability in the treatment of METH abusers.

Methamphetamine mediates apoptosis of vascular smooth muscle cells via the chop-related endoplasmic reticulum stress pathway

Methamphetamine (METH) is a highly addictive amphetamine-type drug that has caused persistent harm to society and human health in recent years. Most studies have shown that METH severely damages the central nervous system, and this drug has been found to be toxic to the cardiovascular system in recent years. Therefore, we hypothesized that METH may also damage vascular smooth muscle. We examined the expression of the apoptosis-related proteins Caspase 3 and PARP after METH treatment in vivo and in vitro and detected the expression of endoplasmic reticulum stress-related proteins. After treatment with the endoplasmic reticulum stress inhibitor 4-PBA, changes in the above indicators were examined. C/EBP homologous protein (Chop) expression was also detected, and the relationship between endoplasmic reticulum stress and apoptosis was further determined by siRNA silencing of Chop. The results indicated that METH can induce apoptosis of vascular smooth muscle cells (VSMCs) and upregulate the expression of Chop and endoplasmic reticulum stress-related proteins. Chop inhibits protein kinase B phosphorylation and further inhibits forkhead box class O3a (Foxo3a) dephosphorylation, resulting in increased p53 upregulated molecular of apoptosis (PUMA) transcription. Increased PUMA induces apoptosis through the mitochondrial pathway. These results indicate that Chop is involved in the METH-induced endoplasmic reticulum stress and apoptosis in VSMCs and may be a potential therapeutic target for METH-induced VSMC injury.

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.

Antibiotics Attenuate Methamphetamine-Induced Hepatotoxicity by Regulating Oxidative Stress and TLR4/MyD88/Traf6 Axis

Methamphetamine (METH) is a major psychostimulant drug of abuse worldwide, and its neurotoxicity has been studied extensively. In addition to neurotoxicity, METH can also induce hepatotoxicity. The underlying mechanism of intestinal microorganisms in METH-induced hepatotoxicity remains unclear. In this study, mice have received antibiotics intragastrically or PBS once each day for 1 week, followed by METH or saline. The antibiotics attenuated METH-induced hepatotoxicity as evidenced by histopathological observation and biochemical analysis; furthermore, they alleviated METH-induced oxidative stress. The effect of antibiotics on METH-induced hepatotoxicity was investigated using RNA-sequencing (RNA-seq). The RNA-seq results demonstrated that antibiotics could regulate 580 differentially expressed genes (DEGs), of which 319 were upregulated after METH treatment and then downregulated with antibiotic pretreatment and 237 were first downregulated after METH administration and then upregulated after antibiotic pretreatment, in addition to 11 upregulated and 13 downregulated ones simultaneously in METH and antibiotic-pretreated groups. RNA-seq analyses revealed that TLR4 is one of the hub genes. Western blot analysis indicated that antibiotics inhibited the increase of TLR4, MyD88 and Traf6 induced by METH. This research suggests that antibiotics may play an important role in preventing METH-induced liver injury by regulating oxidative stress and TLR4/MyD88/Traf6 axis, though further investigation is required.

The Adverse Effects of Prenatal METH Exposure on the Offspring: A Review

Abuse of methamphetamine (METH), an illicit psychostimulant, is a growing public health issue. METH abuse during pregnancy is on the rise due to its stimulant, anorectic, and hallucinogenic properties. METH can lead to multiple organ toxicity in adults, including neurotoxicity, cardiovascular toxicity, and hepatotoxicity. It can also cross the placental barrier and have long-lasting effects on the fetus. This review summarizes neurotoxicity, cardiovascular toxicity, hepatotoxicity, toxicity in other organs, and biomonitoring of prenatal METH exposure, as well as the possible emergence of sensitization associated with METH. We proposed the importance of gut microbiota in studying prenatal METH exposure. There is rising evidence of the adverse effects of METH exposure during pregnancy, which are of significant concern.

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

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

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

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

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.

Luteolin alleviates methamphetamine-induced neurotoxicity by suppressing PI3K/Akt pathway-modulated apoptosis and autophagy in rats

Methamphetamine (METH) is a highly addictive stimulant that results in serious and persistent neurotoxic effects. Studies have indicated that luteolin, a flavonoid, may confer neuroprotection against neurotoxicity. Nevertheless, the effects of luteolin on METH-induced neurotoxicity have not been sufficiently verified. In the present study, Sprague Dawley rats were pretreated with luteolin (100 mg/kg) or sodium dodecyl sulfate water, followed by administration of METH (15 mg/kg) or saline. Rat striata were then collected for RNA-sequencing and subsequent analyses. A total of 347 differentially expressed genes (DEGs) were identified in the METH group with 20 pathways, including the phosphoinositol 3 kinase (PI3K)/protein kinase B (Akt), found to be enriched by the KEGG analysis. Seventy-five of the 347 DEGs were modulated in luteolin-pretreated rats, which were enriched into 12 pathways, containing the PI3K/Akt. Results further showed that luteolin pretreatment significantly repressed the METH-induced increases of PI3K, Akt, p-Akt, p53, Bax, caspase 3, normalized the ratio of p-Akt/Akt, and autophagy-related proteins (Beclin1, Atg5 and LC3-II) expression. Taken together, these findings indicate that luteolin attenuates METH-induced apoptosis and autophagy by suppressing the PI3K/Akt pathway. In this case, it exerts protection against METH-induced neurotoxicity. This provides a platform for development of potential therapies for METH treatment.

RNA-sequencing analysis of the effect of luteolin on methamphetamine-induced hepatotoxicity in rats: a preliminary study

In this study, RNA-sequencing (RNA-seq) was utilized to investigate the effects of luteolin on hepatotoxicity caused by methamphetamine (METH). The rats in METH group were administrated with METH (15 mg/kg, two times per day) via intraperitoneal (i.p.) injections for four consecutive days. The rats in luteolin + METH group were firstly administrated with luteolin (100 mg/kg, once a day) by oral gavage for 3 days before METH treatment. Lueolin attenuated the hepatotoxicity induced by METH via histopathological and biochemical analysis. The results of RNA-seq showed that luteolin could regulate 497 differentially expressed genes (DEGs), and the selected DEGs were mainly enriched in eight pathways, according to KEGG analysis. Furthermore, qRT-PCR was utilized to verify the results of RNA-seq. Six genes were selected as follows: liver enriched antimicrobial peptide 2 (Leap2), fatty acid synthase (Fasn), fatty acid binding protein 5 (Fabp5), patatin like phospholipase domain containing 3 (Pnpla3), myelin basic protein (Mbp) and calmodulin 3 (Calm3). Though because of the design flaws, the luteolin group has not been included, this study demonstrated that luteolin might exert hepato-protective effects from METH via modulation of oxidative phosphorylation, cytochrome P450 and certain signaling pathways.

ATF3 mRNA, but not BTG2, as a possible marker for vital reaction of skin contusion

The detection of vitality of wounds, especially when the wounds are inflicted very close to the time of death, is one of the most challenging issues in forensic pathology. This study investigated expression levels of ATF3 and BTG2 in mouse and human skin wounds. Protein levels examined by western blot showed that there was no significant change in ATF3 and BTG2 between wounded and intact skins. However, mRNA levels demonstrated higher expression of ATF3 and BTG2 in ante-mortem contused mouse skins, compared with the intact and postmortem contused skins. Increased ATF3 and BTG2 in the level of mRNA could also be detected until 96h and 48h after death, respectively. Human wounded skin samples from forensic autopsy cases were also examined. Increased ATF3 mRNA levels were detected until 48h after autopsy in 5 of 6 cases. However, no differences were observed between wounded and intact skins for BTG2. These findings suggest that the detection of mRNA levels of ATF3, but not BTG2, can be considered as a potential marker for vital reaction of skin contusion. Postmortem human samples should be used in order to validate the availability of markers screened by animal experiment.

METH-Induced Neurotoxicity Is Alleviated by Lactulose Pretreatment Through Suppressing Oxidative Stress and Neuroinflammation in Rat Striatum

Abuse of methamphetamine (METH) results in neurological and psychiatric abnormalities. Lactulose is a poorly absorbed derivative of lactose and can effectively alleviate METH-induced neurotoxicity in rats. The present study was designed to investigate the effects of lactulose on METH-induced neurotoxicity. Rats received METH (15 mg/kg, 8 intraperitoneal injections, 12-h interval) or saline and received lactulose (5.3 g/kg, oral gavage, 12-h interval) or vehicle 2 days prior to the METH administration. Reactive oxygen species (ROS) and malondialdehyde (MDA) were measured. Protein levels of toll-like receptor 4 (TLR4), myeloid differentiation factor 88 (MyD88), tumor necrosis factor receptor associated factor 6 (TRAF6), nuclear factor κB (NFκB), interleukin (IL)-1β, IL-6, TNF-α, cleaved caspase 3, and poly(ADP-ribose) polymerase-1 (PARP-1) were determined by western blotting. mRNA expressions of nuclear factor erythroid 2-relatted factor-2 (Nrf2), p62, and heme oxygenase-1 (HO-1) were assessed by RT-qPCR. The lactulose pretreatment decreased METH-induced cytoplasmic damage in rat livers according to histopathological observation. Compared to the control group, overproduction of ROS and MDA were observed in rat striatums in the METH alone-treated group, while the lactulose pretreatment significantly attenuated the METH-induced up-regulation of oxidative stress. The lactulose pretreatment significantly repressed over-expressions of proteins of TLR4, MyD88, TRAF6, NFκB, IL-1β, IL-6, TNF-α, cleaved caspase 3, PARP-1. The lactulose pretreatment increased mRNA expressions of Nrf2, p62, and HO-1. These findings suggest that lactulose pretreatment can alleviate METH-induced neurotoxicity through suppressing neuroinflammation and oxidative stress, which might be attributed to the activation of the Nrf2/HO-1 axis.

mTOR Modulates Methamphetamine-Induced Toxicity through Cell Clearing Systems

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

Role of CXCR1 and Interleukin-8 in Methamphetamine-Induced Neuronal Apoptosis

Methamphetamine (METH), an extremely and widely abused illicit drug, can cause serious nervous system damage and social problems. Previous research has shown that METH use causes dopaminergic neuron apoptosis and astrocyte-related neuroinflammation. However, the relationship of astrocytes and neurons in METH-induced neurotoxicity remains unclear. We hypothesized that chemokine interleukin (IL) eight released by astrocytes and C-X-C motif chemokine receptor 1 (CXCR1) in neurons are involved in METH-induced neuronal apoptosis. We tested our hypothesis by examining the changes of CXCR1 in SH-SY5Y cells and in the brain of C57BL/6 mice exposed to METH by western blotting and immunolabeling. We also determined the effects of knocking down CXCR1 expression with small interfering ribonucleic acid (siRNA) on METH-exposed SH-SY5Y cells. Furthermore, we detected the expression levels of IL-8 and the nuclear factor-kappa B (NF-κB) pathway in U87MG cells and then co-cultured the two cell types to determine the role of CXCR1 and IL-8 in neuronal apoptosis. Our results indicated that METH exposure increased CXCR1 expression both in vitro and in vivo, with the effects obtained in vitro being dose-dependent. Silencing of CXCR1 expression with siRNAs reduced the expression of cleaved caspase-3, cleaved poly (ADP-ribose) polymerase (PARP), and other related proteins. In addition, IL-8 expression and release were increased in METH-exposed U87MG cells, which is regulated by NF-κB pathway. Neuronal apoptosis was attenuated by siCXCR1 after METH treatment in the co-cultured cells, which can be reversed after exposure to recombinant IL-8. These results demonstrate that CXCR1 plays an important role in neuronal apoptosis induced by METH and may be a potential target for METH-induced neurotoxicity therapy. Highlights -Methamphetamine exposure upregulated the expression of CXCR1.-Methamphetamine exposure increased the expression of interleukin-8 through nuclear factor-kappa B pathway.-Activation of CXCR1 by interleukin-8 induces an increase in methamphetamine-related neuronal apoptosis.

The Main Molecular Mechanisms Underlying Methamphetamine- Induced Neurotoxicity and Implications for Pharmacological Treatment

Methamphetamine (METH) is a popular new-type psychostimulant drug with complicated neurotoxicity. In spite of mounting evidence on METH-induced damage of neural cell, the accurate mechanism of toxic effect of the drug on central nervous system (CNS) has not yet been completely deciphered. Besides, effective treatment strategies toward METH neurotoxicity remain scarce and more efficacious drugs are to be developed. In this review, we summarize cellular and molecular bases that might contribute to METH-elicited neurotoxicity, which mainly include oxidative stress, excitotoxicity, and neuroinflammation. We also discuss some drugs that protect neural cells suffering from METH-induced neurotoxic consequences. We hope more in-depth investigations of exact details that how METH produces toxicity in CNS could be carried out in future and the development of new drugs as natural compounds and immunotherapies, including clinic trials, are expected.