Methamphetamine administration impairs behavior, memory and underlying signaling pathways in the hippocampus

The neuroprotective effects of caffeic acid phenethyl ester against methamphetamine-induced neurotoxicity

Methamphetamine (METH) is a highly abused substance on a global scale and has the capacity to elicit toxicity within the central nervous system. The neurotoxicity induced by METH encompasses neuronal degeneration and cellular demise within the substantia nigra-striatum and hippocampus. Caffeic acid phenethyl ester (CAPE), a constituent of propolis, is a diminutive compound that demonstrates antioxidative and anti-inflammatory characteristics. Numerous investigations have demonstrated the safeguarding effects of CAPE in various neurodegenerative ailments. Our hypothesis posits that CAPE may exert a neuroprotective influence on METH-induced neurotoxicity via specific mechanisms. In order to validate the hypothesis, a series of experimental techniques including behavioral tests, immunofluorescence labeling, RNA sequencing, and western blotting were employed to investigate the neurotoxic effects of METH and the potential protective effects of CAPE. The results of our study demonstrate that CAPE effectively ameliorates cognitive memory deficits and anxiety symptoms induced by METH in mice. Furthermore, CAPE has been observed to attenuate the upregulation of neurotoxicity-associated proteins that are induced by METH exposure and also reduced the loss of hippocampal neurons in mice. Moreover, transcriptomics analysis was conducted to determine alterations in gene expression within the hippocampus of mice. Subsequently, bioinformatics analysis was employed to investigate the divergent outcomes and identify potential key genes. Interferon-stimulated gene 15 (ISG15) was successfully identified and confirmed through RT-qPCR, western blotting, and immunofluorescence techniques. Our research findings unequivocally demonstrated the neuroprotective effect of CAPE against METH-induced neurotoxicity, with ISG15 may have an important role in the underlying protective mechanism. These results offer novel perspectives on the treatment of METH-induced neurotoxicity.

Epigenome-wide association study on methamphetamine dependence

Repeated abuse of methamphetamine (METH) can cause dependence, repeated relapse of psychotic symptoms, compulsive drug-seeking behaviour, and various neurological symptoms. These long-term biological changes may be associated with epigenetic mechanisms; however, the association between METH use and epigenetic mechanisms has been poorly investigated. Thus, we performed an epigenome-wide association study of METH dependence using genomic DNA extracted from the blood samples of 24 patients with METH dependence and 24 normal controls. All participants were of Japanese descent. We tested the association between METH dependence and DNA methylation using linear regression analysis. We found epigenome-wide significant associations at four CpG sites, one of which occurred in the CNOT1 gene and another in the PUM1 gene. We especially noted the CNOT1 and PUM1 genes as well as several other genes that indicated some degree of association with METH dependence. Among the relatively enriched Gene Ontology terms, we were interested in terms of mRNA metabolism, respirasome, and excitatory extracellular ligand-gated ion channel activity. Among the relatively enriched Kyoto Encyclopedia of Genes and Genome pathways, we noted pathways of several neurological diseases. Our results indicate that genetic changes akin to those in other psychiatric or neurodegenerative disorders may also occur via epigenetic mechanisms in patients with METH dependence.

Protective effects of alpha-lipoic acid on anxiety-like behavior, memory and prevention of hippocampal oxidative stress in methamphetamine-treated rats

RATIONALE

Alpha-lipoic acid is an essential cofactor for aerobic metabolism and acts as a potent antioxidant in the body. It has been shown that acute exposure to methamphetamine induces oxidative stress, which is responsible for severe cognitive deficits in animals. The hippocampus plays a crucial role in the processing of memory and anxiety-like behavior.

OBJECTIVES

In this study, preventive effect of the alpha-lipoic acid on memory impairment in methamphetamine-induced neurotoxicity was investigated.

METHODS

Wistar male rats (200-220 g) were allocated to five groups (seven rats in each group): (1) saline + saline, (2) saline + vehicle (sunflower oil as alpha-lipoic acid solvent), (3) methamphetamine + vehicle, (4) methamphetamine + alpha-lipoic acid 10 mg/kg, and (5) methamphetamine + alpha-lipoic acid 40 mg/kg. Rats received intraperitoneal methamphetamine repeatedly (2 × 20 mg/kg, 2 h interval). Alpha-lipoic acid was injected 30 min, 24 h, and 48 h after the last injection of methamphetamine. The passive avoidance test and open field were used for evaluation of memory retrieval and anxiety, respectively. After behavioral test, rats were anesthetized, their brains were extracted, and after preparing hippocampal homogenates, malondialdehyde (MDA) level, catalase, and superoxide dismutase (SOD) activities were evaluated.

RESULTS

Statistical analysis showed that injection of saline or sunflower oil had no significant effect on anxiety, memory, or oxidative stress markers. Methamphetamine induced memory impairment, increased anxiety-like behavior and MDA level, but it reduced catalase and SOD activity. Treatment with alpha-lipoic acid decreased MDA, increased catalase and SOD activity, and also prevented memory impairment and anxiety-like behavior. Our results showed that alpha-lipoic acid protected the hippocampus from oxidative stress by elevating SOD and CAT activities and reduced memory impairment following acute methamphetamine injection. These findings suggest that alpha-lipoic acid may have a protective effect against the adverse effects of methamphetamine exposure on the hippocampus. Therefore, the current data indicated that ALA can reduce oxidative stress predominantly by its antioxidant property.

PPARγ/Adiponectin axis attenuates methamphetamine-induced conditional place preference via the hippocampal AdipoR1 signaling pathway

Methamphetamine (METH) is a highly addictive psychostimulant. The adipocyte-derived hormone adiponectin has a broad spectrum of functions in the brain. However, limited research has been conducted on the effect of adiponectin signaling on METH-induced conditioned place preference (CPP) and knowledge of the underlying neural mechanisms is scarce. The METH induced adult male C57/BL6J mice model were used for testing the therapeutic activities of intraperitoneal injection of AdipoRon or Rosiglitazone, and AdipoR1 overexpression in hippocampal dentate gyrus (DG), and chemogenetic inhibiting the neural activity of DG, and the changes of neurotrophic factors, synaptic molecules, and glutamate receptors, and inflammatory cytokines were also measured. We found that adiponectin expression was significantly reduced in METH addicted patients and mice. Our findings also showed that injection of AdipoRon or Rosiglitazone alleviated the METH-induced CPP behavior. Moreover, the expression of AdipoR1 in the hippocampus was also reduced, and AdipoR1 overexpression blocked the development of METH-induced CPP behavior through regulatory effects on neurotrophic factors, synaptic molecules, and glutamate receptors. The observed inhibitory neural activity of the hippocampal dentate gyrus (DG) induced via a chemogenetic approach produced a therapeutic effect on the METH-induced CPP behavior. Finally, we identified an abnormal expression of some key inflammatory cytokines through the PPARγ/Adiponectin/AdipoR1 axis. This study demonstrates that adiponectin signaling is a promising diagnostic and therapeutic target for METH addiction.

Compulsive methamphetamine self-administration in the presence of adverse consequences is associated with increased hippocampal mRNA expression of cellular adhesion molecules

Methamphetamine (METH) is a popular but harmful psychostimulant. METH use disorder (MUD) is characterized by compulsive and continued use despite adverse life consequences. METH users experience impairments in learning and memory functions that are thought to be secondary to METH-induced abnormalities in the hippocampus. Recent studies have reported that about 50% of METH users develop MUD, suggesting that there may be differential molecular effects of METH between the brains of individuals who met criteria for addiction and those who did not after being exposed to the drug. The present study aimed at identifying potential transcriptional differences between compulsive and non-compulsive METH self-administering male rats by measuring global gene expression changes in the hippocampus using RNA sequencing. Herein, we used a model of METH self-administration (SA) accompanied by contingent foot-shock punishment. This approach led to the separation of animals into shock-resistant rats (compulsive) that continued to take METH and shock-sensitive rats (non-compulsive) that suppressed their METH intake in the presence of punished METH taking. Rats were euthanized 2 h after the last METH SA plus foot-shock session. Their hippocampi were immediately removed, frozen, and used later for RNA sequencing and qRT-PCR analyses. RNA sequencing analyses revealed differential expression of mRNAs encoding cell adhesion molecules (CAMs) between the two rat phenotypes. qRT-PCR analyses showed significant higher levels of Cdh1, Glycam1, and Mpzl2 mRNAs in the compulsive rats in comparison to non-compulsive rats. The present results implicate altered CAM expression in the hippocampus in the behavioral manifestations of continuous compulsive METH taking in the presence of adverse consequences. Our results raise the novel possibility that altered CAM expression might play a role in compulsive METH taking and the cognitive impairments observed in MUD patients.

Nanowired Delivery of Mesenchymal Stem Cells with Antioxidant Compound H-290/51 Reduces Exacerbation of Methamphetamine Neurotoxicity in Hot Environment

Military personnel are often exposed to hot environments either for combat operations or peacekeeping missions. Hot environment is a severe stressful situation leading to profound hyperthermia, fatigue and neurological impairments. To avoid stressful environment, some people frequently use methamphetamine (METH) or other psychostimulants to feel comfortable under adverse situations. Our studies show that heat stress alone induces breakdown of the blood-brain barrier (BBB) and edema formation associated with reduced cerebral blood flow (CBF). On the other hand, METH alone induces hyperthermia and neurotoxicity. These effects of METH are exacerbated at high ambient temperatures as seen with greater breakdown of the BBB and brain pathology. Thus, a combination of METH use at hot environment may further enhance the brain damage-associated behavioral dysfunctions. METH is well known to induce severe oxidative stress leading to brain pathology. In this investigation, METH intoxication at hot environment was examined on brain pathology and to explore suitable strategies to induce neuroprotection. Accordingly, TiO₂-nanowired delivery of H-290/51 (150 mg/kg, i.p.), a potent chain-breaking antioxidant in combination with mesenchymal stem cells (MSCs), is investigated in attenuating METH-induced brain damage at hot environment in model experiments. Our results show that nanodelivery of H-290/51 with MSCs significantly enhanced CBF and reduced BBB breakdown, edema formation and brain pathology following METH exposure at hot environment. These observations are the first to point out that METH exacerbated brain pathology at hot environment probably due to enhanced oxidative stress, and MSCs attenuate these adverse effects, not reported earlier.

Endocannabinoids and addiction memory: Relevance to methamphetamine/morphine abuse

AIM

This review aims to summarise the role of endocannabinoid system (ECS), incluing cannabinoid receptors and their endogenous lipid ligands in the modulation of methamphetamine (METH)/morphine-induced memory impairments.

METHODS

Here, we utilized the results from researches which have investigated regulatory role of ECS (including cannabinoid receptor agonists and antagonists) on METH/morphine-induced memory impairments.

RESULTS

Among the neurotransmitters, glutamate and dopamine seem to play a critical role in association with the ECS to heal the drug-induced memory damages. Also, the amygdala, hippocampus, and prefrontal cortex are three important brain regions that participate in both drug addiction and memory task processes, and endocannabinoid neurotransmission have been investigated.

CONCLUSION

ECS can be regarded as a treatment for the side effects of METH and morphine, and their memory-impairing effects.

Common and distinguishing genetic factors for substance use behavior and disorder: an integrated analysis of genomic and transcriptomic studies from both human and animal studies

BACKGROUND AND AIMS

Genomic and transcriptomic findings greatly broaden the biological knowledge regarding substance use. However, systematic convergence and comparison evidence of genome-wide findings is lacking for substance use. Here, we combined all the genome-wide findings from both substance use behavior and disorder (SUBD) and identified common and distinguishing genetic factors for different SUBDs.

METHODS

Systemic literature search for genome-wide association (GWAS) and RNA-seq studies of alcohol/nicotine/drug use behavior (partially meets or not reported diagnostic criteria) and alcohol use behavior and disorder (AUBD), nicotine use behavior and disorder (NUBD) and drug use behavior and disorder (DUBD) was performed using PubMed and the GWAS catalog. Drug use was focused upon cannabis, opioid, cocaine and methamphetamine use. GWAS studies required case-control or case/cohort samples. RNA-seq studies were based on brain tissues. The genes which contained significant single nucleotide polymorphism (P ≤ 1 × 10^-6 ) in GWAS and reported as significant in RNA-seq studies were extracted. Pathway enrichment was performed by using Metascape. Gene interaction networks were identified by using the Protein Interaction Network Analysis database.

RESULTS

Total SUBD-related 2910 genes were extracted from 75 GWAS studies (2 773 889 participants) and 17 RNA-seq studies. By overlapping the genes and pathways of AUBD, NUBD and DUBD, four shared genes (CACNB2, GRIN2B, PLXDC2 and PKNOX2), four shared pathways [two Gene Ontology (GO) terms of 'modulation of chemical synaptic transmission', 'regulation of trans-synaptic signaling', two Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways of 'dopaminergic synapse', 'cocaine addiction'] were identified (significantly higher than random, P < 1 × 10^-5 ). The top shared KEGG pathways (Benjamini-Hochberg-corrected P-value < 0.05) in the pairwise comparison of AUBD versus DUBD, NUBD versus DUBD, AUBD versus NUBD were 'Epstein-Barr virus infection', 'protein processing in endoplasmic reticulum' and 'neuroactive ligand-receptor interaction', respectively. We also identified substance-specific genetic factors: i.e. ADH1B and ALDH2 were unique for AUBD, while CHRNA3 and CHRNA4 were unique for NUBD.

CONCLUSIONS

This systematic review identifies the shared and unique genes and pathways for alcohol, nicotine and drug use behaviors and disorders at the genome-wide level and highlights critical biological processes for the common and distinguishing vulnerability of substance use behaviors and disorders.

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

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

Substance use, microbiome and psychiatric disorders

Accumulating evidence from several studies has shown association between substance use, dysregulation of the microbiome and psychiatric disorders such as depression, anxiety, and psychosis. Many of the abused substances such as cocaine and alcohol have been shown to alter immune signaling pathways and cause inflammation in both the periphery and the central nervous system (CNS). In addition, these substances of abuse also alter the composition and function of the gut microbiome which is known to play important roles such as the synthesis of neurotransmitters and metabolites, that affect the CNS homeostasis and consequent behavioral outcomes. The emerging interactions between substance use, microbiome and CNS neurochemical alterations could contribute to the development of psychiatric disorders. This review provides an overview of the associative effects of substance use such as alcohol, cocaine, methamphetamine, nicotine and opioids on the gut microbiome and psychiatric disorders involving anxiety, depression and psychosis. Understanding the relationship between substance use, microbiome and psychiatric disorders will provide insights for potential therapeutic targets, aimed at mitigating these adverse outcomes.

Cannabidiol inhibits methamphetamine-induced dopamine release via modulation of the DRD1-MeCP2-BDNF-TrkB signaling pathway

RATIONALE

Adaptive alteration of dopamine (DA) system in mesocorticolimbic circuits is an extremely intricate and dynamic process, which contributes to maintaining methamphetamine (METH)-related disorders. There are no approved pharmacotherapies for METH-related disorders. Cannabidiol (CBD), a major non-psychoactive constituent of cannabis, has received attention for its therapeutic potential in treating METH-related disorders. However, the major research obstacles of CBD are the yet to be clarified mechanisms behind its therapeutic potential. Recent evidence showed that DA system may be active target of CBD. CBD could be a promising dopaminergic medication for METH-related disorders.

OBJECTIVES

We investigated the role of the DA receptor D1 (DRD1)-methyl-CpG-binding protein 2 (MeCP2)-brain-derived neurotrophic factor (BDNF)-tyrosine receptor kinase B (TrkB) signaling pathway in DA release induced by METH. Investigating the intervention effects of CBD on the DRD1-MeCP2-BDNF-TrkB signaling pathway could help clarify the underlying mechanisms and therapeutic potential of CBD in METH-related disorders.

RESULTS

METH (400 μM) significantly increased DA release from primary neurons in vitro, which was blocked by CBD (1 μM) pretreatment. METH (400 μM) significantly increased the expression levels of DRD1, BDNF, and TrkB, but decreased the expression of MeCP2 in the neurons, whereas CBD (1 μM) pretreatment notably inhibited the protein changes induced by METH. In addition, DRD1 antagonist SCH23390 (10 μM) inhibited the DA release and protein change induced by METH in vitro. However, DRD1 agonist SKF81297 (10 μM) induced DA release and protein change in vitro, which was also blocked by CBD (1 μM) pretreatment. METH (2 mg/kg) significantly increased the DA level in the nucleus accumbens (NAc) of rats with activation of the DRD1-MeCP2-BDNF-TrkB signaling pathway, but these changes were blocked by CBD (40 or 80 mg/kg) pretreatment.

CONCLUSIONS

This study indicates that METH induces DA release via the DRD1-MeCP2-BDNF-TrkB signaling pathway. Furthermore, CBD significantly inhibits DA release induced by METH through modulation of this pathway.

Quercetin Mitigates Methamphetamine-Induced Anxiety-Like Behavior Through Ameliorating Mitochondrial Dysfunction and Neuroinflammation

Methamphetamine (MA) abuse results in neurotoxic outcomes, including increased anxiety and depression. Studies have reported an association between MA exposure and anxiety, nonetheless, the underlying mechanism remains elusive. In the present study, we developed a mouse model of anxiety-like behavior induced by MA administration. RNA-seq was then performed to profile the gene expression patterns of hippocampus (HIPP), and the differentially expressed genes (DEGs) were significantly enriched in signaling pathways related to psychiatric disorders and mitochondrial function. Based on these, mitochondria was hypothesized to be involved in MA-induced anxiety. Quercetin, as a mitochondrial protector, was used to investigate whether to be a potential treatment for MA-induced anxiety; accordingly, it alleviated anxiety-like behavior and improved mitochondrial impairment in vivo. Further experiments in vitro suggested that quercetin alleviated the dysfunction and morphological abnormalities of mitochondria induced by MA, via decreasing the levels of reactive oxygen species (ROS), mitochondrial membrane potential (MMP), and increasing the oxygen consumption rate (OCR) and ATP production. Moreover, the study examined the effect of quercetin on astrocytes activation and neuroinflammation, and the results indicated that it significantly attenuated the activation of astrocytes and reduced the levels of IL-1β, TNFα but not IL-6. In light of these findings, quantitative evidence is presented in the study supporting the view that MA can evoke anxiety-like behavior via the induction of mitochondrial dysfunction. Quercetin exerted antipsychotic activity through modulation of mitochondrial function and neuroinflammation, suggesting its potential for further therapeutic development in MA-induced anxiety.

Natural Products in Modulating Methamphetamine-Induced Neuronal Apoptosis

Methamphetamine (METH), an amphetamine-type psychostimulant, is highly abused worldwide. Chronic abuse of METH causes neurodegenerative changes in central dopaminergic neurons with numerous neuropsychiatric consequences. Neuronal apoptosis plays a critical role in METH-induced neurotoxicity and may provide promising pharmacological targets for preventing and treating METH addiction. In recent years, accumulating evidence has revealed that natural products may possess significant potentials to inhibit METH-evoked neuronal apoptosis. In this review, we summarized and analyzed the improvement effect of natural products on METH-induced neuronal apoptosis and their potential molecular mechanisms on modulating dopamine release, oxidative stress, mitochondrial-dependent apoptotic pathway, endoplasmic reticulum stress-mediated apoptotic pathway, and neuroinflammation. Hopefully, this review may highlight the potential value of natural products in modulating METH-caused neuronal apoptosis and provide useful information for future research and developments of novel and efficacious pharmacotherapies in this field.

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.

Electroacupuncture alleviates spatial memory deficits in METH withdrawal mice by enhancing astrocyte-mediated glutamate clearance in the dCA1

Methamphetamine (METH) elicits endogenous glutamate (Glu) in the brain, which could partially explain METH-induced memory deficits. Here, we investigated the therapeutic effects of electroacupuncture (EA) on spatial memory deficits in METH withdrawal mice and its potential synaptic mechanisms. We found that EA at acupoints 'Baihui' and 'Yintang' ameliorated the impaired spatial memory in METH withdrawal mice. In parallel, EA attenuated the Glu levels in vivo and suppressed the neuronal activities within dCA1 of METH withdrawal mice, as indicated by the decreasing c-Fos levels and the amplitude of mEPSP. In the dCA1, EA decreased A1-like astrocytes but increased astrocytic glutamatergic transporting molecules including glutamate transporter 1 and glutamine synthase. However, EA seemed to have no effects on presynaptic Glu transmission from the dCA3, as evidenced by the similiar levels of c-Fos in the dCA3 neurons, synaptic vesicular markers of dCA3 neural terminals and values of paired-pulse ratio in the dCA1 neurons between EA-treated and sham EA-treated METH withdrawal mice. These findings suggest that EA might normalize the dCA1 Glu levels at least in part through enhancing astrocyte-mediated Glu clearance. Taken together, astrocytes might be a novel target for developing therapeutic interventions against the impaired memory behaviours in METH users, and EA represents a promising non-invasive therapeutic strategy for the management of drug-caused memory deficits.

Combined molecular, structural and memory data unravel the destructive effect of tramadol on hippocampus

Tramadol is a synthetic analogue of codeine and stimulates neurodegeneration in several parts of the brain that leads to various behavioral impairments. Despite the leading role of hippocampus in learning and memory as well as decreased function of them under influence of tramadol, there are few studies analyzing the effect of tramadol administration on gene expression profiling and structural consequences in hippocampus region. Thus, we sought to determine the effect of tramadol on both PC12 cell line and hippocampal tissue, from gene expression changes to structural alterations. In this respect, we investigated genome-wide mRNA expression using high throughput RNA-seq technology and confirmatory quantitative real-time PCR, accompanied by stereological analysis of hippocampus and behavioral assessment following tramadol exposure. At the cellular level, PC12 cells were exposed to 600μM tramadol for 48 hrs, followed by the assessments of ROS amount and gene expression levels of neurotoxicity associated with neurodegenerative pathways such as apoptosis and autophagy. Moreover, the structural and functional alteration of the hippocampus under chronic exposure to tramadol was also evaluated. In this regard, rats were treated with tramadol at doses of 50 mg/kg for three consecutive weeks. In vitro data revealed that tramadol provoked ROS production and caused the increase in the expression of autophagic and apoptotic genes in PC12 cells. Furthermore, in-vivo results demonstrated that tramadol not only did induce hippocampal atrophy, but it also triggered microgliosis and microglial activation, causing upregulation of apoptotic and inflammatory markers as well as over-activation of neurodegeneration. Tramadol also interrupted spatial learning and memory function along with long-term potentiation (LTP). Taken all together, our data disclosed the neurotoxic effects of tramadol on both in vitro and in-vivo. Moreover, we proposed a potential correlation between disrupted biochemical cascades and memory deficit under tramadol administration.

Krill Oil Alleviated Methamphetamine-Induced Memory Impairment via the MAPK Signaling Pathway and Dopaminergic Synapse Pathway

Methamphetamine (METH) abuse exerts severe harmful effects in multiple organs, especially the brain, and can induce cognitive dysfunction and memory deficits in humans. Krill oil is rich in polyunsaturated fatty acids, while its effect on METH-induced cognitive impairment and mental disorders, and the underlying mechanism remain unknown. The aim of the present study was to investigate the protective effect of krill oil on METH-induced memory deficits and to explore the molecular mechanisms by using an integrated strategy of bioinformatics analysis and experimental verification. METH-exposed mice were treated with or without krill oil. Learning and memory functions were evaluated by the Morris water maze. The drug–component–target network was constructed in combination with network pharmacology. The predicted hub genes and pathways were validated by the Western blot technique. With krill oil treatment, memory impairment induced by METH was significantly improved. 210 predicted targets constituted the drug–compound–target network by network pharmacology analysis. 20 hub genes such as DRD2, MAPK3, CREB, BDNF, and caspase-3 were filtered out as the underlying mechanisms of krill oil on improving memory deficits induced by METH. The KEGG pathway and GO enrichment analyses showed that the MAPK signaling pathway, cAMP signaling pathway, and dopaminergic synapse pathway were involved in the neuroprotective effects of krill oil. In the hippocampus, DRD2, cleaved caspase-3, and γ-H2AX expression levels were significantly increased in the METH group but decreased in the krill oil–treated group. Meanwhile, krill oil enhanced the expressions of p-PKA, p-ERK1/2, and p-CREB. Our findings suggested that krill oil improved METH-induced memory deficits, and this effect may occur via the MAPK signaling pathway and dopaminergic synapse pathways. The combination of network pharmacology approaches with experimental validation may offer a useful tool to characterize the molecular mechanism of multicomponent complexes.

Methamphetamine abuse disturbs the dopaminergic system to impair hippocampal-based learning and memory: An overview of animal and human investigations

Diverse intellectual functions including memory are some important aspects of cognition. Dopamine is a neurotransmitter of the catecholamine family, which contributes to the experience of pleasure and/or emotional states but also plays crucial roles in learning and memory. Methamphetamine is an illegal drug, the abuse of which leads to long lasting pathological manifestations in the brain. Chronic methamphetamine-induced neurotoxicity results in an alteration of various parts of the memory systems by affecting learning processes, an effect attributed to the structural similarities of this drug with dopamine. An evolving field of research established how cognitive deficits in abusers arise and how they could possibly trigger neurodegenerative disorders. Thus, the drugs-induced tenacious neurophysiological changes of the dopamine system trigger cognitive deficits, thereby affirming the influence of this addictive drug on learning, memory and executive function in human abusers. Here we present an overview of the effects of methamphetamine abuse on cognitive functions, dopaminergic transmission and hippocampal integrity as they have been validated in animals and in humans during the past 20 years.

Tetrahydropalmatine Regulates BDNF through TrkB/CAM Interaction to Alleviate the Neurotoxicity Induced by Methamphetamine

Tetrahydropalmatine (THP) has analgesic, hypnotic, sedative, and other pharmacological effects. Brain-derived neurotrophic factor (BDNF) plays an important role in neuronal plasticity, growth, and development. However, their mechanism of action in methamphetamine (MA)-induced neurotoxicity remains unclear. This study aims to explore the important role of BDNF in MA neurotoxicity and whether THP can regulate BDNF through the interaction between tyrosine kinase receptor B (TrkB)/calmodulin (CAM) to alleviate the neurotoxicity induced by MA. SD rats were randomly divided into control, MA, and MA + THP groups. Stereotyped behavior test, captive rejection test, open field test (OFT), and Morris water maze (MWM) were used to evaluate the anxiety, aggression, cognition, learning, and memory. Extracted hippocampus and mesencephalon tissue were detected by Western blot, HE staining, and immunohistochemistry. TUNEL staining was used to detect apoptosis. MOE was used for bioinformatics prediction, and coimmunoprecipitation was used to confirm protein interactions. Long-term abuse of MA resulted in lower weight gain ratio and nerve cell damage and caused various neurotoxicity-related behavioral abnormalities: anxiety, aggression, cognitive motor disorders, and learning and memory disorders. MA-induced neurotoxicity is related to the down-regulation of BDNF and apoptosis. THP attenuated the MA-induced neurotoxicity by decreasing CAM, increasing TrkB, phosphorylating Akt, up-regulating NF-κB and BDNF, and inhibiting cell apoptosis. MA can induce neurotoxicity in rats. BDNF may play a vital role in MA-induced neurotoxicity. THP regulates BDNF through TrkB/CAM interaction to alleviate the neurotoxicity induced by MA. THP may be a potential therapeutic drug for the neurotoxic and neurodegenerative diseases related to MA.

Effects of Aerobic Exercise on Cognitive Function in Women With Methamphetamine Dependence in a Detoxification Program in Tianjin, China: A Randomized Controlled Trial

BACKGROUND

Cognitive impairment is prevalent among individuals, especially women, with methamphetamine dependence. Although aerobic exercise has been shown to affect cognitive function in humans and animals, few related studies have focused on subjects with methamphetamine dependence.

PURPOSE

The aim of this study was to assess the detoxification-related effects of aerobic exercise on cognitive function in women with methamphetamine dependence.

METHODS

A randomized controlled trial was used with 98 women with methamphetamine dependence undergoing a detoxification program at a mental hospital. The women were distributed using a computer-generated grouping random method into either the study or control group. The investigator conducting the baseline questionnaire, the neuropsychologist assessing the cognitive function, and the data analyst were blinded to group assignment. In addition to hospital routine care, the study group received an aerobic exercise intervention for 3 months. The control group only received hospital routine care. Attention and working memory were measured using the Trail Making Test and Digit Span Test, verbal memory was measured using Logical Memory (LM) and Memory for Persons Data (MPD), and executive function was measured using the Color-Word Stroop Test.

RESULTS

Forty-nine participants were randomized into each group, and the valid data of 43 participants in the study group and 46 in the control group were analyzed. The study group showed significantly more improvement over time in terms of Digit Span Test, Trail Making Test, LM-delayed, MPD-5 minutes delayed, MPD-30 minutes delayed, and Color-Word Stroop Test than the control group (p < .05). LM-immediate and MPD-immediate scores showed that the effects of time and the interaction between time and group were significant but that the main effect of group was not.

CONCLUSIONS/IMPLICATIONS FOR PRACTICE

Women undergoing detoxification for methamphetamine dependence may practice aerobic exercise to improve attention, working memory, executive function, and parts of verbal memory. Aerobic exercise may be incorporated into detoxification treatment programs to facilitate the recovery of cognitive functions in women.

Astrocyte-selective STAT3 knockdown rescues methamphetamine withdrawal-disrupted spatial memory in mice via restoring the astrocytic capacity of glutamate clearance in dCA1

Methamphetamine (METH) is a common abused drug. METH-triggered glutamate (Glu) levels in dorsal CA1 (dCA1) could partially explain the etiology of METH-caused abnormal memory, but the synaptic mechanism remains unclear. Here, we found that METH withdrawal disrupted spatial memory in mice, accompanied by the increases in Glu levels and postsynaptic neuronal activities at dCA1 synapses. METH withdrawal weakened the capacity of Glu clearance in astrocytes, as indicated by increasing the A1-like astrocytes and phosphorylated signal transducer and activator of transcription 3 (p-STAT3), decreasing the Glu transporter 1(GLT-1, also known as EAAT2 or SLC1A2), Glu-aspartate-transporter (GLAST also known as EAAT1 or SLC1A3) and astrocytic glutamine synthase (GS), but failed to affect the presynaptic Glu release from dCA3 within dCA1. Moreover, we identified that in vitro A1-like astrocytes exhibited an increased STAT3 activation and the impaired capacity of Glu clearance. Most importantly, selective knockdown of astrocytic STAT3 in vivo in dCA1 restored the astrocytic capacity of Glu clearance, normalized Glu levels at dCA1 synapses, and finally rescued METH withdrawal-disrupted spatial memory in mice. Thus, astrocytic Glu clearance system, especially STAT3, serves as a novel target for future therapies against METH neurotoxicity.

Pixel-Wise Classification in Hippocampus Histological Images

This paper presents a method for pixel-wise classification applied for the first time on hippocampus histological images. The goal is achieved by representing pixels in a 14-D vector, composed of grey-level information and moment invariants. Then, several popular machine learning models are used to categorize them, and multiple metrics are computed to evaluate the performance of the different models. The multilayer perceptron, random forest, support vector machine, and radial basis function networks were compared, achieving the multilayer perceptron model the highest result on accuracy metric, AUC, and F ₁ score with highly satisfactory results for substituting a manual classification task, due to an expert opinion in the hippocampus histological images.

The role of Tetrahydrocannabinol in inducing disrupted signaling cascades, hippocampal atrophy and memory defects

Tetrahydrocannabinol (THC), a major psychoactive constituent of marijuana, can substantially change the function of several brain areas, leading to behavioral impairment including memory and learning dysfunction. Given the importance of hippocampus as one of the chief parts of the brain involved in memory processing, the present study seeks to investigate structural and histological alterations in hippocampus as well as behavioral defects provoked by THC treatment. Besides, using genome-wide sequencing, we adopted a pathway-based approach to discover dysregulated molecular pathways. Our results demonstrated remarkable hippocampal atrophy, and also interrupted memory function and long term potentiation (LTP) under THC exposure. We also detected several dysregulated signaling pathways involved in synaptic plasticity as well as cell-cell interaction in the hippocampus of THC-treated rats. Overall, the results indicate a potential correlation between disrupted signaling cascades, hippocampal atrophy and memory defects caused by THC treatment.

Melatonin reverts methamphetamine-induced learning and memory impairments and hippocampal alterations in mice

AIMS

Methamphetamine (METH) has become a major public health problem because of its abuse and profound neurotoxic effects, causing alterations in brain structure and function, and impairing cognitive functions, including attention, decision making, emotional memory, and working memory. This study aimed to determine whether melatonin (MEL), the circadian-control hormone, which has roles beyond circadian rhythm regulation, could restore METH-induced cognitive and neuronal impairment.

MAIN METHODS

Mice were treated with either METH (1 mg/kg) or saline for 7 days, followed by MEL (10 mg/kg) or saline for another 14 days. The Morris water maze (MWM) test was performed one day after the last saline or MEL injection. The hippocampal neuronal density, synaptic density, and receptors involved in learning and memory, along with downstream signaling molecules (NMDA receptor subunits GluN2A, GluN2B, and CaMKII) were investigated by immunoblotting.

KEY FINDINGS

METH administration significantly extended escape latency in learning phase and reduced the number of target crossings in memory test-phase as well as decreased the expression of BDNF, NMDA receptors, TrkB receptors, CaMKII, βIII tubulin, and synaptophysin. MEL treatment significantly ameliorated METH-induced increased escape latency, decreased the number of target crossings and decreased expression of BDNF, NMDA receptors, TrkB receptors, CaMKII, βIII tubulin and synaptophysin.

SIGNIFICANCE

METH administration impairs learning and memory in mice, and MEL administration restores METH-induced neuronal impairments which is probably through the changes in BDNF, NMDA receptors, TrkB receptors, CaMKII, βIII tubulin and synaptophysin. Therefore, MEL is potentially an innovative and promising treatment for learning and memory impairment of humans.

Neuroanatomical changes of the medial prefrontal cortex of male pups of Wistar rat after prenatal and postnatal noise stress

Recent evidences showed that, noise stress causes abnormal changes in structure and function of central nervous system (CNS). The Current study was conducted to evaluate some stereological parameters of the medial prefrontal cortex (mPFC) of male pups of Wistar rat after prenatal and early postnatal noise stress. 18 pregnant Wistar rats were randomly divided into prenatal noise-exposed (NE) group, postnatal NE group, and controls. Male pups of NE groups were exposed to noise 100 dB at the frequency ranges of 500-8000 Hz, 4 h per day from gestational day one (GD1) to GD21 for the prenatal NE group, and from postnatal day one (PND1) to PND21 in the postnatal NE group. The Control group animals were maintained under standard condition without noise stimulation. Corticosterone level in plasma was measured using ELISA technique. Changes of the neurons and non-neurons cells number and volume of the mPFC were evaluated by stereological analysis. Tunnel assay was also used for detection of apoptotic cells. Increase in plasma corticosterone level, decrease in the number of neurons, and increase in the apoptotic cells number were observed in both NE groups. Decrease in volume of mPFC and also in non-neurons cells number was observed in the prenatal NE group. An increase in the non-neurons number was seen in the postnatal NE group. Data of the current comparative study showed that, noise stress during prenatal and early postnatal periods can induce the abnormal alteration in some stereological parameters of mPFC in male pups of Wistar rat. These negative alterations were more remarkable after prenatal noise stress.

Curcumin-loaded lipid-core nanocapsules attenuates the immune challenge LPS-induced in rats: Neuroinflammatory and behavioral response in sickness behavior

The purpose of current study was to evaluate the effect of curcumin (CUR) loaded lipid-core nanocapsules (CUR-LNC) treatment on neuroinflammatory and behavioral alterations in a model of sickness behavior induced by lipopolysaccharide (LPS) in rats. Rats were treated with CUR-LNC and CUR daily for 14 days. After the last treatments, sickness behavior was induced with LPS. Sickness behavior LPS-induced was confirmed by behavioral tests, an increase in levels of proinflammatory cytokines, decrease in levels of IL-10, overexpression of IDO-1 and IDO-2. In conclusion, CUR-LNC treatment attenuated the neuroinflammatory and behavioral changes caused in sickness behavior model.

Tramadol: a Potential Neurotoxic Agent Affecting Prefrontal Cortices in Adult Male Rats and PC-12 Cell Line

Tramadol is a synthetic analogue of codeine that is often prescribed for the treatment of mild to moderate pains. It has a number of side effects including emotional instability and anxiety. In this study, we focus on the structural and functional changes of prefrontal cortex under chronic exposure to tramadol. At the cellular level, the amounts of ROS and annexin V in PC12 cells were evidently increased upon exposure to tramadol (at a concentration of 600 μM for 48 h). To this end, the rats were daily treated with tramadol at doses of 50 mg/kg for 3 weeks. Our findings reveal that tramadol provokes atrophy and apoptosis by the induction of apoptotic markers such as Caspase 3 and 8, pro-inflammatory markers, and downregulation of GDNF. Moreover, it triggers microgliosis and astrogliosis along with neuronal death in the prefrontal cortex. Behavioral disturbance and cognitive impairment are other side effects of tramadol. Overall, our results indicate tramadol-induced neurodegeneration in the prefrontal cortex mainly through activation of neuroinflammatory response.