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

Sequential pesticide exposure: Concentration addition at high concentrations - Inhibition of hormesis at ultra-low concentrations

Sequential pesticide exposure is a common scenario in both aquatic and terrestrial agricultural ecosystems. Predicting the effects of such exposures is therefore highly relevant for improving risk assessment. However, there is currently no information available for predicting the effects of sequential exposure to the same toxicant at both high and low concentrations. Here we exposed one-week-old individuals of Daphnia magna to the pyrethroid Esfenvalerate for 24 h and compared the effects with individuals treated twice with half the concentration after 7 and 14 days. We showed that at the concentrations close to the LC50, both the survival and population growth rate from the two half-pulses were consistent with the concentration addition approach. At low (1/10th to 1/100th of the LC50) and ultra-low concentrations (1/100th to 1/1000th of the LC50), survival was around 100 %, while the population growth rate showed a hormetic increase following the one-pulse exposure but not for the two-pulse exposure. We hypothesize that this hormetic effect is due to lower systemic stress (SyS) after pesticide exposure in combination with only one rebound stress pulse. Our study suggests that while the lethal effects of sequential exposure are according to the concentration addition model, the sublethal effects at low and ultra-low concentrations need to consider hormetic effects.

Intrarenal Dopaminergic System Is Dysregulated in SS-Resp18mutant Rats

The genetic and molecular basis of developing high blood pressure and renal disease are not well known. Resp18mutant Dahl salt-sensitive (SS-Resp18mutant) rats fed a 2% NaCl diet for six weeks have high blood pressure, increased renal fibrosis, and decreased mean survival time. Impairment of the dopaminergic system also leads to hypertension that involves renal and non-renal mechanisms. Deletion of any of the five dopamine receptors may lead to salt-sensitive hypertension. Therefore, we investigated the interaction between Resp18 and renal dopamine in SS-Resp18mutant and Dahl salt-sensitive (SS) rats. We found that SS-Resp18mutant rats had vascular dysfunction, as evidenced by a decrease in vasorelaxation in response to sodium nitroprusside. The pressure-natriuresis curve in SS-Resp18mutant rats was shifted down and to the right of SS rats. SS-Resp18mutant rats had decreased glomerular filtration rate and dopamine receptor subtypes, D1R and D5R. Renal dopamine levels were decreased, but urinary dopamine levels were increased, which may be the consequence of increased renal dopamine production, followed by secretion into the tubular lumen. The increased renal dopamine production in SS-Resp18mutant rats in vivo was substantiated by the increased dopamine production in renal proximal tubule cells treated with L-DOPA. Overall, our study provides evidence that targeted disruption of the Resp18 locus in the SS rat dysregulates the renal dopaminergic system.

Sex-specific metabolic signatures in methamphetamine addicts

Methamphetamine (METH) is a commonly abused addictive psychostimulant, and METH-induced neurotoxic and behavioural deficits are in a sex-specific manner. However, there is lack of biomarkers to evaluate METH addiction in clinical practice, especially for gender differences. We utilized ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) to detect the serum metabolomics in METH addicts and controls, specially exploring the sex-specific metabolic alterations by METH abuse. We found that many differently expressed metabolites in METH addicts related to metabolisms of amino acid, energy, vitamin and neurological disorders. Further, METH abuse caused different patterns of metabolomics in a sex-specific manner. As to amino acid metabolism, L-phenylalanine, L-tryptophan and L-histidine in serum of male addicts and betaine in serum of female addicts were significantly changed by METH use. In addition, it seemed that purine and pyrimidine-related metabolites (e.g., xanthosine and adenosine 5'-monophosphate) in male and the metabolites of hormone (e.g., cortisol) and folate biosynthesis (e.g., 7,8-dihydrobiopterin and 4-hydroxybenzoic acid) in female were more sensitive to METH addiction. Our findings revealed that L-glutamic acid, L-aspartic acid, alpha-ketoglutarate acid and citric acid may be potential biomarkers for monitoring METH addiction in clinic. Considering sex-specific toxicity by METH, the metabolites of purine and pyrimidine metabolism in male and those of stress-related hormones in female may be used to facilitate the accurate diagnosis and treatment for METH addicts of different genders.

Sex Differences in Psychostimulant Abuse: Implications for Estrogen Receptors and Histone Deacetylases

Substance abuse is a chronic pathological disorder that negatively affects many health and neurological processes. A growing body of literature has revealed gender differences in substance use. Compared to men, women display distinct drug-use phenotypes accompanied by recovery and rehabilitation disparities. These observations have led to the notion that sex-dependent susceptibilities exist along the progression to addiction. Within this scope, neuroadaptations following psychostimulant exposure are thought to be distinct for each sex. This review summarizes clinical findings and animal research reporting sex differences in the subjective and behavioral responses to cocaine, methamphetamine, and nicotine. This discussion is followed by an examination of epigenetic and molecular alterations implicated in the addiction process. Special consideration is given to histone deacetylases and estrogen receptor-mediated gene expression.

Sex-Specific Alterations in Dopamine Metabolism in the Brain after Methamphetamine Self-Administration

Methamphetamine (METH) use disorder affects both sexes, with sex differences occurring in behavioral, structural, and biochemical consequences. The molecular mechanisms underlying these differences are unclear. Herein, we used a rat model to identify potential sex differences in the effects of METH on brain dopaminergic systems. Rats were trained to self-administer METH for 20 days, and a cue-induced drug-seeking test was performed on withdrawal days 3 and 30. Dopamine and its metabolites were measured in the prefrontal cortex (PFC), nucleus accumbens (NAc), dorsal striatum (dSTR), and hippocampus (HIP). Irrespective of conditions, in comparison to females, male rats showed increased 3,4-dihydroxyphenylalanine (DOPA) in the PFC, dSTR, and HIP; increased cys-dopamine in NAc; and increased 3,4-dihydroxyphenylethanol (DOPET) and 3,4-dihydroxyphenylacetic acid (DOPAC) in dSTR. Males also showed METH-associated decreases in DA levels in the HIP but increases in the NAc. Female rats showed METH-associated decreases in DA, DOPAL, and DOPAC levels in the PFC but increases in DOPET and DOPAC levels in the HIP. Both sexes showed METH-associated decreases in NAc DA metabolites. Together, these data document sex differences in METH SA-induced changes in DA metabolism. These observations provide further support for using sex as an essential variable when discussing therapeutic approaches against METH use disorder in humans.

Serum Metabolomic Analysis of Male Patients with Cannabis or Amphetamine Use Disorder

Studies have demonstrated that chronic consumption of abused drugs induces alterations in several proteins that regulate metabolism. For instance, methamphetamine exposure reduces glucose levels. Fatty and amino acid levels were altered in groups exposed to abused drugs. Therefore, in our study, we investigated the serum metabolomic profile of patients diagnosed with cannabis and/or amphetamine use disorders. Blood was obtained from subjects (control, amphetamine, and cannabis). Detection of serum metabolites was performed using gas chromatography. The ratio peak areas for metabolites were analyzed across the three groups. Both cannabis and amphetamine groups showed higher d-erythrotetrafuranose, octadecanoic acid, hexadecenoic acid, trans-9-octadecanoic acid, lactic acid and methyl thio hydantoin metabolites compared with the control group. Moreover, cannabis patients were found to possess higher glycine, 9,12 octadecanoic acid malonic acid, phosphoric acid and prostaglandin F1a than controls. Our analysis showed that the identified metabolic profile of cannabis or amphetamine use disorder patients was different than control group. Our data indicated that chronic exposure to cannabis or amphetamine dysregulated metabolites in the serum. Future studies are warranted to explore the effects of these abused drugs on the metabolic proteins.

The distinct roles of various neurotransmitters in modulating methamphetamine-induced conditioned place preference in relevant brain regions in mice

OBJECTIVES

Previous studies have shown that methamphetamine (METH) can induce complex adaptive changes in the reward system in the brain, including the changes in the content of neurotransmitters in the signal transduction pathway. However, how the changes of various neurotransmitters in relevant brain reward circuits contribute to METH-induced conditioned place preference (CPP) remains unclear.

METHODS

In this study, first, we designed an animal model of METH-induced CPP. Then we used liquid chromatography-mass spectrometry (LC-MS) to simultaneously determine the contents of various neurotransmitters - dopamine (DA), norepinephrine (NE), 5-hydroxytryptamine (5-HT), 5-hydroxyindole acetic acid (5-HIAA), glutamic acid (Glu) and glutamine (Gln) - in different brain regions of the prefrontal cortex (PFc), nucleus accumbens (NAc), caudate-putamen (CPu) and hippocampus (Hip), which are believed to be relevant to the drug's reward effect.

RESULTS

The results of the behavioral experiment suggested that 1.0 mg/kg METH could induce obvious CPP in mice. The results about various neurotransmitters showed that: DA significantly increased in NAc in the METH group; Glu increased significantly in the METH group in PFc and NAc and Gln increased significantly in the METH group in PFc.

CONCLUSIONS

These results suggested that the neurotransmitters of DA, Glu and Gln may work together and play important roles in METH-induced CPP in relevant brain reward circuits, especially in PFc and NAc. These findings therefore could help to advance the comprehensive understanding of the neurochemic and psychopharmacologic properties of METH in reward effect, which is important for future improvements in the treatment of drug addiction.

Combined and sequential effects of alcohol and methamphetamine in animal models

Comorbid drug use, often alcohol with other drugs, poses significant health and societal concerns. Methamphetamine is among the illicit drugs most often co-used with alcohol. The current review examines the animal literature for impacts of comorbid alcohol and methamphetamine exposure. We found evidence for additive or synergistic effects of combined or sequential exposure on behavior and physiology. Dopaminergic, serotonergic, and glutamatergic systems are all impacted by combined exposure to alcohol and methamphetamine and cyclooxygenase-2 activity plays an important role in their combined neurotoxic effects. Adverse consequences of comorbid exposure include altered brain development with prenatal exposure, impaired learning and memory, motor deficits, gastrotoxicity, hepatotoxicity, and augmented intake under some conditions. Given high susceptibility to drug experimentation in adolescence, studies of co-exposure during the adolescent period and of how adolescent exposure to one drug impacts later use or sensitivity to the other drug should be a priority. Further, to gain traction on prevention and treatment, additional research to identify motivational and neurobiological drivers and consequences of comorbid use is needed.

Serum proteomic profiling of patients with amphetamine use disorder

BACKGROUND

Amphetamine use disorder has been recently classified as an epidemic condition. Amphetamine use/abuse has been associated with several neurological and inflammatory effects. However, the exact mechanism involved in these effects warrants further investigation. The aim of this study was to determine any alterations in the serum proteome of individuals classified as patients with amphetamine use disorder compared to that of control subjects.

METHODS

An untargeted proteomic approach employing two-dimensional difference in gel electrophoresis coupled with mass spectrometry was used to identify the patterns of differentially expressed proteins. Serum samples were collected from 20 individuals (males) including 10 subjects with amphetamine use disorder and 10 healthy controls for the present study.

RESULTS

The analysis revealed 78 proteins with a significant difference in protein abundance between the amphetamine-addicted subjects and controls. Among them, 71 proteins were upregulated while 7 proteins remained downregulated in the amphetamine-addicted group. These proteins were further analyzed by ingenuity pathway analysis (IPA) to investigate their correlation with other biomarkers. IPA revealed the correlation of altered proteins with mitogen-activated protein kinase (MAP2K1/K2), p38MAPK, protein kinase-B (PKB; Akt), extracellular signal-regulated kinase (ERK1/2), and nuclear factor-κB signaling pathways. Importantly, these pathways are highly involved in neurological diseases, inflammatory responses, and cellular compromise.

CONCLUSIONS

Our data suggest that the changes in the levels of serum proteins between amphetamine and control groups might affect cellular compromise, inflammatory response, and neurological diseases.

Postmortem Study of Molecular and Histological Changes in the CA1 Hippocampal Region of Chronic Methamphetamine User

Methamphetamine (Meth) is recognized as one of the most important new distributed abused drug that causes severe damage to the different parts of the brain, especially hippocampus. Previous studies have demonstrated that Meth can induce apoptosis and cell death in the brain. In this study, we evaluated the long-term effects of Meth abuse in the CA1 region of postmortem hippocampus. Postmortem molecular and histological analysis was performed for five non-addicted subjects and five Meth addicted ones. Iba-1 (microglia) and glial fibrillary acidic protein, GFAP (astrocytes) expression were assayed by western blotting and immunohistochemistry (IHC) methods. Histopathological assessment was done with stereological counts of hippocampal cells stained with hematoxylin and eosin (H and E). Tunel staining was used to detect DNA damage in human brains. In addition, protein-protein interaction analysis network was investigated. Western blotting and immunohistochemistry assay showed overexpression of GFAP and Iba-1 protein in the CA1 hippocampal region of Meth users’ brain. Stereological analysis in the CA1 region revealed increased neuron degeneration. Furthermore, significant apoptosis and cell death were confirmed by Tunel assay in the hippocampus. The prominent role of TLR4, IL1B, CASP1, and NLRP3 in the molecular mechanism of Meth was highlighted via PPI network analysis. Chronic Meth use can induce GFAP and Iba-1 upregulation and neuronal apoptosis in the CA1 region of the postmortem hippocampus.

An association study between methamphetamine use disorder with psychosis and polymorphisms in MiRNA

BACKGROUND

Methamphetamine (MA) is an addictive psychostimulant substance that mainly leads to schizophrenia-like psychotic symptoms. The expression of miRNAs in brain plays an important role in neurological disorders and may affect by genetic variant(s) in the target site (MiRSNPs). In this study, we investigated whether polymorphisms in miRNAs are associated with MA disorder with psychosis.

METHODS

We carried out a case-control association study in 400 MA users with psychotic characters and 448 controls. Six MiRSNPs with predicted functional relevance miRNAs (miR-181b, miR-181a, miR-15b, miR-let-7e and miRlet-7d) were selected for genotyping. Allele and genotype frequencies were compared between MA users and healthy individuals. The expression of five miRNAs were measured by quantitative real-time RT-PCR in 55 cases and 57 controls. We also explored an expression Quantitative Trait Loci (eQTL) analysis based on the miRNAs expression and SNP genotype.

RESULTS

The SNP rs10760371 within miR-181a was nominally associated with MA disorder (P = 0.046). For rs1099308, rs10760371 and rs10993081 in strong linkage disequilibrium (LD), no significant association had been detected from haplotype analysis. Discrepancy had been found between MA users and healthy individuals (P < 0.01) in terms of the expression of miR-181a, miR-15b, miR-let-7e and miR-let-7d. and no noticeable difference had been found from the eQTL analysis.

CONCLUSION

Our findings suggest that rs10760371 within miR-181a may relate to the development of MA dependence with psychosis. The miRNAs expression is unlikely to be regulated by the SNPs within it.