Therapeutic effect of implanted and non-invasive vagus nerve stimulation on heroin-induced anxiety.

Substance addiction causes anxiety, which in turn reinforces the maintaining of substance use, resulting in a vicious circle. And this circle is one of the reasons why addiction is so hard to cure. However, there is no treatment involved in addiction-induced anxiety at present. We tested whether VNS (vagus nerve stimulation) can improve heroin-induced anxiety, and made a comparison between nVNS (transcervical vagus nerve stimulation) and taVNS (transauricular vagus nerve stimulation) on therapeutic effect. Mice were subjected to nVNS or taVNS before heroin administration. By observing c-Fos expression in the NTS (nucleus of the solitary tract), we assessed vagal fiber activation. Using the OFT (open field test) and the EPM (elevated cross maze test), we evaluated the anxiety-like behaviors of the mice. Using immunofluorescence, we observed the proliferation and activation of microglia in the hippocampus. And ELISA was used to measure the levels of proinflammatory factors in the hippocampus. Both nVNS and taVNS significantly increased the expression of c-Fos in the nucleus of solitary tract, suggesting the feasibility of nVNS and taVNS. The anxiety level of heroin-treated mice was significantly increased, microglia in the hippocampus was significantly proliferated and activated, and the proinflammatory factors (IL-1ß, IL-6, TNF-α) in the hippocampus were significantly up-regulated. Crucially, both nVNS and taVNS reversed the above changes caused by heroin addiction. SIGNIFICANCE: It was confirmed that the therapeutic effect of VNS on heroin-induced anxiety may be an effective treatment method to break the "addiction-anxiety" cycle and provides some insights for subsequent treatment of addiction.

Messenger RNA expression profiles and bioinformatics analysis of mouse hippocampi during exercise alleviates methamphetamine dependence via mRNA profile change in hippocampi.

Background: Methamphetamine (METH) is a highly addictive, psychoactive drug which can harm individual health and lead to great social problems. Various approaches have been adopted to address the problems arising from METH addiction, but relapse rates remain high. Recently, it has been found that comprehensive treatment combined with scientific and appropriate exercise interventions can improve the mental state and physical fitness of drug addicts and promote their physical and mental rehabilitation. Long-term, regular exercise improves the symptoms of METH withdrawal and reduces METH relapse. This study aimed to investigate the effects and regulated gene expression related to running exercise in METH-addicted mice. Methods: Male C57BL/6J mice were used to construct a METH addiction model. We performed a running exercise intervention and used conditioned place preference (CPP) to measure the effects of the running intervention on the METH-addicted mice. We also performed RNA sequencing (RNA-seq) and transcriptome analysis on the mice hippocampi, and the functions and differentially expressed genes (DEGs) that were significantly regulated by exercise intervention in the METH-addicted mice were analyzed and noted. Results: The results showed that days of CPP were shortened to 3 days in METH-addicted mice that underwent moderate exercise intervention, compared to 6 days in METH-addicted mice that went without exercise intervention. In addition, hippocampal transcriptome analysis revealed 12 DEGs significantly regulated by exercise intervention. By performing Gene Ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis, it was revealed that the function of immune responses was significantly enriched in the METH-addicted mice undertaking exercise. The expression of 12 DEGs was verified by real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR), which showed that relative messenger RNA (mRNA) expression of DEGs was consistent with the RNA-seq results. Conclusions: A running intervention can promote the recovery of METH addiction in mice, and the 12 candidate DEGs from the mouse hippocampus can be used for further research on the regulatory mechanisms of exercise in METH-addicted mice.

Exercise modulates central and peripheral inflammatory responses and ameliorates methamphetamine-induced anxiety-like symptoms in mice.

Anxiety-like symptoms are common symptoms of methamphetamine (METH) users, especially in the acute withdrawal period, which is an important factor for the high relapse rate during METH acute withdrawal. Exercise has been demonstrated to relieve anxiety-like symptoms during METH withdrawal, but the underlying mechanisms of this anti-anxiety effect are still unclear. Activated microglia and abnormal neuroinflammation play an important role in the pathogenesis of anxiety-like symptoms after METH withdrawal. Moreover, peripheral immune factors were also significantly associated with anxiety symptoms. However, the effects of treadmill exercise on microglial function and neuroinflammation in the striatum and hippocampus during acute METH withdrawal have not been reported. In the current study, we found severe peripheral immune dysfunction in METH users during acute withdrawal, which may in part contribute to anxiety symptoms during METH acute withdrawal. We also showed that 2 weeks of METH exposure induced anxiety-like symptoms in the acute withdrawal period. Additionally, METH exposure resulted in increased microglial activation and proinflammatory cytokines released in the mouse striatum and hippocampus during acute withdrawal. We next evaluated the effects of treadmill exercise in countering anxiety-like symptoms induced by METH acute withdrawal. The results showed that anxiety-like symptoms induced by acute METH withdrawal were attenuated by coadministration of treadmill exercise. In addition, treadmill exercise counteracted METH-induced microglial activation in the mouse striatum and various subregions of the hippocampus. Furthermore, treadmill exercise also reversed the increase in proinflammatory cytokines induced by acute METH withdrawal in the mouse striatum, hippocampus and serum. Our findings suggest that the anti-anxiety effect of treadmill exercise may be mediated by reducing microglial activation and regulating central and peripheral inflammatory responses.

Effects and associated transcriptomic landscape changes of methamphetamine on immune cells.

BACKGROUND: Methamphetamine (METH) abuse causes serious health problems, including injury to the immune system, leading to increased incidence of infections and even making withdrawal more difficult. Of course, immune cells, an important part of the immune system, are also injured in methamphetamine abuse. However, due to different research models and the lack of bioinformatics, the mechanism of METH injury to immune cells has not been clarified. METHODS: We examined the response of three common immune cell lines, namely Jurkat, NK-92 and THP-1 cell lines, to methamphetamine by cell viability and apoptosis assay in vitro, and examined their response patterns at the mRNA level by RNA-sequencing. Differential expression analysis of two conditions (control and METH treatment) in three types of immune cells was performed using the DESeq2 R package (1.20.0). And some of the differentially expressed genes were verified by qPCR. We performed Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analysis of differentially expressed genes by the clusterProfiler R package (3.14.3). And gene enrichment analysis was also performed using MetaScape ( www.metascape.org ). RESULTS: The viability of the three immune cells was differentially affected by methamphetamine, and the rate of NK-cell apoptosis was significantly increased. At the mRNA level, we found disorders of cholesterol metabolism in Jurkat cells, activation of ERK1 and ERK2 cascade in NK-92 cells, and disruption of calcium transport channels in THP-1 cells. In addition, all three cells showed changes in the phospholipid metabolic process. CONCLUSIONS: The results suggest that both innate and adaptive immune cells are affected by METH abuse, and there may be commonalities between different immune cells at the transcriptome level. These results provide new insights into the potential effects by which METH injures the immune cells.

Long-term exercise at different intensities can reduce the inflammatory response in the brains of methamphetamine-treated mice.

Methamphetamine (METH) is a highly addictive psychoactive drug that is used worldwide. Various approaches have been used to address METH dependence, but many of them have little effect. Previous studies have shown that exercise on a treadmill could reduce METH dependence in mice, but the intensity and duration of exercise that was needed to be effective was unknown. This study investigated the effects of low- and medium-intensity treadmill exercise on methamphetamine reward in male mice via conditioned place preference (CPP) training, and the levels of the inflammatory factors IL-1ß, IL-6 and TNF-α in three brain regions (cerebral cortex, hippocampus and striatum) were determined. The results showed that long-term medium-intensity exercise reduced the effects of methamphetamine on inflammation markers in the brain and CPP scores. In addition, long-term medium-intensity exercise decreased IL-1ß concentrations in the cerebral cortex and hippocampus, reduced IL-6 concentrations in the striatum, and reduced TNF-α concentrations in the cerebral cortex, hippocampus, and striatum in methamphetamine-treated mice; low-intensity exercise was less effective. The results indicated that long-term medium-intensity exercise could reduce concentrations of methamphetamine-induced encephalitis factors in male mice, while low-intensity exercise was less effective in alleviating dependence and inflammatory responses. It is suggested that exercise intensity is an important factor affecting the dependence level and inflammatory responses in the brain in mice administered methamphetamine.

Dynamics and correlations in multiplex immune profiling reveal persistent immune inflammation in male drug users after withdrawal.

Drug withdrawal elicits immune responses that contribute to the development of withdrawal symptoms and relapse. The understanding of the immunologic dynamics after drug withdrawal is limited, precluding the finding of promising immune intervention measures. Here, we performed cytokine and multiplex immune profiling in heroin, methamphetamine (METH) and ephedrine users after withdrawal and identified the correlation between cytokines and other immune parameters. We showed that broad and strong inflammatory responses occurred at the early stage after drug withdrawal, and the inflammatory responses showed a downtrend with the extension of withdrawal time. Notably, immune dysregulation remained through and may last longer than 12 months after withdrawal in heroin and METH users. Our findings suggest that cytokines, immune cells, complement and immunoglobulin form a complex immune network that regulates immune responses after withdrawal. These data provide a reference for future scientific research and drug research and development.