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, Ltryptophan 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 0 -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, alphaketoglutarate 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.

Anxiety is one of the most common withdrawal symptoms of methamphetamine (METH) abuse, which further drives relapse to drugs. Interpeduncular nucleus (IPN) has been implicated in anxiety-like behaviors and addiction, yet its role in METH abstinence-induced anxiety remains unknown. Here, we found that prolonged abstinence from METH enhanced anxiety-like behaviors in male mice, accompanied by more excited IPN GABAergic neurons, as indicated by the increased c-Fos expression and the enhanced neuronal excitability by electrophysiological recording in the GABAergic neurons. Using the DREADDs method, specific inhibition of IPN GABAergic neurons rescued the aberrant neuronal excitation of IPN GABAergic neurons, and efficiently reduced anxiety-like behaviors, whereas did not induce depression-like behaviors in male mice of prolonged abstinence from METH. These findings reveal that IPN GABAergic neurons should be a promising brain target to alleviate late withdrawal symptoms of METH with few side effects.SIGNIFICANCE STATEMENT:Prolonged abstinence from METH triggers IPN GABAergic neurons, and ultimately increases anxiety in male mice. Suppressing IPN GABAergic neurons rescues METH abstinence-induced aberrant neuronal excitation of IPN GABAergic neurons, and efficiently reduces anxiety in mice.

The cerebellum is implicated in drug addiction. However, the cerebellar neuronal circuitry underlying addiction, especially classic pathway of Purkinje cells (PCs) to deep cerebellar nuclei (DCN), are largely unknown. Here, tracing experiments showed robust projections from the cerebellar lobule VI tyrosine hydroxylase (TH)-positive PCs (PCTH+) to CaMKII-positive glutamatergic neurons in medial cerebellar nucleus (MedCaMKII), forming PCTH+─MedCaMKII pathway. Then, mice were subjected to methylamphetamine (METH)-induced conditioned place preference (CPP), showing that METH exposure excited MedCaMKII and inhibited PCTH+. Silencing MedCaMKII by tettox suppressed the formation and expression of METH-induced CPP, but produced serious motor coordination deficits. Chemogenetic activation of lobule VI PCTH+─Med pathway during METH CPP training blocked the formation and expression of METH-induced CPP without affecting motor coordination, locomotor activity and sucrose reinforcements in mice. Our findings revealed a novel cerebellar lobule VI PCTH+ ─MedCaMKII pathway and pointed out is critical role in encoding METH-preferred behaviors.

As a highly addictive psychostimulant drug, paternal methamphetamine (METH) exposure enhances the risk of developing addiction to drugs in descendants, however the underlying mechanism remains unclear. Medial prefrontal cortex (mPFC) is a key brain region that implicated in susceptibility to drugs. Here, male adult mice were exposed to METH for 30 days, followed by mating with naive female mice to create the first-generation (F1) mice. In METH-sired mice, baseline levels of c-Fos were decreased but β1-adrenergic receptor (ADRB1) were increased in mPFC by paternal METH exposure. Trained with subthreshold-dosed administration of METH, METH-sired mice exhibited significant METH-preferred behaviors, accompanied with higher levels of c-Fos, ADRB1 and dendritic spines density in mPFC. Importantly, local blocking ADRB1 activity or specific knockdown of ADRB1 on excitatory neurons of mPFC, both efficiently inhibited METH-preferred behaviors in METH-sired mice. In parallel, levels of p-ERK1/2 and ΔFosB, as well as dendritic spine density were reduced by knocking-down mPFC ADRB1 in METH-sired mice. Collectively, these findings suggested that targeting ADRB1 signals in mPFC may represent a promising therapeutic strategy for preventing drug addiction, particularly in progeny with a history of paternal drugs exposure.