Stress-induced neural activation is altered during early withdrawal from chronic methamphetamine

Specific Inhibition of Interpeduncular Nucleus GABAergic Neurons Alleviates Anxiety-Like Behaviors in Male Mice after Prolonged Abstinence from Methamphetamine

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 designer receptors exclusively activated by designer drugs method, specific inhibition of IPN GABAergic neurons rescued the aberrant neuronal excitation of IPN GABAergic neurons and efficiently reduced anxiety-like behaviors, whereas it did not induce depression-like behaviors in male mice after prolonged abstinence from METH. These findings reveal that IPN GABAergic neurons should be a promising brain target to alleviate late withdrawal symptoms from 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.

Methamphetamine Disturbs Gut Homeostasis and Reshapes Serum Metabolome, Inducing Neurotoxicity and Abnormal Behaviors in Mice

As an illicit psychostimulant, repeated methamphetamine (MA) exposure results in addiction and causes severe neurotoxicity. Studies have revealed complex interactions among gut homeostasis, metabolism, and the central nervous system (CNS). To investigate the disturbance of gut homeostasis and metabolism in MA-induced neurotoxicity, 2 mg/kg MA or equal volume saline was intraperitoneally (i.p.) injected into C57BL/6 mice. Behavioral tests and western blotting were used to evaluate neurotoxicity. To determine alterations of colonic dysbiosis, 16s rRNA gene sequencing was performed to analyze the status of gut microbiota, while RNA-sequencing (RNA-seq) and Western Blot analysis were performed to detect colonic damage. Serum metabolome was profiled by LC–MS analysis. We found that MA induced locomotor sensitization, depression-, and anxiety-like behaviors in mice, along with dysfunction of the dopaminergic system and stimulation of autophagy as well as apoptosis in the striatum. Notably, MA significantly decreased microbial diversity and altered the component of microbiota. Moreover, findings from RNA-seq implied stimulation of the inflammation-related pathway after MA treatment. Western blotting confirmed that MA mediated colonic inflammation by activating the TLR4-MyD88-NF-κB pathway and impaired colonic barrier. In addition, serum metabolome was reshaped after MA treatment. Specifically, bacteroides-derived sphingolipids and serotonin were obviously altered, which were closely correlated with locomotor sensitization, depression-, and anxiety-like behaviors. These findings suggest that MA disrupts gut homeostasis by altering its microbiome and arousing inflammation, and reshapes serum metabolome, which provide new insights into understanding the interactions between gut homeostasis and MA-induced neurotoxicity.

Goofballing of Opioid and Methamphetamine: The Science Behind the Deadly Cocktail

Globally, millions of people suffer from various substance use disorders (SUD), including mono-and polydrug use of opioids and methamphetamine. Brain regions such as the cingulate cortex, infralimbic cortex, dorsal striatum, nucleus accumbens, basolateral and central amygdala have been shown to play important roles in addiction-related behavioral changes. Clinical and pre-clinical studies have characterized these brain regions and their corresponding neurochemical changes in numerous phases of drug dependence such as acute drug use, intoxication, craving, withdrawal, and relapse. At present, many studies have reported the individual effects of opioids and methamphetamine. However, little is known about their combined effects. Co-use of these drugs produces effects greater than either drug alone, where one decreases the side effects of the other, and the combination produces a prolonged intoxication period or a more desirable intoxication effect. An increasing number of studies have associated polydrug abuse with poorer treatment outcomes, drug-related deaths, and more severe psychopathologies. To date, the pharmacological treatment efficacy for polydrug abuse is vague, and still at the experimental stage. This present review discusses the human and animal behavioral, neuroanatomical, and neurochemical changes underlying both morphine and methamphetamine dependence separately, as well as its combination. This narrative review also delineates the recent advances in the pharmacotherapy of mono- and poly drug-use of opioids and methamphetamine at clinical and preclinical stages.

Voluntary oral methamphetamine increases memory deficits and contextual sensitization during abstinence associated with decreased PKMζ and increased κOR in the hippocampus of female mice

BACKGROUND

Female populations exhibit vulnerabilities to psychostimulant addiction, as well as cognitive dysfunction following bouts of abuse.

AIMS

The goal for this study was to advance our understanding of the mechanisms that produce sex disparities in drug addiction.

METHODS

We used an animal model for voluntary oral methamphetamine administration (VOMA) and focused on male and female mice that consumed 7.6-8.2 mg/kg of methamphetamine (MA) per day during the last 18 days of the paradigm.

RESULTS

The VOMA-exposed female mice displayed increased locomotor activity in the drug-administration context compared to male mice, demonstrating sex-specific changes in contextual sensitization. During 2 weeks of forced abstinence, mice underwent further behavioral testing. We show that abstinence increased open-arm entries on the elevated plus maze in both sexes. There were no differences in immobility on the tail suspension test. In a hippocampal-dependent radial arm maze task, VOMA-treated female mice, but not male mice, showed working memory deficits. Hippocampal tissue was collected and analyzed using Western blotting. VOMA-exposed female mice exhibited increased kappa opioid receptor (κOR) expression in the hippocampus compared to male mice, suggesting a vulnerability toward abstinence-induced dysphoria. Female VOMA mice also exhibited a decrease in the memory protein marker, protein kinase M zeta (PKMζ), in the hippocampus.

CONCLUSIONS

Our study reveals sex-specific effects following abstinence from chronic MA consumption on hippocampal κOR and PKMζ expression, suggesting that these neural changes in female mice may underlie spatial memory deficits and identify an increased susceptibility to dysregulated neural mechanisms. These data validate VOMA as a model sensitive to sex differences in behavior and hippocampal neurochemistry following chronic MA exposure.

Alterations in corticotropin-releasing factor receptor type 1 in the preoptic area and hypothalamus in mice during the postpartum period

Corticotropin-releasing factor (CRF) signaling through CRF receptor 1 (CRFR1) regulates autonomic, endocrine, and behavioral responses to stress, as well as behavioral changes during the maternal period. Previous work in our lab reported higher levels of CRFR1 in female, compared to male, mice within the rostral anteroventral periventricular nucleus (AVPV/PeN), a brain region involved in maternal behaviors. In this study, we used CRFR1-GFP reporter mice to investigate whether the reproductive status (postpartum vs. nulliparous) of acutely stressed females affects levels of CRFR1 in the AVPV/PeN and other regions involved in maternal functions. Compared to nulliparous, postpartum day 14 females showed increased AVPV/PeN CRFR1-GFP immunoreactivity and an elevated number of restraint stress-activated AVPV/PeN CRFR1 cells as assessed by immunohistochemical co-localization of CRFR1-GFP and phosphorylated CREB (pCREB). The medial preoptic area (MPOA) and paraventricular hypothalamus (PVN) of postpartum mice showed modest decreases in CRFR1-GFP immunoreactivity, while increased CRFR1-GFP/pCREB co-expressing cells were found in the PVN following restraint stress relative to nulliparous mice. Tyrosine hydroxylase (TH) and CRFR1-GFP co-localization was also assessed in the AVPV/PeN and other regions and revealed a decrease in co-localized neurons in the AVPV/PeN and ventral tegmental area of postpartum mice. Corticosterone analysis of restrained mice revealed blunted peak, but elevated recovery, levels in postpartum compared to nulliparous mice. Finally, we investigated projection patterns of AVPV/PeN CRFR1 neurons using female CRFR1-Cre mice and revealed dense efferent projections to several preoptic, hypothalamic, and hindbrain regions known to control stress-associated and maternal functions. Together, these findings contribute to our understanding of the neurobiology that might underlie changes in stress-related functions during the postpartum period.

The role of childhood maltreatment in cortisol in the hypothalamic-pituitary-adrenal (HPA) axis in methamphetamine-dependent individuals with and without depression comorbidity and suicide attempts

BACKGROUND

The hypothalamic-pituitary-adrenal (HPA) axis dysregulation which was found to have an important role in the pathophysiology of depression, suicide, and substance dependence, may be influenced by childhood maltreatment (CM). The present study aimed to investigate the relationship between CM and cortisol changes in methamphetamine-dependent individuals.

METHODS

In a cross-sectional study, methamphetamine-dependent individuals (n = =195) with or without both comorbid major depressive disorder (MDD) and a history of suicide attempts were selected and completed the Childhood Trauma Questionnaire-Short Form (CTQ-SF), the Beck Scale for Suicide Ideation (BSSI), and the Beck Depression Inventory-II (BDI-II). To assess cortisol levels, saliva samples were collected at six time intervals for two consecutive days.

RESULTS

A history of CM significantly predicted wake-up cortisol level, cortisol awakening response (CAR), and diurnal cortisol slope. Methamphetamine-dependent individuals with both MDD and lifetime suicide attempts had higher CM and higher cortisol levels with a blunted diurnal cortisol slope than individuals who were merely methamphetamine-dependent. Individuals with high CM showed higher cortisol levels with a blunted diurnal slope than those with low or without CM.

LIMITATIONS

Cross-sectional data and use of self-report scales, especially retrospective measurements (e.g., the CTQ-SF), were important limitations of this study.

CONCLUSION

Findings suggest that methamphetamine-dependent individuals with adverse psychological factors such as CM, MDD, and suicide attempts may show dysregulation in biological factors including cortisol level. In addition, CM and its effects on cortisol in the HPA axis may emerge as important factors regarding psychopathological use of methamphetamine.