Transgenic Analyses of Homer2 Function Within Nucleus Accumbens Subregions in the Regulation of Methamphetamine Reward and Reinforcement in Mice

Utilization of Social Media for the Prevention and Control of HIV/AIDS: A Scoping Review

Social media has been used widely in public health for understanding health risks and intervening to improve health. However, the utilization of social media for HIV prevention and control interventions has not been clearly characterized. We conducted a scoping review on the utilization of social media for HIV prevention and control to identify gaps in the literature and highlight opportunities for future research and intervention. A comprehensive search of seven databases was performed: PubMed, Embase, CINAHL Complete (EBSCO), PsycInfo (EBSCO), Scopus, and WOS (Science Citation Index Expanded (SCI-EXPANDED). The Preferred Reporting Items for Systematic Review and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) was used as a framework. A total of 790 articles were screened at the title and abstract level, and 78 were screened at the full-text level. Twenty-three articles met the eligibility criteria for review. We found that Facebook was still the most common social media service used to reach target populations. Lesbian, gay, bisexual and transgender (LGBT) individuals were the primary groups and were the most common targets of social media-based HIV prevention interventions. Outcomes of social media-based interventions, such as increased HIV testing, social networking and social support, condom use attitudes, behavioral skills, and research participation, were reported. Most social media-based interventions have emphasized HIV prevention, with fewer interventions focused on improving linkage to care and adherence to treatment among people living with HIV. Future studies may benefit from using social media for interventions to improve HIV-related outcomes in high-risk populations. This review highlights the potential and challenges of social media approaches for HIV/AIDS prevention and control.

The Impact of Problematic Smartphone Use on Sleep Quality Among Chinese Young Adults: Investigating Anxiety and Depression as Mediators in a Three-Wave Longitudinal Study

Background

Sleep disorders are a significant health issue that urgently needs to be addressed among undergraduate students, and one of the potential underlying problems could be problematic smartphone use (PSU). This study aimed to clarify the relationship between PSU and poor sleep quality by investigating the independent and serial mediating roles of anxiety and depressive symptoms in a population of university students in Tibet, China.

Methods

A total of 2993 Tibetan college students completed three waves of data surveys, with all participants completing questionnaires on PSU, anxiety, depressive symptoms, and sleep quality (Time 1 (T1) -Time 3 (T3)). Bootstrapped mediation analysis was used to explore the mediating role of anxiety and depressive symptoms in the longitudinal relationship between PSU and sleep quality.

Results

Both direct and indirect effects of PSU on poor sleep quality were found. PSU (T1) can had not only a direct negative influence on poor sleep quality (T3) among young adults (direct effect = 0.021, 95% CI = 0.010-0.033) but also an indirect negative impact via three pathways: the independent mediating effect of anxiety symptoms (T2) (indirect effect 1 = 0.003, 95% CI = 0.001-0.006), the independent mediating effect of depressive symptoms (T2) (indirect effect 2 = 0.004, 95% CI = 0.002-0.006), and the serial mediating effects of anxiety (T2) and depressive symptoms (T2) (indirect effect 3 = 0.008, 95% CI=0.005-0.011).

Conclusion

These findings highlight the role of anxiety and depression symptoms as joint mediating factors in the relationship between PSU and sleep disturbances. Interventions focused on improving sleep that incorporate behavioural measures could benefit from treatment approaches targeting mental disorders.

Effects of systemic pretreatment with the NAALADase inhibitor 2-PMPA on oral methamphetamine reinforcement in C57BL/6J mice

Introduction

Repeated exposure to methamphetamine (MA) in laboratory rodents induces a sensitization of glutamate release within the corticoaccumbens pathway that drives both the rewarding and reinforcing properties of this highly addictive drug. Such findings argue the potential for pharmaceutical agents inhibiting glutamate release or its postsynaptic actions at glutamate receptors as treatment strategies for MA use disorder. One compound that may accomplish both of these pharmacological actions is the N-acetylated-alpha-linked-acidic dipeptidase (NAALADase) inhibitor 2-(phosphonomethyl)pentanedioic acid (2-PMPA). 2-PMPA elevates brain levels of the endogenous agonist of glutamate mGluR3 autoreceptors, N-acetyl-aspartatylglutamate (NAAG), while potentially acting as an NMDA glutamate receptor antagonist. Of relevance to treating psychomotor stimulant use disorders, 2-PMPA is reported to reduce indices of both cocaine and synthetic cathinone reward, as well as cocaine reinforcement in preclinical rodent studies.

Method

Herein, we conducted three experiments to pilot the effects of systemic pretreatment with 2-PMPA (0-100 mg/kg, IP) on oral MA self-administration in C57BL/6J mice. The first experiment employed female mice with a prolonged history of MA exposure, while the mice in the second (females) and third (males and females) experiment were MA-naïve prior to study. In all experiments, mice were trained daily to nose-poke for delivery of unadulterated MA solutions until responding stabilized. Then, mice were pretreated with 2-PMPA prior to operant-conditioning sessions in which nose-poking behavior was reinforced by delivery of 120 mg/L or 200 mg/L MA (respectively, in Experiments 1 and 2/3).

Results

Contrary to our expectations, 30 mg/kg 2-PMPA pretreatment altered neither appetitive nor consummatory measures related to MA self-administration. In Experiment 3, 100 mg/kg 2-PMPA reduced responding in the MA-reinforced hole, as well as the number of reinforcers earned, but did not significantly lower drug intake.

Discussion

These results provide mixed evidenced related to the efficacy of this NAALADase inhibitor for reducing oral MA reinforcement in female mice.

Alleviating the Effects of the COVID-19 Pandemic on the Physical, Psychological Health, and Wellbeing of Students: Coping Behavior as a Mediator

Background

Public health procedures under the COVID-19 pandemic lockdown policy negatively affect people's health. Students' physical issues have been increased due to restrictions which further impact their psychological and overall well-being.

Objective

The research looks at the influence of coping behavior in mitigating the impact of the COVID-19 epidemic on students' physical/psychological health and general well-being.

Methods

The study's participants were chosen from a pool of 2200 people using convenience sampling. Using an anonymous online poll, the main data were gathered. The collected data were analyzed by using Smart-PLS.

Results

From eight direct correlations, seven were found to be true, except the route pandemic -> overall wellbeing, which was not true. Furthermore, it was shown that the mediating effect of coping behavior was statistically significant in the routes of mediation.

Conclusion

Coping strategies have a significant role in how a person responds to trying circumstances. Our study's results suggest that coping strategies had a statistically significant mediation role in reducing the effects of the COVID-19 pandemic. It is concluded that appropriate coping strategies are an effective adaptation of a protective barrier against the damaging effects of COVID-19 on health.

Prevalence and Modifiable Factors for Holistic Non-Adherence in Renal Transplant Patients: A Cross-Sectional Study

Introduction

In renal transplant recipients, compliance with medical therapy is vital. Non-adherence is considered a risk factor for worst outcomes in kidney recipients, with attributed outcomes of 64% for graft loss and 80% for late acute rejection. Most literature defines adherence as self-based immunosuppression compliance but does not consider other relevant factors such as consult and procedure compliance. Therefore, this study aims to describe adherence prevalence in kidney transplant recipients and the factors related to non-adherence.

Methods

This cross-sectional study included 1030 renal transplant patients followed by Colombiana de Trasplantes between January 2019 and July 2021. Sociodemographic and clinical variables were obtained based on clinical records. The mental-health group diagnosed holistic adherence in a semi-structured interview. The diagnosis considered medication intake failure, frequency and number of failures to medical controls or other procedures, suspicious non-adherence behaviors, and serum levels of immunosuppressants. A bivariate followed a descriptive analysis, and a forward logistic regression was performed for non-adherence.

Results

Patients had a median of 47 years, and 58.1% were male. Non-adherence was presented in 30.7% of patients. The non-adherence patients were younger, with a higher prevalence of males, single, divided transplant care, had a longer time after transplantation, psychopathological diagnosis, and more reinforcement education by only nursing. Older age and multidisciplinary reinforcement education were protective factors. On the other hand, poor social support, psychopathology diagnosis, and longer time after transplant presented as non-adherence risk factors.

Conclusion

Holistic non-adherence was diagnosed in approximately one-third of renal transplant recipients. Its definition included more than just medication non-compliance and could identify more non-adherent patients. Notably, there is a need to consider the related factors in the health follow-up and encourage future research in modifiable factor interventions aiming to increase adherence and achieve better outcomes for renal transplant patients.

Prevalence and correlates of stocking up on drugs during the COVID-19 pandemic: Data from the C3PNO Consortium

BACKGROUND

Data from the COVID-19 pandemic describes increases in drug use and related harms, especially fatal overdose. However, evidence is needed to better understand the pathways from pandemic-related factors to substance use behaviours. Thus, we investigated stockpiling drugs among people who use drugs (PWUD) in five cities in the United States and Canada.

METHODS

We used data from two waves of interviews among participants in nine prospective cohorts to estimate the prevalence and correlates of stockpiling drugs in the previous month. Longitudinal correlates were identified using bivariate and multivariate generalized linear mixed-effects modeling analyses.

RESULTS

From May 2020 to February 2021, we recruited 1873 individuals who completed 2242 interviews, of whom 217 (11.6%) reported stockpiling drugs in the last month at baseline. In the multivariate model, stockpiling drugs was significantly and positively associated with reporting being greatly impacted by COVID-19 (Adjusted Odds Ratio [AOR]= 1.21, 95% CI: 1.09-1.45), and at least daily use of methamphetamine (AOR = 4.67, 95% CI: 2.75-7.94) in the past month.

CONCLUSIONS

We observed that approximately one-in-ten participants reported stocking up on drugs during the COVID-19 pandemic. This behaviour was associated with important drug-related risk factors including high-intensity methamphetamine use. While these correlations need further inquiry, it is possible that addressing the impact of COVID-19 on vulnerable PWUD could help limit drug stockpiling, which may lower rates of high-intensity stimulant use.

White matter alterations in chronic MDMA use: Evidence from diffusion tensor imaging and neurofilament light chain blood levels

3,4-Methylenedioxymethamphetamine (MDMA, "Ecstasy") is a serotonin- and noradrenaline-releasing substance, currently among the most widely used illicit substances worldwide. In animal studies, repeated exposure to MDMA has been associated with dendritic but also axonal degeneration in the brain. However, translation of the axonal findings, specifically, to humans has been repeatedly questioned and the few existing studies investigating white matter alterations in human chronic MDMA users have yielded conflicting findings. In this study, we combined whole-brain diffusion tensor imaging and neurofilament light chain (NfL) analysis in blood to reveal potential MDMA-induced axonal neuropathology. To this end, we assessed 39 chronic MDMA users and 39 matched MDMA-naïve healthy controls. MDMA users showed increased fractional anisotropy in several white matter tracts, most prominently in the corpus callosum as well as corticospinal tracts, with these findings partly related to MDMA use intensity. However, the NfL levels of MDMA users were not significantly different from those of controls. We conclude that MDMA use is not associated with significant white matter lesions due to the absence of reduced fractional anisotropy and increased NfL levels commonly observed in conditions associated with white matter lesions, including stimulant and ketamine use disorders. Hence, the MDMA-induced axonal degradation demonstrated in animal models was not observed in this human study of chronic MDMA users.

Midazolam, methamphetamine, morphine and nicotine intake in high‐drinking‐in‐the‐dark mice

The high-drinking-in-the-dark (HDID) lines of mice were selectively bred for achieving high blood alcohol levels in the drinking-in-the-dark (DID) task and have served as a unique genetic risk model for binge-like alcohol intake. However, little is known about their willingness to consume other addictive drugs. Here, we examined (a) whether the HDID-1 and HDID-2 lines of mice would voluntarily consume midazolam, methamphetamine, morphine and nicotine in a DID test and (b) whether the HDID lines differ from their founders, heterogeneous stock/Northport (HS/NPT), in consumption levels of these drugs at the concentrations tested. Separate groups of HDID-1, HDID-2 and HS/NPT mice were given 4 days of access to each drug, using the single-bottle, limited-access DID paradigm. Male and female mice of both HDID lines consumed all four offered drugs. We observed no genotype differences in 40 μg/ml methamphetamine intake, but significant differences in nicotine, midazolam and morphine intake. Both HDID lines drank significantly more (150 μg/ml) midazolam than their founders, providing strong support for a shared genetic contribution to binge ethanol and midazolam intake. HDID-2 mice, but not HDID-1 mice, consumed more morphine (700 μg/ml) and more nicotine across a range of concentrations than HS/NPT mice. These results demonstrate that the HDID mice can be utilized for tests of voluntary drug consumption other than ethanol and highlight potentially important differences between HDID lines in risk for elevated drug intake.

Selective Inhibition of PDE4B Reduces Methamphetamine Reinforcement in Two C57BL/6 Substrains

Methamphetamine (MA) is a highly addictive psychostimulant drug, and the number of MA-related overdose deaths has reached epidemic proportions. Repeated MA exposure induces a robust and persistent neuroinflammatory response, and the evidence supports the potential utility of targeting neuroimmune function using non-selective phosphodiesterase 4 (PDE4) inhibitors as a therapeutic strategy for attenuating addiction-related behavior. Off-target, emetic effects associated with non-selective PDE4 blockade led to the development of isozyme-selective inhibitors, of which the PDE4B-selective inhibitor A33 was demonstrated recently to reduce binge drinking in two genetically related C57BL/6 (B6) substrains (C57BL/6NJ (B6NJ) and C57BL/6J (B6J)) that differ in their innate neuroimmune response. Herein, we determined the efficacy of A33 for reducing MA self-administration and MA-seeking behavior in these two B6 substrains. Female and male mice of both substrains were first trained to nose poke for a 100 mg/L MA solution followed by a characterization of the dose-response function for oral MA reinforcement (20 mg/L-3.2 g/L), the demand-response function for 400 mg/L MA, and cue-elicited MA seeking following a period of forced abstinence. During this substrain comparison of MA self-administration, we also determined the dose-response function for A33 pretreatment (0-1 mg/kg) on the maintenance of MA self-administration and cue-elicited MA seeking. Relative to B6NJ mice, B6J mice earned fewer reinforcers, consumed less MA, and took longer to reach acquisition criterion with males of both substrains exhibiting some signs of lower MA reinforcement than their female counterparts during the acquisition phase of the study. A33 pretreatment reduced MA reinforcement at all doses tested. These findings provide the first evidence that pretreatment with a selective PDE4B inhibitor effectively reduces MA self-administration in both male and female mice of two genetically distinct substrains but does not impact cue-elicited MA seeking following abstinence. If relevant to humans, these results posit the potential clinical utility of A33 or other selective PDE4B inhibitors for curbing active drug-taking in MA use disorder.

The Association Between Depressive Symptoms and Sarcopenia Among Community-Dwelling Older Adults: A Cross-Sectional Study

Purpose

To evaluate the relationship between depressive symptoms and sarcopenia among older adults.

Materials and Methods

This is a cross-sectional study. A total of 700 community-dwelling older persons enrolled in this study. Sarcopenia is defined according to the Asian Working Group for Sarcopenia 2019 (AWGS 2019). The bioelectrical impedance analysis assessed muscle mass while a digital dynamometer quantified muscle strength. Furthermore, a 6-meter gait speed test measured physical performance. The Geriatric Depression Scale (GDS-30) screened for depressive symptoms. Data collected include those of socio-demographic, lifestyle, and comorbidity.

Results

The sample comprised 700 participants (455 women) with a mean age of 70.4±6.8 years. 21.5% had sarcopenia, among them, 5.6% at severe stage, while depressive symptoms were present in 8.1% (57/700). After adjusting for the potential confounders of age, sex, marital status, living status, hypertension, body mass index, and physical activity, the depressive symptoms that were found were not associated with sarcopenia but, instead, low gait speed. However, severe sarcopenia significantly impacted the risk of depressive symptoms, particularly in females.

Conclusion

Depressive symptoms are not associated with sarcopenia, but severe sarcopenia increases the risk of depressive symptoms in females, according to updated AWGS 2019 criteria. Gait speed is independently associated with depressive symptoms. The finding highlights that older people with sarcopenia should be screened for depressive symptoms, especially females. Future studies should evaluate the value of gait speed interventions for depressive symptoms among older adults.

What do measures of self-report interoception measure? Insights from a systematic review, latent factor analysis, and network approach

Recent conceptualizations of interoception suggest several facets to this construct, including "interoceptive sensibility" and "self-report interoceptive scales", both of which are assessed with questionnaires. Although these conceptual efforts have helped move the field forward, uncertainty remains regarding whether current measures converge on their measurement of a common construct. To address this question, we first identified -via a systematic review- the most cited questionnaires of interoceptive sensibility. Then, we examined their correlations, their overall factorial structure, and their network structure in a large community sample (n = 1003). The results indicate that these questionnaires tap onto distinct constructs, with low overall convergence and interrelationships between questionnaire items. This observation mitigates the interpretation and replicability of findings in self-report interoception research. We call for a better match between constructs and measures.

Does the gut microbiome mediate antipsychotic-induced metabolic side effects in schizophrenia?

INTRODUCTION

Second-generation antipsychotics (SGAs) are the most effective treatment for people with schizophrenia. Despite their effectiveness in treating psychotic symptoms, they have been linked to metabolic, cardiovascular and gastrointestinal side-effects. The gut microbiome has been implicated in potentiating symptoms of schizophrenia, response to treatment and medication-induced side effects and thus presents a novel target mediating second-generation antipsychotic-induced side effects in patients.

AREAS COVERED

This narrative review presents evidence from clinical and pre-clinical studies exploring the relationship between the gut microbiome, schizophrenia, second-generation antipsychotics and antipsychotic-induced side-effects. It also covers evidence for psychobiotic treatment as a potential supplementary therapy for people with schizophrenia.

EXPERT OPINION

The gut microbiome has the potential to mediate antipsychotic-induced side-effects in people with schizophrenia. Microbiome-focused treatments should be considered in combination with standard therapy in order to ameliorate debilitating drug-induced side effects, increase quality of life and potentially improve psychotic symptoms. Future studies should aim to collect not only microbiome data, but also metabolomic measures, dietary information and behavioral data.

Risk and protective factors of quality of life for children with autism spectrum disorder and their families during the COVID-19 lockdown. An Italian study

BACKGROUND

The lockdown due to the COVID-19 pandemic has been a difficult period for children with Autism Spectrum Disorder (ASD), and their families.

AIMS

The aim of this study was to investigate the predictors of the quality of life (QoL) of children with ASD and their parents throughout the first lockdown, providing a snapshot of the impact of the pandemic on these families life.

METHOD AND PROCEDURES

A cohort of 243 parents of children with ASD (2-15 years old) completed an original online survey regarding the modification of ASD cores symptoms during lockdown, the type of interventions they had done before and during lockdown and the activities performed by the child. Respondents filled the PedsQL for themselves and their children.

OUTCOME AND RESULTS

The data obtained show a worsening of specific ASD core symptoms during lockdown and their role in predicting parents and children's QoL. Furthermore, protective factors for a better children's QoL as the Telehealth intervention, and some activities done at home during the lockdown as physical activity and play with parents are identified.

CONCLUSIONS

This study identifies the QoL's risk and protective factors for children with ASD and their families. Furthermore, reveals the fundamental role of the parents as children's QoL protective factor, suggesting a higher collaboration between families and health care providers, whilst potentially improving families and children's QoL.

Effects of the COVID-19 Pandemic on Physical Activity Behavior across Domains and Settings

COVID-19 restrictions and alterations to daily living (e.g. working from home, caregiving responsibilities) necessitated changes in physical activity (PA) behavior. The purpose of this study was to understand how PA within specific domains and behavior settings changed during the COVID-19 pandemic, as well as the extent to which PA increased or decreased as a function of participants' gender, work location (i.e., home vs. jobsite) and caregiving responsibilities. An e-survey, conducted April-June 2020, examined changes in PA across domains and settings in a national sample of 805 adults. Respondents reported domain-specific increases in household and recreational PA, but decreases in active transportation, occupational PA, and public transportation use. Weekly minutes of PA changed significantly across all behavior settings, with reported increases in home-based, neighborhood, parks/trails, and total PA, and decreases in PA through recreational sports and fitness facilities. Total weekly PA minutes increased by 10.6%. Those with caregiving responsibilities reported increases in household PA and PA frequency, whereas those without caregiving responsibilities were more likely to report increases in sitting. Those working from home reported a larger increase in neighborhood PA. Those working at a jobsite with caregiving responsibilities reported less weekly PA, while those working from home with caregiving responsibilities reported greater weekly PA. The overall increase in weekly PA minutes and ability to adapt to different domains/settings was encouraging. Future interventions should capitalize on domain- and setting-specific changes, while considering work location and caregiving responsibilities to develop innovative PA promotion strategies.

Targeting mGlu5 for Methamphetamine Use Disorder

Methamphetamine abuse leads to devastating consequences, including addiction, crime, and death. Despite decades of research, no medication has been approved by the U.S. Food and Drug Administration for the treatment of Methamphetamine Use Disorder. Thus, there is a need for new therapeutic approaches. Animal studies demonstrate that methamphetamine exposure dysregulates forebrain function involving the Group-I metabotropic glutamate receptor subtype 5 (mGlu₅), which is predominantly localized to postsynaptic sites. Allosteric modulators of mGlu₅ offer a unique opportunity to modulate glutamatergic neurotransmission selectively, thereby potentially ameliorating methamphetamine-induced disruptions. Negative allosteric modulators of mGlu₅ attenuate the effects of methamphetamine, including rewarding/reinforcing properties of the drug across animal models, and have shown promising effects in clinical trials for Anxiety Disorder and Major Depressive Disorder. Preclinical studies have also sparked great interest in mGlu₅ positive allosteric modulators, which exhibit antipsychotic and anxiolytic properties, and facilitate extinction learning when access to methamphetamine is removed, possibly via the amelioration of methamphetamine-induced cognitive deficits. Clinical research is now needed to elucidate the mechanisms underlying the mGlu₅ receptor-related effects of methamphetamine and the contributions of these effects to addictive behaviors. The growing array of mGlu₅ allosteric modulators provides excellent tools for this purpose and may offer the prospect of developing tailored and effective medications for Methamphetamine Use Disorder.

ERK-Directed Phosphorylation of mGlu5 Gates Methamphetamine Reward and Reinforcement in Mouse

Methamphetamine (MA) is a highly addictive psychomotor stimulant drug. In recent years, MA use has increased exponentially on a global scale, with the number of MA-involved deaths reaching epidemic proportions. There is no approved pharmacotherapy for treating MA use disorder, and we know relatively little regarding the neurobiological determinants of vulnerability to this disease. Extracellular signal-regulated kinase (ERK) is an important signaling molecule implicated in the long-lasting neuroadaptations purported to underlie the development of substance use disorders, but the role for this kinase in the propensity to develop addiction, particularly MA use disorder, is uncharacterized. In a previous MA-induced place-conditioning study of C57BL/6J mice, we characterized mice as MA-preferring, -neutral, or -avoiding and collected tissue from the medial prefrontal cortex (mPFC). Using immunoblotting, we determined that elevated phosphorylated ERK expression within the medial prefrontal cortex (mPFC) is a biochemical correlate of the affective valence of MA in a population of C57BL/6J mice. We confirmed the functional relevance for mPFC ERK activation for MA-induced place-preference via site-directed infusion of the MEK inhibitor U0126. By contrast, ERK inhibition did not have any effect upon MA-induced locomotion or its sensitization upon repeated MA treatment. Through studies of transgenic mice with alanine point mutations on T1123/S1126 of mGlu5 that disrupt ERK-dependent phosphorylation of the receptor, we discovered that ERK-dependent mGlu5 phosphorylation normally suppresses MA-induced conditioned place-preference (MA-CPP), but is necessary for this drug’s reinforcing properties. If relevant to humans, the present results implicate individual differences in the capacity of MA-associated cues/contexts to hyper-activate ERK signaling within mPFC in MA Use Disorder vulnerability and pose mGlu5 as one ERK-directed target contributing to the propensity to seek out and take MA.

mGlu5 function in the nucleus accumbens core during the incubation of methamphetamine craving

Many studies have demonstrated that negative allosteric modulators (NAM) of metabotropic glutamate receptor 5 (mGlu5) reduce cocaine and methamphetamine seeking in extinction-reinstatement animal models of addiction. Less is known about effects of mGlu5 NAMs in abstinence models, particularly for methamphetamine. We used the incubation of drug craving model, in which cue-induced craving progressively intensifies after withdrawal from drug self-administration, to conduct the first studies of the following aspects of mGlu5 function in the rat nucleus accumbens (NAc) core during abstinence from methamphetamine self-administration: 1) functionality of the major form of synaptic depression in NAc medium spiny neurons, which is induced postsynaptically via mGlu5 and expressed presynaptically via cannabinoid type 1 receptors (CB1Rs), 2) mGlu5 surface expression and physical associations between mGlu5, Homer proteins, and diacylglycerol lipase-α, and 3) the effect of systemic and intra-NAc core administration of the mGlu5 NAM 3-((2-methyl-4-)ethynyl)pyridine (MTEP) on expression of incubated methamphetamine craving. We found that mGlu5/CB1R-dependent synaptic depression was lost during the rising phase of methamphetamine incubation but then recovered, in contrast to its persistent impairment during the plateau phase of incubation of cocaine craving. Furthermore, whereas the cocaine-induced impairment was accompanied by reduced mGlu5 levels and mGlu5-Homer associations, this was not the case for methamphetamine. Systemic MTEP reduced incubated methamphetamine seeking, but also reduced inactive hole nose-pokes and locomotion, while intra-NAc core MTEP had no significant effects. These findings provide the first insight into the role of mGlu5 in the incubation of methamphetamine craving and reveal differences from incubation of cocaine craving.

Hippocampal blood-brain barrier of methamphetamine self-administering HIV-1 transgenic rats

Combined antiretroviral therapy for HIV infection reduces plasma viral load and prolongs life. However, the brain is a viral reservoir, and pathologies such as cognitive decline and blood-brain barrier (BBB) disruption persist. Methamphetamine abuse is prevalent among HIV-infected individuals. Methamphetamine and HIV toxic proteins can disrupt the BBB, but it is unclear if there exists a common pathway by which HIV proteins and methamphetamine induce BBB damage. Also unknown are the BBB effects imposed by chronic exposure to HIV proteins in the comorbid context of chronic methamphetamine abuse. To evaluate these scenarios, we trained HIV-1 transgenic (Tg) and non-Tg rats to self-administer methamphetamine using a 21-day paradigm that produced an equivalency dose range at the low end of the amounts self-titrated by humans. Markers of BBB integrity were measured for the hippocampus, a brain region involved in cognitive function. Outcomes revealed that tight junction proteins, claudin-5 and occludin, were reduced in Tg rats independent of methamphetamine, and this co-occurred with increased levels of lipopolysaccharide, albumin (indicating barrier breakdown) and matrix metalloproteinase-9 (MMP-9; indicating barrier matrix disruption); reductions in GFAP (indicating astrocytic dysfunction); and microglial activation (indicating inflammation). Evaluations of markers for two signaling pathways that regulate MMP-9 transcription, NF-κB and ERK/∆FosB revealed an overall genotype effect for NF-κB. Methamphetamine did not alter measurements from Tg rats, but in non-Tg rats, methamphetamine reduced occludin and GFAP, and increased MMP-9 and NF-κB. Study outcomes suggest that BBB dysregulation resulting from chronic exposure to HIV-1 proteins or methamphetamine both involve NF-κB/MMP-9.

The motivational valence of methamphetamine relates inversely to subsequent methamphetamine self-administration in female C57BL/6J mice

Understanding the mechanisms underpinning individual variance in addiction vulnerability requires the development of validated, high-throughput screens. In a prior study of a large sample of male isogenic C57BL/6J mice, the direction and magnitude of methamphetamine (MA)-induced place-conditioning predicts the propensity to acquire oral MA self-administration, as well as the efficacy of MA to serve as a reinforcer. The present study examined whether or not such a predictive relationship also exists in females. Adult C57BL/6J females underwent a 4-day MA place-conditioning paradigm (once daily injections of 2 mg/kg) and were then trained to nose-poke for delivery of a 20 mg/L MA solution under increasing schedules of reinforcement, followed by dose-response testing (5-400 mg/L MA). Akin to males, 53 % of the females exhibited a conditioned place-preference, while 32 % of the mice were MA-neutral and 15 % exhibited a conditioned place-aversion. However, unlike males, the place-conditioning phenotype did not transfer to MA-reinforced nose-poking behavior under operant-conditioning procedures, with 400 mg/L MA intake being inversely correlated place-conditioning. While only one MA-conditioning dose has been assayed to date, these data indicate that sex does not significantly shift the proportion of C57BL/6J mice that perceive MA's interoceptive effects as positive, neutral or aversive. However, a sex difference appears to exist regarding the predictive relationship between the motivational valence of MA and subsequent drug-taking behavior; females exhibit MA-taking behavior and reinforcement, despite their initial perception of the stimulant interoceptive effects as positive, neutral or negative.