The Effect of Dehydroepiandrosterone Administration during Rehabilitation on White Matter Integrity Among Individuals With Polysubstance Use Disorder.

OBJECTIVES: Individuals with polysubstance use disorder (pSUD) exhibit vulnerability to relapse even after prolonged abstinence, with rehabilitation efforts achieving limited success. Previous studies highlighted dehydroepiandrosterone (DHEA) as a putative therapeutic agent that may aid rehabilitation, potentially by impacting white matter (WM) properties. The current study tested, for the first time, the effect of DHEA administration during rehabilitation on WM integrity among pSUD individuals, while assessing its putative association with long-term relapse rates. METHODS: Immediately after admission to rehabilitation, 30 pSUD individuals were assigned to receive either placebo or DHEA (100 mg) daily for 3 months, via a randomized double-blind counterbalanced design. Participants also provided blood samples to assess circulating DHEA levels at treatment initiation and completed a diffusion tensor imaging (DTI) scan approximately 1 month after treatment initiation. Clinical status was evaluated 16 months after treatment initiation. Thirty matched healthy controls also underwent a DTI scan without any intervention. RESULTS: DHEA administration was not associated with reduced relapse rates compared with placebo. Nevertheless, exploratory analysis revealed that DHEA was associated with successful rehabilitation among pSUD individuals with low circulating DHEA levels at treatment initiation. White matter integrity in the splenium corpus callosum (CC) was reduced in pSUD individuals compared with healthy controls, yet pSUD individuals receiving DHEA exhibited recovery of splenium CC WM integrity. CONCLUSIONS: DHEA administration during rehabilitation may restore WM integrity in the CC among pSUD individuals. Although DHEA was not associated with reduced relapse rates in here, its therapeutic efficacy may depend on circulating DHEA levels at treatment initiation.

Placenta-Derived Mesenchymal-like Adherent Stromal Cells as an Effective Cell Therapy for Cocaine Addiction in a Rat Model.

Recent research points to mesenchymal stem cells' potential for treating neurological disorders, especially drug addiction. We examined the longitudinal effect of placenta-derived mesenchymal stromal-like cells (PLX-PAD) in a rat model for cocaine addiction. Sprague-Dawley male rats were trained to self-administer cocaine or saline daily until stable maintenance. Before the extinction phase, PLX-PAD cells were administered by intracerebroventricular or intranasal routes. Neurogenesis was evaluated, as was behavioral monitoring for craving. We labeled the PLX-PAD cells with gold nanoparticles and followed their longitudinal migration in the brain parallel to their infiltration of essential peripheral organs both by micro-CT and by inductively coupled plasma-optical emission spectrometry. Cell locations in the brain were confirmed by immunohistochemistry. We found that PLX-PAD cells attenuated cocaine-seeking behavior through their capacity to migrate to specific mesolimbic regions, homed on the parenchyma in the dentate gyrus of the hippocampus, and restored neurogenesis. We believe that intranasal cell therapy is a safe and effective approach to treating addiction and may offer a novel and efficient approach to rehabilitation.

The Effect of Dehydroepiandrosterone Treatment on Neurogenesis, Astrogliosis and Long-Term Cocaine-Seeking Behavior in a Cocaine Self-Administration Model in Rats.

Cocaine addiction is an acquired behavioral state developed in vulnerable individuals after cocaine exposure. It is characterized by compulsive drug-seeking and high vulnerability to relapse even after prolonged abstinence, associated with decreased neurogenesis in the hippocampus. This addictive state is hypothesized to be a form of "memory disease" in which the drug exploits the physiological neuroplasticity mechanisms that mediate regular learning and memory processes. Therefore, a major focus of the field has been to identify the cocaine-induced neuroadaptations occurring in the usurped brain's reward circuit. The neurosteroid dehydroepiandrosterone (DHEA) affects brain cell morphology, differentiation, neurotransmission, and memory. It also reduces drug-seeking behavior in an animal model of cocaine self-administration. Here, we examined the long-lasting effects of DHEA treatment on the attenuation of cocaine-seeking behavior. We also examined its short- and long-term influence on hippocampal cells architecture (neurons and astrocytes). Using a behavioral examination, immunohistochemical staining, and diffusion tensor imaging, we found an immediate effect on tissue density and activation of astrocytes, which has a continuous beneficial effect on neurogenesis and tissue organization. This research emphasizes the requites concert between astrocytes and neurons in the rehabilitation from addiction behavior. Thus, DHEA may serve as a treatment that corrects brain damage following exposure to and abstinence from cocaine.

Reduction of DNMT3a and RORA in the nucleus accumbens plays a causal role in post-traumatic stress disorder-like behavior: reversal by combinatorial epigenetic therapy.

Post-traumatic stress disorder (PTSD) is an incapacitating trauma-related disorder, with no reliable therapy. Although PTSD has been associated with epigenetic alterations in peripheral white blood cells, it is unknown where such changes occur in the brain, and whether they play a causal role in PTSD. Using an animal PTSD model, we show distinct DNA methylation profiles of PTSD susceptibility in the nucleus accumbens (NAc). Data analysis revealed overall hypomethylation of different genomic CG sites in susceptible animals. This was correlated with the reduction in expression levels of the DNA methyltransferase, DNMT3a. Since epigenetic changes in diseases involve different gene pathways, rather than single candidate genes, we next searched for pathways that may be involved in PTSD. Analysis of differentially methylated sites identified enrichment in the RAR activation and LXR/RXR activation pathways that regulate Retinoic Acid Receptor (RAR) Related Orphan Receptor A (RORA) activation. Intra-NAc injection of a lentiviral vector expressing either RORA or DNMT3a reversed PTSD-like behaviors while knockdown of RORA and DNMT3a increased PTSD-like behaviors. To translate our results into a potential pharmacological therapeutic strategy, we tested the effect of systemic treatment with the global methyl donor S-adenosyl methionine (SAM), for supplementing DNA methylation, or retinoic acid, for activating RORA downstream pathways. We found that combined treatment with the methyl donor SAM and retinoic acid reversed PTSD-like behaviors. Thus, our data point to a novel approach to the treatment of PTSD, which is potentially translatable to humans.

Modulation of PARP-1 Activity in a Broad Time Window Attenuates Memorizing Fear.

The amygdala plays a critical role in the acquisition and consolidation of fear-related memories. Recent studies have demonstrated that ADP-ribosylation of histones, accelerated by PARPs, affects the chromatin structure and the binding of chromatin remodeling complexes with transcription factors. Inhibition of PARP-1 activity during the labile phase of re-consolidation may erase memory. Accordingly, we investigated the possibility of interfering with fear conditioning by PARP-1 inhibition. Herein, we demonstrate that injection of PARP-1 inhibitors, specifically into the CeA or i.p., in different time windows post-retrieval, attenuates freezing behavior. Moreover, the association of memory with pharmacokinetic timing of PARP inhibitor arrival to the brain enabled/achieved attenuation of a specific cue-associated memory of fear but did not hinder other memories (even traumatic events) associated with other cues. Our results suggest using PARP-1 inhibitors as a new avenue for future treatment of PTSD by disrupting specific traumatic memories in a broad time window, even long after the traumatic event. The safety of using these PARP inhibitors, that is, not interfering with other natural memories, is an added value.

Discovering the Lost Reward: Critical Locations for Endocannabinoid Modulation of the Cortico-Striatal Loop That Are Implicated in Major Depression.

Depression, the most prevalent psychiatric disorder in the Western world, is characterized by increased negative affect (i.e., depressed mood, cost value increase) and reduced positive affect (i.e., anhedonia, reward value decrease), fatigue, loss of appetite, and reduced psychomotor activity except for cases of agitative depression. Some forms, such as post-partum depression, have a high risk for suicidal attempts. Recent studies in humans and in animal models relate major depression occurrence and reoccurrence to alterations in dopaminergic activity, in addition to other neurotransmitter systems. Imaging studies detected decreased activity in the brain reward circuits in major depression. Therefore, the location of dopamine receptors in these circuits is relevant for understanding major depression. Interestingly, in cortico-striatal-dopaminergic pathways within the reward and cost circuits, the expression of dopamine and its contribution to reward are modulated by endocannabinoid receptors. These receptors are enriched in the striosomal compartment of striatum that selectively projects to dopaminergic neurons of substantia nigra compacta and is vulnerable to stress. This review aims to show the crosstalk between endocannabinoid and dopamine receptors and their vulnerability to stress in the reward circuits, especially in corticostriatal regions. The implications for novel treatments of major depression are discussed.

RNA editing of the 5-HT2C receptor in the central nucleus of the amygdala is involved in resilience behavior.

Post-traumatic-stress-disorder (PTSD) is a stress-related condition that may develop after exposure to a severe trauma-event. One of the core brain areas that is considered to be a key regulatory region of PTSD is the amygdala. Specifically, the central amygdala (CeA) is involved in emotion processing and associative fear learning memory, two main circuits involved in PTSD. Long term dysregulation of trauma-related emotional processing may be caused by neuroadaptations that affect gene expression. The adenosine-(A) to-inosine (I) RNA editing machinery is a post-transcriptional process that converts a genomic encoded A to I and is critical for normal brain function and development. Such editing has the potential to increase the transcriptome diversity, and disruption of this process has been linked to various central nervous system disorders. Here, we employed a unique animal model to examine the possibility that the RNA editing machinery is involved in PTSD. Detection of RNA editing specifically in the CeA revealed changes in the editing pattern of the 5-HT2C serotonin receptor (5-HT2CR) transcript accompanied by dynamic changes in the expression levels of the ADAR family enzymes (ADAR and ADARb1). Deamination by ADAR and ADARb1 enzymes induces conformational changes in the 5-HT2CR that decrease the G-protein-coupling activity, agonist affinity, and thus serotonin signaling. Significantly, a single intra-CeA administration of a 5-HT2CR pharmacological antagonist produced a robust alleviation of PTSD-like behaviors (that was maintained for three weeks) as well as single systemic treatment. This work may suggest the way to a new avenue in the understanding of PTSD regulation.

Chronic opipramol treatment extinguishes cocaine craving through Rac1 in responders: A rat model study.

Ras-related C3 botulinum toxin substrate 1 (Rac1), of the Rho small GTPase family, is a key regulator of actin cytoskeleton rearrangement and plays an important role in dendritic morphogenesis. Cocaine produces neuronal alterations, including structural changes in dendritic number and morphology. Emerging data indicate sigma-1 receptors (σ-1Rs) as a promising candidate for the prevention of cocaine craving. Opipramol is a σ-1R agonist approved in some European countries for depression and anxiety. Here we report that opipramol, mediated by Rac1, attenuates cocaine-seeking behavior in a rat model of self-administration. The opipramol effect was shown in two phases. It decreased cocaine-seeking behavior throughout the withdrawal phase and, interestingly, showed a significant reduction of cocaine-primed reinstatement in 75% of the opipramol-treated group (termed 'responders'). All opipramol-treated rats showed a decrease in σ-1R mRNA expression levels in the nucleus accumbens (NAc) versus controls. Responders also exhibited significantly decreased NAc Rac1 mRNA expression levels, compared with non-responder rats. Hence, Rac1 differentiated responders from non-responders. Rac1 correlated positively with σ-1R mRNA levels in opipramol responders. In another experiment, Rac1 inhibitor injected directly into the NAc core decreased active lever presses on the first day of extinction, indicating the critical role of Rac1 in the opipramol effect on drug seeking. We postulate that chronic activation of σ-1R, through a dynamic interaction with Rac1, may suggest a new approach to treat substance use disorder (SUD). Rac1 inhibition is a prerequisite for decreasing drug seeking and rehabilitation, and this can be achieved by opipramol, a medication that can be given during detoxification.

Novel Opipramol-Baclofen Combination Alleviates Depression and Craving and Facilitates Recovery From Substance Use Disorder-An Animal Model and a Human Study.

Substance use disorders (SUDs) are associated with depression and anxiety, with the latter being one of the major factors in substance-seeking and relapse. Due to dose-dependent sedative side effects there is limited efficacy of baclofen treatment for SUDs. Here we suggest the use of a novel combination of opipramol and baclofen (O/B) which is known to attenuate anxiety and depression, for the facilitation of recovery from SUDs. Since both opipramol and baclofen have a common downstream signal transduction, their individual doses could be reduced while still maintaining the benefits of the combination. We tested the O/B combination in both animals and patients. Rats treated with O/B showed significant attenuation in craving behavior and in relapse rate during withdrawal from cocaine. In a double-blind, placebo-controlled pilot study, conducted in a residential detoxification center, 14 males and 3 females, aged 28-60 years were assigned to a study (n = 6) and a placebo (n = 11) group (placebo group: 40 ± 10.5 years; O/B group 40 ± 10.8 years). The participants completed scales measuring depression, anxiety and craving symptoms and provided saliva samples for stress hormone examination [cortisol and dehydroepiandrosterone-sulfate (DHEA-S)]. Participants with polysubstance use disorder (PsUD) treated with O/B showed a reduction in cravings and depression and an increase in DHEA-S and in the DHEA-S/cortisol ratio. Our findings indicate a beneficial effect of O/B treatment. This study suggests a novel candidate for pharmacological treatment of patients with SUD and comorbid mood/anxiety disorders that may facilitate their rehabilitation.

Who becomes addicted and to what? psychosocial predictors of substance and behavioral addictive disorders.

A multitude of psychological and social factors likely contribute to the development and maintenance of addictive disorders. As different people develop different addictions, it is important to understand whether psychosocial factors are related differently to different types of addictive disorders. In this study, we examined the unique interaction of personality traits, family environment, and life events in predicting substance (drugs, alcohol) and behavioral (gambling, sex) addictive disorders, among 207 participants suffering from an addictive disorder and 79 controls. Results identified several psychosocial factors, including impulsivity and reported negative life events, that predicted all types of addictive disorders. There was also a unique prediction model for each addiction. Drug and alcohol use disorders were predicted by lower agreeableness and less intellectual-cultural family orientation, with alcohol use disorder further predicted by lower extraversion and higher family organization. Gambling disorder was predicted by a family with lower intellectual-cultural orientation and higher organization and control, whereas compulsive sexual behavior was predicted by lower extraversion and agreeableness and higher neuroticism, and by higher family control. These findings suggest that the complex interplay among psychosocial factors is manifested differently across addictive disorders and may thus have important implications for research, prevention, and intervention.

Sex differences in testosterone reactivity and sensitivity in a non-model gerbil.

Although testosterone (T) is a key regulator in vertebrate development, physiology, and behaviour in both sexes, studies suggest that its regulation may be sex-specific. We measured circulating T levels in Baluchistan gerbils (Gerbillus nanus) in the field and in the lab all year round and found no significant sex differences. However, we observed sex differences in circulating T levels following gonadotropin-releasing hormone (GnRH) challenge and T implants in this non-model species. Whereas only males elevated T following a GnRH challenge, females had higher serum T concentrations following T implant insertion. These differences may be a result of different points of regulation along the hypothalamic-pituitary-gonadal (HPG) axis. Consequently, we examined sex differences in the mRNA expression of the androgen receptor (AR) in multiple brain regions. We identified AR and ß-actin sequences in assembled genomic sequences of members of the Gerbillinae, which were analogous to rat sequences, and designed primers for them. The distribution of the AR in G. nanus brain regions was similar to documented expression profiles in rodents. We found lower AR mRNA levels in females in the striatum. Additionally, G. nanus that experienced housing in mixed-sex pairs had higher adrenal AR expression than G. nanus that were housed alone. Regulation of the gerbil HPG axis may reflect evolutionary sex differences in life-history strategies, with males ready to reproduce when receptive females are available, while the possible reproductive costs associated with female T direct its regulation upstream.

Negative and positive life events and their relation to substance and behavioral addictions.

BACKGROUND: Research has shown that negative life events (LEs) may be connected to the development and maintenance of addictions. However, few studies have examined the potential relationship between positive events and addictive disorders, and even fewer studies evaluated the subjective perception of LEs that may underlie these relationships. Importantly, addictive disorders include both substance-related and behavioral addictions, but the relative relationship of each type of addiction with LEs remains unclear. METHODS: The present study compared 212 participants suffering from an addiction (drugs, alcohol, gambling, and sex) and 79 controls on self-report measures of negative and positive LEs. RESULTS: Compared with controls, individuals with an addiction reported experiencing a larger number of both negative and positive LEs and also tended to be more influenced by negative LEs. Findings also demonstrated differential patterns across addiction types, such that participants with compulsive sexual behavior (CSB) reported experiencing less negative events than those with drug use disorders (DUD) and were less influenced by these events than participants with alcohol use disorder (AUD). Finally, analyses within each group further revealed differences in the way each group experienced negative compared to positive events. Controls and participants with CSB reported experiencing a similar number of positive and negative events, whereas participants with DUD, AUD, and gambling disorder reported more negative events in their lives. CONCLUSIONS: These findings suggest a unique profile among different types of addictions, which should be taken into account when planning personalized prevention and intervention approaches.

Qualitative review and quantitative effect size meta-analyses in brain regions identified by cue-reactivity addiction studies.

OBJECTIVE: Various brain regions have been identified as involved in addictions, yet inconsistencies remain regarding the primary regions that may underlie addictive behaviors. To address this, we conducted a meta-analysis investigating cue-reactivity functional MRI studies for different addictions. METHOD: We explored 8 different addiction-related brain regions in 27 studies (29 samples) using homogeneity tests of effect sizes. RESULTS: An initial qualitative review failed to identify consistent activations in any brain region. We subsequently explored possible moderators related to either the addiction, participants, or study design, and found addiction type to be a relevant moderator, suggesting that different addictions may not necessarily involve the same brain regions. Successive quantitative analyses found that internet gaming addiction and heroin dependence modulated neural activation in the right dorsolateral prefrontal cortex and heroin dependence further in the right orbitofrontal cortex. Our analyses also demonstrated the expected mean effect sizes in each region when conducting cue-reactivity experiments on addictions. CONCLUSIONS: It appears that distinct addiction types may manifest differently in the brain and may moderate cue reactivity to a greater extent than previously suggested factors. This study underscores the need for additional research comparing the neural mechanisms underlying different addiction types. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Evidence for a differential visual M300 brain response in gamblers.

OBJECTIVE: Gambling disorder is the first behavioral addiction recognized in the DSM-5. This marks the growing realization that both behavioral and substance-related addictions are manifestations of an 'addicted brain', displaying similar altered neurophysiological mechanisms. A decreased electrophysiological visual P300 is considered a hallmark effect of substance-related addictions, but has not yet been shown in behavioral addictions. METHODS: Magnetoencephalographic recordings of 15 gamblers and 17 controls were taken as they performed a cue-reactivity paradigm in which they passively viewed addiction- and non-addiction-related cues. RESULTS: The main finding of the study is a reduction in the magnetic counterpart of P300 (M300) for gamblers beyond cue condition over frontal regions. Additionally, we found a significant group by cue-type interaction. Gamblers exhibited heightened sensitivity to addiction-related cues in regions corresponding to the frontoparietal attentional network, whereas controls exhibited an opposite effect localized to the right insula. CONCLUSIONS: The results suggest that a reduced P300 characterizes addictions in general, not just substance-related addictions, thus providing important neurophysiological support for the inclusion of behavioral addictions in the DSM-5 and in the incentive-sensitization theory. SIGNIFICANCE: The study offers important insights into neural mechanisms underlying behavioral addictions, and may assist in developing better prevention and intervention strategies.

A DNA Methylation Signature of Addiction in T Cells and Its Reversal With DHEA Intervention.

Previous studies in animal models of cocaine craving have delineated broad changes in DNA methylation profiles in the nucleus accumbens. A crucial factor for progress in behavioral and mental health epigenetics is the discovery of epigenetic markers in peripheral tissues. Several studies in primates and humans have associated differences in behavioral phenotypes with changes in DNA methylation in T cells and brain. Herein, we present a pilot study (n = 27) showing that the T cell DNA methylation profile differentiates persons with a substance use disorder from controls. Intervention with dehydroepiandrosterone (DHEA), previously shown to have a long-term therapeutic effect on human addicts herein resulted in reversal of DNA methylation changes in genes related to pathways associated with the addictive state.

Dehydroepiandrosterone and Addiction.

Drug addiction has a great negative influence on society, both social and economic burden. It was widely thought that addicts could choose to stop using drugs if only they had some self-control and principles. Nowadays, science has changed this view, defining drug addiction as a complex brain disease that affects behavior in many ways, both biological and psychological. Currently there is no ground-breaking reliable treatment for drug addiction. For more than a decade we are researching an alternative approach for intervention with drug craving and relapse to its usage, using DHEA, a well-being and antiaging food supplement. In this chapter we navigate through the significant therapeutic effect of DHEA on the brain circuits that control addiction and on behavioral performance both in animal models and addicts. We suggest that an integrative program of add-on DHEA treatment may further enable to dynamically evaluate the progress of rehabilitation of an individual patient, in a comprehensive assessment. Such a program may boost and support the detoxification and rehabilitation process, and help patients regain a normal life in a shorter amount of time.

Personality profiles of substance and behavioral addictions.

Substance-related and behavioral addictions are extremely prevalent and represent a major public health concern. In the ongoing attempt to understand the addictive personality, contradictory results have arisen from studies that have explored personality traits in different addiction populations. The diversity across addiction types suggests that some of these inconsistencies stem from distinct personalities underlying each addiction. The present study compares the personality profiles of several addictions, representing both substance (drugs and alcohol) and behavioral (gambling and sex) subtypes. 216 addicted individuals and 78 controls completed personality and sociodemographic questionnaires. Notable personality distinctions were found among different types of addiction. Whereas impulsivity and neuroticism were higher across all addiction populations, as compared to controls, people with alcohol use disorders also scored significantly lower on the traits of extraversion, agreeableness, and openness to experience. People with drug use disorders and those with compulsive sexual behavior were surprisingly similar, scoring lowest on the traits of agreeableness and conscientiousness. Finally, people with gambling disorder demonstrated a personality profile similar to that of the control group. Of note, personality profiles were also related to several demographic characteristics, including socioeconomic status and religiosity. Our findings support a potential role for personality in distinguishing among different types of addiction. This study suggests that different addictions may, to some extent, stem from distinct processes that are involved in personality development. These findings may provide a useful framework for understanding why different people develop different addictions.

Social rank-associated stress vulnerability predisposes individuals to cocaine attraction.

Studies of personality have suggested that dissimilarities in ability to cope with stressful situations results in differing tendency to develop addictive behaviors. The present study used selectively bred stress-resilient, socially-dominant (Dom) and stress-vulnerable, socially-submissive (Sub) mice to investigate the interaction between environmental stress and inbred predisposition to develop addictive behavior to cocaine. In a Conditioned Place Preference (CPP) paradigm using cocaine, Sub mice displayed an aversion to drug, whereas Dom mice displayed drug attraction. Following a 4-week regimen of Chronic Mild Stress (CMS), Sub mice in CPP displayed a marked increase (>400%) in cocaine attraction, whereas Dom mice did not differ in attraction from their non-stressed state. Examination of hippocampal gene expression revealed in Sub mice, exposure to external stimuli, stress or cocaine, increased CRH expression (>100%), which was evoked in Dom mice only by cocaine exposure. Further, stress-induced decreases in DRD1 (>60%) and DRD2 (>50%) expression in Sub mice differed markedly from a complete lack of change in Dom mice. From our findings, we propose that social stratification dictates vulnerability to stress-induced attraction that may lead to addiction via differential regulation of hippocampal response to dopaminergic input, which in turn may influence differing tendency to develop addictive behaviors.

In Vivo Neuroimaging of Exosomes Using Gold Nanoparticles.

Exosomes are emerging as effective therapeutic tools for various pathologies. These extracellular vesicles can bypass biological barriers, including the blood-brain barrier, and can serve as powerful drug and gene therapy transporters. However, the progress of therapy development is impeded by several challenges, including insufficient data on exosome trafficking and biodistribution and the difficulty to image deep brain structures in vivo. Herein, we established a method for noninvasive in vivo neuroimaging and tracking of exosomes, based on glucose-coated gold nanoparticle (GNP) labeling and computed tomography imaging. Labeling of exosomes with the GNPs was achieved directly, as opposed to the typical and less efficient indirect labeling mode through parent cells. On the mechanistic level, we found that the glucose-coated GNPs were uptaken into MSC-derived exosomes via an active, energy-dependent mechanism that is mediated by the glucose transporter GLUT-1 and involves endocytic proteins. Next, we determined optimal parameters of size and administration route; we demonstrated that 5 nm GNPs enabled improved exosome labeling and that intranasal, compared to intravenous, administration led to superior brain accumulation and thus enhanced in vivo neuroimaging. Furthermore, using a mouse model of focal brain ischemia, we noninvasively tracked intranasally administered GNP-labeled exosomes, which showed increased accumulation at the lesion site over 24 h, as compared to nonspecific migration and clearance from control brains over the same period. Thus, this exosome labeling technique can serve as a powerful diagnostic tool for various brain disorders and could potentially enhance exosome-based treatments for neuronal recovery.

Therapeutic Effect of Astroglia-like Mesenchymal Stem Cells Expressing Glutamate Transporter in a Genetic Rat Model of Depression.

Recent studies have proposed that abnormal glutamatergic neurotransmission and glial pathology play an important role in the etiology and manifestation of depression. It was postulated that restoration of normal glutamatergic transmission, by enhancing glutamate uptake, may have a beneficial effect on depression. We examined this hypothesis using unique human glial-like mesenchymal stem cells (MSCs), which in addition to inherent properties of migration to regions of injury and secretion of neurotrophic factors, were differentiated to express high levels of functional glutamate transporters (excitatory amino acid transporters; EAAT). Additionally, gold nanoparticles (GNPs), which serve as contrast agents for CT imaging, were loaded into the cells for non-invasive, real-time imaging and tracking of MSC migration and final location within the brain. MSC-EAAT (2×105; 10 µl) were administered (i.c.v.) to Flinder Sensitive Line rats (FSLs), a genetic model for depression, and longitudinal behavioral and molecular changes were monitored. FSL rats treated with MSC-EAAT showed attenuated depressive-like behaviors (measured by the forced swim test, novelty exploration test and sucrose self-administration paradigm), as compared to controls. CT imaging, Flame Atomic Absorption Spectroscopy analysis and immunohistochemistry showed that the majority of MSCs homed specifically to the dentate gyrus of the hippocampus, a region showing structural brain changes in depression, including loss of glial cells. mRNA and protein levels of EAAT1 and BDNF were significantly elevated in the hippocampus of MSC-EAAT-treated FSLs. Our findings indicate that MSC-EAATs effectively improve depressive-like manifestations, possibly in part by increasing both glutamate uptake and neurotropic factor secretion in the hippocampus.