Genetically determined dopamine availability predicts disposition for depression

The Structural Basis of the Activity Cliff in Modafinil-Based Dopamine Transporter Inhibitors

Modafinil analogs with either a sulfoxide or sulfide moiety have improved binding affinities at the human dopamine transporter (hDAT) compared to modafinil, with lead sulfoxide-substituted analogs showing characteristics of atypical inhibition (e.g., JJC8-091). Interestingly, the only distinction between sulfoxide and sulfide substitution is the presence of one additional oxygen atom. To elucidate why such a subtle difference in ligand structure can result in different typical or atypical profiles, we investigated two pairs of analogs. Our quantum mechanical calculations revealed a more negatively charged distribution of the electrostatic potential surface of the sulfoxide substitution. Using molecular dynamics simulations, we demonstrated that sulfoxide-substituted modafinil analogs have a propensity to attract more water into the binding pocket. They also exhibited a tendency to dissociate from Asp79 and form a new interaction with Asp421, consequently promoting an inward-facing conformation of hDAT. In contrast, sulfide-substituted analogs did not display these effects. These findings elucidate the structural basis of the activity cliff observed with modafinil analogs and also enhance our understanding of the functionally relevant conformational spectrum of hDAT.

Association between stress and catecholamines with painful TMD in children

BACKGROUND

Studying biomarkers in children with temporomandibular disorders (TMD) such as epinephrine, norepinephrine, and dopamine may reveal factors like screen time or sleep loss that affect these biomarkers and predict TMD-related pain, offering new research opportunities.

AIM

To determine the association between stress and catecholamines with myofascial pain and headache related to TMD in children.

DESIGN

Sixty-six 9- to 11-year-old children assisting at the clinics of Pediatric Dentistry of Universidad CES participated in the study. Myofascial pain and headache attributed to TMD were determined according to the Diagnostic Criteria for TMD (DC/TMD) Axis I. Stress was evaluated with the Perceived Stress Scale-Children (PSS-C), and a 24-h urine sample was analyzed using liquid chromatography to assay catecholamines. Single and multiple regression analyses were performed.

RESULTS

Children with a mean age of 10.3 years participated in the study. The mean score of stress was 29 ± 4. Perceived stress, dopamine, epinephrine, and norepinephrine were statistically significant predictors of myofascial pain and headache attributed to TMD in the single- and multiple variable logistic regression analyses.

CONCLUSION

Stressful states and its biological biomarkers increase the probability of developing myofascial pain and headache attributed to TMD in children.

The 3'UTR VNTR SLC6A3 Genetic Variant and Major Depressive Disorder: A Systematic Review

Major Depressive Disorder (MDD) is a disabling and particularly persistent mental disorder that is considered to be a priority public health problem. The active human dopamine transporter (DAT), which is encoded by the SLC6A3 gene, regulates the dopamine concentration in the synaptic cleft. In this sense, this neurotransmitter is primordial in modulating human emotions. This systematic review aims to verify the SLC6A3 (DAT1) 3'UTR VNTR (rs28363170) gene variant's SS (9R/9R) genotype and S (9R) allele frequency fluctuation and its influence on the modulation of pharmacotherapy in MDD. For this purpose, we searched different databases, and after applying the eligibility criteria, six articles were selected. Studies have shown an association between the SS (9R/9R) genotypic and S (9R) allelic presence with the risk of developing MDD, in addition to influencing the decrease in response to antidepressant therapy. However, despite the findings, disagreements were observed between other studies. For this reason, further studies with the SLC6A3 3'UTR VNTR (rs28363170) variant in different populations are necessary to understand this polymorphism's role in the onset of this disease.

Disordered eating in early childhood: DRD4 and DAT1 gene polymorphisms and quality of mother-child interaction

PURPOSE

Eating disturbances are complex heritable conditions that can be influenced by both genetic and environmental factors but are poorly studied in early development. The aim of this research was to investigate the association of genetic polymorphisms within dopaminergic pathways with early feeding problems.

METHODS

We analyzed the presence of VNTR polymorphisms of DRD4 (rs1805186) and DAT1 (rs28363170) in overeating (N = 45), undereating (N = 48) and control (N = 44) young children. We also assessed presence of externalizing, internalizing and dysregulation symptoms by the Child Behavior Checklist and quality of mother-child interactions during feeding by the Italian adaptation of the Scale for the Assessment of Feeding Interaction, respectively.

RESULTS

Both polymorphisms were associated with children's eating behavior, psychological symptoms and quality of interaction with their mothers, suggesting that: (a) the DRD4 4-repeat allele behaves as a protective factor, the 2-repeats and 7-repeats alleles as risk factors, for undereating behavior, the general quality of mother-child interaction and internalizing, externalizing and dysregulated symptoms; and (b) the DAT1 9-repeats allele behaves as a protective factor, the 10-repeats allele as a risk factor, for overeating behavior, the general quality of mother-child interaction, internalizing, externalizing and dysregulated symptoms. Finally, a gene x gene interaction is suggested between the DAT1 9-repeat or 10-repeat allele and the DRD4 4-repeat allele.

CONCLUSIONS

Our results suggest a role for DRD4 and DAT1 in an early susceptibility to eating disturbances.

LEVEL OF EVIDENCE III

Evidence obtained from well-designed case-control analytic study.

ADHD co-morbidities: A review of implication of gene × environment effects with dopamine-related genes

ADHD is a major burden in adulthood, where co-morbid conditions such as depression, substance use disorder and obesity often dominate the clinical picture. ADHD has substantial shared heritability with other mental disorders, contributing to comorbidity. However, environmental risk factors exist but their interaction with genetic makeup, especially in relation to comorbid disorders, remains elusive. This review for the first time summarizes present knowledge on gene x environment (GxE) interactions regarding the dopamine system. Hitherto, mainly candidate (GxE) studies were performed, focusing on the genes DRD4, DAT1 and MAOA. Some evidence suggest that the variable number tandem repeats in DRD4 and MAOA may mediate GxE interactions in ADHD generally, and comorbid conditions specifically. Nevertheless, even for these genes, common variants are bound to suggest risk only in the context of gender and specific environments. For other polymorphisms, evidence is contradictory and less convincing. Particularly lacking are longitudinal studies testing the interaction of well-defined environmental with polygenic risk scores reflecting the dopamine system in its entirety.

Interaction between COMT Val158 Met polymorphism and childhood trauma predicts risk for depression in men

Depression is a disabling illness with complex etiology. While the Catechol-O-Methyltransferase (COMT) gene, in particular the functional Val¹⁵⁸ Met polymorphism, has been related to depression, the mechanisms underlying this gene-disease association are not completely understood. Therefore, we explore the association of COMT Val¹⁵⁸ Met polymorphism with depression as well as its interaction with childhood trauma in 1,136 young adults from a population-based study carried out in the city of Pelotas-Brazil. The diagnosis was performed through the Mini International Neuropsychiatric Interview 5.0 (MINI 5.0), and trauma was assessed with the childhood trauma questionnaire (CTQ). Total DNA was extracted and genotyped by real-time PCR and the QTLbase dataset was queried to perform large-scale quantitative trait locus (QTL) analysis. Our research showed no direct association between the Val¹⁵⁸ Met polymorphism and the diagnosis of depression (women: χ2=0.10, d=1, p=0.751 and men: χ2=0.003, df=1 p=0.956). However, the Met-allele of the Val¹⁵⁸ Met polymorphism modified the effect of childhood trauma in men [OR=2.58 (95% CI:1.05-6.29); p=0.038] conferring risk for depression only on those who suffer from trauma. The conditional effect from moderation analysis showed that trauma impacts the risk of depression only in men carrying the Met-allele (Effect: 0.9490, Standard Error (SE): 0.2570; p=0.0002). QTLbase and dataset for Val¹⁵⁸ Met polymorphism were consistent for markers that influence chromatin accessibility transcription capacity including histone methylation and acetylation. The changes caused in gene regulation by childhood trauma exposure and polymorphism may serve as evidence of the mechanism whereby the interaction increases susceptibility to this disorder in men.

Genetic Variants Associated With Resilience in Human and Animal Studies

Resilience is broadly defined as the ability to maintain or regain functioning in the face of adversity and is influenced by both environmental and genetic factors. The identification of specific genetic factors and their biological pathways underpinning resilient functioning can help in the identification of common key factors, but heterogeneities in the operationalisation of resilience have hampered advances. We conducted a systematic review of genetic variants associated with resilience to enable the identification of general resilience mechanisms. We adopted broad inclusion criteria for the definition of resilience to capture both human and animal model studies, which use a wide range of resilience definitions and measure very different outcomes. Analyzing 158 studies, we found 71 candidate genes associated with resilience. OPRM1 (Opioid receptor mu 1), NPY (neuropeptide Y), CACNA1C (calcium voltage-gated channel subunit alpha1 C), DCC (deleted in colorectal carcinoma), and FKBP5 (FKBP prolyl isomerase 5) had both animal and human variants associated with resilience, supporting the idea of shared biological pathways. Further, for OPRM1, OXTR (oxytocin receptor), CRHR1 (corticotropin-releasing hormone receptor 1), COMT (catechol-O-methyltransferase), BDNF (brain-derived neurotrophic factor), APOE (apolipoprotein E), and SLC6A4 (solute carrier family 6 member 4), the same allele was associated with resilience across divergent resilience definitions, which suggests these genes may therefore provide a starting point for further research examining commonality in resilience pathways.

Attenuated dopamine signaling after aversive learning is restored by ketamine to rescue escape actions

Escaping aversive stimuli is essential for complex organisms, but prolonged exposure to stress leads to maladaptive learning. Stress alters neuronal activity and neuromodulatory signaling in distributed networks, modifying behavior. Here, we describe changes in dopaminergic neuron activity and signaling following aversive learning in a learned helplessness paradigm in mice. A single dose of ketamine suffices to restore escape behavior after aversive learning. Dopaminergic neuron activity in the ventral tegmental area (VTA) systematically varies across learning, correlating with future sensitivity to ketamine treatment. Ketamine’s effects are blocked by chemogenetic inhibition of dopamine signaling. Rather than directly altering the activity of dopaminergic neurons, ketamine appears to rescue dopamine dynamics through actions in the medial prefrontal cortex (mPFC). Chemogenetic activation of Drd1 receptor positive mPFC neurons mimics ketamine’s effects on behavior. Together, our data link neuromodulatory dynamics in mPFC-VTA circuits, aversive learning, and the effects of ketamine.

Over 264 million people around the world suffer from depression, according to the World Health Organization (WHO). Depression can be debilitating, and while anti-depressant drugs are available, they do not always work. A small molecule drug mainly used for anesthesia called ketamine has recently been shown to ameliorate depressive symptoms within hours, much faster than most anti-depressants. However, the molecular mechanisms behind this effect are still largely unknown.

Most anti-depressant drugs work by restoring the normal balance of dopamine and other chemical messengers in the brain. Dopamine is released by a specialized group of cells called dopaminergic neurons, and helps us make decisions by influencing a wide range of other cells in the brain. In a healthy brain, dopamine directs us to rewarding choices, while avoiding actions with negative outcomes. During depression, these dopamine signals are perturbed, resulting in reduced motivation and pleasure. But it remained unclear whether ketamine’s anti-depressant activity also relied on dopamine.

To investigate this, Wu et al. used a behavioral study called “learned helplessness” which simulates depression by putting mice in unavoidable stressful situations. Over time the mice learn that their actions do not change the outcome and eventually stop trying to escape from unpleasant situations, even if they are avoidable. The experiment showed that dopaminergic neurons in an area of the brain that is an important part of the “reward and aversion” system became less sensitive to unpleasant stimuli following learned helplessness. When the mice received ketamine, these neurons recovered after a few hours.

Individual mice also responded differently to ketamine. The most ‘resilient’, stress-resistant mice, which had distinct patterns of dopamine signaling, also responded most strongly to the drug. Genetic and chemical manipulation of dopaminergic neurons confirmed that ketamine needed intact dopamine signals to work, and revealed that it acted indirectly on dopamine dynamics via another brain region called the medial prefrontal cortex.

These results shed new light on how a promising new anti-depressant works. In the future, they may also explain why drugs like ketamine work better for some people than others, ultimately helping clinicians select the most effective treatment for individual patients.

A comprehensive review of studies using the Affective Neuroscience Personality Scales in the psychological and psychiatric sciences

Jaak Panksepp's Affective Neuroscience Theory (ANT) belongs to the most prominent emotion theories in the psychological and psychiatric sciences. ANT proposes the existence of seven primary emotional systems deeply anchored in the mammalian brain. These emotional/motivational systems have been shaped by evolutionary processes and function as tools for survival in mammalian species. The systems are called SEEKING, LUST, CARE, and PLAY, as well as ANGER, FEAR, and SADNESS. Panksepp carved out these emotional systems via means of deep brain stimulation, brain lesion and pharmacological manipulation studies. Davis et al. (2003) designed the Affective Neuroscience Personality Scales (ANPS) against the background of findings from ANT. This self-report inventory is meant to enable researchers to assess individual differences in primary emotional systems. Seventeen years have passed since the first version of the ANPS has been published. Therefore, we now provide a comprehensive overview on studies using the ANPS including work from personality science, psychiatry and the neurosciences.

Predictors of recurrence of major depressive disorder

A total of 201 patients with major depressive disorder from four hospitals in Malaysia were followed up for 5 years to determine the prognostic factors of recurrent major depressive disorder that could potentially contribute to improving the management of MDD patients. For each individual patient, at the time of recruitment as part of a case-control study, information was collected on recent threatening life events, personality and social and occupational functioning, while blood samples were collected to genotype single nucleotide polymorphisms of vitamin D receptor (VDR), zinc transporter-3 (ZnT3), dopamine transporter-1 (DAT1), brain-derived neurotropic factor (BDNF), serotonin receptor 1A (HT1A) and 2A (HT2A) genes. Kaplan-Meier and Cox-regression were used to estimate hazard functions for recurrence of major depressive disorder. Individuals with severe MDD in previous major depressive episodes had five and a half times higher hazard of developing recurrence compared to mild and moderate MDD (HR = 5.565, 95% CI = 1.631–18.994, p = 0.006). Individuals who scored higher on social avoidance had three and a half times higher hazard of recurrence of MDD (HR = 3.525, 95% CI = 1.349–9.209; p = 0.010). There was significant interaction between ApaI +64978C>A single nucleotide polymorphism and severity. The hazard ratio increased by 6.4 times from mild and moderate to severe MDD for A/A genotype while that for C/A genotype increased by 11.3 times. Social avoidance and severity of depression at first episode were prognostic of recurrence. Screening for personality factors at first encounter with MDD patients needs to be considered as part of the clinical practice. For those at risk of recurrence in relation to social avoidance, the psychological intervention prescribed should be customized to focus on this modifiable factor. Prompt and appropriate management of severe MDD is recommended to reduce risk of recurrence.

Associations Among Monoamine Neurotransmitter Pathways, Personality Traits, and Major Depressive Disorder

Major depressive disorder (MDD) is a complex psychiatric disease requiring multidisciplinary approaches to identify specific risk factors and establish more efficacious treatment strategies. Although the etiology and pathophysiology of MDD are not clear until these days, it is acknowledged that they are almost certainly multifactorial and comprehensive. Monoamine neurotransmitter system dysfunction and specific personality traits are independent risk factors for depression and suicide. These factors also demonstrate complex interactions that influence MDD pathogenesis and symptom expression. In this review, we assess these relationships with the aim of providing a reference for the development of precision medicine.

The Mesolimbic Dopamine System in Chronic Pain and Associated Affective Comorbidities

Chronic pain is a complex neuropsychiatric disorder characterized by sensory, cognitive, and affective symptoms. Over the past 2 decades, researchers have made significant progress toward understanding the impact of mesolimbic dopamine circuitry in acute and chronic pain. These efforts have provided insights into the circuits and intracellular pathways in the brain reward center that are implicated in sensory and affective manifestations of chronic pain. Studies have also identified novel therapeutic targets as well as factors that affect treatment responsiveness. Dysregulation of dopamine function in the brain reward center may further promote comorbid mood disorders and vulnerability to addiction. This review discusses recent clinical and preclinical findings on the neuroanatomical and neurochemical adaptations triggered by prolonged pain states in the brain reward pathway. Furthermore, this discussion highlights evidence of mechanisms underlying comorbidities among pain, depression, and addiction.

Emotional insecurity as a mediator of the moderating role of dopamine genes in the association between interparental conflict and youth externalizing problems

This study tested whether the association between interparental conflict and adolescent externalizing symptoms was moderated by a polygenic composite indexing low dopamine activity (i.e., 7-repeat allele of DRD4; Val alleles of COMT; 10-repeat variants of DAT1) in a sample of seventh-grade adolescents (Mean age = 13.0 years) and their parents. Using a longitudinal, autoregressive design, observational assessments of interparental conflict at Wave 1 predicted increases in a multi-informant measurement of youth externalizing symptoms 2 years later at Wave 3 only for children who were high on the hypodopaminergic composite. Moderation was expressed in a “for better” or “for worse” form hypothesized by differential susceptibility theory. Thus, children high on the dopaminergic composite experienced more externalizing problems than their peers when faced with more destructive conflicts but also fewer externalizing problems when exposed to more constructive interparental conflicts. Mediated moderation findings indicated that adolescent reports of their emotional insecurity in the interparental relationship partially explained the greater genetic susceptibility experienced by these children. More specifically, the dopamine composite moderated the association between Wave 1 interparental conflict and emotional insecurity 1 year later at Wave 2 in the same “for better” or “for worse” pattern as externalizing symptoms. Adolescent insecurity at Wave 2, in turn, predicted their greater externalizing symptoms 1 year later at Wave 3. Post hoc analyses further revealed that the 7-repeat allele of the dopamine receptor D4 (DRD4) gene was the primary source of plasticity in the polygenic composite. Results are discussed as to how they advance process-oriented Gene x Environment models of emotion regulation.

Systems pharmacogenomics - gene, disease, drug and placebo interactions: a case study in COMT

Disease, drugs and the placebos used as comparators are inextricably linked in the methodology of the double-blind, randomized controlled trial. Nonetheless, pharmacogenomics, the study of how individuals respond to drugs based on genetic substrate, focuses primarily on the link between genes and drugs, while the link between genes and disease is often overlooked and the link between genes and placebos is largely ignored. Herein, we use the example of the enzyme catechol-O-methyltransferase to examine the hypothesis that genes can function as pharmacogenomic hubs across system-wide regulatory processes that, if perturbed in andomized controlled trials, can have primary and combinatorial effects on drug and placebo responses.

Time-on-Task Effect During Sleep Deprivation in Healthy Young Adults Is Modulated by Dopamine Transporter Genotype

Study Objectives

The time-on-task (TOT) effect and total sleep deprivation (TSD) have similar effects on neurobehavioral functioning, including increased performance instability during tasks requiring sustained attention. The TOT effect is exacerbated by TSD, suggesting potentially overlapping mechanisms. We probed these mechanisms by investigating genotype-phenotype relationships on psychomotor vigilance test (PVT) performance for 3 a-priori selected genes previously linked to the TOT effect and/or TSD: dopamine active transporter 1 (DAT1), catechol-O-methyltransferase (COMT), and tumor necrosis factor alpha (TNFα).

Methods

N = 82 healthy adults participated in 1 of 3 laboratory studies. A 10-min PVT was administered repeatedly during 38 h of TSD. We assessed changes in response time (RT) across each minute of the PVT as a function of time awake and genotype. Additionally, cumulative relative RT frequency distributions were constructed to examine changes in performance from the first to the second 5 min of the PVT as a function of genotype.

Results

DAT1, COMT, and TNFα were associated with differences in the build-up of the TOT effect across the 10-min PVT. DAT1 additionally modulated the interaction between TSD and the TOT effect. Subjects homozygous for the DAT1 10-repeat allele were relatively protected against TOT deficits on the PVT during TSD compared to carriers of the 9-repeat allele.

Conclusions

DAT1 is known to regulate dopamine reuptake and is highly expressed in the striatum. Our results implicate striatal dopamine in mechanisms involved in performance instability that appear to be common to TSD and the TOT effect. Furthermore, DAT1 may be a candidate biomarker of resilience to the build-up of performance impairment across TOT due to TSD.

The Catechol-O-Methyltransferase and Dopamine Transporter Genes Moderated the Impact of Peer Relationships on Adolescent Depressive Symptoms: A Gene-Gene-Environment Study

Behavioral genetics studies and new empirical evidence suggest that depression cannot simply be explained by the influence of single genes but that gene-gene-environment interactions are important to better understanding the etiology of depression. The present study investigated the main and interactive effects of COMT gene Val158Met polymorphism, DAT1 gene rs27072 polymorphism, and peer relationships (i.e., peer acceptance and rejection) on adolescent depressive symptoms. In a sample of 1045 Chinese Han adolescents (M_age = 12.34 ± 0.47 years, 50.1% girls), saliva samples, self-reported depressive symptoms and within-classroom peer nominations were collected. After controlling for gender, age, and SES, the three-way interaction of COMT, DAT1, and peer acceptance significantly concurrently predicted adolescent depressive symptoms. Adolescents with ValVal genotype of COMT and CC genotype of DAT1 were more sensitive to acceptance, compared to their counterparts carrying other combined genotypes. However, a similar three-way interaction was not significant in the case of peer rejection. Additionally, the split-half validation generally replicated these findings. More importantly, this study underscores complex polygenic underpinnings of depression and lends support for the gene-gene-environment interactions implicated in the etiology of depressive symptoms.

Affective Neuroscience Theory and Personality: An Update

The present work gives a short overview of central aspects of Jaak Panksepp's Affective Neuroscience Theory (AN theory) and its relevance for modern personality neuroscience. In contrast to the widely used Big Five approach to studying and understanding human personality, AN theory provides researchers with a distinct roadmap to the biological basis of personality, including molecular and neuroanatomical candidates, to understand individual differences in human behavior. Such molecular and neuroanatomical brain candidates have been derived by means of electrical brain stimulation and pharmacological challenges, while investigating primary emotional systems anchored in the subcortical mammalian brain. Research results derived from the study of emotions in mammals are also of relevance for humans because ancient layers of our minds-those layers where primary emotions originate-have been homologously conserved across species. From an evolutionary perspective, this makes sense because primal emotions represent "built-in tools for survival" for all mammals. In this context, Montag and Panksepp recently illustrated a potential ancient neurobiological effect by carving out robust associations between individual differences in primary emotions (assessed via self-report) and the Big Five in a cross-cultural study with data from the United States, Germany, and China. These associations together with some ideas derived from MacLean's Triune Brain concept highlighted (a) that primary emotions likely represent the phylogenetically oldest parts of human personality and (b) that primary emotions influence human personality in a bottom-up fashion given their localization in ancient subcortical brain regions. A comment on the work by Montag and Panksepp asked for insights on putative links between primary emotions and facets of the Big Five. Therefore, we provide some first insights into such associations from recent Germany data. In addition, the present work provides a new short version of the Affective Neuroscience Personality Scales to assess individual differences in primary emotions.

The effects of DAT1 genotype on fMRI activation in an emotional go/no-go task

Dopaminergic brain circuits participate in emotional processing and impulsivity. The dopamine transporter (DAT) modulates dopamine reuptake. A variable number tandem repeat (VNTR) in the dopamine transporter gene (DAT1) affects DAT expression. The influence of DAT1 genotype on neural activation during emotional processing and impulse inhibition has not been examined. Forty-two healthy subjects were classified as 9DAT (n = 17) or 10DAT (n = 25) based on DAT1 genotype (9DAT = 9R/9R and 9R/10R; 10DAT = 10R/10R). Subjects underwent fMRI during non-emotional and emotional go/no-go tasks. Subjects were instructed to inhibit responses to letters, happy faces, or sad faces in separate blocks. Accuracy and reaction time did not differ between groups. Within group results showed activation in regions previously implicated in emotional processing and response inhibition. Between groups results showed increased activation in 9DAT individuals during inhibition. During letter inhibition, 9DAT individuals exhibited greater activation in right inferior parietal regions. During sad inhibition, 9DAT Individuals exhibited greater activation in frontal, posterior cingulate, precuneus, right cerebellar, left paracentral, and right occipital brain regions. The interaction between DAT genotype and response type in sad versus letter stimuli showed increased activation in 9DAT individuals during sad no-go responses in the anterior cingulate cortex, extending into frontal-orbital regions. 9DAT individuals have greater activation than 10DAT individuals during neutral and sad inhibition, showing that genotypic variation influencing basal dopamine levels can alter the neural basis of emotional processing and response inhibition. This may indicate that 9R carriers exert more effort to overcome increased basal dopamine activation when inhibiting responses in emotional contexts.

Unpredictable chronic mild stress differentially impairs social and contextual discrimination learning in two inbred mouse strains

Alterations in the social and cognitive domain are considered important indicators for increased disability in many stress-related disorders. Similar impairments have been observed in rodents chronically exposed to stress, mimicking potential endophenotypes of stress-related psychopathologies such as major depression disorder (MDD), anxiety, conduct disorder, and posttraumatic stress disorder (PTSD). Data from numerous studies suggest that deficient plasticity mechanisms in hippocampus (HC) and prefrontal cortex (PFC) might underlie these social and cognitive deficits. Specifically, stress-induced deficiencies in neural plasticity have been associated with a hypodopaminergic state and reduced neural plasticity persistence. Here we assessed the effects of unpredictable chronic mild stress (UCMS) on exploratory, social and cognitive behavior of females of two inbred mouse strains (C57BL/6J and DBA/2J) that differ in their dopaminergic profile. Exposure to chronic stress resulted in impaired circadian rhythmicity, sociability and social cognition in both inbred strains, but differentially affected activity patterns and contextual discrimination performance. These stress-induced behavioral impairments were accompanied by reduced expression levels of brain derived neurotrophic factor (BDNF) in the prefrontal cortex. The strain-specific cognitive impairment was coexistent with enhanced plasma corticosterone levels and reduced expression of genes related to dopamine signaling in hippocampus. These results underline the importance of assessing different strains with multiple test batteries to elucidate the neural and genetic basis of social and cognitive impairments related to chronic stress.

Mediating Role of the Reward Network in the Relationship between the Dopamine Multilocus Genetic Profile and Depression

Multiple genetic loci in the dopamine (DA) pathway have been associated with depression symptoms in patients with major depressive disorder (MDD). However, the neural mechanisms underlying the polygenic effects of the DA pathway on depression remain unclear. We used an imaging genetic approach to investigate the polygenic effects of the DA pathway on the reward network in MDD. Fifty-three patients and 37 cognitively normal (CN) subjects were recruited and underwent resting-state functional magnetic resonance imaging (R-fMRI) scans. Multivariate linear regression analysis was employed to measure the effects of disease and multilocus genetic profile scores (MGPS) on the reward network, which was constructed using the nucleus accumbens (NAc) functional connectivity (NAFC) network. DA-MGPS was widely associated within the NAFC network, mainly in the inferior frontal cortex, insula, hypothalamus, superior temporal gyrus, and occipital cortex. The pattern of DA-MGPS effects on the fronto-striatal pathway differed in MDD patients compared with CN subjects. More importantly, NAc-putamen connectivity mediates the association between DA MGPS and anxious depression traits in MDD patients. Our findings suggest that the DA multilocus genetic profile makes a considerable contribution to the reward network and anxious depression in MDD patients. These results expand our understanding of the pathophysiology of polygenic effects underlying brain network abnormalities in MDD.

The Isomeric Preference of an Atypical Dopamine Transporter Inhibitor Contributes to Its Selection of the Transporter Conformation

Cocaine, a widely abused psychostimulant, inhibits the dopamine transporter (DAT) by trapping the protein in an outward-open conformation, whereas atypical DAT inhibitors such as benztropine have low abuse liability and prefer less outward-open conformations. Here, we use a spectrum of computational modeling and simulation approaches to obtain the underlying molecular mechanism in atomistic detail. Interestingly, our quantum mechanical calculations and molecular dynamics (MD) simulations suggest that a benztropine derivative JHW007 prefers a different stereoisomeric conformation of tropane in binding to DAT compared to that of a cocaine derivative, CFT. To further investigate the different inhibition mechanisms of DAT, we carried out MD simulations in combination with Markov state modeling analysis of wild-type and Y156F DAT in the absence of any ligand or the presence of CFT or JHW007. Our results indicate that the Y156F mutation and CFT shift the conformational equilibrium toward an outward-open conformation, whereas JHW007 prefers an inward-occluded conformation. Our findings reveal the mechanistic details of DAT inhibition by JHW007 at the atomistic level, which provide clues for rational design of atypical inhibitors.

Identifying affective personality profiles: A latent profile analysis of the Affective Neuroscience Personality Scales

Based on evolutionary theory, a recent model in affective neuroscience delineated six emotional brain systems at the core of human personality: SEEKING, CARING, PLAYFULNESS, FEAR, ANGER, SADNESS. The Affective Neuroscience Personality Scales (ANPS) assess their functioning. Using a person-centred approach of the ANPS, this study: (i) examined the existence of latent personality profiles, (ii) studied their gender invariance, (iii) assessed their longitudinal (4 years) stability, and (iv) explored how they relate to several intrapersonal, interpersonal, and emotion regulation skills. Latent Profile Analysis in 2 samples (Canadian, longitudinal, N = 520; French, cross-sectional, N = 830) found that, qualitatively, 3 profiles characterized both populations and genders, with one distinction for the second profile where the French women endorsed slightly higher and lower scores for, respectively, the negative and positive emotions. Whilst not being quantitatively similar across genders, the personality profiles remained consistent across time in the longitudinal sample. Associations between profiles and intrapersonal (e.g. depression), interpersonal (e.g. empathy), and emotion regulation skills measures (e.g. emotional intelligence) offered concurrent validity evidence. This person centred approach to ANPS offers a holistic and parsimonious way to study affective personality dimensions. It opens promising avenues for future studies on the predictive value of ANPS profiles, and for personality-targeted interventions.

Primary Emotional Systems and Personality: An Evolutionary Perspective

The present article highlights important concepts of personality including stability issues from the perspective of situational demands and stability over the life-course. Following this more introductory section, we argue why individual differences in primary emotional systems may represent the phylogenetically oldest parts of human personality. Our argumentation leads to the need to increasingly consider individual differences in the raw affects/emotions of people to understand human personality in a bottom-up fashion, which can be coordinated with top-down perspectives. In support of this idea, we also review existing evidence linking individual differences in primal emotions as assessed with the Affective Neuroscience Personality Scales and the widely accepted Big Five Model of Personality. In this context, we provide additional evidence on the link between primal emotions and personality in German and Chinese sample populations. In short, this article addresses evolutionary perspectives in the evaluation of human personality, highlighting some of the ancestral emotional urges that probably still control variations in the construction of human personality structures. Moreover, we address how individual differences in primary emotional systems can illuminate linkages to major human psychopathologies and the potential advantages and disadvantages of carrying a certain personality trait within certain cultural/environmental niches.

Association between COMT Val158Met and DAT1 polymorphisms and depressive symptoms in the obese population

OBJECTIVES

Depressive symptoms are common among patients with obesity. Abnormalities in dopamine signaling involved in the reward circuit may ensue excessive consumption of food, resulting in obesity and leading to neuropsychiatric disorders such as depression. This study sought to investigate the association of polymorphisms in the genes encoding DAT1/SLC6A3 and COMT with the intensity of depressive symptoms in obese subjects.

PARTICIPANTS AND METHODS

Prevalence and severity of depressive symptoms were assessed in a group of 364 obese patients using the Beck Depression Inventory (BDI) and the Hamilton Depression Rating Scale (HDRS). Genetic polymorphisms in DAT1 and COMT were evaluated in peripheral blood samples.

RESULTS

The results indicated an association between DAT1 alleles and depressive symptoms, as well as severity of obesity. Subjects homozygous for the nine-repeat allele scored higher in BDI (P=0.022) and HDRS (P=0.00001), suggesting higher intensity of depression in both sexes. This allele was also associated with the highest body mass index (BMI; P=0.001). Carriers of the Val158Met allele of COMT scored higher on both depression scales (BDI, P=0.0005; HRDS, P=0.002) and had the highest BMI values.

CONCLUSION

Polymorphisms in the DAT1 and COMT genes are associated with a greater intensity of depressive symptoms in the obese population.

An Affective Neuroscience Framework for the Molecular Study of Internet Addiction

Internet addiction represents an emerging global health issue. Increasing efforts have been made to characterize risk factors for the development of Internet addiction and consequences of excessive Internet use. During the last years, classic research approaches from psychology considering personality variables as vulnerability factor, especially in conjunction with neuroscience approaches such as brain imaging, have led to coherent theoretical conceptualizations of Internet addiction. Although such conceptualizations can be valuable aid, the research field is currently lacking a comprehensive framework for determining brain-based and neurochemical markers of Internet addiction. The present work aims at providing a framework on the molecular level as a basis for future research on the neural and behavioral level, in order to facilitate a comprehensive neurobiological model of Internet addiction and its clinical symptomatology. To help establish such a molecular framework for the study of Internet addiction, we investigated in N = 680 participants associations between individual differences in tendencies toward Internet addiction measured by the Generalized Problematic Internet Use Scale-2 (GPIUS-2) and individual differences in primary emotional systems as assessed by the Affective Neuroscience Personality Scales (ANPS). Regression analysis revealed that the ANPS scales FEAR and SADNESS were the ANPS scales most robustly positively linked to several (sub)scales of the GPIUS-2. Also the scales SEEKING, CARE and PLAY explain variance in some of the GPIUS-2 subscales. As such, these scales are negatively linked to the GPIUS-2 subscales. As the ANPS has been constructed on substantial available brain data including an extensive molecular body with respect to evolutionary highly conserved emotional circuitry in the ancient mammalian brain, the present study gives first ideas on putative molecular mechanisms underlying different facets of Internet addiction as derived from associations between tendencies toward Internet addiction and individual differences in primary emotional systems. For example, as SADNESS is linked to the overall GPIUS-2 score, and the neuropeptide oxytocin is known to downregulate SADNESS, it is conceivable that the neuropeptide might play a role in Internet addition on the molecular level. Our findings provide a theoretical framework potentially illuminating the molecular underpinnings of Internet addiction. Finally, we also present data on the ANPS and smartphone addiction at the end of the paper. Similar to the reported associations between the ANPS and the GPIUS-2, these correlations might provide an initial outline for a framework guiding future studies that aim to address the molecular basis of smartphone addiction.

Longitudinal and Sex Measurement Invariance of the Affective Neuroscience Personality Scales

The Affective Neuroscience Personality Scales (ANPS) is a personality instrument based on six evolutionary-related brain systems that are at the foundation of human emotions and behaviors: SEEKING, CARING, PLAYFULNESS, FEAR, ANGER, and SADNESS. We sought to assess for the short and long versions of the ANPS: (a) the longitudinal measurement invariance and long-term (4-year) stability and (b) the sex measurement invariance. Using data from a Canadian cohort ( N = 518), we used single-group confirmatory factor analysis to assess longitudinal invariance and multiple-group confirmatory factor analysis to assess sex invariance, according to a five-step approach evaluating five invariance levels (configural, metric, scalar, residual, and complete). Results supported full longitudinal invariance for both versions for all invariance levels. Partial residual invariance was supported for sex invariance. The long-term stability of both versions was good to excellent. Implications for personality assessment and ANPS development are discussed.

The Role of Nature and Nurture for Individual Differences in Primary Emotional Systems: Evidence from a Twin Study

The present study investigated for the first time the relative importance of genetics and environment on individual differences in primary emotionality as measured with the Affective Neuroscience Personality Scales (ANPS) by means of a twin-sibling study design. In N = 795 participants (n = 303 monozygotic twins, n = 172 dizygotic twins and n = 267 non-twin full siblings), moderate to strong influences of genetics on individual differences in these emotional systems are observed. Lowest heritability estimates are presented for the SEEKING system (33%) and highest for the PLAY system (69%). Further, multivariate genetic modeling was applied to the data showing that associations among the six ANPS scales were influences by both, a genetic as well as an environmental overlap between them. In sum, the study underlines the usefulness of the ANPS for biologically oriented personality psychology research.

Studies of the biogenic amine transporters 15. Identification of novel allosteric dopamine transporter ligands with nanomolar potency

Novel allosteric modulators of the dopamine transporter (DAT) have been identified. We have shown previously that SRI-9804 [N-(diphenylmethyl)-2-phenyl-4-quinazolinamine], SRI-20040 [N-(2,2-diphenylethyl)-2-phenyl-4-quinazolinamine], and SRI-20041 [N-(3,3-diphenylpropyl)-2-phenyl-4-quinazolinamine] partially inhibit [(125)I]RTI-55 ([(125)I]3β-(4'-iodophenyl)tropan-2β-carboxylic acid methyl ester) binding and [(3)H]dopamine ([(3)H]DA) uptake, slow the dissociation rate of [(125)I]RTI-55 from the DAT, and allosterically modulate d-amphetamine-induced, DAT-mediated DA release. We synthesized and evaluated the activity of >500 analogs of these ligands and report here on 36 selected compounds. Using synaptosomes prepared from rat caudate, we conducted [(3)H]DA uptake inhibition assays, DAT binding assays with [(3)H]WIN35428 ([(3)H]2β-carbomethoxy-3β-(4-fluorophenyl)tropane), and DAT-mediated release assays with either [(3)H]MPP(+) ([(3)H]1-methyl-4-phenylpyridinium) or [(3)H]DA. We observed three groups of [(3)H]DA uptake inhibitors: 1) full-efficacy agents with a one-site fit, 2) full-efficacy agents with a two-site fit, and 3) partial-efficacy agents with a one-site fit-the focus of further studies. These agents partially inhibited DA, serotonin, and norepinephrine uptake, yet were much less potent at inhibiting [(3)H]WIN35428 binding to the DAT. For example, SRI-29574 [N-(2,2-diphenylethyl)-2-(imidazo[1,2-a]pyridin-6-yl)quinazolin-4-amine] partially inhibited DAT uptake, with an IC50 = 2.3 ± 0.4 nM, without affecting binding to the DAT. These agents did not alter DAT-mediated release of [(3)H]MPP(+) in the absence or presence of 100 nM d-amphetamine. SRI-29574 had no significant effect on the d-amphetamine EC50 or Emax value for DAT-mediated release of [(3)H]MPP(+). These studies demonstrate the existence of potent DAT ligands that partially block [(3)H]DA uptake, without affecting DAT binding or d-amphetamine-induced [(3)H]MPP(+) release. These compounds may prove to be useful probes of biogenic amine transporter function as well as novel therapeutics.

The assessment of the relationship between personality, the presence of the 5HTT and MAO-A polymorphisms, and the severity of climacteric and depressive symptoms in postmenopausal women

The purpose of this study is to determine the relationship between personality, the serotonin transporter (5HTT) and monoamine oxidase A (MAO-A) polymorphisms and the severity of climacteric and depressive symptoms in postmenopausal women. The study involved 272 healthy postmenopausal women from Poland. This survey-based study was performed using the following: the Beck Depression Inventory for depressive symptoms, the Blatt-Kupperman Menopausal Index and the Neuroticism-Extroversion-Openness-Five Factor Inventory for personality. A polymerase chain reaction was employed to identify the DNA polymorphisms. The women were aged 55.4 ± 5.5 years on average. Significant correlations were proved between the allele frequency of the 30-bp variable-number tandem repeat (VNTR) polymorphism in the MAO-A promoter region and the incidence of depressive symptoms in the women analysed (p ≤ 0.05), as well as between the severity of climacteric symptoms in the postmenopausal women and the allele frequency of the polymorphism in the 5HTT gene (the 5HTT 's' variant) (p ≤ 0.05). There was a significant correlation between the severity of climacteric and depressive symptoms (p < 0.001). (1) The severity of climacteric and depressive symptoms depends on personality traits. (2) Personality traits are biologically determined, and the level of their expression is associated with the 5HTT polymorphism. (3) Identification of homogeneous groups of women having predispositions to depressive and severe climacteric symptoms may help to implement early prevention programmes for this group of recipients.

Decreased dopamine brain reactivity in marijuana abusers is associated with negative emotionality and addiction severity

Moves to legalize marijuana highlight the urgency to investigate effects of chronic marijuana in the human brain. Here, we challenged 48 participants (24 controls and 24 marijuana abusers) with methylphenidate (MP), a drug that elevates extracellular dopamine (DA) as a surrogate for probing the reactivity of the brain to DA stimulation. We compared the subjective, cardiovascular, and brain DA responses (measured with PET and [(11)C]raclopride) to MP between controls and marijuana abusers. Although baseline (placebo) measures of striatal DA D2 receptor availability did not differ between groups, the marijuana abusers showed markedly blunted responses when challenged with MP. Specifically, compared with controls, marijuana abusers had significantly attenuated behavioral ("self-reports" for high, drug effects, anxiety, and restlessness), cardiovascular (pulse rate and diastolic blood pressure), and brain DA [reduced decreases in distribution volumes (DVs) of [(11)C]raclopride, although normal reductions in striatal nondisplaceable binding potential (BPND)] responses to MP. In ventral striatum (key brain reward region), MP-induced reductions in DVs and BPND (reflecting DA increases) were inversely correlated with scores of negative emotionality, which were significantly higher for marijuana abusers than controls. In marijuana abusers, DA responses in ventral striatum were also inversely correlated with addiction severity and craving. The attenuated responses to MP, including reduced decreases in striatal DVs, are consistent with decreased brain reactivity to the DA stimulation in marijuana abusers that might contribute to their negative emotionality (increased stress reactivity and irritability) and addictive behaviors.

Association of dopamine gene variants, emotion dysregulation and ADHD in autism spectrum disorder

The aim of the present study was to evaluate the association of dopaminergic gene variants with emotion dysregulation (EMD) and attention-deficit/hyperactivity disorder (ADHD) symptoms in children with autism spectrum disorder (ASD). Three dopamine transporter gene (SLC6A3/DAT1) polymorphisms (intron8 5/6 VNTR, 3'-UTR 9/10 VNTR, rs27072 in the 3'-UTR) and one dopamine D2 receptor gene (DRD2) variant (rs2283265) were selected for genotyping based on à priori evidence of regulatory activity or, in the case of DAT1 9/10 VNTR, commonly reported associations with ADHD. A sample of 110 children with ASD was assessed with a rigorously validated DSM-IV-referenced rating scale. Global EMD severity (parents' ratings) was associated with DAT1 intron8 (ηp(2)=.063) and rs2283265 (ηp(2)=.044). Findings for DAT1 intron8 were also significant for two EMD subscales, generalized anxiety (ηp(2)=.065) and depression (ηp(2)=.059), and for DRD2 rs2283265, depression (ηp(2)=.053). DRD2 rs2283265 was associated with teachers' global ratings of ADHD (ηp(2)=.052). DAT1 intron8 was associated with parent-rated hyperactivity (ηp(2)=.045) and both DAT1 9/10 VNTR (ηp(2)=.105) and DRD2 rs2283265 (ηp(2)=.069) were associated with teacher-rated inattention. These findings suggest that dopaminergic gene polymorphisms may modulate EMD and ADHD symptoms in children with ASD but require replication with larger independent samples.

A study examining depression in restless legs syndrome

BACKGROUND

Distress is known to occur in RLS subjects consequent to symptoms. However, studies regarding prevalence of depression in RLS are scarce. This study was conducted to find out prevalence of depression in RLS patients and to explore possible underlying factors.

METHOD

112 consecutive RLS subjects presenting to sleep-clinic were included in this study. History regarding RLS, depression and sleep-disturbances was sought. Depression and insomnia were diagnosed using DSM-IV-TR criteria. Subjects were specifically asked whether they had depressive episodes in past one year. Severity of RLS and insomnia was measured using Hindi versions of IRLS and ISI, respectively. Family history of depression and RLS was also asked.

RESULTS

One year prevalence of depression was 41.8%. MDD was reported by 33% and dysthymia by 8.8%. Both the groups were comparable with respects to demographic and clinical features, viz., age, gender, duration, severity and family history of RLS. Duration, number of episodes and severity of insomnia were comparable between groups, so was the family history of depression. In 37.8% of the subjects with MDD, depressive symptoms preceded RLS while in 51.4% of them, they followed onset of RLS. Total duration of RLS symptoms did not correlate with total duration of depression (r(2)=0.07; P=0.64).

CONCLUSION

Clinical depression is seen in more than a third of RLS patients. Depression is not affected by clinical picture of RLS and it is not consequent to sleep disturbance. Perhaps, it is a co-morbid condition.

Nonclassical pharmacology of the dopamine transporter: atypical inhibitors, allosteric modulators, and partial substrates

The dopamine transporter (DAT) is a sodium-coupled symporter protein responsible for modulating the concentration of extraneuronal dopamine in the brain. The DAT is a principle target of various psychostimulant, nootropic, and antidepressant drugs, as well as certain drugs used recreationally, including the notoriously addictive stimulant cocaine. DAT ligands have traditionally been divided into two categories: cocaine-like inhibitors and amphetamine-like substrates. Whereas inhibitors block monoamine uptake by the DAT but are not translocated across the membrane, substrates are actively translocated and trigger DAT-mediated release of dopamine by reversal of the translocation cycle. Because both inhibitors and substrates increase extraneuronal dopamine levels, it is often assumed that all DAT ligands possess an addictive liability equivalent to that of cocaine. However, certain recently developed ligands, such as atypical benztropine-like DAT inhibitors with reduced or even a complete lack of cocaine-like rewarding effects, suggest that addictiveness is not a constant property of DAT-affecting compounds. These atypical ligands do not conform to the classic preconception that all DAT inhibitors (or substrates) are functionally and mechanistically alike. Instead, they suggest the possibility that the DAT exhibits some of the ligand-specific pleiotropic functional qualities inherent to G-protein-coupled receptors. That is, ligands with different chemical structures induce specific conformational changes in the transporter protein that can be differentially transduced by the cell, ultimately eliciting unique behavioral and psychological effects. The present overview discusses compounds with conformation-specific activity, useful not only as tools for studying the mechanics of dopamine transport, but also as leads for medication development in addictive disorders.

Catechol-O-Methyltransferase Polymorphism Influences Outcome After Ischemic Stroke

Background. To explore whether a polymorphism in dopamine metabolism influences the effectiveness of neurological rehabilitation and the outcome after ischemic stroke. Methods. The Barthel Index (BI) and the Rivermead Motor Assessment (RMA) were assessed in 78 moderately affected stroke patients (1) after they had entered a neurological inpatient rehabilitation, (2) after 4 weeks of rehabilitation therapy, and (3) 6 months later. Polymorphisms of the gene encoding catechol- O-methyltransferase (COMT) were determined. BI and RMA results were analyzed with respect to the genetic profiles of COMT. Results. Carriers of COMT Val/Val alleles showed better results in BI and RMA than COMT Met/Met carriers at all 3 time points. Val/Met carriers exhibited results in between the homozygotes, suggesting a gene–dose relationship. Altogether, BI and RMA results were highly correlated. Conclusion. Stroke patients with COMT Val/Val alleles had higher motor functions and abilities of activities of daily living even at the beginning of the rehabilitation period. All patient groups improved during the rehabilitation period to a similar degree, suggesting that physical therapy is comparably effective in all polymorphism subtypes.

The role of the catechol-O-methyltransferase (COMT) gene in personality and related psychopathological disorders

This review provides a short overview of the most significant biologically oriented theories of human personality. Personality concepts of Eysenck, Gray and McNaughton, Cloninger and Panksepp will be introduced and the focal evidence for the heritability of personality will be summarized. In this context, a synopsis of a large number of COMT genetic association studies (with a focus on the COMT Val158Met polymorphism) in the framework of the introduced biologically oriented personality theories will be given. In line with the theory of a continuum model between healthy anxious behavior and related psychopathological behavior, the role of the COMT gene in anxiety disorders will be discussed. A final outlook considers new research strategies such as genetic imaging and epigenetics for a better understanding of human personality.

Mild affective symptoms in de novo Parkinson's disease patients: relationship with dopaminergic dysfunction

BACKGROUND AND PURPOSE

The investigation of the relationship between affective symptoms and dopamine transporter (DAT) density provided conflicting data in both Parkinson's disease (PD) and non-PD patients. However, the potential interference of psychoactive as well as anti-parkinsonian drugs on DAT density should be taken into account.

OBJECTIVE

To investigate the relationship between affective symptoms and pre-synaptic dopaminergic function in de novo PD patients.

METHODS

Forty-four de novo PD consecutive outpatients were recruited, and the severity of anxious symptoms was evaluated with the Hamilton Anxiety Rating Scale (HAM-A), the severity of depressive symptoms with the Hamilton Depression Scale (HAM-D) and the Beck Depression Inventory (BDI). Six patients had a formal diagnosis of depression. All patients performed (123) I-FP-CIT SPECT, and semi-quantitative striatal indices were calculated.

RESULTS

Disease severity, as measured by Unified Parkinson's Disease Rating Scale (UPDRSIII), was inversely correlated with bilateral striatal indices. Bilateral striatal uptake was significantly positively correlated with HAM-D (r.329; r.423, respectively, right and left), BDI (r.377; r.360, respectively, right and left) and HAM-A (r.338; r.340, respectively, right and left). After controlling for age, disease duration and severity, and Mini Mental State Examination (MMSE), no significant reduction in r-values was observed (P < 0.05).

CONCLUSION

Our data support the existence of a relationship between depressive and anxious symptoms and the striatal (123) I-FP-CIT uptake. The finding of an increased DAT density associated with mild affective symptoms could be due to the lack of compensatory mechanisms usually present in early PD, and/or it might have a pathogenic role in affective symptoms by reducing the dopaminergic tone in the synaptic cleft.

Prefrontal-limbic change in dopamine turnover by acupuncture in maternally separated rat pups

The present study investigated the possible role of acupuncture in alleviating depression-like behavioral changes and examined changes in the levels of serotonin (5-HT), dopamine (DA), and their metabolites in the hippocampus (HP) and prefrontal cortex (PFC) of maternally separated rat pups. On postnatal day 15, rat pups were maternally separated and received acupuncture stimulation at acupoint HT7 or ST36 once a day for 7 days. Then, on postnatal day 21, a tail suspension test was performed, and the HP and PFC were harvested. Levels of 5-HT, 5-hydroxyindole-3-acetic acid (5-HIAA), DA, and 3,4-dihydroxyphenylacetic acid (DOPAC) in the tissue and corticosterone (CORT) in plasma were then measured. The total duration of immobility in maternally separated rat pups increased after maternal separation, and this increase was alleviated by acupuncture stimulation at HT7. The 5-HIAA/5-HT ratio and the levels of 5-HT and 5-HIAA were not significantly changed, but those of the DA and the DOPAC/DA ratio were significantly lower and that of CORT was significantly higher after maternal separation. The maternal separation-induced changes of the DOPAC/DA ratio and the CORT level significantly alleviated after acupuncture stimulation at HT7. These results suppose that the functional recovery of prefrontal-limbic system by acupuncture stimulation plays an important role in acupuncture-induced benefits in this animal model of depression.