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Darcq E, Nouel D, Hernandez G, Pokinko M, Ash P, Moquin L, Gratton A, Kieffer B, Flores C. Reduced dopamine release in Dcc haploinsufficiency male mice abolishes the rewarding effects of cocaine but not those of morphine and ethanol. Psychopharmacology (Berl) 2023; 240:637-646. [PMID: 36471064 PMCID: PMC10296775 DOI: 10.1007/s00213-022-06288-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Accepted: 11/23/2022] [Indexed: 12/12/2022]
Abstract
RATIONALE The Netrin-1/DCC guidance cue pathway is critically involved in the adolescent organization of the mesocorticolimbic dopamine circuitry. Adult mice heterozygous for Dcc show reduced dopamine release in the nucleus accumbens in response to amphetamine and, in turn, blunted sensitivity to the rewarding effects of this drug. OBJECTIVE Here, we tested whether the protective effects of Dcc haploinsufficiency are specific to stimulant drugs of abuse or instead extrapolate to opioids and ethanol. METHODS We used the place preference paradigm to measure the rewarding effects of cocaine (20 mg/kg), morphine (5 or 10 mg/Kg), or ethanol (20%) in adult (PND 75) male Dcc haploinsufficient mice or their wild-type litter mates. In a second experiment, we compared in these two genotypes, in vivo dopamine release in the nucleus accumbens after a single i.p. injection of morphine (10 mg/kg). RESULTS We found reduced morphine-induced dopamine release in the nucleus accumbens of Dcc haploinsufficient male mice, but, contrary to the effects of stimulant drugs, there is no effect of genotype on morphine-induced conditioned preference. CONCLUSION These findings show that reduced drug-induced mesolimbic dopamine in Dcc haploinsufficient male mice protects specifically against the rewarding effects of stimulant drugs, but not against the rewarding properties of morphine and ethanol. These results suggest that these drugs exert their rewarding effect via different brain circuits.
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Affiliation(s)
- Emmanuel Darcq
- Douglas Mental Health University Institute, Montréal, Québec, Canada
- Department of Psychiatry, McGill University, Montréal, Québec, Canada
- INSERM U1114, Centre de Recherche en Biomédecine de Strasbourg, Université de Strasbourg, Strasbourg, France
| | - Dominique Nouel
- Douglas Mental Health University Institute, Montréal, Québec, Canada
| | | | - Matthew Pokinko
- Douglas Mental Health University Institute, Montréal, Québec, Canada
- Integrated Program in Neuroscience (IPN), McGill University, Montréal, Québec, Canada
| | - Polina Ash
- Douglas Mental Health University Institute, Montréal, Québec, Canada
- Integrated Program in Neuroscience (IPN), McGill University, Montréal, Québec, Canada
| | - Luc Moquin
- Douglas Mental Health University Institute, Montréal, Québec, Canada
| | - Alain Gratton
- Douglas Mental Health University Institute, Montréal, Québec, Canada
- Department of Psychiatry, McGill University, Montréal, Québec, Canada
| | - Brigitte Kieffer
- Douglas Mental Health University Institute, Montréal, Québec, Canada
- Department of Psychiatry, McGill University, Montréal, Québec, Canada
- INSERM U1114, Centre de Recherche en Biomédecine de Strasbourg, Université de Strasbourg, Strasbourg, France
| | - Cecilia Flores
- Douglas Mental Health University Institute, Montréal, Québec, Canada.
- Department of Psychiatry, McGill University, Montréal, Québec, Canada.
- Department of Neurology and Neurosurgery, McGill University, Montréal, Québec, Canada.
- Department of Psychiatry, Douglas Mental Health University Institute, Perry Pavilion, Room 2111, 6875 LaSalle Boulevard, Montréal (Verdun), Québec, H4H 1R3, Canada.
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Reynolds LM, Flores C. Mesocorticolimbic Dopamine Pathways Across Adolescence: Diversity in Development. Front Neural Circuits 2021; 15:735625. [PMID: 34566584 PMCID: PMC8456011 DOI: 10.3389/fncir.2021.735625] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Accepted: 08/17/2021] [Indexed: 12/26/2022] Open
Abstract
Mesocorticolimbic dopamine circuity undergoes a protracted maturation during adolescent life. Stable adult levels of behavioral functioning in reward, motivational, and cognitive domains are established as these pathways are refined, however, their extended developmental window also leaves them vulnerable to perturbation by environmental factors. In this review, we highlight recent advances in understanding the mechanisms underlying dopamine pathway development in the adolescent brain, and how the environment influences these processes to establish or disrupt neurocircuit diversity. We further integrate these recent studies into the larger historical framework of anatomical and neurochemical changes occurring during adolescence in the mesocorticolimbic dopamine system. While dopamine neuron heterogeneity is increasingly appreciated at molecular, physiological, and anatomical levels, we suggest that a developmental facet may play a key role in establishing vulnerability or resilience to environmental stimuli and experience in distinct dopamine circuits, shifting the balance between healthy brain development and susceptibility to psychiatric disease.
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Affiliation(s)
- Lauren M Reynolds
- Plasticité du Cerveau CNRS UMR8249, École supérieure de physique et de chimie industrielles de la Ville de Paris (ESPCI Paris), Paris, France.,Neuroscience Paris Seine CNRS UMR 8246 INSERM U1130, Institut de Biologie Paris Seine, Sorbonne Université, Paris, France
| | - Cecilia Flores
- Department of Psychiatry and Department of Neurology and Neurosurgery, McGill University, Douglas Mental Health University Institute, Montréal, QC, Canada
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Injury during adolescence leads to sex-specific executive function deficits in adulthood in a pre-clinical model of mild traumatic brain injury. Behav Brain Res 2020; 402:113067. [PMID: 33333110 DOI: 10.1016/j.bbr.2020.113067] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Revised: 12/01/2020] [Accepted: 12/09/2020] [Indexed: 12/13/2022]
Abstract
Adolescents are more likely than adults to develop chronic symptoms, such as impulsivity and difficulty concentrating, following a mild traumatic brain injury (mTBI) which may relate to disruption of pre-frontal cortex (PFC development). During adolescence the PFC is undergoing extensive remodelling, driving maturation of executive functions incorporating attention, motivation and impulse control. In part maturation of the PFC is driven by outgrowth of dopaminergic neurons to the PFC under the guidance of specific axonal targeting cues, including netrin-1. How a mTBI in adolescence may alter the expression of these axonal targeting cues, and the influence on PFC development is not yet known. As such the effects of mTBI in mid-adolescence on executive functioning in adulthood (12 weeks) were examined via the 5-choice serial reaction task in both male and female Sprague Dawley rats. Animals at p35 (n = 12-16 per group) were injured via weight drop (100 g from 0.75 m) and injury confirmed by a significant increase in righting reflex. Interestingly, while a mid-adolescence mTBI in females led to significantly higher omissions and decreased accuracy when task difficulty was high (stimulus duration 1 s), males had significantly increased premature response rate when the intertrial interval was varied. Examination of levels of TH, as a reflection of dopaminergic innervation, found no difference in either gender post-TBI in the PFC, but a significant increase in the limbic system (nucleus accumbens) in males, but not females, chronically post-TBI, suggesting an imbalance between the regions. The increase in TH was accompanied by a chronic reduction in netrin-1 within the nucleus accumbens in males only. Taken together, these results indicate that mTBI in adolescence leads to sex specific effects in different domains of PFC function in adulthood, which may relate to subtle alterations in the developmental trajectory of the mesocortical limbic pathway in males only.
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Li HJ, Qu N, Hui L, Cai X, Zhang CY, Zhong BL, Zhang SF, Chen J, Xia B, Wang L, Jia QF, Li W, Chang H, Xiao X, Li M, Li Y. Further confirmation of netrin 1 receptor (DCC) as a depression risk gene via integrations of multi-omics data. Transl Psychiatry 2020; 10:98. [PMID: 32184385 PMCID: PMC7078234 DOI: 10.1038/s41398-020-0777-y] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 02/21/2020] [Accepted: 03/03/2020] [Indexed: 12/15/2022] Open
Abstract
Genome-wide association studies (GWAS) of major depression and its relevant biological phenotypes have been extensively conducted in large samples, and transcriptome-wide analyses in the tissues of brain regions relevant to pathogenesis of depression, e.g., dorsolateral prefrontal cortex (DLPFC), have also been widely performed recently. Integrating these multi-omics data will enable unveiling of depression risk genes and even underlying pathological mechanisms. Here, we employ summary data-based Mendelian randomization (SMR) and integrative risk gene selector (iRIGS) approaches to integrate multi-omics data from GWAS, DLPFC expression quantitative trait loci (eQTL) analyses and enhancer-promoter physical link studies to prioritize high-confidence risk genes for depression, followed by independent replications across distinct populations. These integrative analyses identify multiple high-confidence depression risk genes, and numerous lines of evidence supporting pivotal roles of the netrin 1 receptor (DCC) gene in this illness across different populations. Our subsequent explorative analyses further suggest that DCC significantly predicts neuroticism, well-being spectrum, cognitive function and putamen structure in general populations. Gene expression correlation and pathway analyses in DLPFC further show that DCC potentially participates in the biological processes and pathways underlying synaptic plasticity, axon guidance, circadian entrainment, as well as learning and long-term potentiation. These results are in agreement with the recent findings of this gene in neurodevelopment and psychiatric disorders, and we thus further confirm that DCC is an important susceptibility gene for depression, and might be a potential target for new antidepressants.
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Affiliation(s)
- Hui-Juan Li
- Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences and Yunnan Province, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan, China
- Kunming College of Life Science, University of Chinese Academy of Sciences, Kunming, Yunnan, China
| | - Na Qu
- Affiliated Wuhan Mental Health Center, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
- Research Center for Psychological and Health Sciences, China University of Geosciences, Wuhan, Hubei, China
| | - Li Hui
- Suzhou Guangji Hospital, The Affiliated Guangji Hospital of Soochow University, Suzhou, Jiangsu, China
| | - Xin Cai
- Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences and Yunnan Province, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan, China
- Kunming College of Life Science, University of Chinese Academy of Sciences, Kunming, Yunnan, China
| | - Chu-Yi Zhang
- Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences and Yunnan Province, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan, China
- Kunming College of Life Science, University of Chinese Academy of Sciences, Kunming, Yunnan, China
| | - Bao-Liang Zhong
- Affiliated Wuhan Mental Health Center, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
- Research Center for Psychological and Health Sciences, China University of Geosciences, Wuhan, Hubei, China
| | - Shu-Fang Zhang
- Affiliated Wuhan Mental Health Center, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
- Research Center for Psychological and Health Sciences, China University of Geosciences, Wuhan, Hubei, China
| | - Jing Chen
- Affiliated Wuhan Mental Health Center, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
- Research Center for Psychological and Health Sciences, China University of Geosciences, Wuhan, Hubei, China
| | - Bin Xia
- Affiliated Wuhan Mental Health Center, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
- Research Center for Psychological and Health Sciences, China University of Geosciences, Wuhan, Hubei, China
| | - Lu Wang
- Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences and Yunnan Province, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan, China
| | - Qiu-Fang Jia
- Suzhou Guangji Hospital, The Affiliated Guangji Hospital of Soochow University, Suzhou, Jiangsu, China
| | - Wei Li
- Department of Blood Transfusion, The Second Affiliated Hospital of Kunming Medical University, Kunming, Yunnan, China
| | - Hong Chang
- Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences and Yunnan Province, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan, China
| | - Xiao Xiao
- Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences and Yunnan Province, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan, China.
| | - Ming Li
- Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences and Yunnan Province, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan, China.
| | - Yi Li
- Affiliated Wuhan Mental Health Center, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China.
- Research Center for Psychological and Health Sciences, China University of Geosciences, Wuhan, Hubei, China.
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Vosberg DE, Leyton M, Flores C. The Netrin-1/DCC guidance system: dopamine pathway maturation and psychiatric disorders emerging in adolescence. Mol Psychiatry 2020; 25:297-307. [PMID: 31659271 PMCID: PMC6974431 DOI: 10.1038/s41380-019-0561-7] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Revised: 08/01/2019] [Accepted: 08/19/2019] [Indexed: 02/02/2023]
Abstract
Axon guidance molecules direct growing axons toward their targets, assembling the intricate wiring of the nervous system. One of these molecules, Netrin-1, and its receptor, DCC (deleted in colorectal cancer), has profound effects, in laboratory animals, on the adolescent expansion of mesocorticolimbic pathways, particularly dopamine. Now, a rapidly growing literature suggests that (1) these same alterations could occur in humans, and (2) genetic variants in Netrin-1 and DCC are associated with depression, schizophrenia, and substance use. Together, these findings provide compelling evidence that Netrin-1 and DCC influence mesocorticolimbic-related psychopathological states that emerge during adolescence.
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Affiliation(s)
- Daniel E Vosberg
- Department of Psychiatry, McGill University, Montreal, QC, Canada
- Integrated Program in Neuroscience (IPN), McGill University, Montreal, QC, Canada
- Population Neuroscience and Developmental Neuroimaging, Bloorview Research Institute, Holland Bloorview Kids Rehabilitation Hospital, Toronto, ON, Canada
| | - Marco Leyton
- Department of Psychiatry, McGill University, Montreal, QC, Canada.
- Integrated Program in Neuroscience (IPN), McGill University, Montreal, QC, Canada.
- Neurology and Neurosurgery, McGill University, Montreal, QC, Canada.
| | - Cecilia Flores
- Department of Psychiatry, McGill University, Montreal, QC, Canada.
- Integrated Program in Neuroscience (IPN), McGill University, Montreal, QC, Canada.
- Neurology and Neurosurgery, McGill University, Montreal, QC, Canada.
- Douglas Mental Health University Institute, Montreal, QC, Canada.
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Mesocorticolimbic Connectivity and Volumetric Alterations in DCC Mutation Carriers. J Neurosci 2018; 38:4655-4665. [PMID: 29712788 DOI: 10.1523/jneurosci.3251-17.2018] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Revised: 03/29/2018] [Accepted: 04/07/2018] [Indexed: 01/25/2023] Open
Abstract
The axon guidance cue receptor DCC (deleted in colorectal cancer) plays a critical role in the organization of mesocorticolimbic pathways in rodents. To investigate whether this occurs in humans, we measured (1) anatomical connectivity between the substantia nigra/ventral tegmental area (SN/VTA) and forebrain targets, (2) striatal and cortical volumes, and (3) putatively associated traits and behaviors. To assess translatability, morphometric data were also collected in Dcc-haploinsufficient mice. The human volunteers were 20 DCC+/- mutation carriers, 16 DCC+/+ relatives, and 20 DCC+/+ unrelated healthy volunteers (UHVs; 28 females). The mice were 11 Dcc+/- and 16 wild-type C57BL/6J animals assessed during adolescence and adulthood. Compared with both control groups, the human DCC+/- carriers exhibited the following: (1) reduced anatomical connectivity from the SN/VTA to the ventral striatum [DCC+/+: p = 0.0005, r(effect size) = 0.60; UHV: p = 0.0029, r = 0.48] and ventral medial prefrontal cortex (DCC+/+: p = 0.0031, r = 0.53; UHV: p = 0.034, r = 0.35); (2) lower novelty-seeking scores (DCC+/+: p = 0.034, d = 0.82; UHV: p = 0.019, d = 0.84); and (3) reduced striatal volume (DCC+/+: p = 0.0009, d = 1.37; UHV: p = 0.0054, d = 0.93). Striatal volumetric reductions were also present in Dcc+/- mice, and these were seen during adolescence (p = 0.0058, d = 1.09) and adulthood (p = 0.003, d = 1.26). Together these findings provide the first evidence in humans that an axon guidance gene is involved in the formation of mesocorticolimbic circuitry and related behavioral traits, providing mechanisms through which DCC mutations might affect susceptibility to diverse neuropsychiatric disorders.SIGNIFICANCE STATEMENT Opportunities to study the effects of axon guidance molecules on human brain development have been rare. Here, the identification of a large four-generational family that carries a mutation to the axon guidance molecule receptor gene, DCC, enabled us to demonstrate effects on mesocorticolimbic anatomical connectivity, striatal volumes, and personality traits. Reductions in striatal volumes were replicated in DCC-haploinsufficient mice. Together, these processes might influence mesocorticolimbic function and susceptibility to diverse neuropsychiatric disorders.
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Li Y, Qiao X, Yin F, Guo H, Huang X, Lai J, Wei S. A Population-Based Study of Four Genes Associated with Heroin Addiction in Han Chinese. PLoS One 2016; 11:e0163668. [PMID: 27676367 PMCID: PMC5038970 DOI: 10.1371/journal.pone.0163668] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Accepted: 09/11/2016] [Indexed: 12/11/2022] Open
Abstract
Recent studies have shown that variants in FAT atypical cadherin 3 (FAT3), kinectin 1 (KTN1), discs large homolog2 (DLG2) and deleted in colorectal cancer (DCC) genes influence the structure of the human mesolimbic reward system. We conducted a systematic analysis of the potential functional single nucleotide polymorphisms (SNPs) in these genes associated with heroin addiction. We scanned the functional regions of these genes and identified 20 SNPs for genotyping by using the SNaPshot method. A total of 1080 samples, comprising 523 cases and 557 controls, were analyzed. We observed that DCC rs16956878, rs12607853, and rs2292043 were associated with heroin addiction. The T alleles of rs16956878 (p = 0.0004) and rs12607853 (p = 0.002) were significantly enriched in the case group compared with the controls. A lower incidence of the C allele of rs2292043 (p = 0.002) was observed in the case group. In block 2 of DCC (rs2292043-rs12607853-rs16956878), the frequency of the T-T-T haplotype was significantly higher in the case group than in the control group (p = 0.024), and fewer C-C-C haplotypes (p = 0.006) were detected in the case group. DCC may be an important candidate gene in heroin addiction, and rs16956878, rs12607853, and rs2292043 may be risk factors, thereby providing a basis for further genetic and biological research.
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Affiliation(s)
- Yunxiao Li
- College of Forensic Science, Xi’an Jiaotong University, Key Laboratory of Ministry of Public Health for Forensic Science, Xi’an, PR China
| | - Xiaomeng Qiao
- College of Forensic Science, Xi’an Jiaotong University, Key Laboratory of Ministry of Public Health for Forensic Science, Xi’an, PR China
| | - Fangyuan Yin
- College of Forensic Science, Xi’an Jiaotong University, Key Laboratory of Ministry of Public Health for Forensic Science, Xi’an, PR China
| | - Hao Guo
- College of Forensic Science, Xi’an Jiaotong University, Key Laboratory of Ministry of Public Health for Forensic Science, Xi’an, PR China
| | - Xin Huang
- College of Forensic Science, Xi’an Jiaotong University, Key Laboratory of Ministry of Public Health for Forensic Science, Xi’an, PR China
| | - Jianghua Lai
- College of Forensic Science, Xi’an Jiaotong University, Key Laboratory of Ministry of Public Health for Forensic Science, Xi’an, PR China
- Key Laboratory of Environment and Genes Related to Diseases, Xi’an Jiaotong University, Ministry of Education, Xi’an, PR China
| | - Shuguang Wei
- College of Forensic Science, Xi’an Jiaotong University, Key Laboratory of Ministry of Public Health for Forensic Science, Xi’an, PR China
- Key Laboratory of Environment and Genes Related to Diseases, Xi’an Jiaotong University, Ministry of Education, Xi’an, PR China
- * E-mail:
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Kim JH. Youth is not wasted on the young: Commentary on a BBR themed issue on developmental regulation of memory in anxiety and addiction. Behav Brain Res 2015; 298:1-3. [PMID: 26546879 DOI: 10.1016/j.bbr.2015.10.043] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Jee Hyun Kim
- Behavioural Neuroscience Division, The Florey Institute of Neuroscience and Mental Health, Parkville, VIC 3052, Australia; Florey Department of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC 3052, Australia.
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Pokinko M, Moquin L, Torres-Berrío A, Gratton A, Flores C. Resilience to amphetamine in mouse models of netrin-1 haploinsufficiency: role of mesocortical dopamine. Psychopharmacology (Berl) 2015; 232:3719-29. [PMID: 26264903 DOI: 10.1007/s00213-015-4032-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/27/2015] [Accepted: 07/13/2015] [Indexed: 11/25/2022]
Abstract
RATIONALE Signaling through the netrin-1 receptor, deleted in colorectal cancer (DCC), in dopamine neurons controls the extent of their innervation to the medial prefrontal cortex (mPFC) during adolescence. In mice, dcc haploinsufficiency results in increased mPFC dopamine innervation and concentrations in adulthood. In turn, dcc haploinsufficiency leads to resilience to the effects of stimulant drugs of abuse on dopamine release in the nucleus accumbens and behavior. OBJECTIVES First, we set out to determine whether increased mPFC dopamine innervation causes blunted behavioral responses to amphetamine in adult dcc haploinsufficient mice. Second, we investigated whether unc5c, another netrin-1 receptor expressed by dopamine neurons, is involved in these effects. Third, we assessed whether haploinsufficiency of netrin-1 itself leads to blunted behavioral responding to amphetamine, whether this phenotype emerges before or after adolescence and whether increased mPFC dopamine input is the underlying mechanism. RESULTS Adult, but not adolescent, dcc, unc5c and netrin-1 haploinsufficient mice exhibit blunted behavioral responses to amphetamine. Furthermore, adult dcc, unc5c, and netrin-1 haploinsufficient mice have exaggerated mPFC dopamine concentrations in comparison to their wild-type littermates. Importantly, resilience to amphetamine-induced behavioral activation in all the three mouse models is abolished by selective dopamine depletion in the medial prefrontal cortex. CONCLUSIONS dcc, unc5c, or netrin-1 haploinsufficiency leads to increased dopamine content in the mPFC and to resilience against amphetamine-induced behavioral activation. Our findings raise the hypothesis that DCC, UNC5C, and netrin-1 act in concert to organize the adolescent development of mesocortical dopamine innervation and, in turn, determine behavioral responses to drugs of abuse.
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Affiliation(s)
- Matthew Pokinko
- Integrated Program in Neuroscience, McGill University, Montréal, Québec, Canada
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