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Background: Cannabis remains one of the most widely abused drugs during pregnancy. In utero exposure to its principal psychoactive component, Δ 9 -tetrahydrocannabinol (THC), can result in long-term neuropsychiatric risk for the progeny. This study investigated epigenetic signatures underlying these enduring consequences., Methods: Rat dams were exposed daily to THC (0.15 mg/kg) during pregnancy, and adult male offspring were examined for reward and depressive-like behavioral endophenotypes. Using unbiased sequencing approaches, we explored transcriptional and epigenetic profiles in the nucleus accumbens (NAc), a brain area central to reward and emotional processing. An in vitro CRISPR (clustered regularly interspaced short palindromic repeats) activation model coupled with RNA sequencing was also applied to study specific consequences of epigenetic dysregulation, and altered molecular signatures were compared with human major depressive disorder transcriptome datasets., Results: Prenatal THC exposure induced increased motivation for food, heightened learned helplessness and anhedonia, and altered stress sensitivity. We identified a robust increase specific to males in the expression of Kmt2a (histone-lysine N-methyltransferase 2A) that targets H3K4 (lysine 4 on histone H3) in cellular chromatin. Normalizing Kmt2a in the NAc rescued the motivational phenotype of prenatally THC-exposed animals. Comparison of RNA- and H3K4me3-sequencing datasets from the NAc of rat offspring with the in vitro model of Kmt2a upregulation revealed overlapping, significant disturbances in pathways that mediate synaptic plasticity. Similar transcriptional alterations were detected in human major depressive disorder., Conclusions: These studies provide direct evidence for the persistent effects of prenatal cannabis exposure on transcriptional and epigenetic deviations in the NAc via Kmt2a dysregulation and associated psychiatric vulnerability., (Copyright © 2021 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.)

Competing Interests: Declaration of interests KH has been supported by the Esther Ting Memorial Professorship at Stanford University School of Medicine and research grants from the US Veterans Administration Health Services Research and Development Service (RCS 04-141-3, HX-12-001, and HX002714-01A2), the US National Institute on Drug Abuse (3UG1 DA015815-17S4 and 2UG1DA015815-19), the US Food and Drug Administration, Wu Tsai Neurosciences Institute, the Silicon Valley Community Foundation, the County of Santa Clara California, and the American Board of Family Medicine. He has received speaking honoraria and travel expenses from the American College of Medical Toxicology, Arizona State University, Barclays Bank, Caron Foundation, the University of Florida, the New York Museum of Modern Art, Syracuse University, West Virginia University School of Medicine, and the West Virginia Medical Professionals Health Program. He has received writing honoraria or royalties from the Association of Psychological Science, American Academy of Political and Social Science, Brookings Institution, Cambridge University Press, and Washington Monthly. He has been a paid consultant to AELIS Pharma, Harvard Medical School, and Harvard University Press. CLS has been employed by Stanford University, the University of California, Los Angeles (UCLA), the Los Angeles County Department of Public Health, Heluna Health, and the Los Angeles LGBT Center. She has received research funding or stipends from the US National Institute on Drug Abuse (K01DA050771, T32DA035165), the RAND Opioid Policy Tools and Information Center), Wu Tsai Neurosciences Institute, and UCLA David Geffen School of Medicine, and speaking honoraria or travel expenses from Emory University, New York University, UCLA, the University of North Carolina at Chapel Hill, the University of Southern California, the University of Pittsburgh, the University of Chicago, the University of Western Ontario, the Nevada State Medical Association, RAND, the University of California, Irvine, the US Centers for Disease Control and Prevention, College on Problems of Drug Dependence, the Conference on Retroviruses and Opportunistic Infections, HIV Research for Prevention, Addiction Health Services Research, and the American Psychopathological Association. CMA has been supported by the Arnold School of Public Health at the University of South Carolina, and by research grants from the US National Institute on Drug Abuse (R01DA034634, K01DA041628, U2CDA050097, R01DA049776, and R01DA052425), the US National Institute on Alcoholism and Alcohol Abuse (R01AA029097 and R01AA029821), and the South Carolina Department of Alcohol and Other Drug Abuse Services, and has been a paid consultant to the Robert Wood Johnson Foundation, RTI International, the Medical University of South Carolina, the State of Pennsylvania Department of Public Health, and the State of Illinois Division of Health Care and Family Services. ASBB has been supported by grants from the US National Institutes for Health (R01 DA045705), the US Veterans Health Administration (IIR 13-322 and C19 21-278), the US Centers for Disease Control and Prevention (U01CE002780), Blue Cross Blue Shield of Michigan, the US Department of Defense, the Patient-Centered Outcomes Research Institute, the Michigan Health Endowment Fund, and the Substance Abuse and Mental Health Services Administration via sub-contracts from the Michigan Department of Health and Human Services, has received speaker honoraria or travel expenses from the Illinois Health and Hospital Association, the International Summit on Suicide Research, the Washington State Department of Labor & Industries, the American Psychopathological Association, and the High Intensity Drug Trafficking Area program, has been paid as a consultant by New York University, and has received products from Fitbit at a reduced cost and Headspace for free for research purposes. MLB has been supported by research grants from the US Department of Veterans Affairs and the US National Institute on Drug Abuse (R37-DA15612), and a Koret Foundation gift for Smart Cities and Digital Living, has received travel expenses from the University of Maryland, the University of Auckland, Massachusetts Institute of Technology, the European Working Group on Stochastic Modeling, INSEAD, the University of Michigan, and the University of Oklahoma, and has been a paid consultant to Compass Lexecon and DE Shaw. JPC has received a National Science Foundation EAGER Grant on Detecting and Disrupting Illicit Supply Networks via Traffic Distribution Systems, is a consultant to the RAND Corporation's Drug Policy Research Center, has consulted with or received honoraria from the Actis—Norwegian Policy Network on Alcohol and Drugs, the Arnold Foundation, Bank of Montreal, Boston University, the Foreign Affairs, Justice Research and Statistics Association, Lisbon Addictions Conference, Massachusetts Institute of Technology, National Affairs, the National Institute of Justice, Oxford University Press, Pew, PIRE, the Russell Sage Foundation, Springer Verlag, Stanford University, the US State Department, Texas Research Society on Alcoholism, the US Veteran's Administration, Washington Monthly, and the WT Grant Foundation. JHC has received research support or funding from the US National Institutes of Health and National Library of Medicine (R56LM013365), the Gordon and Betty Moore Foundation (GBMF8040), the US National Science Foundation (SPO181514); Google (SPO13604), the Stanford Clinical Excellence Research Center, the Stanford Department of Medicine and Department of Pathology, and the Stanford Aging and Ethnogeriatrics Research Center (P30AG059307), which is part of the Resource Centers for Minority Aging Research programme led by the US National Institute on Aging at the National Institutes of Health, is the co-founder of Reaction Explorer (which develops and licenses organic chemistry education software), and has been paid consulting or speaker fees by the US National Institute of Drug Abuse Clinical Trials Network, Tuolc, Roche, and Younker Hyde MacFarlane. M-FC has served as president of the Carnegie Endowment for International Peace, a justice of the Supreme Court of California, the Herman Phleger Professor at Stanford Law School, a distinguished visiting jurist at the New York University School of Law, the Castle Distinguished Lecturer in Ethics, Politics, and Economics at Yale University, a member of the President & Fellows of Harvard College (the Harvard Corporation), a member of the board of directors of the William and Flora Hewlett Foundation, a member of the Council of the American Law Institute, chair of the board of directors of the Center for Advanced Study in the Behavioral Sciences, chair of the advisory board of the Seed Initiative at the Stanford Graduate School of Business, and a member of the advisory board at the Stanford Human-Centered Artificial Intelligence Institute. His work has been supported by Stanford Law School and by a grant from the Stanford Human-Centered Artificial Intelligence Institute, and he was previously chair of the advisory board of the AI Now Institute at New York University. YLH has received research grants from the US National Institute on Drug Abuse (DA050323, DA048613, DA008227, DA043247, DA030359, DA037317, and DA15446), research funding from GW Pharmaceuticals, speaking honoraria or travel expenses, or both, from the University of North Carolina, the American Society for the Advancement of Science, the Society for Neuroscience Public Education & Communication Committee, Washington University in St Louis, Temple University, Tufts School of Medicine, Indiana University, the American College of Neuropsychopharmacology, the Iowa Neuroscience Institute, the Franklin Institute, State University of New York Upstate Medical University, the Canadian Consortium for the Investigation of Cannabinoids, the University of Michigan, Cold Spring Harbor Laboratory, the US National Institutes of Health, Penn State Hershey College of Medicine, the US National Academy of Medicine, the Mediterranean Neuroscience Society, the Wu Tsai Neurosciences Institute, Society of Biological Psychiatry, International College of Neuropharmacology, the Federation of European Neuroscience Societies, Gordon Research Conference, the National Institutes of Health Center for Scientific Research Council, and the Society of Neuroscience. DNJ has received research grants from the Canadian Institutes for Health Research and the Ontario Ministry of Health, financial support from the departments of medicine at both the University of Toronto and Sunnybrook Health Sciences Centre, travel expenses or speaking honoraria from Dalhousie University, the University of Ottawa, the University of Saskatchewan, the University of Calgary, the Bloomberg Johns Hopkins School of Public Health, the American College of Physicians, the University of Alabama at Birmingham, the American Society of Nephrology, the Canadian Society of Internal Medicine, the Canadian Anesthesiologists' Society, The Canadian Society of Obstetricians and Gynecologists, the Western Canada Addiction Forum, and the Canadian House of Commons Standing Committee on Health, and payment for expert witness testimony from (and has been retained by) Sanis, a generic drug manufacturer and distributor to provide advice related to an ongoing Canadian class action, and is a volunteer member of Physicians for Responsible Opioid Prescribing. HKK has been supported by grants from the Robert Wood Johnson Foundation (77667, 74275, and 73359), the John Templeton Foundation (52125), the JPB Foundation (1085 and 439), and the Association of State and Territorial Health Officers (1584), has received honoraria from Jefferson University, Jefferson Health, the Perelman School of Medicine at the University of Pennsylvania, MaineHealth Center for Tobacco Independence, Harvard University Memorial Church, the Association of State and Territorial Health Officials, the University of Wisconsin Medical School, Wake Forest Baptist Health (in partnership with Shaw University), the Robert Wood Johnson Foundation advisory committee, the American College of Gastroenterology, and Tufts University School of Medicine, has been a consultant to the Commonwealth Fund, and is a member of the Community COVID Coalition Advisory Group, Phillips Academy Public Health Expert Advisory Panel, the Policy Advisory Group, the board of the Bipartisan Policy Center, the Palliative and Advanced Illness Research Center External Advisory Board (at the Perelman School of Medicine), the American Cancer Society Eastern New England Area Council of Advisors, the American University of Beirut International Advisory Council, the US National Advisory Board, the Culture of Health Year in Review Advisory Committee and Culture of Health as a Business Imperative Initiative of the Robert Wood Johnson Foundation, the editorial board of the Journal of the American Medical Association, the New England Donor Services board of trustees, the Josiah Macy Jr Foundation board of directors, and the Lancet–O'Neill Institute, Georgetown University Commission on Global Health and the Law. EEK has received research funding from the US Department of Veterans Affairs Health Services Research and Development (COR 19-489, 1I01HX003063-01A1, 5I01HX001752-05, 5I01HX002737-02, 5I01HX001288-05, and 5I01HX000911-06), the Patient Centered Outcomes Research Institute (OPD-1511-33052), the US National Center for Complementary and Integrative Health (5R01AT008387-04, 5UH3AT009761- 04/5UG3AT009761-02, and 4UH3AT009765-03/5UG3AT009765-02), and the US National Institute of Diabetes and Digestive and Kidney Diseases (1U01DK123816-01), and travel expenses from the law firm Nix Patterson representing the state of Oklahoma (to serve as an expert witness in support of the state's litigation against opioid manufacturers), the American Society of Health-System Pharmacists, the Association of Academic Physiatrists, the Australian Pain Society, the Cleveland VA Medical Research and Education Foundation, the Duke-Margolis Center for Health Policy, the Foundation for Medical Excellence, the Foundation for Opioid Response Efforts, the Friends of VA Medical Care and Health Research, the Hennepin Healthcare Research Institute, the Indiana Institute for Medical Research, the US National Academies of Medicine, the US National Center for Complementary and Integrative Health, the National Governors Association, the North American Spine Society, the Patient Centered Outcomes Research Institute at Stanford University, the US Food and Drug Administration, and the Washington State Department of Labor & Industries. AL has received consulting fees for her work as a medical expert witness in federal and state litigation against opioid manufacturers, distributors, and pharmacies, book royalties from Johns Hopkins University Press and Dutton Penguin Random House, speaking honoraria or travel expenses, or both, from the Vanderbilt University School of Medicine, the Ohio State University School of Medicine, the University of Kansas School of Medicine (sponsorship of the Alpha Omega Alpha Visiting Professorship), the Oregon Pain Guidance, the Indiana Prosecuting Attorneys Council, the Perrin's Opioid Litigation Conference, the Public Funds Forum, the Baton Rouge Health District, the Montrose Colorado Annual Continuing Medical Education Conference, the PerformRX Pharmacy Benefits Manager Annual Conference, the American Academy of Psychiatry and the Law, the Psych Congress, the 69th Annual Canadian Refresher Course for Family Physicians, the Ohio State University Inter-Professional Summit, the University of Texas, the Geminus Community Partners Annual Conference of Indiana, the National Council on Alcoholism and Drug Abuse, the Stanford Sierra Camp Womens' Alumni Wellness Retreat, the American Psychiatric Association, the Association for Medical Education and Research in Substance Abuse, and the Southwestern Gynecologic Assembly. SCM has been supported by the Redlich Professorship and the Rosekrans Pain Research Endowment Fund at Stanford University School of Medicine and research grants awarded to Stanford University from the US National Institutes of Health (R61NS118651, R03HD094577, R01DA045027, R01NS109450, R01AT008561, K24DA02926207, R01DA035484, and P01AT00665105), the Patient Centered Outcomes Research Institute (PCORI OPD-1610- 370707), the Stanford Wu Tsai Neurosciences Institute, and the University of California, San Francisco–Stanford Center of Excellence in Regulatory Science and Innovation (FDA) (2U01FD005978-06), has received speaking honoraria or travel expenses from Walter Reed, Harvard University, the American Academy of Pain Medicine, Washington University, the US Food and Drug Administration, the US National Institutes of Health, the US National Institute of Neurological Disorders and Stroke, the University of Washington, George Washington University, New York University, Weill Cornell Medical College, Duke University, the University of Utah, the World Institute of Pain, and the Canadian Pain Society, has received payment for testimony (unrelated to opioids) from Lauria Tokunaga Gates and Linn, and has received payment for consulting (unrelated to opioids) from the American Society of Anesthesiology; Favros Law; Fain Anderson VanDerhoef Rosendahl O'Halloran Spillane; Cox, Wootton, Lerner, Griffin & Hansen; Lewis Brisbois Bisgaard & Smith; Muro & Lampe; McCormick Barstow; Schmid & Voiles; and the University of Oklahoma Health Sciences Center. LLO has received travel expenses or honoraria from Cardozo Law School, Claremont McKenna College, Duke University, ETH Zürich, Georgetown University, Harvard University, the Los Angeles Intellectual Property Law Association, Michigan State University, New York University, Northwestern University, the University of Chicago, the University of Houston, the University of Kansas, the University of Nebraska, the University of San Diego, the University of Texas, the University of Villanova, the World Intellectual Property Organization, and Yale University, has received a writing honoraria from the Brookings Institution (to write a policy proposal for the Hamilton Project), and is a paid consultant to the MITRE Corporation (to assist with evaluations of the US Patent and Trademark Office requested by the Department of Commerce). BS has received research support from the US National Institute on Alcohol Abuse and Alcoholism (R01 AA023650 and K23 AA023284), the US National Institute of Drug Abuse (R21 DA043181), the US National Institute of Mental Health (P50MH115838), and the US National Highway Transportation Safety Authority, has received royalties from a software licence to healthStratica, and has several invention disclosures with the University of Pittsburgh for digital behavioral interventions. CT has been supported by the US Department of Veterans Affairs (VA HSR&D IIR 15-298, IIR 18-253, IIR 20-058, and PPO 16-337) and the US National Institutes of Health (NIAAA 1R01AA024136-01).

Background: Opiate abuse and overdose reached epidemic levels in the United States. However, despite significant advances in animal and in vitro models, little knowledge has been directly accrued regarding the neurobiology of the opiate-addicted human brain., Methods: We used postmortem human brain specimens from a homogeneous European Caucasian population of heroin users for transcriptional and epigenetic profiling, as well as direct assessment of chromatin accessibility in the striatum, a brain region central to reward and emotion. A rat heroin self-administration model was used to obtain translational molecular and behavioral insights., Results: Our transcriptome approach revealed marked impairments related to glutamatergic neurotransmission and chromatin remodeling in the human striatum. A series of biochemical experiments tracked the specific location of the epigenetic disturbances to hyperacetylation of lysine 27 of histone H3, showing dynamic correlations with heroin use history and acute opiate toxicology. Targeted investigation of GRIA1, a glutamatergic gene implicated in drug-seeking behavior, verified the increased enrichment of lysine-27 acetylated histone H3 at discrete loci, accompanied by enhanced chromatin accessibility at hyperacetylated regions in the gene body. Analogous epigenetic impairments were detected in the striatum of heroin self-administering rats. Using this translational model, we showed that bromodomain inhibitor JQ1, which blocks the functional readout of acetylated lysines, reduced heroin self-administration and cue-induced drug-seeking behavior., Conclusions: Overall, our data suggest that heroin-related histone H3 hyperacetylation contributes to glutamatergic transcriptional changes that underlie addiction behavior and identify JQ1 as a promising candidate for targeted clinical interventions in heroin use disorder., (Copyright © 2016 Society of Biological Psychiatry. All rights reserved.)

The past decade has witnessed a number of societal and political changes that have raised critical questions about the long-term impact of marijuana (Cannabis sativa) that are especially important given the prevalence of its abuse and that potential long-term effects still largely lack scientific data. Disturbances of the epigenome have generally been hypothesized as the molecular machinery underlying the persistent, often tissue-specific transcriptional and behavioral effects of cannabinoids that have been observed within one's lifetime and even into the subsequent generation. Here, we provide an overview of the current published scientific literature that has examined epigenetic effects of cannabinoids. Though mechanistic insights about the epigenome remain sparse, accumulating data in humans and animal models have begun to reveal aberrant epigenetic modifications in brain and the periphery linked to cannabis exposure. Expansion of such knowledge and causal molecular relationships could help provide novel targets for future therapeutic interventions., (Copyright © 2016 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.)

The observation of increased hyperphosphorylated tau levels correlating with microglial activation in opiate abusers has been interpreted as predisposition to accelerated Alzheimer disease-related changes. The present study focused on evaluating additional neurodegeneration-related proteins, including α-synuclein and TDP-43, and p62-positive deposits. We performed a systematic mapping of protein deposits in the brains of 27 individuals with documented heroin addiction (age: 19-40 years) and compared with 11 controls (age: 15-40 years). We confirm previous findings that heroin addiction associates with tau hyperphosphorylation in predilection brain areas for aging and Alzheimer disease. Furthermore, we show that this occurs also in areas implicated in the molecular disturbances and in vivo neuronal networks related to heroin abuse. There was, however, no presence of amyloid-beta deposits. We extend previous findings by showing the lack of TDP-43 or α-synuclein pathology and emphasize the independent effect of the duration of drug use on the appearance of age-related p62-positive neuritic profiles. These observations provide unique insights about neuropathological alterations in the brains of young heroin addicts and have implications about brain aging and the influences of environmental and toxic factors., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Background: Abuse of heroin and prescription opiate medications has grown to disturbing levels. Opioids mediate their effects through mu opioid receptors (MOR), but minimal information exists regarding MOR-related striatal signaling relevant to the human condition. The striatum is a structure central to reward and habitual behavior and neurobiological changes in this region are thought to underlie the pathophysiology of addiction disorders., Methods: We examined molecular mechanisms related to MOR in postmortem human brain striatal specimens from a homogenous European Caucasian population of heroin abusers and control subjects and in an animal model of heroin self-administration. Expression of ets-like kinase 1 (ELK1) was examined in relation to polymorphism of the MOR gene OPRM1 and drug history., Results: A characteristic feature of heroin abusers was decreased expression of MOR and extracellular regulated kinase signaling networks, concomitant with dysregulation of the downstream transcription factor ELK1. Striatal ELK1 in heroin abusers associated with the polymorphism rs2075572 in OPRM1 in a genotype dose-dependent manner and correlated with documented history of heroin use, an effect reproduced in an animal model that emphasizes a direct relationship between repeated heroin exposure and ELK1 dysregulation. A central role of ELK1 was evidenced by an unbiased whole transcriptome microarray that revealed ~20% of downregulated genes in human heroin abusers are ELK1 targets. Using chromatin immune precipitation, we confirmed decreased ELK1 promoter occupancy of the target gene Use1., Conclusions: ELK1 is a potential key transcriptional regulatory factor in striatal disturbances associated with heroin abuse and relevant to genetic mutation of OPRM1., (© 2013 Society of Biological Psychiatry.)

Background: Marijuana use by teenagers often predates the use of harder drugs, but the neurobiological underpinnings of such vulnerability are unknown. Animal studies suggest enhanced heroin self-administration (SA) and dysregulation of the endogenous opioid system in the nucleus accumbens shell (NAcsh) of adults following adolescent Δ(9)-tetrahydrocannabinol (THC) exposure. However, a causal link between proenkephalin (Penk) expression and vulnerability to heroin has yet to be established., Methods: To investigate the functional significance of NAcsh Penk tone, selective viral-mediated knockdown and overexpression of Penk was performed, followed by analysis of subsequent heroin SA behavior. To determine whether adolescent THC exposure was associated with chromatin alteration, we analyzed levels of histone H3 methylation in the NAcsh via chromatin immunoprecipitation at five sites flanking the Penk gene transcription start site., Results: Here we show that regulation of the Penk opioid neuropeptide gene in NAcsh directly regulates heroin SA behavior. Selective viral-mediated knockdown of Penk in striatopallidal neurons attenuates heroin SA in adolescent THC-exposed rats, whereas Penk overexpression potentiates heroin SA in THC-naïve rats. Furthermore, we report that adolescent THC exposure mediates Penk upregulation through reduction of histone H3 lysine 9 (H3K9) methylation in the NAcsh, thereby disrupting the normal developmental pattern of H3K9 methylation., Conclusions: These data establish a direct association between THC-induced NAcsh Penk upregulation and heroin SA and indicate that epigenetic dysregulation of Penk underlies the long-term effects of THC., (Copyright © 2012 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.)

Background: Prenatal cannabis exposure has been linked to addiction vulnerability, but the neurobiology underlying this risk is unknown., Methods: Striatal dopamine and opioid-related genes were studied in human fetal subjects exposed to cannabis (as well as cigarettes and alcohol). Cannabis-related gene disturbances observed in the human fetus were subsequently characterized with an animal model of prenatal Δ-9-tetrahydrocannabinol (THC) (.15 mg/kg) exposure., Results: Prenatal cannabis exposure decreased dopamine receptor D2 (DRD2) messenger RNA expression in the human ventral striatum (nucleus accumbens [NAc]), a key brain reward region. No significant alterations were observed for the other genes in cannabis-exposed subjects. Maternal cigarette use was associated with reduced NAc prodynorphin messenger RNA expression, and alcohol exposure induced broad alterations primarily in the dorsal striatum of most genes. To explore the mechanisms underlying the cannabis-associated disturbances, we exposed pregnant rats to THC and examined the epigenetic regulation of the NAc Drd2 gene in their offspring at postnatal day 2, comparable to the human fetal period studied, and in adulthood. Chromatin immunoprecipitation of the adult NAc revealed increased 2meH3K9 repressive mark and decreased 3meH3K4 and RNA polymerase II at the Drd2 gene locus in the THC-exposed offspring. Decreased Drd2 expression was accompanied by reduced dopamine D2 receptor (D(2)R) binding sites and increased sensitivity to opiate reward in adulthood., Conclusions: These data suggest that maternal cannabis use alters developmental regulation of mesolimbic D(2)R in offspring through epigenetic mechanisms that regulate histone lysine methylation, and the ensuing reduction of D(2)R might contribute to addiction vulnerability later in life., (Copyright © 2011 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.)

Background: Glutamatergic transmission in the amygdala is hypothesized as an important mediator of stimulus-reward associations contributing to drug-seeking behavior and relapse. Insight is, however, lacking regarding the amygdala glutamatergic system in human drug abusers., Methods: We examined glutamate receptors and scaffolding proteins associated with the postsynaptic density in the human postmortem amygdala. Messenger RNA or protein levels were studied in a population of multidrug (seven heroin, eight cocaine, seven heroin/cocaine, and seven controls) or predominant heroin (29 heroin and 15 controls) subjects., Results: The amygdala of drug abusers was characterized by a striking positive correlation (r > .8) between α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid glutamate receptor subunit 1 (GluA1) and postsynaptic density protein-95 (PSD-95) mRNA levels, which was not evident in control subjects. Structural equation multigroup analysis of protein correlations also identified the relationship between GluA1 and PSD-95 protein levels as the distinguishing feature of abusers. In line with the GluA1-PSD-95 implications of enhanced synaptic plasticity, Homer 1b/c protein expression was increased in both heroin and cocaine users as was its binding partner, dynamin-3. Furthermore, there was a positive relationship between Homer 1b/c and dynamin-3 in drug abusers that reflected an increase in the direct physical coupling between the proteins. A noted age-related decline of Homer 1b/c-dynamin-3 interactions, as well as GluA1 levels, was blunted in abusers., Conclusions: Impairment of key components of the amygdala postsynaptic density and coupling to the endocytic zone, critical for the regulation of glutamate receptor cycling, may underlie heightened synaptic plasticity in human drug abusers., (Copyright © 2011 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.)

Adolescence is a critical phase of active brain development often characterized by the initiation of marijuana (Cannabis sativa) use. Limited information is known regarding the endogenous cannabinoid system of the adolescent brain as well as related neurotransmitters that appear sensitive to cannabis exposure. We recently observed that adult rats pre-exposed to Delta-9-tetrahydrocannabinol (THC) during adolescence self-administered higher amounts of heroin and had selective impairments of the enkephalin opioid system within the nucleus accumbens (NAc) implicated in reward-related behavior. To explore the ontogeny of the cannabinoid and opioid neuronal systems in association with adolescence THC exposure, rats were examined at different adolescent stages during an intermittent THC paradigm (1.5 mg/kg i.p. every third day) from postnatal days (PNDs) 28-49. Rat brains were examined 24 h after injection at PND 29 (early adolescence), PND 38 (mid adolescence) and PND 50 (late adolescence) and analyzed for endocannabinoids (anandamide and 2-arachidonoylglycerol), Met-enkephalin, cannabinoid CB(1) receptors and micro opioid receptors (microOR) in the NAc, caudate-putamen and prefrontal cortex (PFC). Of the markers studied, the endocannabinoid levels had the most robust alterations throughout adolescence and were specific to the PFC and NAc. Normal correlations between anandamide and 2-arachidonoylglycerol concentrations in the NAc (positive) and PFC (negative) were reversed by THC. Other significant THC-induced effects were confined to the NAc - increased anandamide, decreased Met-enkephalin and decreased microORs. These findings emphasize the dynamic nature of the mesocorticolimbic endocannabinoid system during adolescence and the selective mesocorticolimbic disturbance as a consequence of adolescent cannabis exposure.

Background: Prenatal cannabis exposure is a growing concern with little known about the long-term consequences on behavior and neural systems relevant for reward and emotional processing., Methods: We used an animal model to study the effects of prenatal exposure to Delta(9)-tetrahydrocannabinol (THC) on heroin self-administration behavior and opioid neural systems in adult males (postnatal day 62). Rats were exposed to THC (.15 mg/kg) or vehicle from gestational day 5 to postnatal day 2., Results: Both pretreatment groups showed similar heroin intake, but THC-exposed rats exhibited shorter latency to the first active lever press, responded more for low heroin doses, and had higher heroin-seeking during mild stress and drug extinction. THC exposure reduced preproenkephalin (PENK) mRNA expression in the nucleus accumbens during early development, but was elevated in adulthood; no adult striatal changes on preprodynorphin mRNA or PENK in caudate-putamen. PENK mRNA was also increased in the central and medial amygdala in adult THC-exposed animals. THC animals had reduced heroin-induced locomotor activity and nucleus accumbens mu opioid receptor coupling., Conclusions: This study demonstrates enduring effects of prenatal THC exposure into adulthood that is evident on heroin-seeking behavior during extinction and allostatic changes in mesocorticolimbic PENK systems relevant to drug motivation/reward and stress response.

Very limited is known about p53 expression in the normal mammalian brain and only few alternative splice variants have been reported thus far in human and rat peripheral tissues. Here, we detected eight new p53 transcripts in the human brain generated by alternative splicing, whereas two were present in the rat brain. Almost all alternative splice events occurred due to atypical splice mechanism employing direct repeats at splice sites. All discovered transcripts retain untranslated 5' area of the p53 gene and thus could be translated into peptides consisting of different functional domains.

Background: Marijuana (Cannabis sativa) is the illicit drug most used by pregnant women, and behavioral and cognitive impairments have been documented in cannabis-exposed offspring. Despite the extensive use of marijuana, very limited information exists as to the consequences of prenatal cannabis exposure on the developing human brain., Methods: We optimized an in situ hybridization histochemistry technique to visualize mRNA expression in midgestation (weeks 18-22) human fetal specimens from mothers with and without documented evidence of cannabis use during pregnancy. The cannabinoid receptor type 1 (CB(1)) and major dopamine receptor subtypes, D(1) and D(2), were examined in the striatum and mesocorticolimbic structures (amygdala and hippocampus)., Results: Adjusting for various covariates, we found a specific reduction, particularly in male fetuses, of the D(2) mRNA expression levels in the amygdala basal nucleus in association with maternal marijuana use. The reduction was positively correlated with the amount of maternal marijuana intake during pregnancy. No significant cannabis-related alterations were detected in the hippocampus or caudal striatum for the D(2), D(1), and CB(1) mRNA levels, although alcohol showed significant contribution to striatal D(1)/D(2) expression., Conclusions: These human fetal findings suggest that in utero cannabis exposure may impair distinct mesocorticolimbic neural systems that regulate emotional behavior.

In vivo microdialysis was utilized to evaluate the role of extracellular Na+ in regulating dopamine (DA) neurotransmission in the caudate-putamen of halothane-anaesthetized rats. Reduction of the extracellular Na+ concentration by introduction of a perfusion media containing 50mM Na+ (with choline replacement) produced an excessive release of DA that could be effectively blocked by nomifensine and Lu 19-005, potent inhibitors of an amine transport carrier. These results substantiate reports of a carrier-mediated efflux of DA from presynaptic terminals. Pretreatment with amphetamine, considered both a DA uptake inhibitor and releaser, did not, however, influence the efflux of DA induced by the low extracellular Na+ environment. Although the release of DA from an apparent non-granular cytosolic pool was greatly enhanced by the low extracellular Na+ environment, 3,4-dihydrophenylacetic acid (DOPAC) levels, which supposedly reflect metabolism of non-vesicular DA, were minimally effected. In contrast, homovanillic acid (HVA) was sensitive to extracellular Na+ and not directly related to extracellular levels of either DA or DOPAC, suggesting the possibility of a Na+-sensitive (carrier-mediated?) process involved in the formation of HVA. Overall, the results of this paper cannot be completely reconciled with the traditional concept of intracellular organization of DA pools and suggests the possibility of various non-granular pools being differentially sensitive to efflux and metabolism.