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Maal-Bared G, Yee M, Harding EK, Ghebreselassie M, Bergamini M, Choy R, Kim E, Di Vito S, Patel M, Amirzadeh M, Grieder TE, Coles BL, Nagy JI, Bonin RP, Steenland HW, van der Kooy D. Connexin-36-positive gap junctions in ventral tegmental area GABA neurons sustain opiate dependence. Eur J Neurosci 2024; 59:3422-3444. [PMID: 38679044 DOI: 10.1111/ejn.16366] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Revised: 03/20/2024] [Accepted: 04/03/2024] [Indexed: 05/01/2024]
Abstract
Drug dependence is characterized by a switch in motivation wherein a positively reinforcing substance can become negatively reinforcing. Put differently, drug use can transform from a form of pleasure-seeking to a form of relief-seeking. Ventral tegmental area (VTA) GABA neurons form an anatomical point of divergence between two double dissociable pathways that have been shown to be functionally implicated and necessary for these respective motivations to seek drugs. The tegmental pedunculopontine nucleus (TPP) is necessary for opiate conditioned place preferences (CPP) in previously drug-naïve rats and mice, whereas dopaminergic (DA) transmission in the nucleus accumbens (NAc) is necessary for opiate CPP in opiate-dependent and withdrawn (ODW) rats and mice. Here, we show that this switch in functional anatomy is contingent upon the gap junction-forming protein, connexin-36 (Cx36), in VTA GABA neurons. Intra-VTA infusions of the Cx36 blocker, mefloquine, in ODW rats resulted in a reversion to a drug-naïve-like state wherein the TPP was necessary for opiate CPP and where opiate withdrawal aversions were lost. Consistent with these data, conditional knockout mice lacking Cx36 in GABA neurons (GAD65-Cre;Cx36 fl(CFP)/fl(CFP)) exhibited a perpetual drug-naïve-like state wherein opiate CPP was always DA independent, and opiate withdrawal aversions were absent even in mice subjected to an opiate dependence and withdrawal induction protocol. Further, viral-mediated rescue of Cx36 in VTA GABA neurons was sufficient to restore their susceptibility to an ODW state wherein opiate CPP was DA dependent. Our findings reveal a functional role for VTA gap junctions that has eluded prevailing circuit models of addiction.
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Affiliation(s)
- Geith Maal-Bared
- Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
| | - Mandy Yee
- Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
| | - Erika K Harding
- Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada
| | - Martha Ghebreselassie
- Terrence Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, Ontario, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Michael Bergamini
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
- Department of Human Biology, University of Toronto, Toronto, Ontario, Canada
| | - Roxanne Choy
- Department of Human Biology, University of Toronto, Toronto, Ontario, Canada
| | - Ethan Kim
- Department of Human Biology, University of Toronto, Toronto, Ontario, Canada
| | - Stephanie Di Vito
- Department of Human Biology, University of Toronto, Toronto, Ontario, Canada
| | - Maryam Patel
- Department of Human Biology, University of Toronto, Toronto, Ontario, Canada
| | - Mohammadreza Amirzadeh
- Terrence Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, Ontario, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Taryn E Grieder
- Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
| | - Brenda L Coles
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - James I Nagy
- Department of Physiology and Pathophysiology, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Robert P Bonin
- Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada
| | | | - Derek van der Kooy
- Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
- Terrence Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, Ontario, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
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Involvement of GABAA receptors of lateral habenula in the acquisition and expression phases of morphine-induced place preference in male rats. Behav Pharmacol 2022; 33:452-465. [PMID: 36148835 DOI: 10.1097/fbp.0000000000000695] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The lateral habenula (LHb) is a critical brain structure involved in the aversive response to drug abuse. It has been determined that the gamma-aminobutyric acid (GABA)-ergic system plays the main role in morphine dependency. The role of GABA type A receptors (GABAARs) in LHb on morphine-induced conditioned place preference (CPP) remains unknown. In this study, the effect of bilateral intra-LHb microinjection of GABAAR agonist and antagonist on the acquisition and expression phases of CPP, utilizing a 5-day CPP paradigm in male rats, was evaluated. Subcutaneous administration of different doses of morphine caused a dose-dependent CPP. Intra-LHb microinjection of the GABAAR agonist, muscimol, in combination with morphine (5 mg/kg; subcutaneously) enhanced CPP scores in the acquisition phase of morphine CPP, whereas the GABAAR antagonist, bicuculline, significantly reduced the conditioning scores in the acquisition phase. Furthermore, pretreatment with a high dose of bicuculline reversed the additive effect of muscimol during the acquisition phase, yet the low dose of antagonist had no significant effect on agonist-induced CPP scores. On the other hand, muscimol (3 µg/rat) significantly increased CPP scores in the expression phase but bicuculline did not induce a significant effect on CPP scores. Bicuculline and muscimol microinjections did not affect locomotor activity in the testing sessions. Our results confirm that GABAARs in LHb play an active role in morphine reward. In addition, microinjections of bicuculline/muscimol may alter the morphine response through the GABAergic system.
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In-house fabrication of bipolar electrode-cannula assembly for electrical stimulation and drug delivery at the same site in rat brain. J Pharmacol Toxicol Methods 2022; 118:107194. [PMID: 35779851 DOI: 10.1016/j.vascn.2022.107194] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Revised: 06/08/2022] [Accepted: 06/25/2022] [Indexed: 11/21/2022]
Abstract
Strategies drawn at understanding the functional attributes of specific neural circuits often necessitate electrical stimulation and pharmacological manipulation at the same anatomical site. We describe a simple, inexpensive and reliable method to fabricate a bipolar electrode-cannula assembly for delivery of electric pulses and administration of neuroactive agents at the same site in the rat brain. The assembly consisting of a guide cannula, dummy cannula, internal cannula and bipolar electrode was fabricated using syringe needles, wires and simple electronic components. To test the usefulness of the device, it was implanted on the skull of a rat specifically targeting the posterior ventral tegmental area (pVTA). The rat was conditioned to press the lever in intracranial self-stimulation (ICSS) protocol in an operant chamber. The number of lever presses in a 30 min task was monitored. Intra-pVTA administration with bicuculline (GABAA receptor antagonist) increased the lever press activity, while muscimol (GABAA receptor agonist) had opposite effect. The results confirm that the group of neurons responding to the electrical stimulation probably receive GABAergic inputs. The device is light in weight, costs less than a dollar and can be fabricated from readily available components. It can serve a useful purpose in electrically stimulating any given target in the brain - before, during or after pharmacological manipulation at the same locus and may find application in neuropharmacological and neurobehavioral studies.
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Digital Addiction and Sleep. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2022; 19:ijerph19116910. [PMID: 35682491 PMCID: PMC9179985 DOI: 10.3390/ijerph19116910] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/15/2022] [Revised: 06/02/2022] [Accepted: 06/03/2022] [Indexed: 12/25/2022]
Abstract
In 2020, the World Health Organization formally recognized addiction to digital technology (connected devices) as a worldwide problem, where excessive online activity and internet use lead to inability to manage time, energy, and attention during daytime and produce disturbed sleep patterns or insomnia during nighttime. Recent studies have shown that the problem has increased in magnitude worldwide during the COVID-19 pandemic. The extent to which dysfunctional sleep is a consequence of altered motivation, memory function, mood, diet, and other lifestyle variables or results from excess of blue-light exposure when looking at digital device screens for long hours at day and night is one of many still unresolved questions. This article offers a narrative overview of some of the most recent literature on this topic. The analysis provided offers a conceptual basis for understanding digital addiction as one of the major reasons why people, and adolescents in particular, sleep less and less well in the digital age. It discusses definitions as well as mechanistic model accounts in context. Digital addiction is identified as functionally equivalent to all addictions, characterized by the compulsive, habitual, and uncontrolled use of digital devices and an excessively repeated engagement in a particular online behavior. Once the urge to be online has become uncontrollable, it is always accompanied by severe sleep loss, emotional distress, depression, and memory dysfunction. In extreme cases, it may lead to suicide. The syndrome has been linked to the known chronic effects of all drugs, producing disturbances in cellular and molecular mechanisms of the GABAergic and glutamatergic neurotransmitter systems. Dopamine and serotonin synaptic plasticity, essential for impulse control, memory, and sleep function, are measurably altered. The full spectrum of behavioral symptoms in digital addicts include eating disorders and withdrawal from outdoor and social life. Evidence pointing towards dysfunctional melatonin and vitamin D metabolism in digital addicts should be taken into account for carving out perspectives for treatment. The conclusions offer a holistic account for digital addiction, where sleep deficit is one of the key factors.
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Abstract
Addictive drugs are habit-forming. Addiction is a learned behavior; repeated exposure to addictive drugs can stamp in learning. Dopamine-depleted or dopamine-deleted animals have only unlearned reflexes; they lack learned seeking and learned avoidance. Burst-firing of dopamine neurons enables learning-long-term potentiation (LTP)-of search and avoidance responses. It sets the stage for learning that occurs between glutamatergic sensory inputs and GABAergic motor-related outputs of the striatum; this learning establishes the ability to search and avoid. Independent of burst-firing, the rate of single-spiking-or "pacemaker firing"-of dopaminergic neurons mediates motivational arousal. Motivational arousal increases during need states and its level determines the responsiveness of the animal to established predictive stimuli. Addictive drugs, while usually not serving as an external stimulus, have varying abilities to activate the dopamine system; the comparative abilities of different addictive drugs to facilitate LTP is something that might be studied in the future.
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Affiliation(s)
- Roy A Wise
- Intramural Research Program, National Institute on Drug Abuse, 250 Mason Lord Drive, Baltimore, MD, USA.
- Behavior Genetics Laboratory, McLean Hospital, Harvard Medical School, 115 Mill Street, Belmont, MA, 02478, USA.
| | - Chloe J Jordan
- Division of Alcohol, Drugs and Addiction, Department of Psychiatry, Harvard Medical School, McLean Hospital, 115 Mill Street, Belmont, MA, 02478, USA
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Tavassoli M, Ardjmand A. Pentylenetetrazol and Morphine Interaction in a State-dependent Memory Model: Role of CREB Signaling. Basic Clin Neurosci 2021; 11:557-572. [PMID: 33613894 PMCID: PMC7878041 DOI: 10.32598/bcn.11.4.1482.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2018] [Revised: 09/20/2018] [Accepted: 10/15/2019] [Indexed: 11/20/2022] Open
Abstract
Introduction: State-dependent (STD) memory is a process, in which the learned information can be optimally retrieved only when the subject is in the state similar to the encoding phase. This phenomenon has been widely studied with morphine. Several studies have reported that Pentylenetetrazole (PTZ) impairs memory in experimental animal models. Due to certain mechanistic interactions between morphine and PTZ, it is hypothesized that PTZ may interfere with the morphine-STD. The cyclic adenosine monophosphate Response Element-Binding (CREB) is considered as the main downstream marker for long-term memory. This study was designed to determine the possible interaction between PTZ and morphine STD and the presumable changes in CREB mRNA. Methods: In an Inhibitory Avoidance (IA) model, posttraining morphine (2.5, 5, and 7.5 mg/ kg-i.p.) was used. The pre-test morphine was evaluated for morphine-induced STD memory. Moreover, the effect of a pre-test PTZ (60 mg/kg-i.p.) was studied along with morphine STD. Locomotion testing was carried out using open-field. Eventually, using real-time-PCR, the CREB mRNA changes in the hippocampus were evaluated. Results: Posttraining MOR (7.5 mg/kg-i.p.) impaired IA memory (P<0.001). The pre-test injection of similar doses of morphine recovered the morphine-induced memory impairment (P<0.001). The pre-test PTZ impaired the IA memory recall (P<0.001); however, the pre-test PTZ along with morphine STD potentiated the morphine-induced STD (P<0.001). Alterations in CREB mRNA were observed in all groups. No difference was seen in the locomotor activity. Conclusion: Presumably, the certain interactive effect of PTZ on morphine-induced STD is mediated through gamma-aminobutyric acid and opioid systems via CREB signaling.
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Affiliation(s)
- Marziyeh Tavassoli
- Institute for Basic Sciences, Physiology Research Center, Kashan University of Medical Sciences, Kashan, Iran
| | - Abolfazl Ardjmand
- Institute for Basic Sciences, Physiology Research Center, Kashan University of Medical Sciences, Kashan, Iran.,Department of Physiology, School of Medicine, Kashan University of Medical Sciences, Kashan, Iran
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Chen Y, Ou M, Hao X, Liang P, Liang Y, Wang Y, Li Y, Zhou C. Sub-chronic exposure to morphine alters general anesthetic potency by differentially regulating the expression of neurotransmitter receptor subunits in mice. Brain Res Bull 2021; 169:136-144. [PMID: 33484757 DOI: 10.1016/j.brainresbull.2021.01.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Revised: 01/04/2021] [Accepted: 01/06/2021] [Indexed: 02/08/2023]
Abstract
BACKGROUND Sub-chronic exposure to morphine can increase the potency of propofol but decrease the potency of ketamine by unknown mechanisms. The present study was designed to investigate the effects of sub-chronic exposure to morphine on the expression of neurotransmitter receptor subunits, which might contribute to the potency changes of ketamine and propofol in vivo. METHODS Sub-chronic exposure to morphine was established by administering subcutaneous injections of morphine for 5 consecutive days. The median effective dose (ED50) of ketamine and/or propofol was measured on day 1, day 3, day 7 and day 15, after the last morphine dosage. Mice in the sham group received an equal volume of normal saline. The expressions of N-methyl D-aspartate (NMDA) receptor and γ-aminobutyric acid A (GABAA) receptor subunits in the forebrain were measured. Knockdown or overexpression of a subunit was used to determine the causality between the change in anesthetic potency and the expression of an identified receptor subunit. RESULTS After sub-chronic exposure of mice to morphine, the expression of NMDA receptor 1 (NR1) was most elevated in the forebrain on day 1 (P < 0.0001 vs. sham). In contrast, the expression of GABAA receptor β3 (GABAARβ3) gradually decreased to its lowest level on day 7 (P = 0.005 vs. sham) in the forebrain. Regression analysis revealed that the expression of NR1 in the forebrain was relevant to the increased ED50 of ketamine (P = 0.0002), while the expression of GABAARβ3 in the forebrain was relevant to the decreased ED50 of propofol (P = 0.0051) after morphine exposure. Knockdown expression of NR1 in the forebrain reversed the elevated ED50 of ketamine after morphine treatment. Overexpression of GABAARβ3 in the forebrain increased the ED50 of propofol to the sham-level after morphine treatment. CONCLUSIONS Sub-chronic exposure to morphine can differentially modulate the expressions of NR1 and GABAARβ3 in mice, which may contribute to the changes in ED50 of ketamine and propofol in vivo.
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Affiliation(s)
- Yali Chen
- Departments of Anesthesiology, West China Hospital of Sichuan University, Chengdu, 610041, China; Laboratory of Anesthesia & Critical Care Medicine, Translational Neuroscience Center, West China Hospital of Sichuan University, Chengdu, 610041, China
| | - Mengchan Ou
- Departments of Anesthesiology, West China Hospital of Sichuan University, Chengdu, 610041, China; Laboratory of Anesthesia & Critical Care Medicine, Translational Neuroscience Center, West China Hospital of Sichuan University, Chengdu, 610041, China; The Research Units of West China-Chinese Academy of Medical Sciences (2018RU012), West China Hospital of Sichuan University, Chengdu, 610041, China
| | - Xuechao Hao
- Departments of Anesthesiology, West China Hospital of Sichuan University, Chengdu, 610041, China; Laboratory of Anesthesia & Critical Care Medicine, Translational Neuroscience Center, West China Hospital of Sichuan University, Chengdu, 610041, China
| | - Peng Liang
- Departments of Anesthesiology, West China Hospital of Sichuan University, Chengdu, 610041, China
| | - Yan Liang
- Research Core Facility, West China Hospital of Sichuan University, Chengdu, 610041, China
| | - Yangyang Wang
- Laboratory of Anesthesia & Critical Care Medicine, Translational Neuroscience Center, West China Hospital of Sichuan University, Chengdu, 610041, China
| | - Yu Li
- Departments of Anesthesiology, West China Hospital of Sichuan University, Chengdu, 610041, China.
| | - Cheng Zhou
- Laboratory of Anesthesia & Critical Care Medicine, Translational Neuroscience Center, West China Hospital of Sichuan University, Chengdu, 610041, China.
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Li X, Slesinger PA. GABA B Receptors and Drug Addiction: Psychostimulants and Other Drugs of Abuse. Curr Top Behav Neurosci 2020; 52:119-155. [PMID: 33442842 DOI: 10.1007/7854_2020_187] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Metabotropic GABAB receptors (GABABRs) mediate slow inhibition and modulate synaptic plasticity throughout the brain. Dysfunction of GABABRs has been associated with psychiatric illnesses and addiction. Drugs of abuse alter GABAB receptor (GABABR) signaling in multiple brain regions, which partly contributes to the development of drug addiction. Recently, GABABR ligands and positive allosteric modulators (PAMs) have been shown to attenuate the initial rewarding effect of addictive substances, inhibit seeking and taking of these drugs, and in some cases, ameliorate drug withdrawal symptoms. The majority of the anti-addiction effects seen with GABABR modulation can be localized to ventral tegmental area (VTA) dopamine neurons, which receive complex inhibitory and excitatory inputs that are modified by drugs of abuse. Preclinical research suggests that GABABR PAMs are emerging as promising candidates for the treatment of drug addiction. Clinical studies on drug dependence have shown positive results with GABABR ligands but more are needed, and compounds with better pharmacokinetics and fewer side effects are critically needed.
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Affiliation(s)
- Xiaofan Li
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
| | - Paul A Slesinger
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
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Fujita M, Ide S, Ikeda K. Opioid and nondopamine reward circuitry and state-dependent mechanisms. Ann N Y Acad Sci 2018. [PMID: 29512887 DOI: 10.1111/nyas.13605] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
A common notion is that essentially all addictive drugs, including opioids, activate dopaminergic pathways in the brain reward system, and the inappropriate use of such drugs induces drug dependence. However, an opioid reward response is reportedly still observed in several models of dopamine depletion, including in animals that are treated with dopamine blockers, animals that are subjected to dopaminergic neuron lesions, and dopamine-deficient mice. The intracranial self-stimulation response is enhanced by stimulants but reduced by morphine. These findings suggest that dopaminergic neurotransmission may not always be required for opioid reward responses. Previous findings also indicate the possibility that dopamine-independent opioid reward may be observed in opioid-naive states but not in opioid-dependent states. Therefore, a history of opioid use should be considered when evaluating the dopamine dependency of opioid reward.
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Affiliation(s)
- Masayo Fujita
- Addictive Substance Project, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan
| | - Soichiro Ide
- Addictive Substance Project, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan
| | - Kazutaka Ikeda
- Addictive Substance Project, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan
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Effect of subchronic exposure to opioids on the effective dose of intravenous and inhalation anaesthetics. Behav Pharmacol 2018; 28:272-279. [PMID: 28059998 DOI: 10.1097/fbp.0000000000000280] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
This study aimed to investigate the effect of subchronic exposure to morphine on the 50% effective dose (EC50) (median effective concentration/EC50) values of intravenous (propofol and ketamine) and inhalation (sevoflurane) anaesthetics in mice. Eight to 12-week-old male mice were administered morphine subcutaneously for 5 days to create a subchronic morphine exposure model. Control mice were injected with saline. The EC50 for righting reflex loss and tail clip reflex of general anaesthetics on the first (D1), third (D3) and seventh days (D7), after establishing a subchronic morphine exposure model, were determined. Sevoflurane: No change in the minimum alveolar concentration for righting reflex loss or tail clip reflex loss was observed between the treated and the control values (P>0.05). Propofol: the EC50 for righting reflex loss of D7 was significantly lower than the control and D1 (P<0.05). The EC50 for tail clip reflex loss of D3 and D7 decreased compared with the control (P<0.05). Ketamine: the EC50 for righting reflex loss of D3 and D7 was significantly higher than that of the controls. The EC50 for tail clip reflex loss at D1, D3 and D7 increased compared with the control (P<0.05). In summary, after subchronic exposure to morphine, the minimum alveolar concentration value of sevoflurane did not change significantly; the EC50 of propofol decreased, whereas the EC50 of ketamine increased. The changes induced by subchronic exposure to morphine can alter the response to anaesthetics, and the effects vary with the modes of action of anaesthetics.
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Barrow TM, Byun HM, Li X, Smart C, Wang YX, Zhang Y, Baccarelli AA, Guo L. The effect of morphine upon DNA methylation in ten regions of the rat brain. Epigenetics 2018; 12:1038-1047. [PMID: 29111854 DOI: 10.1080/15592294.2017.1398296] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
Abstract
Morphine is one of the most effective analgesics in medicine. However, its use is associated with the development of tolerance and dependence. Recent studies demonstrating epigenetic changes in the brain after exposure to opiates have provided insight into mechanisms possibly underlying addiction. In this study, we sought to identify epigenetic changes in ten regions of the rat brain following acute and chronic morphine exposure. We analyzed DNA methylation of six nuclear-encoded genes implicated in brain function (Bdnf, Comt, Il1b, Il6, Nr3c1, and Tnf) and three mitochondrially-encoded genes (Mtco1, Mtco2, and Mtco3), and measured global 5-methylcytosine (5mC) and 5-hydroxymethylcytosine (5 hmC) levels. We observed differential methylation of Bdnf and Il6 in the pons, Nr3c1 in the cerebellum, and Il1b in the hippocampus in response to acute morphine exposure (all P value < 0.05). Chronic exposure was associated with differential methylation of Bdnf and Comt in the pons, Nr3c1 in the hippocampus and Il1b in the medulla oblongata (all P value < 0.05). Global 5mC levels significantly decreased in the superior colliculus following both acute and chronic morphine exposure, and increased in the hypothalamus following chronic exposure. Chronic exposure was also associated with significantly increased global 5hmC levels in the cerebral cortex, hippocampus, and hypothalamus, but significantly decreased in the midbrain. Our results demonstrate, for the first time, highly localized epigenetic changes in the rat brain following acute and chronic morphine exposure. Further work is required to elucidate the potential role of these changes in the formation of tolerance and dependence.
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Affiliation(s)
- Timothy M Barrow
- a Northern Institute for Cancer Research, Newcastle University , Newcastle upon Tyne , NE2 4HH , United Kingdom
| | - Hyang-Min Byun
- b Harvard T.H. Chan School of Public Health , Boston , Massachusetts , MA 02115 , USA
| | - Xinyan Li
- c King's Lab , Shanghai Jiao Tong University School of Pharmacy , Shanghai 200240 , China
| | - Chris Smart
- d Institute of Neuroscience , Newcastle University , Newcastle upon Tyne , NE4 5LP , United Kingdom.,e Northumberland Tyne and Wear Foundation Trust , Newcastle University , Newcastle upon Tyne , NE3 3XT , United Kingdom
| | - Yong-Xiang Wang
- c King's Lab , Shanghai Jiao Tong University School of Pharmacy , Shanghai 200240 , China
| | - Yacong Zhang
- f Department of Occupational & Environmental Health , School of Public Health, Tianjin Medical University , Tianjin 300070 , China
| | - Andrea A Baccarelli
- b Harvard T.H. Chan School of Public Health , Boston , Massachusetts , MA 02115 , USA
| | - Liqiong Guo
- f Department of Occupational & Environmental Health , School of Public Health, Tianjin Medical University , Tianjin 300070 , China
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Yang H, de Jong JW, Tak Y, Peck J, Bateup HS, Lammel S. Nucleus Accumbens Subnuclei Regulate Motivated Behavior via Direct Inhibition and Disinhibition of VTA Dopamine Subpopulations. Neuron 2018; 97:434-449.e4. [PMID: 29307710 DOI: 10.1016/j.neuron.2017.12.022] [Citation(s) in RCA: 237] [Impact Index Per Article: 39.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2017] [Revised: 11/01/2017] [Accepted: 12/14/2017] [Indexed: 11/18/2022]
Abstract
Mesolimbic dopamine (DA) neurons play a central role in motivation and reward processing. Although the activity of these mesolimbic DA neurons is controlled by afferent inputs, little is known about the circuits in which they are embedded. Using retrograde tracing, electrophysiology, optogenetics, and behavioral assays, we identify principles of afferent-specific control in the mesolimbic DA system. Neurons in the medial shell subdivision of the nucleus accumbens (NAc) exert direct inhibitory control over two separate populations of mesolimbic DA neurons by activating different GABA receptor subtypes. In contrast, NAc lateral shell neurons mainly synapse onto ventral tegmental area (VTA) GABA neurons, resulting in disinhibition of DA neurons that project back to the NAc lateral shell. Lastly, we establish a critical role for NAc subregion-specific input to the VTA underlying motivated behavior. Collectively, our results suggest a distinction in the incorporation of inhibitory inputs between different subtypes of mesolimbic DA neurons.
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Affiliation(s)
- Hongbin Yang
- Department of Molecular and Cell Biology and Helen Wills Neuroscience Institute, University of California, Berkeley, 142 Life Science Addition #3200, CA 94720, USA
| | - Johannes W de Jong
- Department of Molecular and Cell Biology and Helen Wills Neuroscience Institute, University of California, Berkeley, 142 Life Science Addition #3200, CA 94720, USA
| | - YeEun Tak
- Department of Molecular and Cell Biology and Helen Wills Neuroscience Institute, University of California, Berkeley, 142 Life Science Addition #3200, CA 94720, USA
| | - James Peck
- Department of Molecular and Cell Biology and Helen Wills Neuroscience Institute, University of California, Berkeley, 142 Life Science Addition #3200, CA 94720, USA
| | - Helen S Bateup
- Department of Molecular and Cell Biology and Helen Wills Neuroscience Institute, University of California, Berkeley, 142 Life Science Addition #3200, CA 94720, USA
| | - Stephan Lammel
- Department of Molecular and Cell Biology and Helen Wills Neuroscience Institute, University of California, Berkeley, 142 Life Science Addition #3200, CA 94720, USA.
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Sustkova-Fiserova M, Charalambous C, Havlickova T, Lapka M, Jerabek P, Puskina N, Syslova K. Alterations in Rat Accumbens Endocannabinoid and GABA Content during Fentanyl Treatment: The Role of Ghrelin. Int J Mol Sci 2017; 18:E2486. [PMID: 29165386 PMCID: PMC5713452 DOI: 10.3390/ijms18112486] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Revised: 11/07/2017] [Accepted: 11/17/2017] [Indexed: 12/20/2022] Open
Abstract
The opioid-induced rise of extracellular dopamine, endocannabinoid anandamide and γ-aminobutyric acid (GABA) concentrations triggered by opioids in the nucleus accumbens shell (NACSh) most likely participate in opioid reward. We have previously demonstrated that systemic administration of ghrelin antagonist (JMV2959) significantly decreased morphine-induced dopamine and anandamide (N-arachidonoylethanolamine, AEA) increase in the NACSh. Fentanyl is considered as a µ-receptor-selective agonist. The aim of this study was to test whether JMV2959, a growth hormone secretagogue receptor (GHS-R1A) antagonist, can influence the fentanyl-induced effects on anandamide, 2-arachidonoylglycerol (2-AG) and GABA in the NACSh and specify the involvement of GHS-R1A located in the ventral tegmental area (VTA) and nucleus accumbens (NAC). Using in vivo microdialysis in rats, we have found that pre-treatment with JMV2959 reversed dose dependently fentanyl-induced anandamide increases in the NACSh, resulting in a significant AEA decrease and intensified fentanyl-induced decreases in accumbens 2-AG levels, with both JMV2959 effects more expressed when administered into the NACSh in comparison to the VTA. JMV2959 pre-treatment significantly decreased the fentanyl-evoked accumbens GABA efflux and reduced concurrently monitored fentanyl-induced behavioural stimulation. Our current data encourage further investigation to assess if substances affecting GABA or endocannabinoid concentrations and action, such as GHS-R1A antagonists, can be used to prevent opioid-seeking behaviour.
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Affiliation(s)
- Magdalena Sustkova-Fiserova
- Department of Pharmacology, Third Faculty of Medicine, Charles University, Ruska 87, 100 34 Prague 10, Czech Republic; (C.C.); (T.H.); (M.L.); (P.J.)
| | - Chrysostomos Charalambous
- Department of Pharmacology, Third Faculty of Medicine, Charles University, Ruska 87, 100 34 Prague 10, Czech Republic; (C.C.); (T.H.); (M.L.); (P.J.)
| | - Tereza Havlickova
- Department of Pharmacology, Third Faculty of Medicine, Charles University, Ruska 87, 100 34 Prague 10, Czech Republic; (C.C.); (T.H.); (M.L.); (P.J.)
| | - Marek Lapka
- Department of Pharmacology, Third Faculty of Medicine, Charles University, Ruska 87, 100 34 Prague 10, Czech Republic; (C.C.); (T.H.); (M.L.); (P.J.)
| | - Pavel Jerabek
- Department of Pharmacology, Third Faculty of Medicine, Charles University, Ruska 87, 100 34 Prague 10, Czech Republic; (C.C.); (T.H.); (M.L.); (P.J.)
| | - Nina Puskina
- Department of Addictology, First Faculty of Medicine, Charles University, Apolinarska 4, 128 00 Prague 2, Czech Republic;
| | - Kamila Syslova
- Laboratory of Medicinal Diagnostics, Department of Organic Technology ICT, Technicka 5, 166 28 Prague 6, Czech Republic;
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Opioid-induced rewards, locomotion, and dopamine activation: A proposed model for control by mesopontine and rostromedial tegmental neurons. Neurosci Biobehav Rev 2017; 83:72-82. [PMID: 28951251 DOI: 10.1016/j.neubiorev.2017.09.022] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2017] [Revised: 08/12/2017] [Accepted: 09/21/2017] [Indexed: 01/06/2023]
Abstract
Opioids, such as morphine or heroin, increase forebrain dopamine (DA) release and locomotion, and support the acquisition of conditioned place preference (CPP) or self-administration. The most sensitive sites for these opioid effects in rodents are in the ventral tegmental area (VTA) and rostromedial tegmental nucleus (RMTg). Opioid inhibition of GABA neurons in these sites is hypothesized to lead to arousing and rewarding effects through disinhibition of VTA DA neurons. We review findings that the laterodorsal tegmental (LDTg) and pedunculopontine tegmental (PPTg) nuclei, which each contain cholinergic, GABAergic, and glutamatergic cells, are important for these effects. LDTg and/or PPTg cholinergic inputs to VTA mediate opioid-induced locomotion and DA activation via VTA M5 muscarinic receptors. LDTg and/or PPTg cholinergic inputs to RMTg also modulate opioid-induced locomotion. Lesions or inhibition of LDTg or PPTg neurons reduce morphine-induced increases in forebrain DA release, acquisition of morphine CPP or self-administration. We propose a circuit model that links VTA and RMTg GABA with LDTg and PPTg neurons critical for DA-dependent opioid effects in drug-naïve rodents.
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Ebihara K, Fujiwara H, Awale S, Dibwe DF, Araki R, Yabe T, Matsumoto K. Decrease in endogenous brain allopregnanolone induces autism spectrum disorder (ASD)-like behavior in mice: A novel animal model of ASD. Behav Brain Res 2017; 334:6-15. [PMID: 28743598 DOI: 10.1016/j.bbr.2017.07.019] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Revised: 07/11/2017] [Accepted: 07/17/2017] [Indexed: 01/11/2023]
Abstract
Autism spectrum disorder (ASD) is a neurodevelopmental disorder with core symptoms of social impairments and restrictive repetitive behaviors. Recent evidence has implicated a dysfunction in the GABAergic system in the pathophysiology of ASD. We investigated the role of endogenous allopregnanolone (ALLO), a neurosteroidal positive allosteric modulator of GABAA receptors, in the regulation of ASD-like behavior in male mice using SKF105111 (SKF), an inhibitor of type I and type II 5α-reductase, a rate-limiting enzyme of ALLO biosynthesis. SKF impaired sociability-related performance, as analyzed by three different tests; i.e., the 3-chamber test and social interaction in the open field and resident-intruder tests, without affecting olfactory function elucidated by the buried food test. SKF also induced repetitive grooming behavior without affecting anxiety-like behavior. SKF had no effect on short-term spatial working memory or long-term fear memory, but enhanced latent learning ability in male mice. SKF-induced ASD-like behavior in male mice was abolished by the systemic administration of ALLO (1mg/kg, i.p.) and methylphenidate (MPH: 2.5mg/kg, i.p.), a dopamine transporter inhibitor. The effects of SKF on brain ALLO contents in male mice were reversed by ALLO, but not MPH. On the other hand, SKF failed to induce ASD-like behavior or a decline in brain ALLO contents in female mice. These results suggest that ALLO regulates episodes of ASD-like behavior by positively modulating the function of GABAA receptors linked to the dopaminergic system. Moreover, a sex-dependently induced decrease in brain ALLO contents may provide an animal model to study the main features of ASD.
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Affiliation(s)
- Ken Ebihara
- Institute of Natural Medicine, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan
| | - Hironori Fujiwara
- Institute of Natural Medicine, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan.
| | - Suresh Awale
- Institute of Natural Medicine, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan
| | - Dya Fita Dibwe
- Institute of Natural Medicine, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan
| | - Ryota Araki
- Laboratory of Functional Biomolecules and Chemical Pharmacology, Faculty of Pharmaceutical Sciences, Setsunan University, 45-1 Nagaotoge-cho, Hirakata City, Osaka 573-0101, Japan
| | - Takeshi Yabe
- Laboratory of Functional Biomolecules and Chemical Pharmacology, Faculty of Pharmaceutical Sciences, Setsunan University, 45-1 Nagaotoge-cho, Hirakata City, Osaka 573-0101, Japan
| | - Kinzo Matsumoto
- Institute of Natural Medicine, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan.
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Leung LS, Jin M, Chu L, Ma J. Positive allosteric modulator of GABAB receptor alters behavioral effects but not afterdischarge progression induced by partial hippocampal kindling. Neuropharmacology 2016; 110:154-164. [DOI: 10.1016/j.neuropharm.2016.07.017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Revised: 06/17/2016] [Accepted: 07/15/2016] [Indexed: 12/22/2022]
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17
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Cahill CM, Walwyn W, Taylor AMW, Pradhan AAA, Evans CJ. Allostatic Mechanisms of Opioid Tolerance Beyond Desensitization and Downregulation. Trends Pharmacol Sci 2016; 37:963-976. [PMID: 27670390 DOI: 10.1016/j.tips.2016.08.002] [Citation(s) in RCA: 77] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Revised: 08/18/2016] [Accepted: 08/19/2016] [Indexed: 12/20/2022]
Abstract
Mechanisms of opioid tolerance have focused on adaptive modifications within cells containing opioid receptors, defined here as cellular allostasis, emphasizing regulation of the opioid receptor signalosome. We review additional regulatory and opponent processes involved in behavioral tolerance, and include mechanistic differences both between agonists (agonist bias), and between μ- and δ-opioid receptors. In a process we will refer to as pass-forward allostasis, cells modified directly by opioid drugs impute allostatic changes to downstream circuitry. Because of the broad distribution of opioid systems, every brain cell may be touched by pass-forward allostasis in the opioid-dependent/tolerant state. We will implicate neurons and microglia as interactive contributors to the cumulative allostatic processes creating analgesic and hedonic tolerance to opioid drugs.
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Affiliation(s)
- Catherine M Cahill
- Department of Anesthesiology and Perioperative Care, University of California, Irvine, 837 Health Sciences Road, Irvine, CA 92697, USA
| | - Wendy Walwyn
- Hatos Center for Neuropharmacology, Department of Psychiatry and Biobehavioral Sciences, Semel Institute for Neuroscience and Human Behavior, University of California Los Angeles, 675 Charles E. Young Drive South, Los Angeles, CA 90095, USA
| | - Anna M W Taylor
- Hatos Center for Neuropharmacology, Department of Psychiatry and Biobehavioral Sciences, Semel Institute for Neuroscience and Human Behavior, University of California Los Angeles, 675 Charles E. Young Drive South, Los Angeles, CA 90095, USA
| | - Amynah A A Pradhan
- Department of Psychiatry, University of Illinois at Chicago, 1601 West Taylor Street, Chicago, IL 60612, USA
| | - Christopher J Evans
- Hatos Center for Neuropharmacology, Department of Psychiatry and Biobehavioral Sciences, Semel Institute for Neuroscience and Human Behavior, University of California Los Angeles, 675 Charles E. Young Drive South, Los Angeles, CA 90095, USA.
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18
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Neonatal finasteride administration decreases dopamine release in nucleus accumbens after alcohol and food presentation in adult male rats. Behav Brain Res 2016; 309:44-50. [PMID: 27139934 DOI: 10.1016/j.bbr.2016.04.047] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Revised: 04/26/2016] [Accepted: 04/28/2016] [Indexed: 12/13/2022]
Abstract
Endogenous levels of the neurosteroid (NS) allopregnanolone (AlloP) during neonatal stages are crucial for the correct development of the central nervous system (CNS). In a recent work we reported that the neonatal administration of AlloP or finasteride (Finas), an inhibitor of the enzyme 5α-reductase needed for AlloP synthesis, altered the voluntary consumption of ethanol and the ventrostriatal dopamine (DA) levels in adulthood, suggesting that neonatal NS manipulations can increase alcohol abuse vulnerability in adulthood. Moreover, other authors have associated neonatal NS alterations with diverse dopaminergic (DAergic) alterations. Thus, the aim of the present work is to analyse if manipulations of neonatal AlloP alter the DAergic response in the nucleus accumbens (NAcc) during alcohol intake in rats. We administered AlloP or Finas from postnatal day (PND) 5 to PND9. At PND98, we measured alcohol consumption using a two-bottle free-choice model (ethanol 10% (v/v)+glucose 3% (w/v), and glucose 3% (w/v)) for 12 days. On the last day of consumption, we measured the DA and 3,4-dihydroxyphenylacetic acid (DOPAC) release in NAcc in response to ethanol intake. The samples were obtained by means of in vivo microdialysis in freely moving rats, and DA and DOPAC levels were determined by means of high-performance liquid chromatography analysis (HPLC). The results revealed that neonatal Finas increased ethanol consumption in some days of the consumption phase, and decreased the DA release in the NAcc in response to solutions (ethanol+glucose) and food presentation. Taken together, these results suggest that neonatal NS alterations can affect alcohol rewarding properties.
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19
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Guan YZ, Ye JH. Glycine blocks long-term potentiation of GABAergic synapses in the ventral tegmental area. Neuroscience 2016; 318:134-42. [PMID: 26806277 DOI: 10.1016/j.neuroscience.2016.01.017] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Revised: 01/07/2016] [Accepted: 01/08/2016] [Indexed: 10/22/2022]
Abstract
The mesocorticolimbic dopamine system, originating in the ventral tegmental area (VTA) is normally constrained by GABA-mediated synaptic inhibition. Accumulating evidence indicates that long-term potentiation of GABAergic synapses (LTPGABA) in VTA dopamine neurons plays an important role in the actions of drugs of abuse, including ethanol. We previously showed that a single infusion of glycine into the VTA of rats strongly reduces ethanol intake for 24h. In the current study, we examined the effect of glycine on the electrophysiological activities of putative dopamine VTA neurons in midbrain slices from ethanol-naïve rats. We report here that a 15-min exposure to 10 μM glycine prevented trains of high-frequency stimulation (HFS) from producing LTPGABA, which was rescued by the glycine receptor (GlyR) antagonist strychnine. Glycine also concentration-dependently decreased the frequency of spontaneous excitatory postsynaptic currents (sEPSCs). By contrast, glycine pretreatment did not prevent potentiation of inhibitory postsynaptic currents (IPSCs) during a continuous exposure to the nitric oxide (NO) donor, SNAP (S-nitroso-N-acetylpenicillamine), or a brief exposure to 10 μM glycine and 10 μM NMDA (N-methyl-D-aspartate), an agonist of NMDA-type glutamate receptors. Thus, the blockade of LTPGABA by glycine is probably resulted from suppressing glutamate release by activating the GlyRs on the glutamatergic terminals. This effect of glycine may contribute to the reduction in ethanol intake induced by intra-VTA glycine observed in vivo.
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Affiliation(s)
- Y-Z Guan
- Department of Anesthesiology, Pharmacology and Physiology, Rutgers, The State University of New Jersey, New Jersey Medical School, Newark, NJ, USA; Department of Physiology, Mudanjiang Medical University, Mudanjiang, China.
| | - J-H Ye
- Department of Anesthesiology, Pharmacology and Physiology, Rutgers, The State University of New Jersey, New Jersey Medical School, Newark, NJ, USA.
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20
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Abstract
UNLABELLED Treating pain is one of the most difficult challenges in medicine and a key facet of disease management. The isolation of morphine by Friedrich Sertürner in 1804 added an essential pharmacological tool in the treatment of pain and spawned the discovery of a new class of drugs known collectively as opioid analgesics. Revered for their potent pain-relieving effects, even Morpheus the god of dreams could not have dreamt that his opium tincture would be both a gift and a burden to humankind. To date, morphine and other opioids remain essential analgesics for alleviating pain. However, their use is plagued by major side effects, such as analgesic tolerance (diminished pain-relieving effects), hyperalgesia (increased pain sensitivity), and drug dependence. This review highlights recent advances in understanding the key causes of these adverse effects and explores the effect of chronic pain on opioid reward. SIGNIFICANCE STATEMENT Chronic pain is pervasive and afflicts >100 million Americans. Treating pain in these individuals is notoriously difficult and often requires opioids, one of the most powerful and effective classes of drugs used for controlling pain. However, their use is plagued by major side effects, such as a loss of pain-relieving effects (analgesic tolerance), paradoxical pain (hyperalgesia), and addiction. Despite the potential side effects, opioids remain the pharmacological cornerstone of modern pain therapy. This review highlights recent breakthroughs in understanding the key causes of these adverse effects and explores the cellular control of opioid systems in reward and aversion. The findings will challenge traditional views of the good, the bad, and the ugly of opioids.
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21
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Blacktop JM, Vranjkovic O, Mayer M, Van Hoof M, Baker DA, Mantsch JR. Antagonism of GABA-B but not GABA-A receptors in the VTA prevents stress- and intra-VTA CRF-induced reinstatement of extinguished cocaine seeking in rats. Neuropharmacology 2015; 102:197-206. [PMID: 26596556 DOI: 10.1016/j.neuropharm.2015.11.013] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Revised: 10/23/2015] [Accepted: 11/12/2015] [Indexed: 12/25/2022]
Abstract
Stress-induced reinstatement of cocaine seeking requires corticotropin releasing factor (CRF) actions in the ventral tegmental area (VTA). However the mechanisms through which CRF regulates VTA function to promote cocaine use are not fully understood. Here we examined the role of GABAergic neurotransmission in the VTA mediated by GABA-A or GABA-B receptors in the reinstatement of extinguished cocaine seeking by a stressor, uncontrollable intermittent footshock, or bilateral intra-VTA administration of CRF. Rats underwent repeated daily cocaine self-administration (1.0 mg/kg/ing; 14 × 6 h/day) and extinction and were tested for reinstatement in response to footshock (0.5 mA, 0.5" duration, average every 40 s; range 10-70 s) or intra-VTA CRF delivery (500 ng/side) following intra-VTA pretreatment with the GABA-A antagonist, bicuculline, the GABA-B antagonist, 2-hydroxysaclofen or vehicle. Intra-VTA bicuculline (1, 10 or 20 ng/side) failed to block footshock- or CRF-induced cocaine seeking at either dose tested. By contrast, 2-hydroxysaclofen (0.2 or 2 μg/side) prevented reinstatement by both footshock and intra-VTA CRF at a concentration that failed to attenuate food-reinforced lever pressing (45 mg sucrose-sweetened pellets; FR4 schedule) in a separate group of rats. These data suggest that GABA-B receptor-dependent CRF actions in the VTA mediate stress-induced cocaine seeking and that GABA-B receptor antagonists may have utility for the management of stress-induced relapse in cocaine addicts.
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Affiliation(s)
- Jordan M Blacktop
- Department of Biomedical Sciences, Marquette University, Milwaukee, WI 53233, USA
| | - Oliver Vranjkovic
- Department of Biomedical Sciences, Marquette University, Milwaukee, WI 53233, USA
| | - Matthieu Mayer
- Department of Biomedical Sciences, Marquette University, Milwaukee, WI 53233, USA
| | - Matthew Van Hoof
- Department of Biomedical Sciences, Marquette University, Milwaukee, WI 53233, USA
| | - David A Baker
- Department of Biomedical Sciences, Marquette University, Milwaukee, WI 53233, USA
| | - John R Mantsch
- Department of Biomedical Sciences, Marquette University, Milwaukee, WI 53233, USA.
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Rosen LG, Sun N, Rushlow W, Laviolette SR. Molecular and neuronal plasticity mechanisms in the amygdala-prefrontal cortical circuit: implications for opiate addiction memory formation. Front Neurosci 2015; 9:399. [PMID: 26594137 PMCID: PMC4633496 DOI: 10.3389/fnins.2015.00399] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Accepted: 10/09/2015] [Indexed: 01/23/2023] Open
Abstract
The persistence of associative memories linked to the rewarding properties of drugs of abuse is a core underlying feature of the addiction process. Opiate class drugs in particular, possess potent euphorigenic effects which, when linked to environmental cues, can produce drug-related "trigger" memories that may persist for lengthy periods of time, even during abstinence, in both humans, and other animals. Furthermore, the transitional switch from the drug-naïve, non-dependent state to states of dependence and withdrawal, represents a critical boundary between distinct neuronal and molecular substrates associated with opiate-reward memory formation. Identifying the functional molecular and neuronal mechanisms related to the acquisition, consolidation, recall, and extinction phases of opiate-related reward memories is critical for understanding, and potentially reversing, addiction-related memory plasticity characteristic of compulsive drug-seeking behaviors. The mammalian prefrontal cortex (PFC) and basolateral nucleus of the amygdala (BLA) share important functional and anatomical connections that are involved importantly in the processing of associative memories linked to drug reward. In addition, both regions share interconnections with the mesolimbic pathway's ventral tegmental area (VTA) and nucleus accumbens (NAc) and can modulate dopamine (DA) transmission and neuronal activity associated with drug-related DAergic signaling dynamics. In this review, we will summarize research from both human and animal modeling studies highlighting the importance of neuronal and molecular plasticity mechanisms within this circuitry during critical phases of opiate addiction-related learning and memory processing. Specifically, we will focus on two molecular signaling pathways known to be involved in both drug-related neuroadaptations and in memory-related plasticity mechanisms; the extracellular-signal-regulated kinase system (ERK) and the Ca(2+)/calmodulin-dependent protein kinases (CaMK). Evidence will be reviewed that points to the importance of critical molecular memory switches within the mammalian brain that might mediate the neuropathological adaptations resulting from chronic opiate exposure, dependence, and withdrawal.
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Affiliation(s)
- Laura G Rosen
- Addiction Research Group, Schulich School of Medicine and Dentistry, University of Western Ontario London, ON, Canada ; Department of Anatomy and Cell Biology, Schulich School of Medicine and Dentistry, University of Western Ontario London, ON, Canada
| | - Ninglei Sun
- Addiction Research Group, Schulich School of Medicine and Dentistry, University of Western Ontario London, ON, Canada ; Department of Anatomy and Cell Biology, Schulich School of Medicine and Dentistry, University of Western Ontario London, ON, Canada
| | - Walter Rushlow
- Addiction Research Group, Schulich School of Medicine and Dentistry, University of Western Ontario London, ON, Canada ; Department of Anatomy and Cell Biology, Schulich School of Medicine and Dentistry, University of Western Ontario London, ON, Canada ; Department of Psychiatry, Schulich School of Medicine and Dentistry, University of Western Ontario London, ON, Canada
| | - Steven R Laviolette
- Addiction Research Group, Schulich School of Medicine and Dentistry, University of Western Ontario London, ON, Canada ; Department of Anatomy and Cell Biology, Schulich School of Medicine and Dentistry, University of Western Ontario London, ON, Canada ; Department of Psychiatry, Schulich School of Medicine and Dentistry, University of Western Ontario London, ON, Canada
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Authement M, Kodangattil J, Gouty S, Rusnak M, Symes A, Cox B, Nugent F. Histone Deacetylase Inhibition Rescues Maternal Deprivation-Induced GABAergic Metaplasticity through Restoration of AKAP Signaling. Neuron 2015; 86:1240-52. [DOI: 10.1016/j.neuron.2015.05.024] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Revised: 04/23/2015] [Accepted: 05/07/2015] [Indexed: 12/27/2022]
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Leung BK, Balleine BW. Ventral pallidal projections to mediodorsal thalamus and ventral tegmental area play distinct roles in outcome-specific Pavlovian-instrumental transfer. J Neurosci 2015; 35:4953-64. [PMID: 25810525 PMCID: PMC6705367 DOI: 10.1523/jneurosci.4837-14.2015] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Revised: 02/01/2015] [Accepted: 02/17/2015] [Indexed: 11/21/2022] Open
Abstract
Outcome-specific Pavlovian-instrumental transfer (PIT) demonstrates the way that reward-related cues influence choice between instrumental actions. The nucleus accumbens shell (NAc-S) contributes critically to this effect, particularly through its output to the rostral medial ventral pallidum (VP-m). Using rats, we investigated in two experiments the role in the PIT effect of the two major outputs of this VP-m region innervated by the NAc-S, the mediodorsal thalamus (MD) and the ventral tegmental area (VTA). First, two retrograde tracers were injected into the MD and VTA to compare the neuronal activity of the two populations of projection neurons in the VP-m during PIT relative to controls. Second, the functional role of the connection between the VP-m and the MD or VTA was assessed using asymmetrical pharmacological manipulations before a PIT test. It was found that, whereas neurons in the VP-m projecting to the MD showed significantly more neuronal activation during PIT than those projecting to the VTA, neuronal activation of these latter neurons correlated with the size of the PIT effect. Disconnection of the two pathways during PIT also revealed different deficits in performance: disrupting the VP-m to MD pathway removed the response biasing effects of reward-related cues, whereas disrupting the VP-m to VTA pathway preserved the response bias but altered the overall rate of responding. The current results therefore suggest that the VP-m exerts distinct effects on the VTA and MD and that these latter structures mediate the motivational and cognitive components of specific PIT, respectively.
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Affiliation(s)
- Beatrice K Leung
- Brain and Mind Research Institute, University of Sydney, Sydney, NSW 2050, Australia
| | - Bernard W Balleine
- Brain and Mind Research Institute, University of Sydney, Sydney, NSW 2050, Australia
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NMDA receptor blockade in the prelimbic cortex activates the mesolimbic system and dopamine-dependent opiate reward signaling. Psychopharmacology (Berl) 2014; 231:4669-79. [PMID: 24871699 DOI: 10.1007/s00213-014-3616-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/07/2014] [Accepted: 04/29/2014] [Indexed: 10/25/2022]
Abstract
RATIONALE N-Methyl-D-aspartate (NMDA) receptors in the medial prefrontal cortex (mPFC) are involved in opiate reward processing and modulate sub-cortical dopamine (DA) activity. NMDA receptor blockade in the prelimbic (PLC) division of the mPFC strongly potentiates the rewarding behavioural properties of normally sub-reward threshold doses of opiates. However, the possible functional interactions between cortical NMDA and sub-cortical DAergic motivational neural pathways underlying these effects are not understood. OBJECTIVE This study examines how NMDA receptor modulation in the PLC influences opiate reward processing via interactions with sub-cortical DAergic transmission. We further examined whether direct intra-PLC NMDA receptor modulation may activate DA-dependent opiate reward signaling via interactions with the ventral tegmental area (VTA). METHODS Using an unbiased place conditioning procedure (CPP) in rats, we performed bilateral intra-PLC microinfusions of the competitive NMDA receptor antagonist, (2R)-amino-5-phosphonovaleric acid (AP-5), prior to behavioural morphine place conditioning and challenged the rewarding effects of morphine with DA receptor blockade. We next examined the effects of intra-PLC NMDA receptor blockade on the spontaneous activity patterns of presumptive VTA DA or GABAergic neurons, using single-unit, extracellular in vivo neuronal recordings. RESULTS We show that intra-PLC NMDA receptor blockade strongly activates sub-cortical DA neurons within the VTA while inhibiting presumptive non-DA GABAergic neurons. Behaviourally, NMDA receptor blockade activates a DA-dependent opiate reward system, as pharmacological blockade of DA transmission blocked morphine reward only in the presence of intra-PLC NMDA receptor antagonism. CONCLUSIONS These findings demonstrate a cortical NMDA-mediated mechanism controlling mesolimbic DAergic modulation of opiate reward processing.
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Vashchinkina E, Panhelainen A, Aitta-Aho T, Korpi ER. GABAA receptor drugs and neuronal plasticity in reward and aversion: focus on the ventral tegmental area. Front Pharmacol 2014; 5:256. [PMID: 25505414 PMCID: PMC4243505 DOI: 10.3389/fphar.2014.00256] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2014] [Accepted: 11/03/2014] [Indexed: 12/13/2022] Open
Abstract
GABAA receptors are the main fast inhibitory neurotransmitter receptors in the mammalian brain, and targets for many clinically important drugs widely used in the treatment of anxiety disorders, insomnia and in anesthesia. Nonetheless, there are significant risks associated with the long-term use of these drugs particularly related to development of tolerance and addiction. Addictive mechanisms of GABAA receptor drugs are poorly known, but recent findings suggest that those drugs may induce aberrant neuroadaptations in the brain reward circuitry. Recently, benzodiazepines, acting on synaptic GABAA receptors, and modulators of extrasynaptic GABAA receptors (THIP and neurosteroids) have been found to induce plasticity in the ventral tegmental area (VTA) dopamine neurons and their main target projections. Furthermore, depending whether synaptic or extrasynaptic GABAA receptor populations are activated, the behavioral outcome of repeated administration seems to correlate with rewarding or aversive behavioral responses, respectively. The VTA dopamine neurons project to forebrain centers such as the nucleus accumbens and medial prefrontal cortex, and receive afferent projections from these brain regions and especially from the extended amygdala and lateral habenula, forming the major part of the reward and aversion circuitry. Both synaptic and extrasynaptic GABAA drugs inhibit the VTA GABAergic interneurons, thus activating the VTA DA neurons by disinhibition and this way inducing glutamatergic synaptic plasticity. However, the GABAA drugs failed to alter synaptic spine numbers as studied from Golgi-Cox-stained VTA dendrites. Since the GABAergic drugs are known to depress the brain metabolism and gene expression, their likely way of inducing neuroplasticity in mature neurons is by disinhibiting the principal neurons, which remains to be rigorously tested for a number of clinically important anxiolytics, sedatives and anesthetics in different parts of the circuitry.
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Affiliation(s)
- Elena Vashchinkina
- Department of Pharmacology, Institute of Biomedicine, University of Helsinki Helsinki, Finland
| | - Anne Panhelainen
- Institute of Biotechnology, University of Helsinki Helsinki, Finland
| | - Teemu Aitta-Aho
- Department of Pharmacology, Institute of Biomedicine, University of Helsinki Helsinki, Finland ; Department of Pharmacology, University of Cambridge Cambridge, UK
| | - Esa R Korpi
- Department of Pharmacology, Institute of Biomedicine, University of Helsinki Helsinki, Finland ; Department of Pharmacology, Yong Loo Lin School of Medicine, National University Health System, Neurobiology and Ageing Programme, Life Sciences Institute, National University of Singapore, and SINAPSE, Singapore Institute for Neurotechnology Singapore, Singapore
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Draycott B, Loureiro M, Ahmad T, Tan H, Zunder J, Laviolette SR. Cannabinoid transmission in the prefrontal cortex bi-phasically controls emotional memory formation via functional interactions with the ventral tegmental area. J Neurosci 2014; 34:13096-109. [PMID: 25253856 PMCID: PMC6608340 DOI: 10.1523/jneurosci.1297-14.2014] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Revised: 08/15/2014] [Accepted: 08/15/2014] [Indexed: 01/01/2023] Open
Abstract
Disturbances in cortical cannabinoid CB1 receptor signaling are well established correlates of various neuropsychiatric disorders, including depression and schizophrenia. Importantly, the ability of cannabinoid transmission to modulate emotional processing is functionally linked to interactions with subcortical DA systems. While considerable evidence demonstrates that CB1 receptor-mediated modulation of emotional processing and related behaviors follows a biphasic functional curve, little is known regarding how CB1 signaling within cortical networks may interact with subcortical DAergic systems involved in emotional behavior regulation. Using a combination of in vivo electrophysiological recordings and behavioral pharmacology in rats, we investigated the relationship between mPFC cannabinoid transmission, fear memory formation, and subcortical DA neuron activity patterns. We report that direct intra-mPFC CB1 activation biphasically modulates spontaneous, subcortical VTA DA neuron activity in a dose-dependent fashion; while lower doses of a CB1 receptor agonist, WIN 55,212-2, significantly increased spontaneous firing and bursting rates of VTA DA neurons, higher doses strongly inhibited spontaneous DA neuron activity. Remarkably, this same dose-related functional difference was observed with the regulation of fear-related emotional memory formation. Thus, lower levels of CB1 activation potentiated the emotional salience of normally subthreshold fear memory, whereas higher levels completely blocked fear memory acquisition. Furthermore, while the potentiation of subthreshold fear memory salience was blocked by DA receptor antagonism, CB1-mediated blunting of suprathreshold fear memory was rescued by intra-VTA administration of a GABAB receptor antagonist, demonstrating that reversal of GABAergic inhibitory mechanisms in the VTA can reverse the inhibitory influence of intra-PFC CB1 transmission on mesolimbic DA activity.
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Affiliation(s)
| | - Michael Loureiro
- Addiction Research Group, Departments of Anatomy and Cell Biology
| | - Tasha Ahmad
- Addiction Research Group, Departments of Anatomy and Cell Biology
| | - Huibing Tan
- Addiction Research Group, Departments of Anatomy and Cell Biology
| | - Jordan Zunder
- Addiction Research Group, Departments of Anatomy and Cell Biology
| | - Steven R Laviolette
- Addiction Research Group, Departments of Anatomy and Cell Biology, Department of Psychiatry, and Department of Psychology, Schulich School of Medicine and Dentistry. University of Western Ontario, London, Ontario, Canada N6A 5C1
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Tsutsui K, Haraguchi S. Breakthrough in neuroendocrinology by discovering novel neuropeptides and neurosteroids: 2. Discovery of neurosteroids and pineal neurosteroids. Gen Comp Endocrinol 2014; 205:11-22. [PMID: 24704561 DOI: 10.1016/j.ygcen.2014.03.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Bargmann-Scharrer's discovery of "neurosecretion" in the first half of the 20th century has since matured into the scientific discipline of neuroendocrinology. Identification of novel neurohormones, such as neuropeptides and neurosteroids, is essential for the progress of neuroendocrinology. Our studies over the past two decades have significantly broadened the horizons of this field of research by identifying novel neuropeptides and neurosteroids in vertebrates that have opened new lines of scientific investigation in neuroendocrinology. We have established de novo synthesis and functions of neurosteroids in the brain of various vertebrates. Recently, we discovered 7α-hydroxypregnenolone (7α-OH PREG), a novel bioactive neurosteroid that acts as a key regulator for inducing locomotor behavior by means of the dopaminergic system. We further discovered that the pineal gland, an endocrine organ located close to the brain, is an important site of production of neurosteroids de novo from cholesterol (CHOL). The pineal gland secretes 7α-OH PREG and 3α,5α-tetrahydroprogesterone (3α,5α-THP; allopregnanolone) that are involved in locomotor rhythms and neuronal survival, respectively. Subsequently, we have demonstrated their mode of action and functional significance. This review summarizes the discovery of these novel neurosteroids and its contribution to the progress of neuroendocrinology.
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Affiliation(s)
- Kazuyoshi Tsutsui
- Laboratory of Integrative Brain Sciences, Department of Biology and Center for Medical Life Science, Waseda University, Tokyo 162-8480, Japan.
| | - Shogo Haraguchi
- Laboratory of Integrative Brain Sciences, Department of Biology and Center for Medical Life Science, Waseda University, Tokyo 162-8480, Japan
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Mikulecká A, Subrt M, Pařízková M, Mareš P, Kubová H. Consequences of early postnatal benzodiazepines exposure in rats. II. Social behavior. Front Behav Neurosci 2014; 8:169. [PMID: 24982619 PMCID: PMC4055859 DOI: 10.3389/fnbeh.2014.00169] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2013] [Accepted: 04/19/2014] [Indexed: 12/24/2022] Open
Abstract
Social behavior represents an integral part of behavioral repertoire of rats particularly sensitive to pharmacological and environmental influences. The aim of the present study was to investigate whether early postnatal clonazepam (CZP) exposure can induce age-dependent changes related to expression of social behavior. The drug was administered from postnatal day (P) 7 until P11 at daily doses of 0.1, 0.5 and 1.0 mg/kg i.p. We designed three experiments to assess whether exposure to CZP affects social behavior in respect to the age of rats and the test circumstances, specifically their familiarity with test conditions during adolescence (P32), social behavior in juveniles and adolescents (P18–P42) and social behavior in a resident-intruder paradigm. The frequency and duration of a various patterns of social behavior related to play and social investigation not related to play were evaluated. The results showed that CZP postnatal exposure decreased social play behavior regardless of age and familiarity or unfamiliarity of experimental environment but did not affect the social investigation per se. When rats were confronted with an intruder in their home cages intense wrestling and inhibition of genital investigation were found. In conclusion, these findings show that short-term CZP postnatal exposure inhibits social play behavior and alters specific patterns of social behavior in an age and environment related manner.
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Affiliation(s)
- Anna Mikulecká
- Institute of Physiology, Academy of Sciences of the Czech Republic Prague, Czech Republic
| | - Martin Subrt
- Institute of Physiology, Academy of Sciences of the Czech Republic Prague, Czech Republic
| | - Martina Pařízková
- Institute of Physiology, Academy of Sciences of the Czech Republic Prague, Czech Republic
| | - Pavel Mareš
- Institute of Physiology, Academy of Sciences of the Czech Republic Prague, Czech Republic
| | - Hana Kubová
- Institute of Physiology, Academy of Sciences of the Czech Republic Prague, Czech Republic
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Tobiansky DJ, Roma PG, Hattori T, Will RG, Nutsch VL, Dominguez JM. The medial preoptic area modulates cocaine-induced activity in female rats. Behav Neurosci 2013; 127:293-302. [PMID: 23565937 DOI: 10.1037/a0031949] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Drugs of abuse exert their effects by exploiting natural neurobiological reward mechanisms, especially the mesolimbic dopamine (DA) system. However, the mesolimbic system does not operate in isolation, and input from other reward-relevant structures may play a role in cocaine's rewarding effects. The medial preoptic area (mPOA) of the hypothalamus is involved in the regulation of two essential and naturally rewarding behaviors: sexual and maternal behaviors. It also makes strong neuroanatomical connections with areas of the mesolimbic system, particularly the ventral tegmental area (VTA). As such, the mPOA is a logical candidate for a neuroanatomical locus modulating activity in the mesolimbic system and emergent behavioral expressions of drug reward, yet the role of this structure is largely unexplored. Here, using a female rat model, we show that the mPOA innervates the VTA in a region-specific manner, that lesions of the mPOA augment cocaine-induced Fos expression in the nucleus accumbens (NAc) and cocaine-induced conditioned place preference. We also show that approximately 68% of mPOA-VTA efferents release γ-aminobutyric acid (GABA), over 75% are sensitive to DA as evidenced by colocalization with DA receptors, and nearly 60% of these contain both DA receptors and GABA, which suggests a novel key role for the mPOA in the inhibition of the mesolimbic DA circuit. Combined, these results reveal the mPOA as a critical modulating structure in cocaine-induced mesolimbic activity and behavioral manifestation of reward, at least in part, via GABAergic output that is sensitive to DA input.
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Affiliation(s)
- Daniel J Tobiansky
- Department of Psychology, University of Texas at Austin, Austin, TX 78712, USA
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Tsutsui K, Haraguchi S, Fukada Y, Vaudry H. Brain and pineal 7α-hydroxypregnenolone stimulating locomotor activity: identification, mode of action and regulation of biosynthesis. Front Neuroendocrinol 2013; 34:179-89. [PMID: 23685042 DOI: 10.1016/j.yfrne.2013.05.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/23/2013] [Revised: 05/01/2013] [Accepted: 05/08/2013] [Indexed: 11/30/2022]
Abstract
Biologically active steroids synthesized in the central and peripheral nervous systems are termed neurosteroids. However, the biosynthetic pathways leading to the formation of neurosteroids are still incompletely elucidated. 7α-Hydroxypregnenolone, a novel bioactive neurosteroid stimulating locomotor activity, has been recently identified in the brain of newts and quail. Subsequently, the mode of action and regulation of biosynthesis of 7α-hydroxypregnenolone have been determined. Moreover, recent studies on birds have demonstrated that the pineal gland, an endocrine organ located close to the brain, is an important site of production of neurosteroids de novo from cholesterol. 7α-Hydroxypregnenolone is a major pineal neurosteroid that stimulates locomotor activity in juvenile chickens, connecting light-induced gene expression with locomotion. This review summarizes the advances in our understanding of the identification, mode of action and regulation of biosynthesis of brain and pineal 7α-hydroxypregnenolone, a potent stimulator of locomotor activity.
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Affiliation(s)
- Kazuyoshi Tsutsui
- Laboratory of Integrative Brain Sciences, Department of Biology and Center for Medical Life Science, Waseda University, Tokyo 162-8480, Japan.
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Schlussman SD, Buonora M, Brownstein AJ, Zhang Y, Ho A, Kreek MJ. Regional mRNA expression of GABAergic receptor subunits in brains of C57BL/6J and 129P3/J mice: strain and heroin effects. Brain Res 2013; 1523:49-58. [PMID: 23732339 DOI: 10.1016/j.brainres.2013.05.040] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Revised: 05/07/2013] [Accepted: 05/24/2013] [Indexed: 12/19/2022]
Abstract
C57BL/6J and 129 substrains of mice are known to differ in their basal levels of anxiety and behavioral response to drugs of abuse. We have previously shown strain differences in heroin-induced conditioned place preference (CPP) between C57BL/6J (C57) and 129P3/J (129) mice, and in the regional expression of several receptor and peptide mRNAs. In this study, we examined the contribution of the GABAergic system in the cortex, nucleus accumbens (NAc), caudate putamen (CPu) and the region containing the substantia nigra and ventral tegmental area (SN/VTA) to heroin reward by measuring mRNA levels of 7 of the most commonly expressed GABA-A receptor subunits, and both GABA-B receptor subunits, in these same mice following saline (control) or heroin administration in a CPP design. Using real-time PCR, we studied the effects of strain and heroin administration on GABA-A α1, α2, α3, β2, and γ2 subunits, which typically constitute synaptic GABA-A receptors, GABA-A α4 and δ subunits, which typically constitute extrasynaptic GABA-A receptors, and GABA-B R1 and R2 subunits. In saline-treated animals, we found an experiment-wise significant strain difference in GABA-Aα2 mRNA expression in the SN/VTA. Point-wise significant strain differences were also observed in GABA-Aα2, GABA-Aα3, and GABA-Aα4 mRNA expression in the NAc, as well as GABA-BR2 mRNA expression in the NAc and CPu, and GABA-BR1 mRNA expression in the cortex. For all differences, 129 mice had higher mRNA expression compared to C57 animals, with the exception of GABA-BR1 mRNA in the cortex where we observed lower levels in 129 mice. Therefore, it may be possible that known behavioral differences between these two strains are, in part, due to differences in their GABAergic systems. While we did not find heroin dose-related changes in mRNA expression levels in C57 mice, we did observe dose-related differences in 129 mice. These results may relate to our earlier behavioral finding that 129 mice are hyporesponsive to the rewarding effects of heroin.
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Affiliation(s)
- S D Schlussman
- The Laboratory of the Biology of Addictive Diseases, The Rockefeller University, 1230 York Ave, New York, NY 10065, USA
| | - M Buonora
- The Laboratory of the Biology of Addictive Diseases, The Rockefeller University, 1230 York Ave, New York, NY 10065, USA
| | - A J Brownstein
- The Laboratory of the Biology of Addictive Diseases, The Rockefeller University, 1230 York Ave, New York, NY 10065, USA
| | - Y Zhang
- The Laboratory of the Biology of Addictive Diseases, The Rockefeller University, 1230 York Ave, New York, NY 10065, USA
| | - A Ho
- The Laboratory of the Biology of Addictive Diseases, The Rockefeller University, 1230 York Ave, New York, NY 10065, USA
| | - M J Kreek
- The Laboratory of the Biology of Addictive Diseases, The Rockefeller University, 1230 York Ave, New York, NY 10065, USA
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Tsutsui K, Haraguchi S, Inoue K, Miyabara H, Ubuka T, Hatori M, Hirota T, Fukada Y. New biosynthesis and biological actions of avian neurosteroids. J Exp Neurosci 2013; 7:15-29. [PMID: 25157204 PMCID: PMC4089810 DOI: 10.4137/jen.s11148] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
De novo neurosteroidogenesis from cholesterol occurs in the brain of various avian species. However, the biosynthetic pathways leading to the formation of neurosteroids are still not completely elucidated. We have recently found that the avian brain produces 7α-hydroxypregnenolone, a novel bioactive neurosteroid that stimulates locomotor activity. Until recently, it was believed that neurosteroids are produced in neurons and glial cells in the central and peripheral nervous systems. However, our recent studies on birds have demonstrated that the pineal gland, an endocrine organ located close to the brain, is an important site of production of neurosteroids de novo from cholesterol. 7α-Hydroxypregnenolone is a major pineal neurosteroid that stimulates locomotor activity of juvenile birds, connecting light-induced gene expression with locomotion. The other major pineal neurosteroid allopregnanolone is involved in Purkinje cell survival during development. This paper highlights new aspects of neurosteroid synthesis and actions in birds.
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Affiliation(s)
- Kazuyoshi Tsutsui
- Laboratory of Integrative Brain Sciences, Department of Biology and Center for Medical Life Science, Waseda University, Tokyo, Japan
| | - Shogo Haraguchi
- Laboratory of Integrative Brain Sciences, Department of Biology and Center for Medical Life Science, Waseda University, Tokyo, Japan
| | - Kazuhiko Inoue
- Laboratory of Integrative Brain Sciences, Department of Biology and Center for Medical Life Science, Waseda University, Tokyo, Japan
| | - Hitomi Miyabara
- Laboratory of Integrative Brain Sciences, Department of Biology and Center for Medical Life Science, Waseda University, Tokyo, Japan
| | - Takayoshi Ubuka
- Laboratory of Integrative Brain Sciences, Department of Biology and Center for Medical Life Science, Waseda University, Tokyo, Japan
| | - Megumi Hatori
- Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, Tokyo, Japan
| | - Tsuyoshi Hirota
- Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, Tokyo, Japan
| | - Yoshitaka Fukada
- Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, Tokyo, Japan
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Xie G, Krnjević K, Ye JH. Salsolinol modulation of dopamine neurons. Front Behav Neurosci 2013; 7:52. [PMID: 23745110 PMCID: PMC3662897 DOI: 10.3389/fnbeh.2013.00052] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2013] [Accepted: 05/07/2013] [Indexed: 11/25/2022] Open
Abstract
Salsolinol, a tetrahydroisoquinoline present in the human and rat brains, is the condensation product of dopamine and acetaldehyde, the first metabolite of ethanol. Previous evidence obtained in vivo links salsolinol with the mesolimbic dopaminergic (DA) system: salsolinol is self-administered into the posterior of the ventral tegmental area (pVTA) of rats; intra-VTA administration of salsolinol induces a strong conditional place preference and increases dopamine release in the nucleus accumbens (NAc). However, the underlying neuronal mechanisms are unclear. Here we present an overview of some of the recent research on this topic. Electrophysiological studies reveal that DA neurons in the pVTA are a target of salsolinol. In acute brain slices from rats, salsolinol increases the excitability and accelerates the ongoing firing of dopamine neurons in the pVTA. Intriguingly, this action of salsolinol involves multiple pre- and post-synaptic mechanisms, including: (1) depolarizing dopamine neurons; (2) by activating μ opioid receptors on the GABAergic inputs to dopamine neurons – which decreases GABAergic activity – dopamine neurons are disinhibited; and (3) enhancing presynaptic glutamatergic transmission onto dopamine neurons via activation of dopamine type 1 receptors, probably situated on the glutamatergic terminals. These novel mechanisms may contribute to the rewarding/reinforcing properties of salsolinol observed in vivo.
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Affiliation(s)
- Guiqin Xie
- Department of Anesthesiology, Pharmacology, and Physiology, New Jersey Medical School, University of Medicine and Dentistry of New Jersey Newark, NJ, USA ; Department of Physiology, Nanjing Medical University Nanjing, China
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Ting-A-Kee R, Vargas-Perez H, Bufalino MR, Bahi A, Dreyer JL, Tyndale RF, van der Kooy D. Infusion of brain-derived neurotrophic factor into the ventral tegmental area switches the substrates mediating ethanol motivation. Eur J Neurosci 2012; 37:996-1003. [PMID: 23279128 DOI: 10.1111/ejn.12105] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2012] [Revised: 10/26/2012] [Accepted: 11/25/2012] [Indexed: 11/30/2022]
Abstract
Recent work has shown that infusion of brain-derived neurotrophic factor (BDNF) into the ventral tegmental area (VTA) promotes a switch in the mechanisms mediating morphine motivation, from a dopamine-independent to a dopamine-dependent pathway. Here we showed that a single infusion of intra-VTA BDNF also promoted a switch in the mechanisms mediating ethanol motivation, from a dopamine-dependent to a dopamine-independent pathway (exactly opposite to that seen with morphine). We suggest that intra-VTA BDNF, via its actions on TrkB receptors, precipitates a switch similar to that which occurs naturally when mice transit from a drug-naive, non-deprived state to a drug-deprived state. The opposite switching of the mechanisms underlying morphine and ethanol motivation by BDNF in previously non-deprived animals is consistent with their proposed actions on VTA GABAA receptors.
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Affiliation(s)
- Ryan Ting-A-Kee
- Institute of Medical Science, University of Toronto, Toronto, ON, M5S 3E1, Canada.
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Ting-A-Kee R, van der Kooy D. The neurobiology of opiate motivation. Cold Spring Harb Perspect Med 2012; 2:2/10/a012096. [PMID: 23028134 DOI: 10.1101/cshperspect.a012096] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Opiates are a highly addictive class of drugs that have been reported to possess both dopamine-dependent and dopamine-independent rewarding properties. The search for how, if at all, these distinct mechanisms of motivation are related is of great interest in drug addiction research. Recent electrophysiological, molecular, and behavioral work has greatly improved our understanding of this process. In particular, the signaling properties of GABA(A) receptors located on GABA neurons in the ventral tegmental area (VTA) appear to be crucial to understanding the interplay between dopamine-dependent and dopamine-independent mechanisms of opiate motivation.
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Affiliation(s)
- Ryan Ting-A-Kee
- Institute of Medical Science, University of Toronto, Terrence Donnelly Centre for Cellular and Biomolecular Research, Toronto, Ontario M5S 3E1, Canada.
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Identification of rat ventral tegmental area GABAergic neurons. PLoS One 2012; 7:e42365. [PMID: 22860119 PMCID: PMC3409171 DOI: 10.1371/journal.pone.0042365] [Citation(s) in RCA: 135] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2012] [Accepted: 07/06/2012] [Indexed: 12/29/2022] Open
Abstract
The canonical two neuron model of opioid reward posits that mu opioid receptor (MOR) activation produces reward by disinhibiting midbrain ventral tegmental area (VTA) dopamine neurons through inhibition of local GABAergic interneurons. Although indirect evidence supports the neural circuit postulated by this model, its validity has been called into question by growing evidence for VTA neuronal heterogeneity and the recent demonstration that MOR agonists inhibit GABAergic terminals in the VTA arising from extrinsic neurons. In addition, VTA MOR reward can be dopamine-independent. To directly test the assumption that MOR activation directly inhibits local GABAergic neurons, we investigated the properties of rat VTA GABA neurons directly identified with either immunocytochemistry for GABA or GAD65/67, or in situ hybridization for GAD65/67 mRNA. Utilizing co-labeling with an antibody for the neural marker NeuN and in situ hybridization against GAD65/67, we found that 23±3% of VTA neurons are GAD65/67(+). In contrast to the assumptions of the two neuron model, VTA GABAergic neurons are heterogeneous, both physiologically and pharmacologically. Importantly, only 7/13 confirmed VTA GABA neurons were inhibited by the MOR selective agonist DAMGO. Interestingly, all confirmed VTA GABA neurons were insensitive to the GABAB receptor agonist baclofen (0/6 inhibited), while all confirmed dopamine neurons were inhibited (19/19). The heterogeneity of opioid responses we found in VTA GABAergic neurons, and the fact that GABA terminals arising from neurons outside the VTA are inhibited by MOR agonists, make further studies essential to determine the local circuit mechanisms underlying VTA MOR reward.
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Chronic adolescent exposure to delta-9-tetrahydrocannabinol in COMT mutant mice: impact on indices of dopaminergic, endocannabinoid and GABAergic pathways. Neuropsychopharmacology 2012; 37:1773-83. [PMID: 22434221 PMCID: PMC3358747 DOI: 10.1038/npp.2012.24] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Cannabis use confers a two-fold increase in risk for psychosis, with adolescent use conferring an even greater risk. A high-low activity polymorphism in catechol-O-methyltransferase (COMT), a gene encoding the COMT enzyme involved in dopamine clearance in the brain, may interact with adolescent cannabis exposure to increase risk for schizophrenia. The impact of such an interaction on central neurotransmitter pathways implicated in schizophrenia is unknown. Male mice with knockout of the COMT gene were treated chronically with delta-9-tetrahydrocannabinol (THC) during adolescence (postnatal day 32-52). We measured the size and density of GABAergic cells and the protein expression of cannabinoid receptor 1 (CB1R) in the prefrontal cortex (PFC) and hippocampus (HPC) in knockout mice relative to heterozygous mutants and wild-type controls. Size and density of dopaminergic neurons was also assessed in the ventral tegmental area (VTA) across the genotypes. COMT genotype × THC treatment interactions were observed for: (1) dopaminergic cell size in the VTA, (2) CB1R protein expression in the HPC, and (3) parvalbumin (PV) cell size in the PFC. No effects of adolescent THC treatment were observed for PV and dopaminergic cell density across the COMT genotypes. COMT genotype modulates the effects of chronic THC administration during adolescence on indices of neurotransmitter function in the brain. These findings illuminate how COMT deletion and adolescent cannabis use can interact to modulate the function of neurotransmitters systems implicated in schizophrenia.
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Tsutsui K, Haraguchi S, Matsunaga M, Koyama T, Do Rego JL, Vaudry H. 7α-Hydroxypregnenolone, a new key regulator of amphibian locomotion: discovery, progress and prospect. Gen Comp Endocrinol 2012; 176:440-7. [PMID: 22138220 DOI: 10.1016/j.ygcen.2011.11.020] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/07/2011] [Revised: 11/11/2011] [Accepted: 11/13/2011] [Indexed: 11/26/2022]
Abstract
Seasonally-breeding amphibians have served as excellent animal models to investigate the biosynthesis and biological actions of neurosteroids. Previous studies have demonstrated that the brain of amphibians possesses key steroidogenic enzymes and produces pregnenolone, a precursor of steroid hormones, and other various neurosteroids. We recently found that the brain of seasonally-breeding newts actively produces 7α-hydroxypregnenolone, a previously undescribed amphibian neurosteroid. This novel amphibian neurosteroid acts as a neuronal modulator to stimulate locomotor activity in newts. Subsequently, the mode of action of 7α-hydroxypregnenolone has been demonstrated in the newt brain. 7α-Hydroxypregnenolone stimulates locomotor activity through activation of the dopaminergic system. To understand the functional significance of 7α-hydroxypregnenolone in the regulation of locomotor activity, diurnal and seasonal changes in synthesis of 7α-hydroxypregnenolone have also been demonstrated in the newt brain. Melatonin derived from the pineal gland and eyes regulates 7α-hydroxypregnenolone synthesis in the brain, thus inducing diurnal locomotor changes. Prolactin, an adenohypophyseal hormone, regulates 7α-hydroxypregnenolone synthesis in the brain, and also induces seasonal locomotor changes. In addition, 7α-hydroxypregnenolone mediates corticosterone action to increase locomotor activity under stress. This review summarizes the discovery, progress and prospect of 7α-hydroxypregnenolone, a new key regulator of amphibian locomotion.
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Affiliation(s)
- Kazuyoshi Tsutsui
- Laboratory of Integrative Brain Sciences, Department of Biology, Waseda University and Center for Medical Life Science of Waseda University, Tokyo 162-8480, Japan.
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Effects of apomorphine and β-carbolines on firing rate of neurons in the ventral pallidum in the rats. Behav Brain Res 2012; 227:109-15. [DOI: 10.1016/j.bbr.2011.10.041] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2011] [Revised: 10/23/2011] [Accepted: 10/25/2011] [Indexed: 11/22/2022]
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Frye CA, Paris JJ, Walf AA, Rusconi JC. Effects and Mechanisms of 3α,5α,-THP on Emotion, Motivation, and Reward Functions Involving Pregnane Xenobiotic Receptor. Front Neurosci 2012; 5:136. [PMID: 22294977 PMCID: PMC3261425 DOI: 10.3389/fnins.2011.00136] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2011] [Accepted: 11/25/2011] [Indexed: 12/13/2022] Open
Abstract
Progestogens [progesterone (P(4)) and its products] play fundamental roles in the development and/or function of the central nervous system during pregnancy. We, and others, have investigated the role of pregnane neurosteroids for a plethora of functional effects beyond their pro-gestational processes. Emerging findings regarding the effects, mechanisms, and sources of neurosteroids have challenged traditional dogma about steroid action. How the P(4) metabolite and neurosteroid, 3α-hydroxy-5α-pregnan-20-one (3α,5α-THP), influences cellular functions and behavioral processes involved in emotion/affect, motivation, and reward, is the focus of the present review. To further understand these processes, we have utilized an animal model assessing the effects, mechanisms, and sources of 3α,5α-THP. In the ventral tegmental area (VTA), 3α,5α-THP has actions to facilitate affective, and motivated, social behaviors through non-traditional targets, such as GABA, glutamate, and dopamine receptors. 3α,5α-THP levels in the midbrain VTA both facilitate, and/or are enhanced by, affective and social behavior. The pregnane xenobiotic receptor (PXR) mediates the production of, and/or metabolism to, various neurobiological factors. PXR is localized to the midbrain VTA of rats. The role of PXR to influence 3α,5α-THP production from central biosynthesis, and/or metabolism of peripheral P(4), in the VTA, as well as its role to facilitate, or be increased by, affective/social behaviors is under investigation. Investigating novel behavioral functions of 3α,5α-THP extends our knowledge of the neurobiology of progestogens, relevant for affective/social behaviors, and their connections to systems that regulate affect and motivated processes, such as those important for stress regulation and neuropsychiatric disorders (anxiety, depression, schizophrenia, drug dependence). Thus, further understanding of 3α,5α-THP's role and mechanisms to enhance affective and motivated processes is essential.
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Affiliation(s)
- Cheryl A. Frye
- Department of Psychology, The University at Albany-SUNYAlbany, NY, USA
- Biological Sciences, The University at Albany-SUNYAlbany, NY, USA
- The Centers for Neuroscience, The University at Albany-SUNYAlbany, NY, USA
- Life Science Research, The University at Albany-SUNYAlbany, NY, USA
| | - J. J. Paris
- Department of Psychology, The University at Albany-SUNYAlbany, NY, USA
| | - A. A. Walf
- Life Science Research, The University at Albany-SUNYAlbany, NY, USA
| | - J. C. Rusconi
- Biological Sciences, The University at Albany-SUNYAlbany, NY, USA
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Attenuating GABA(A) receptor signaling in dopamine neurons selectively enhances reward learning and alters risk preference in mice. J Neurosci 2012; 31:17103-12. [PMID: 22114279 DOI: 10.1523/jneurosci.1715-11.2011] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Phasic dopamine (DA) transmission encodes the value of reward-predictive stimuli and influences both learning and decision-making. Altered DA signaling is associated with psychiatric conditions characterized by risky choices such as pathological gambling. These observations highlight the importance of understanding how DA neuron activity is modulated. While excitatory drive onto DA neurons is critical for generating phasic DA responses, emerging evidence suggests that inhibitory signaling also modulates these responses. To address the functional importance of inhibitory signaling in DA neurons, we generated mice lacking the β3 subunit of the GABA(A) receptor specifically in DA neurons (β3-KO mice) and examined their behavior in tasks that assessed appetitive learning, aversive learning, and risk preference. DA neurons in midbrain slices from β3-KO mice exhibited attenuated GABA-evoked IPSCs. Furthermore, electrical stimulation of excitatory afferents to DA neurons elicited more DA release in the nucleus accumbens of β3-KO mice as measured by fast-scan cyclic voltammetry. β3-KO mice were more active than controls when given morphine, which correlated with potential compensatory upregulation of GABAergic tone onto DA neurons. β3-KO mice learned faster in two food-reinforced learning paradigms, but extinguished their learned behavior normally. Enhanced learning was specific for appetitive tasks, as aversive learning was unaffected in β3-KO mice. Finally, we found that β3-KO mice had enhanced risk preference in a probabilistic selection task that required mice to choose between a small certain reward and a larger uncertain reward. Collectively, these findings identify a selective role for GABA(A) signaling in DA neurons in appetitive learning and decision-making.
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Xie G, Hipólito L, Zuo W, Polache A, Granero L, Krnjevic K, Ye JH. Salsolinol stimulates dopamine neurons in slices of posterior ventral tegmental area indirectly by activating μ-opioid receptors. J Pharmacol Exp Ther 2011; 341:43-50. [PMID: 22209890 DOI: 10.1124/jpet.111.186833] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Previous studies in vivo have shown that salsolinol, the condensation product of acetaldehyde and dopamine, has properties that may contribute to alcohol abuse. Although opioid receptors, especially the μ-opioid receptors (MORs), may be involved, the cellular mechanisms mediating the effects of salsolinol have not been fully explored. In the current study, we used whole-cell patch-clamp recordings to examine the effects of salsolinol on dopamine neurons of the ventral tegmental area (VTA) in acute brain slices from Sprague-Dawley rats. Salsolinol (0.01-1 μM) dose-dependently and reversibly increased the ongoing firing of dopamine neurons; this effect was blocked by naltrexone, an antagonist of MORs, and gabazine, an antagonist of GABA(A) receptors. We further showed that salsolinol reduced the frequency without altering the amplitude of spontaneous GABA(A) receptor-mediated inhibitory postsynaptic currents in dopamine neurons. The salsolinol-induced reduction was blocked by both naltrexone and [D-Ala2,N-Me-Phe4,Gly5-ol]enkephalin, an agonist of MORs. Thus, salsolinol excites VTA-dopamine neurons indirectly by activating MORs, which inhibit GABA neurons in the VTA. This form of disinhibition seems to be a novel mechanism underlying the effects of salsolinol.
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Affiliation(s)
- Guiqin Xie
- Department of Anesthesiology, Pharmacology, and Physiology, UMDNJ, New Jersey Medical School, 185 South Orange Avenue, Newark, NJ 07103, USA
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Dacher M, Nugent FS. Opiates and plasticity. Neuropharmacology 2011; 61:1088-96. [DOI: 10.1016/j.neuropharm.2011.01.028] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2010] [Revised: 01/07/2011] [Accepted: 01/17/2011] [Indexed: 11/30/2022]
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Hayes DJ, Hoang J, Greenshaw AJ. The role of nucleus accumbens shell GABA receptors on ventral tegmental area intracranial self-stimulation and a potential role for the 5-HT(2C) receptor. J Psychopharmacol 2011; 25:1661-75. [PMID: 21169393 DOI: 10.1177/0269881110389212] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Brain γ-aminobutyric acid (GABA) and 5-hydroxytryptamine (5-HT)(2C) receptors are implicated in the neuronal regulation of reward- and aversion-related behaviour. Within the mesocorticolimbic pathways of the brain, relationships between GABA containing neurons and 5-HT(2C) receptor activity may be important in this context. The primary aim of this study was to investigate the role of NAc shell GABA receptors on ventral tegmental area intracranial self-stimulation (ICSS) and to examine the systemic effects of GABAergic ligands in this context. The second aim was to investigate the relationship between GABA receptor- and 5-HT(2C) receptor-related ICSS behaviour, using systemic administration of the selective agonist WAY 161503. Locomotor activity was assessed to compare the potential motor effects of drugs; feeding behaviour and intra-NAc injections of amphetamine (1.0 µg/side) were used as positive controls. When administered systemically the GABA(A) receptor agonist muscimol and antagonist picrotoxin did not selectively change ICSS reward thresholds, although the 5-HT(2C) receptor agonist WAY 161503 (1.0 mg/kg) decreased reward measures. Intra-NAc shell administration of muscimol (225 ng/side) and picrotoxin (125 ng/side), respectively, decreased and increased measures of reward. Intra-NAc shell baclofen (0-225 ng/side; GABA(B) receptor agonist) did not affect any ICSS measures although it increased feeding. Combining picrotoxin and WAY 161503 attenuated the effects of each. These results suggest that a 5-HT(2C) and GABA(A) receptor-mediated neuronal relationship in the NAc shell may be relevant for the regulation of brain reward pathways.
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Affiliation(s)
- Dave J Hayes
- Centre for Neuroscience, University of Alberta, Edmonton, AB, Canada.
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Pereira M, Morrell JI. Functional mapping of the neural circuitry of rat maternal motivation: effects of site-specific transient neural inactivation. J Neuroendocrinol 2011; 23:1020-35. [PMID: 21815954 PMCID: PMC3196804 DOI: 10.1111/j.1365-2826.2011.02200.x] [Citation(s) in RCA: 99] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The present review focuses on recent studies from our laboratory examining the neural circuitry subserving rat maternal motivation across postpartum. We employed a site-specific neural inactivation method by infusion of bupivacaine to map the maternal motivation circuitry using two complementary behavioural approaches: unconditioned maternal responsiveness and choice of pup- over cocaine-conditioned incentives in a concurrent pup/cocaine choice conditioned place preference task. Our findings revealed that, during the early postpartum period, distinct brain structures, including the medial preoptic area, ventral tegmental area and medial prefrontal cortex infralimbic and anterior cingulate subregions, contribute a pup-specific bias to the motivational circuitry. As the postpartum period progresses and the pups grow older, it is further revealed that maternal responsiveness becomes progressively less dependent on the medial preoptic area and medial prefrontal cortex infralimbic activity, and more distributed in the maternal circuitry, such that additional network components, including the medial prefrontal cortex prelimbic subregion, are recruited with maternal experience, and contribute to the expression of late postpartum maternal behaviour. Collectively, our findings provide strong evidence that the remarkable ability of postpartum females to successfully care for their developing infants is subserved by a distributed neural network that carries out efficient and dynamic processing of complex, constantly changing incoming environmental and pup-related stimuli, ultimately allowing the progression of appropriate expression and waning of maternal responsiveness across the postpartum period.
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Affiliation(s)
- M Pereira
- Center for Molecular and Behavioral Neuroscience, Rutgers University, Newark Campus, Newark, NJ 07102, USA.
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Melón LC, Boehm SL. GABAA receptors in the posterior, but not anterior, ventral tegmental area mediate Ro15-4513-induced attenuation of binge-like ethanol consumption in C57BL/6J female mice. Behav Brain Res 2011; 220:230-7. [PMID: 21320533 DOI: 10.1016/j.bbr.2011.02.014] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2010] [Revised: 02/02/2011] [Accepted: 02/08/2011] [Indexed: 02/05/2023]
Abstract
GABA(A) receptors have been shown to modulate dopaminergic output from the ventral tegmental area (VTA) in studies of both natural and drug rewards, including alcohol. Ro15-4513, the imidazobenzodiazepine derivative and allosteric modulator at the GABA(A) receptor, reliably antagonizes the behavioral effects of alcohol. Various models of alcohol consumption show a decrease in consummatory behaviors, specific to ethanol, following acute administration of the drug. In the present study, Ro15-4513 was systemically administered, or microinjected into the anterior or posterior VTA, to explore the role of GABA(A) receptors at this region in modulating the high pattern of alcohol consumption by C57BL/6J inbred mice in the Drinking in the Dark (DID) model. Animals had 2h access to ethanol for 6 days prior to drug manipulations. Immediately before the seventh day of access, mice were systemically (I.P.) or site-specifically administered Ro15-4513. Systemic Ro15-4513 (at 10mg/kg) decreased binge-like ethanol intake in the DID paradigm. Additionally, there was a stepwise decrease in consumption following Ro15-4513 microinjection into the posterior VTA, with the highest dose significantly decreasing ethanol intake. There was no effect found following microinjection into the anterior VTA, nor was there an effect of systemic or intra-posterior VTA Ro15-4513 on consumption of a 5% sucrose solution or water. The present findings support a role for Ro15-4513 sensitive VTA-GABA(A) receptors in modulating binge-like ethanol consumption. Moreover, the work here adds to the growing body of literature suggesting regional heterogeneity in the VTA.
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Affiliation(s)
- Laverne C Melón
- Psychobiology of Addictions, Department of Psychology, Indiana University/Purdue University-Indianapolis, Indianapolis, IN 46202, USA.
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Wang DV, Tsien JZ. Conjunctive processing of locomotor signals by the ventral tegmental area neuronal population. PLoS One 2011; 6:e16528. [PMID: 21304590 PMCID: PMC3029369 DOI: 10.1371/journal.pone.0016528] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2010] [Accepted: 12/29/2010] [Indexed: 11/18/2022] Open
Abstract
The ventral tegmental area (VTA) plays an essential role in reward and motivation. How the dopamine (DA) and non-DA neurons in the VTA engage in motivation-based locomotor behaviors is not well understood. We recorded activity of putative DA and non-DA neurons simultaneously in the VTA of awake mice engaged in motivated voluntary movements such as wheel running. Our results revealed that VTA non-DA neurons exhibited significant rhythmic activity that was correlated with the animal's running rhythms. Activity of putative DA neurons also correlated with the movement behavior, but to a lesser degree. More importantly, putative DA neurons exhibited significant burst activation at both onset and offset of voluntary movements. These findings suggest that VTA DA and non-DA neurons conjunctively process locomotor-related motivational signals that are associated with movement initiation, maintenance and termination.
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Affiliation(s)
- Dong V. Wang
- Key Laboratory of MOE and STCSM, Shanghai Institute of Brain Functional Genomics, East China Normal University, Shanghai, China
- Brain and Behavior Discovery Institute, Medical College of Georgia, Georgia Health Sciences University, Augusta, Georgia, United States of America
| | - Joe Z. Tsien
- Brain and Behavior Discovery Institute, Medical College of Georgia, Georgia Health Sciences University, Augusta, Georgia, United States of America
- * E-mail:
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Lane DA, Reed B, Kreek MJ, Pickel VM. Differential glutamate AMPA-receptor plasticity in subpopulations of VTA neurons in the presence or absence of residual cocaine: implications for the development of addiction. Neuropharmacology 2011; 61:1129-40. [PMID: 21215761 DOI: 10.1016/j.neuropharm.2010.12.031] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2010] [Revised: 11/30/2010] [Accepted: 12/22/2010] [Indexed: 01/18/2023]
Abstract
Cocaine-induced plasticity of mesocorticolimbic dopamine (DA) neurons, originating in the ventral tegmental area (VTA), persists in the absence of cocaine and may contribute to both drug-craving and relapse. Glutamate AMPA receptors (AMPARs) in these neurons are implicated in this plasticity. However, there is no ultrastructural evidence that the absence of cocaine following repeated administrations affects the critical surface/synaptic availability of AMPAR GluR1 subunits in either DA or non-DA, putative GABAergic neurons within the VTA. To assess this, we used electron microscopic immunolabeling in the VTA of adult male mice sacrificed at 30 min or 72 h after receiving the final of six (15 mg/kg) cocaine injections, a dosing paradigm that resulted in development of locomotor sensitization. At each time point, both cocaine- and saline-injected mice showed AMPAR GluR1 immunogold labeling in somatodendritic profiles, many of which contained immunoperoxidase labeling for the DA-synthesizing enzyme, tyrosine hydroxylase (TH). At 30 min after the last injection, when cocaine was systemically present, only the non-TH labeled dendrites showed a significant increase in the synaptic/plasmalemmal density of GluR1 immunogold particles. At 72 h, when systemic cocaine was depleted, synaptic GluR1 labeling was greatly enhanced in TH-containing dendrites throughout the VTA and in non-TH dendrites of the limbic-associated paranigral VTA. Our results demonstrate that systemic cocaine produces GluR1 trafficking specifically in non-DA neurons of the VTA, which may subsequently contribute to the abstinent-induced enhancement of AMPA receptor synaptic transmission in mesocorticolimbic DA neurons leading to heightened drug seeking behavior.
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Affiliation(s)
- D A Lane
- Department of Neurology and Neuroscience, Weill Medical College of Cornell University, New York, NY 10065, USA.
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Haraguchi S, Matsunaga M, Vaudry H, Tsutsui K. Mode of action and functional significance of 7α-hydroxypregnenolone stimulating locomotor activity. Front Endocrinol (Lausanne) 2011; 2:23. [PMID: 22645507 PMCID: PMC3355833 DOI: 10.3389/fendo.2011.00023] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2011] [Accepted: 08/04/2011] [Indexed: 11/13/2022] Open
Abstract
Previous studies over the past two decades have demonstrated that the brain and other nervous systems possess key steroidogenic enzymes and produces pregnenolone and other various neurosteroids in vertebrates in general. Recently, 7α-hydroxypregnenolone, a novel bioactive neurosteroid, was identified in the brain of newts and quail. Importantly, this novel neurosteroid is produced from pregnenolone through the enzymatic activity of cytochrome P450(7α) and acts on brain tissue as a neuronal modulator to stimulate locomotor activity in these vertebrates. Subsequently, the mode of action of 7α-hydroxypregnenolone was demonstrated. 7α-Hydroxypregnenolone stimulates locomotor activity through activation of the dopaminergic system. To understand the functional significance of 7α-hydroxypregnenolone in the regulation of locomotor activity, diurnal, and seasonal changes in 7α-hydroxypregnenolone synthesis were further characterized. Melatonin derived from the pineal gland and eyes regulates 7α-hydroxypregnenolone synthesis in the brain, thus inducing diurnal locomotor changes. Prolactin, an adenohypophyseal hormone, regulates 7α-hydroxypregnenolone synthesis in the brain, and also induces seasonal locomotor changes. In addition, 7α-hydroxypregnenolone mediates corticosterone action to modulate locomotor activity under stress. This review summarizes the current knowledge regarding the mode of action and functional significance of 7α-hydroxypregnenolone, a newly identified bioactive neurosteroid stimulating locomotor activity.
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Affiliation(s)
- Shogo Haraguchi
- Laboratory of Integrative Brain Sciences, Department of Biology, Waseda University, and Center for Medical Life Science of Waseda UniversityTokyo, Japan
| | - Masahiro Matsunaga
- Laboratory of Integrative Brain Sciences, Department of Biology, Waseda University, and Center for Medical Life Science of Waseda UniversityTokyo, Japan
| | - Hubert Vaudry
- Laboratory of Neuronal and Neuroendocrine Differentiation and Communication (INSERM U982), European Institute for Peptide Research, University of RouenMont-Saint-Aignan, France
| | - Kazuyoshi Tsutsui
- Laboratory of Integrative Brain Sciences, Department of Biology, Waseda University, and Center for Medical Life Science of Waseda UniversityTokyo, Japan
- *Correspondence: Kazuyoshi Tsutsui, Laboratory of Integrative Brain Sciences, Department of Biology, Waseda University, and Center for Medical Life Science of Waseda University, 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo 162-8480, Japan. e-mail:
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