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Zhang YX, Zhu YM, Yang XX, Gao FF, Chen J, Yu DY, Gao JQ, Chen ZN, Yang JS, Yan CX, Huo FQ. Phosphorylation of Neurofilament Light Chain in the VLO Is Correlated with Morphine-Induced Behavioral Sensitization in Rats. Int J Mol Sci 2023; 24:ijms24097709. [PMID: 37175416 PMCID: PMC10177919 DOI: 10.3390/ijms24097709] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Revised: 04/07/2023] [Accepted: 04/15/2023] [Indexed: 05/15/2023] Open
Abstract
Neurofilament light chain (NF-L) plays critical roles in synapses that are relevant to neuropsychiatric diseases. Despite postmortem evidence that NF-L is decreased in opiate abusers, its role and underlying mechanisms remain largely unknown. We found that the microinjection of the histone deacetylase (HDAC) inhibitor Trichostatin A (TSA) into the ventrolateral orbital cortex (VLO) attenuated chronic morphine-induced behavioral sensitization. The microinjection of TSA blocked the chronic morphine-induced decrease of NF-L. However, our chromatin immunoprecipitation (ChIP)-qPCR results indicated that this effect was not due to the acetylation of histone H3-Lysine 9 and 14 binding to the NF-L promotor. In line with the behavioral phenotype, the microinjection of TSA also blocked the chronic morphine-induced increase of p-ERK/p-CREB/p-NF-L. Finally, we compared chronic and acute morphine-induced behavioral sensitization. We found that although both chronic and acute morphine-induced behavioral sensitization were accompanied by an increase of p-CREB/p-NF-L, TSA exhibited opposing effects on behavioral phenotype and molecular changes at different addiction contexts. Thus, our findings revealed a novel role of NF-L in morphine-induced behavioral sensitization, and therefore provided some correlational evidence of the involvement of NF-L in opiate addiction.
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Affiliation(s)
- Yu-Xiang Zhang
- College of Forensic Medicine, Xi'an Jiaotong University Health Science Center, Xi'an 710061, China
- NHC Key Laboratory of Drug Addiction Medicine, Kunming Medical University, Kunming 650032, China
| | - Yuan-Mei Zhu
- College of Forensic Medicine, Xi'an Jiaotong University Health Science Center, Xi'an 710061, China
| | - Xi-Xi Yang
- College of Forensic Medicine, Xi'an Jiaotong University Health Science Center, Xi'an 710061, China
| | - Fei-Fei Gao
- College of Forensic Medicine, Xi'an Jiaotong University Health Science Center, Xi'an 710061, China
| | - Jie Chen
- College of Forensic Medicine, Xi'an Jiaotong University Health Science Center, Xi'an 710061, China
| | - Dong-Yu Yu
- College of Forensic Medicine, Xi'an Jiaotong University Health Science Center, Xi'an 710061, China
| | - Jing-Qi Gao
- College of Forensic Medicine, Xi'an Jiaotong University Health Science Center, Xi'an 710061, China
| | - Zhen-Nan Chen
- College of Forensic Medicine, Xi'an Jiaotong University Health Science Center, Xi'an 710061, China
| | - Jing-Si Yang
- College of Forensic Medicine, Xi'an Jiaotong University Health Science Center, Xi'an 710061, China
| | - Chun-Xia Yan
- College of Forensic Medicine, Xi'an Jiaotong University Health Science Center, Xi'an 710061, China
- The Key Laboratory of Environment and Genes Related to Diseases, Ministry of Education, Xi'an Jiaotong University, Xi'an 710061, China
| | - Fu-Quan Huo
- The Key Laboratory of Environment and Genes Related to Diseases, Ministry of Education, Xi'an Jiaotong University, Xi'an 710061, China
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an 710061, China
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The role of opioidergic system in modulating cost/benefit decision-making in alcohol-preferring AA rats and Wistar rats. Behav Pharmacol 2020; 32:220-228. [PMID: 33229893 DOI: 10.1097/fbp.0000000000000606] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Research has highlighted the association of a positive family history of alcoholism with a positive treatment response to opioid antagonists in those with a gambling disorder. However, the role of the opioidergic system in gambling behavior is not well understood, and preclinical studies are needed to clarify this. In this study, Alko Alcohol (AA) and Wistar rats went through operant lever pressing training where the task was to choose the more profitable of two options. Different sized sucrose rewards guided the lever choices, and the probability of gaining rewards changed slowly to a level where choosing the smaller reward was the most profitable option. After training, rats were administered subcutaneously with opioid agonist morphine or opioid antagonist naltrexone to study the impact of opioidergic mechanisms on cost/benefit decisions. No difference was found in the decision-making between AA rats or Wistar rats after the morphine administration, but control data revealed a minor decision enhancing effect in AA rats. Naltrexone had no impact on the decisions in AA rats but promoted unprofitable decisions in Wistar rats. Supporting behavioral data showed that in both rat strains morphine increased, and naltrexone decreased, sucrose consumption. Naltrexone also increased the time to accomplish the operant task. The results suggest that opioid agonists could improve decision-making in cost-benefit settings in rats that are naturally prone to high alcohol drinking. The naltrexone results are ambiguous but may partly explain why opioid antagonists lack a positive pharmacotherapeutic effect in some subgroups of gamblers.
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Adedayo AD, Aderinola AA, Adekilekun TA, Olaolu OO, Olanike AM, Olayemi IK. Morphine-alcohol treatment impairs cognitive functions and increases neuro-inflammatory responses in the medial prefrontal cortex of juvenile male rats. Anat Cell Biol 2018; 51:41-51. [PMID: 29644109 PMCID: PMC5890016 DOI: 10.5115/acb.2018.51.1.41] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2017] [Revised: 12/04/2017] [Accepted: 12/13/2017] [Indexed: 02/01/2023] Open
Abstract
In the developed and developing world, opioid consumption in combination with alcohol has become one of the substances abused. In this experiment, we examined the effects of alcohol, morphine, and morphine+alcohol combination on cognitive functions and neuroinflammatory responses in the medial prefrontal cortex (mPFC) of juvenile male rats. Alcohol (1.0 ml of 15% v/v ethanol twice daily, subcutaneously, 7 hours apart), morphine (0.5 ml/kg of 0.4 mg/kg morphine chlorate twice daily, subcutaneously, 7 hours apart), morphine+alcohol co-treatment (0.5 ml/kg of 0.4 mg/kg morphine chlorate+1.0 ml of 15% v/v ethanol twice daily, subcutaneously, 7 hours apart) were administered for 21 days. Treatment with morphine+alcohol significantly impairs cognition functions in the Morris water maze, passive avoidance, and novel object recognition tests, furthermore, the treatment significantly increased the quantitative count of astrocytic cells and also conferred marked neuronal cell death in the mPFC, which were studied by glial fibrillary acidic protein immunochemistry for astrocytes and Cresyl violet for Nissl's substance distribution in neurons respectively. These results suggest that alcohol, morphine, and morphine+alcohol co-treatment may trigger cognitive deficits and neuroinflammatory responses in the brain.
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Affiliation(s)
| | | | | | - Olaniyan Olayinka Olaolu
- Department of Medical Biochemistry (Chemical Pathology Unit), Osun State University (Osogbo Campus), Osogbo, Nigeria
| | | | - Ijomone Kafilat Olayemi
- Department of Anatomy, Faculty of Basic Medical Science, University of Medical Sciences, Ondo, Nigeria
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Kemppainen H, Nurmi H, Raivio N, Kiianmaa K. Enhanced Extracellular Glutamate and Dopamine in the Ventral Pallidum of Alcohol-Preferring AA and Alcohol-Avoiding ANA Rats after Morphine. Front Psychiatry 2015; 6:1. [PMID: 25653621 PMCID: PMC4299289 DOI: 10.3389/fpsyt.2015.00001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/23/2014] [Accepted: 01/01/2015] [Indexed: 11/20/2022] Open
Abstract
The purpose of the present study was to investigate the role of ventral pallidal opioidergic mechanisms in the control of ethanol intake by studying the effects of acute administration of morphine on the levels of GABA, glutamate, and dopamine in the ventral pallidum. The study was conducted using the alcohol-preferring Alko Alcohol (AA) and alcohol-avoiding Alko Non-Alcohol (ANA) rat lines that have well-documented differences in their voluntary ethanol intake and brain opioidergic systems. Therefore, examination of neurobiological differences between the lines is supposed to help to identify the neuronal mechanisms underlying ethanol intake, since selection pressure is assumed gradually to lead to enrichment of alleles promoting high or low ethanol intake, respectively. The effects of an acute dose of morphine (1 or 10 mg/kg s.c.) on the extracellular levels of GABA and glutamate in the ventral pallidum were monitored with in vivo microdialysis. The concentrations of GABA and glutamate in the dialyzates were determined with a high performance liquid chromatography system using fluorescent detection, while electrochemical detection was used for dopamine. The levels of glutamate in the rats injected with morphine 1 mg/kg were significantly above the levels found in the controls and in the rats receiving morphine 10 mg/kg. Morphine 10 mg/kg also increased the levels of dopamine. Morphine could not, however, modify the levels of GABA. The rat lines did not differ in any of the effects of morphine. The data suggest that the glutamatergic and dopaminergic systems in the ventral pallidum may mediate some effects of morphine. Since there were no differences between the AA and ANA lines, the basic hypothesis underlying the use of the genetic animal model suggests that the effects of morphine detected probably do not underlie the different intake of ethanol by the lines and contribute to the control of ethanol intake in these animals.
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Affiliation(s)
- Heidi Kemppainen
- Department of Alcohol, Drugs and Addiction, National Institute for Health and Welfare , Helsinki , Finland
| | - Harri Nurmi
- Department of Alcohol, Drugs and Addiction, National Institute for Health and Welfare , Helsinki , Finland
| | - Noora Raivio
- Department of Alcohol, Drugs and Addiction, National Institute for Health and Welfare , Helsinki , Finland
| | - Kalervo Kiianmaa
- Department of Alcohol, Drugs and Addiction, National Institute for Health and Welfare , Helsinki , Finland
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Liu P, Wu C, Song W, Yu L, Yang X, Xiang R, Wang F, Yang J. Uridine decreases morphine-induced behavioral sensitization by decreasing dorsal striatal dopamine release possibly via agonistic effects at GABAA receptors. Eur Neuropsychopharmacol 2014; 24:1557-66. [PMID: 25088943 DOI: 10.1016/j.euroneuro.2014.06.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Revised: 06/14/2014] [Accepted: 06/20/2014] [Indexed: 11/29/2022]
Abstract
Uridine, a potential endogenous neuromodulator, has been demonstrated to interact with the dopaminergic system and to regulate dopamine-related behaviors. The present study investigated the effects of uridine on morphine-induced hyperactivity and behavioral sensitization and on modulating dopaminergic neurotransmission in mice, which may help to understand how uridine and its metabolites act as modulators of the GABAA receptors. The results showed that either systemic (30 or 100mg/kg) or central (30, 100 or 300nM) uridine administration significantly attenuated the hyperactivity induced by acute morphine treatment in mice. Intracerebroventricular administration of uracil and β-alanine also inhibited morphine-induced hyperactivity. Uridine, a known modulator of the GABA receptors, increased the extracellular levels of GABA in the brain. In addition, the GABAA receptors antagonist bicuculline significantly attenuated the effects of uridine on morphine-induced hyperactivity, suggesting that the GABAA receptors potentially mediate the effects of uridine and its metabolites on morphine-related activity. It was also observed that morphine-induced locomotor sensitization was abolished after chronic uridine treatment. In vivo microdialysis demonstrated that uridine reversed morphine-induced dopamine release in the dorsal striatum of morphine-sensitized mice. In conclusion, these data suggest that the therapeutic effects of uridine and its metabolites on morphine-induced hyperactivity and established behavioral sensitization may be mediated in part by interfering with the dopaminergic system possibly via agonistic effects at GABAA receptors.
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Affiliation(s)
- Ping Liu
- Department of Pharmacology, Shenyang Pharmaceutical University, Box 31, 103 Wenhua Road, 110016 Shenyang, PR China
| | - Chunfu Wu
- Department of Pharmacology, Shenyang Pharmaceutical University, Box 31, 103 Wenhua Road, 110016 Shenyang, PR China
| | - Wu Song
- Department of Pharmacology, Shenyang Pharmaceutical University, Box 31, 103 Wenhua Road, 110016 Shenyang, PR China
| | - Lisha Yu
- Department of Pharmacology, Shenyang Pharmaceutical University, Box 31, 103 Wenhua Road, 110016 Shenyang, PR China
| | - Xiaofeng Yang
- Department of Pharmacology, Shenyang Pharmaceutical University, Box 31, 103 Wenhua Road, 110016 Shenyang, PR China
| | - Rongwu Xiang
- Mathematics Teaching & Research Section, Shenyang Pharmaceutical University, 110016 Shenyang, PR China
| | - Fang Wang
- Department of Pharmacology, Shenyang Pharmaceutical University, Box 31, 103 Wenhua Road, 110016 Shenyang, PR China
| | - Jingyu Yang
- Department of Pharmacology, Shenyang Pharmaceutical University, Box 31, 103 Wenhua Road, 110016 Shenyang, PR China.
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Raivio N, Miettinen P, Kiianmaa K. Innate BDNF expression is associated with ethanol intake in alcohol-preferring AA and alcohol-avoiding ANA rats. Brain Res 2014; 1579:74-83. [PMID: 25044407 DOI: 10.1016/j.brainres.2014.07.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2014] [Revised: 06/26/2014] [Accepted: 07/04/2014] [Indexed: 12/20/2022]
Abstract
We have shown recently that acute administration of ethanol modulates the expression of brain-derived neurotrophic factor (BDNF) in several rat brain areas known to be involved in the development of addiction to ethanol and other drugs of abuse, suggesting that BDNF may be a factor contributing to the neuroadaptive changes set in motion by ethanol exposure. The purpose of the present study was to further clarify the role of BDNF in reinforcement from ethanol and in the development of addiction to ethanol by specifying the effect of acute administration of ethanol (1.5 or 3.0 g/kg i.p.) on the expression profile of BDNF mRNA in the ventral tegmental area and in the terminal areas of the mesolimbic dopamine pathway in the brain of alcohol-preferring AA and alcohol-avoiding ANA rats, selected for high and low voluntary ethanol intake, respectively. The level of BDNF mRNA expression was higher in the amygdala and ventral tegmental area of AA than in those of ANA rats, and there was a trend for a higher level in the nucleus accumbens. In the amygdala and hippocampus, a biphasic change in the BDNF mRNA levels was detected: the levels were decreased at 3 and 6h but increased above the basal levels at 24h. Furthermore, there was a difference between the AA and ANA lines in the effect of ethanol, the ANA rats showing an increase in BDNF mRNA levels while such a change was not seen in AA rats. These findings suggest that the innate levels of BDNF expression may play a role in the mediation of the reinforcing effects of ethanol and in the control of ethanol intake.
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Affiliation(s)
- Noora Raivio
- Department of Alcohol, Drugs and Addiction, National Institute for Health and Welfare, POB 30, Helsinki 00271, Finland
| | - Pekka Miettinen
- Department of Alcohol, Drugs and Addiction, National Institute for Health and Welfare, POB 30, Helsinki 00271, Finland
| | - Kalervo Kiianmaa
- Department of Alcohol, Drugs and Addiction, National Institute for Health and Welfare, POB 30, Helsinki 00271, Finland.
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7
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Taracha E, Dyr W, Ćwiek M, Turzyńska D, Walkowiak J, Wyszogrodzka E, Kostowski W, Płaźnik A, Chrapusta SJ. Diverse behavioral, monoaminergic and Fos protein responses to opioids in Warsaw high-alcohol preferring and Warsaw low-alcohol preferring rats. Prog Neuropsychopharmacol Biol Psychiatry 2011; 35:588-97. [PMID: 21216264 DOI: 10.1016/j.pnpbp.2010.12.028] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/23/2010] [Revised: 12/28/2010] [Accepted: 12/29/2010] [Indexed: 10/18/2022]
Abstract
Predisposition to addictions is presumably related to a dysfunction of the brain reward system, which can be 'compensated' by the intake of different psychoactive drugs. Hence, animals showing propensity for developing dependence to a specific drug class may also be useful for modeling other addictions. We compared the effects of repeated (14 daily doses) morphine (10 mg/kg) or methadone (2 mg/kg) treatment followed by a 2-week withdrawal and a morphine challenge (5 mg/kg) on locomotor activity, brain Fos expression and selected brain regional levels of dopamine, serotonin and their metabolites in the 38th generations of selectively bred Warsaw low-alcohol-preferring (WLP) and Warsaw high-alcohol-preferring (WHP) rat lines. The rats were given the opioids during the active (i.e. dark) phase of their daily cycle. Drug-naïve WHP rats compared to their WLP counterparts showed higher locomotor activity in an open field test and higher propensity for lasting behavioral sensitization to morphine. Morphine did not significantly enhance, but suppressed Fos expression in certain brain regions of drug-naïve WLP and WHP rats. Fos expression revealed considerable differences in the responses of WLP and WHP rats to morphine challenge, particularly after methadone pretreatment. These differences were associated with differences in monoamine metabolite levels that were suggestive of elevated basal ganglia and lowered frontal cortical dopamine function, and of lowered somatosensory cortex serotonin function, in the morphine-challenged WHP rats (irrespective of the pretreatment type). Hence, the WLP/WHP line pair may be useful for the search of factors that underlie the propensity for developing opiate dependence.
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Affiliation(s)
- Ewa Taracha
- Department of Neurochemistry, Institute of Psychiatry and Neurology, 9 Sobieskiego St., 02-957 Warsaw, Poland.
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Differences in basal and morphine-induced FosB/ΔFosB and pCREB immunoreactivities in dopaminergic brain regions of alcohol-preferring AA and alcohol-avoiding ANA rats. Pharmacol Biochem Behav 2009; 92:655-62. [DOI: 10.1016/j.pbb.2009.03.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2009] [Accepted: 03/17/2009] [Indexed: 11/23/2022]
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Kemppainen H, Hyytiä P, Kiianmaa K. Behavioral Consequences of Repeated Nicotine During Adolescence in Alcohol-Preferring AA and Alcohol-Avoiding ANA Rats. Alcohol Clin Exp Res 2009; 33:340-9. [DOI: 10.1111/j.1530-0277.2008.00838.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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Ojanen SP, Palmén M, Hyytiä P, Kiianmaa K. Extracellular glutamate and GABA in the ventral tegmental area of alcohol-preferring AA and alcohol-avoiding ANA rats treated repeatedly with morphine. Eur J Pharmacol 2007; 559:38-45. [PMID: 17198699 DOI: 10.1016/j.ejphar.2006.11.046] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2006] [Revised: 10/30/2006] [Accepted: 11/20/2006] [Indexed: 10/23/2022]
Abstract
Glutamate and gamma-amino-butyric acid (GABA) have been implicated in neuronal plasticity related to behavioral sensitization. In the present study, we examined morphine-induced changes in the extracellular concentrations of glutamate and GABA in the ventral tegmental area in alcohol-preferring Alko Alcohol (AA) and alcohol-avoiding Alko Non-Alcohol (ANA) rats that have previously been shown to differ in morphine-induced sensitization. The rats were given escalating doses (5-20 mg/kg) of morphine every other day for five days. This treatment produced behavioral sensitization to locomotor effects of morphine in AA, but not in ANA rats, when challenged with an additional injection of morphine (10 mg/kg) 10 days later. Morphine also increased the levels of glutamate in the ventral tegmental area only in AA rats, while no significant changes were found in the extracellular concentrations of GABA between the lines. Challenging the morphine-treated AA rats with ethanol (1.5 g/kg) did not modify the levels of glutamate or GABA. No changes in the concentrations of glutamate or GABA were seen in saline-treated AA and ANA rats after morphine challenge. These results render increased glutamate transmission in the ventral tegmental area a potential contributor to the higher susceptibility of AA rats to morphine-induced behavioral and neurochemical effects relative to ANA rats.
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Affiliation(s)
- Sami P Ojanen
- Department of Mental Health and Alcohol Research, National Public Health Institute, POB 33, 00251 Helsinki, Finland
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Sommer W, Hyytiä P, Kiianmaa K. The alcohol-preferring AA and alcohol-avoiding ANA rats: neurobiology of the regulation of alcohol drinking. Addict Biol 2006; 11:289-309. [PMID: 16961760 DOI: 10.1111/j.1369-1600.2006.00037.x] [Citation(s) in RCA: 118] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The AA (alko, alcohol) and ANA (alko, non-alcohol) rat lines were among the earliest rodent lines produced by bidirectional selection for ethanol preference. The purpose of this review is to highlight the strategies for understanding the neurobiological factors underlying differential alcohol-drinking behavior in these lines. Most early work evaluated functioning of the major neurotransmitter systems implicated in drug reward in the lines. No consistent line differences were found in the dopaminergic system either under baseline conditions or after ethanol challenges. However, increased opioidergic tone in the ventral striatum and a deficiency in endocannabinoid signaling in the prefrontal cortex of AA rats may comprise mechanisms leading to increased ethanol consumption. Because complex behaviors, such as ethanol drinking, are not likely to be controlled by single factors, system-oriented molecular-profiling strategies have been used recently. Microarray based expression analysis of AA and ANA brains and novel data-mining strategies provide a system biological view that allows us to formulate a hypothesis on the mechanism underlying selection for ethanol preference. Two main factors appear active in the selection: a recruitment of signal transduction networks, including mitogen-activated protein kinases and calcium pathways and involving transcription factors such as Creb, Myc and Max, to mediate ethanol reinforcement and plasticity. The second factor acts on the mitochondrion and most likely provides metabolic flexibility for alternative substrate utilization in the presence of low amounts of ethanol.
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Affiliation(s)
- Wolfgang Sommer
- Laboratory of Clinical and Translational Studies, NIAAA, National Institutes of Health, USA
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Ojanen SP, Hyytiä P, Kiianmaa K. Enhanced Morphine-Induced Ethanol Drinking in Alcohol-Preferring Alko Alcohol Rats Sensitized to Morphine. Alcohol Clin Exp Res 2006; 30:621-9. [PMID: 16573579 DOI: 10.1111/j.1530-0277.2006.00072.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
BACKGROUND Alcohol-preferring alko alcohol (AA) rats are more susceptible to morphine-induced behavioral and neurochemical sensitization than alcohol nonpreferring alko nonalcohol (ANA) rats. Alko alcohol rats sensitized to morphine, however, do not show enhanced acquisition of ethanol drinking. The purpose of the present study was to clarify further interactions between morphine-induced behavioral sensitization and voluntary ethanol drinking in the AA rats. METHODS Alko alcohol rats drinking ethanol in a limited 6-hour access paradigm were sensitized to morphine with repeated injections of morphine (5-15 mg/kg). Injection days alternated with days of ethanol access. Controls had access only to water and/or were given injections of saline. After a 5-day washout period from ethanol and morphine, the rats were challenged with morphine or saline and subsequent ethanol drinking or locomotor activity was recorded. RESULTS Ethanol intake was suppressed during the repeated treatment with morphine, and the morphine-treated rats did not differ in ethanol intake from the controls when given access to ethanol after the washout. Intake of ethanol was, however, increased when the rats were challenged with morphine [1 or 10 mg/kg, subcutaneously (s.c.)], while in the controls an increase in ethanol intake was seen only after 1 mg/kg morphine. Sensitization to the locomotor stimulating effects of morphine was revealed in the morphine-treated rats after a challenge with morphine (3 or 10 mg/kg, s.c.). The controls that had been drinking ethanol also showed a sensitized response after morphine (3 mg/kg). CONCLUSIONS Ethanol did not interfere with the development of sensitization to morphine. Furthermore, the neuroadaptations induced by repeated exposure to ethanol were sufficient to cause behavioral cross-sensitization to morphine. Sensitization to the behavioral effects of morphine alone, however, neither enhances the reinforcing properties of voluntarily consumed ethanol nor contributes to increase in its intake. The increase in ethanol intake found after an acute dose of morphine was augmented in rats withdrawn from repeated treatment with morphine. The data suggest that the neuronal mechanisms underlying behavioral sensitization to morphine probably are distinct from those mediating reinforcement from ethanol and that the morphine-induced neuroadaptations contribute to the enhancement of increase in ethanol intake by morphine.
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Affiliation(s)
- Sami P Ojanen
- Department of Mental Health and Alcohol Research, National Public Health Institute, Helsinki, Finland
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Ojanen SP, Hyytiä P, Kiianmaa K. Behavioral sensitization and voluntary ethanol drinking in alcohol-preferring AA rats exposed to different regimens of morphine treatment. Pharmacol Biochem Behav 2005; 80:221-8. [PMID: 15680175 DOI: 10.1016/j.pbb.2004.11.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2004] [Revised: 10/19/2004] [Accepted: 11/13/2004] [Indexed: 11/29/2022]
Abstract
The purpose of the study was to investigate the effects of three different regimens of morphine treatment on subsequent voluntary ethanol drinking in alcohol-preferring AA (Alko Alcohol) rats. The rats were given morphine subcutaneously either intermittently on alternating days (15 x 10 mg/kg or 5 x 5-20 mg/kg in escalating doses) or subchronically on four consecutive days (3-20 mg/kg/d). Horizontal locomotor activity was monitored after challenges with additional morphine injections (3 mg/kg) ten days and six weeks after termination of the pretreatment to test if behavioral sensitization was induced by repeated morphine administration. Both intermittent pretreatments induced sensitized locomotor response after the first challenge, whereas subchronic injections did not. After the challenge the rats were given a free choice between tap water and 10% (v/v) ethanol solution for four weeks. The rats pretreated and challenged with morphine did not differ significantly in the acquisition of ethanol drinking from the saline-treated controls. In contrast, ethanol drinking was impaired during the first week of ethanol access in the saline-treated rats given a single morphine injection. The second morphine challenge given after the ethanol-drinking phase did not reveal sensitization in any of the groups. The results suggest that pattern of morphine administration rather than the dose or number of exposures to the drug is the most important factor in induction of behavioral sensitization, and that exposure to ethanol may interfere with this process. They also support earlier findings showing that acute morphine may suppress voluntary ethanol drinking, but failed to provide clear evidence for behavioral sensitization to morphine contributing to predilection towards ethanol in AA rats.
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Affiliation(s)
- Sami P Ojanen
- Department of Mental Health and Alcohol Research, National Public Health Institute, POB 33, 00251 Helsinki, Finland
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Abstract
This paper is the 26th consecutive installment of the annual review of research concerning the endogenous opioid system, now spanning over a quarter-century of research. It summarizes papers published during 2003 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (Section 2), and the roles of these opioid peptides and receptors in pain and analgesia (Section 3); stress and social status (Section 4); tolerance and dependence (Section 5); learning and memory (Section 6); eating and drinking (Section 7); alcohol and drugs of abuse (Section 8); sexual activity and hormones, pregnancy, development and endocrinology (Section 9); mental illness and mood (Section 10); seizures and neurologic disorders (Section 11); electrical-related activity and neurophysiology (Section 12); general activity and locomotion (Section 13); gastrointestinal, renal and hepatic functions (Section 14); cardiovascular responses (Section 15); respiration and thermoregulation (Section 16); and immunological responses (Section 17).
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Affiliation(s)
- Richard J Bodnar
- Department of Psychology and Neuropsychology, Doctoral Sub-Program, Queens College, City University of New York, 65-30 Kissena Blvd., Flushing, NY 11367, USA.
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