1
|
Rodrigues RF, Fulco BCW, Nogueira CW. m-CF 3-substituted diphenyl diselenide attenuates all phases of morphine-induced behavioral locomotor sensitization in mice. J Trace Elem Med Biol 2022; 69:126889. [PMID: 34798514 DOI: 10.1016/j.jtemb.2021.126889] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Revised: 09/12/2021] [Accepted: 10/28/2021] [Indexed: 11/24/2022]
Abstract
BACKGROUND Behavioral sensitization, thought to underlie some aspects of drug dependence, is typically measured as increased locomotion in response to repeated administration of a drug. The study aimed to investigate the (m-CF3-PhSe)2 effects on the acquisition, withdrawal, and re-exposure phases of morphine-induced behavioral locomotor sensitization. METHODS Swiss male mice were treated with saline or morphine at 10 mg/kg twice a day for 3 days; those of the morphine group were kept in the morphine withdrawal period (5 days). On day 9, mice were re-exposed to morphine. (m-CF3-PhSe)2 (10 mg/kg) or vehicle was administered at all phases of morphine protocol, and mice performed locomotor activity test. Oxidative stress markers and the levels of opioid, dopamine, and glutamate receptors were determined in samples of the cerebral cortex. (m-CF3-PhSe)2 administered at all phases of protocol attenuated morphine-induced locomotor sensitization. RESULTS Mice exposed to morphine showed reduced weight gain and increased locomotor activity, but (m-CF3-PhSe)2 treatment attenuates the weight gain and behavioral hyperlocomotion effects. (m-CF3-PhSe)2, independent of the administration phase, modulated the increase of opioidergic (MOR, DOR, KOR) and glutamatergic (NMDA 2A and 2B) protein contents and attenuated redox imbalance in the cerebral cortex of mice exposed to morphine. However, (m-CF3-PhSe)2 did not modulate cortical protein levels of dopaminergic (D1 and D2) receptors in the acquisition phase of morphine-induced locomotor sensitization protocol. CONCLUSION (m-CF3-PhSe)2 was effective against the behavioral and molecular alterations caused by morphine at all phases of locomotor sensitization.
Collapse
Affiliation(s)
- Renata F Rodrigues
- Departamento de Bioquímica e Biologia Molecular, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, Santa Maria, Brazil
| | - Bruna C W Fulco
- Departamento de Bioquímica e Biologia Molecular, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, Santa Maria, Brazil
| | - Cristina W Nogueira
- Departamento de Bioquímica e Biologia Molecular, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, Santa Maria, Brazil.
| |
Collapse
|
2
|
Kou X, Xian J, Huang Z, Tao Y, Lin Y, Qin C, Wu H, Chang L, Luo C, Zhu D. Disrupting the Interaction of nNOS with CAPON Prevents the Reinstatement of Morphine Conditioned Place Preference. Cereb Cortex 2021; 32:569-582. [PMID: 34297798 DOI: 10.1093/cercor/bhab234] [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: 02/08/2021] [Revised: 06/19/2021] [Accepted: 06/21/2021] [Indexed: 11/12/2022] Open
Abstract
Drug abuse is a dramatic challenge for the whole society because of high relapse rate. Environmental cues are crucial for the preference memory of drug abuse. Extinction therapy has been developed to inhibit the motivational effect of drug cues to prevent the reinstatement of morphine abuse. However, extinction therapy alone only forms a new kind of unstable inhibitory memory. We found that morphine conditioned place preference (CPP) extinction training increased the association of nitric oxide synthase (nNOS) with its carboxy-terminal PDZ ligand (CAPON) in the dorsal hippocampus (dHPC) significantly and blocking the morphine-induced nNOS-CAPON association using Tat-CAPON-12C during and after extinction training reversed morphine-induced hippocampal neuroplasticity defect and prevented the reinstatement and spontaneous recovery of morphine CPP. Moreover, in the hippocampal selective ERK2 knock-out or nNOS knockout mice, the effect of Tat-CAPON-12C on the reinstatement of morphine CPP and hippocampal neuroplasticity disappeared, suggesting ERK2 is necessary for the effects of Tat-CAPON-12C. Together, our findings suggest that nNOS-CAPON interaction in the dHPC may affect the consolidation of morphine CPP extinction and dissociating nNOS-CAPON prevents the reinstatement and spontaneous recovery of morphine CPP, possibly through ERK2-mediated neuroplasticity and extinction memory consolidation, offering a new target to prevent the reinstatement of drug abuse.
Collapse
Affiliation(s)
- Xiaolin Kou
- Department of Pharmacology, School of Pharmacy, Nanjing Medical University, Nanjing 211166, China.,Jiangsu Simovay Pharmaceutical Co., Ltd., Nanjing 210042, China
| | - Jiayun Xian
- Department of Pharmacology, School of Pharmacy, Nanjing Medical University, Nanjing 211166, China
| | - Zhenquan Huang
- Department of Pharmacology, School of Pharmacy, Nanjing Medical University, Nanjing 211166, China
| | - Yan Tao
- Department of Pharmacology, School of Pharmacy, Nanjing Medical University, Nanjing 211166, China
| | - Yuhui Lin
- Department of Pharmacology, School of Pharmacy, Nanjing Medical University, Nanjing 211166, China
| | - Cheng Qin
- Department of Pharmacology, School of Pharmacy, Nanjing Medical University, Nanjing 211166, China
| | - Haiyin Wu
- Department of Pharmacology, School of Pharmacy, Nanjing Medical University, Nanjing 211166, China
| | - Lei Chang
- Department of Pharmacology, School of Pharmacy, Nanjing Medical University, Nanjing 211166, China
| | - Chunxia Luo
- Department of Pharmacology, School of Pharmacy, Nanjing Medical University, Nanjing 211166, China
| | - Dongya Zhu
- Department of Pharmacology, School of Pharmacy, Nanjing Medical University, Nanjing 211166, China.,Institution of Stem Cells and Neuroregeneration, Nanjing Medical University, Nanjing 211166, China.,Guangdong-Hong Kong-Macao Greater Bay Area Center for Brain Science and Brain-Inspired Intelligence, Guangzhou 510507, China
| |
Collapse
|
3
|
Temporal parameters of enhanced opioid reward after initial opioid exposure in rats. Psychopharmacology (Berl) 2021; 238:725-734. [PMID: 33410983 PMCID: PMC7914195 DOI: 10.1007/s00213-020-05725-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Accepted: 11/16/2020] [Indexed: 10/22/2022]
Abstract
RATIONALE Mu opioid receptor agonists are indispensable for the treatment of pain, but clinical use carries the inherent risk of transition from effective treatment to abuse. Abuse potential appears to increase rapidly during periods of initial opioid exposure in humans, and this increase in opioid reward during initial opioid exposure can be modeled in rats using an intracranial self-stimulation (ICSS) procedure. OBJECTIVES The goal of the present study was to examine temporal parameters of this phenomenon. METHODS Adult male Sprague-Dawley rats responded for electrical brain stimulation using a frequency-rate ICSS procedure. In the first experiment, rats received daily morphine injections for 6 days, and morphine effects on ICSS were re-determined 1 day, 1 week, or 1 month after the repeated morphine treatment regimen to evaluate the persistence of enhanced opioid reward. In the second experiment, rats received six repeated morphine injections with different interdose intervals (two per day, one per day, every other day, every fourth day), and morphine effects were re-determined 1 day after the last dose to determine dosing frequencies sufficient to produce enhanced opioid reward. RESULTS Results of the first experiment indicated that enhanced opioid reward was greatest 1 day after the morphine treatment regimen and completely dissipated after 4 weeks. The second experiment indicated that all dosing frequencies tested were sufficient to produce enhanced reward. CONCLUSIONS Taken together, these results suggest that enhancement of opioid reward after initial opioid exposure is relatively transient but can be produced by a range of different dosing frequencies.
Collapse
|
4
|
Prenatal Opioid Exposure Enhances Responsiveness to Future Drug Reward and Alters Sensitivity to Pain: A Review of Preclinical Models and Contributing Mechanisms. eNeuro 2020; 7:ENEURO.0393-20.2020. [PMID: 33060181 PMCID: PMC7768284 DOI: 10.1523/eneuro.0393-20.2020] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Revised: 10/01/2020] [Accepted: 10/05/2020] [Indexed: 12/21/2022] Open
Abstract
The opioid crisis has resulted in an unprecedented number of neonates born with prenatal opioid exposure (POE); however, the long-term effects of POE on offspring behavior and neurodevelopment remain relatively unknown. The advantages and disadvantages of the various preclinical POE models developed over the last several decades are discussed in the context of clinical and translational relevance. Although considerable and important variability exists among preclinical models of POE, the examination of these preclinical models has revealed that opioid exposure during the prenatal period contributes to maladaptive behavioral development as offspring mature including an altered responsiveness to rewarding drugs and increased pain response. The present review summarizes key findings demonstrating the impact of POE on offspring drug self-administration (SA), drug consumption, the reinforcing properties of drugs, drug tolerance, and other reward-related behaviors such as hypersensitivity to pain. Potential underlying molecular mechanisms which may contribute to this enhanced addictive phenotype in POE offspring are further discussed with special attention given to key brain regions associated with reward including the striatum, prefrontal cortex (PFC), ventral tegmental area (VTA), hippocampus, and amygdala. Improvements in preclinical models and further areas of study are also identified which may advance the translational value of findings and help address the growing problem of POE in clinical populations.
Collapse
|
5
|
Formation of a morphine-conditioned place preference does not change the size of evoked potentials in the ventral hippocampus-nucleus accumbens projection. Sci Rep 2019; 9:5206. [PMID: 30914714 PMCID: PMC6435809 DOI: 10.1038/s41598-019-41568-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Accepted: 02/27/2019] [Indexed: 12/26/2022] Open
Abstract
In opioid addiction, cues and contexts associated with drug reward can be powerful triggers for drug craving and relapse. The synapses linking ventral hippocampal outputs to medium spiny neurons of the accumbens may be key sites for the formation and storage of associations between place or context and reward, both drug-related and natural. To assess this, we implanted rats with electrodes in the accumbens shell to record synaptic potentials evoked by electrical stimulation of the ventral hippocampus, as well as continuous local-field-potential activity. Rats then underwent morphine-induced (10 mg/kg) conditioned-place-preference training, followed by extinction. Morphine caused an acute increase in the slope and amplitude of accumbens evoked responses, but no long-term changes were evident after conditioning or extinction of the place preference, suggesting that the formation of this type of memory does not lead to a net change in synaptic strength in the ventral hippocampal output to the accumbens. However, analysis of the local field potential revealed a marked sensitization of theta- and high-gamma-frequency activity with repeated morphine administration. This phenomenon may be linked to the behavioral changes—such as psychomotor sensitization and the development of drug craving—that are associated with chronic use of addictive drugs.
Collapse
|
6
|
Pfaus JG, Scardochio T, Parada M, Gerson C, Quintana GR, Coria-Avila GA. Do rats have orgasms? SOCIOAFFECTIVE NEUROSCIENCE & PSYCHOLOGY 2016; 6:31883. [PMID: 27799081 PMCID: PMC5087696 DOI: 10.3402/snp.v6.31883] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Revised: 06/29/2016] [Accepted: 06/29/2016] [Indexed: 12/23/2022]
Abstract
BACKGROUND Although humans experience orgasms with a degree of statistical regularity, they remain among the most enigmatic of sexual responses; difficult to define and even more difficult to study empirically. The question of whether animals experience orgasms is hampered by similar lack of definition and the additional necessity of making inferences from behavioral responses. METHOD Here we define three behavioral criteria, based on dimensions of the subjective experience of human orgasms described by Mah and Binik, to infer orgasm-like responses (OLRs) in other species: 1) physiological criteria that include pelvic floor and anal muscle contractions that stimulate seminal emission and/or ejaculation in the male, or that stimulate uterine and cervical contractions in the female; 2) short-term behavioral changes that reflect immediate awareness of a pleasurable hedonic reward state during copulation; and 3) long-term behavioral changes that depend on the reward state induced by the OLR, including sexual satiety, the strengthening of patterns of sexual arousal and desire in subsequent copulations, and the generation of conditioned place and partner preferences for contextual and partner-related cues associated with the reward state. We then examine whether physiological and behavioral data from observations of male and female rats during copulation, and in sexually-conditioned place- and partner-preference paradigms, are consistent with these criteria. RESULTS Both male and female rats display behavioral patterns consistent with OLRs. CONCLUSIONS The ability to infer OLRs in rats offers new possibilities to study the phenomenon in neurobiological and molecular detail, and to provide both comparative and translational perspectives that would be useful for both basic and clinical research.
Collapse
Affiliation(s)
- James G Pfaus
- Department of Psychology, Center for Studies in Behavioral Neurobiology, Concordia University, Montréal, QC, Canada;
| | - Tina Scardochio
- Department of Psychology, Center for Studies in Behavioral Neurobiology, Concordia University, Montréal, QC, Canada
| | - Mayte Parada
- Department of Psychology, Center for Studies in Behavioral Neurobiology, Concordia University, Montréal, QC, Canada
- Laboratory for the Biopsychosocial Study of Sexuality, Department of Psychology, McGill University, Montréal, QC, Canada
- Montréal Neurological Institute, McGill University, Montréal, QC, Canada
| | - Christine Gerson
- Department of Psychology, Center for Studies in Behavioral Neurobiology, Concordia University, Montréal, QC, Canada
| | - Gonzalo R Quintana
- Department of Psychology, Center for Studies in Behavioral Neurobiology, Concordia University, Montréal, QC, Canada
| | - Genaro A Coria-Avila
- Centro de Investigaciones Cerebrales, Universidad Veracruzana, Xalapa, VER, México
| |
Collapse
|
7
|
Camarini R, Pautassi RM. Behavioral sensitization to ethanol: Neural basis and factors that influence its acquisition and expression. Brain Res Bull 2016; 125:53-78. [PMID: 27093941 DOI: 10.1016/j.brainresbull.2016.04.006] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Revised: 04/07/2016] [Accepted: 04/08/2016] [Indexed: 12/29/2022]
Abstract
Ethanol-induced behavioral sensitization (EBS) was first described in 1980, approximately 10 years after the phenomenon was described for psychostimulants. Ethanol acts on γ-aminobutyric acid (GABA) and glutamate receptors as an allosteric agonist and antagonist, respectively, but it also affects many other molecular targets. The multiplicity of factors involved in the behavioral and neurochemical effects of ethanol and the ensuing complexity may explain much of the apparent disparate results, found across different labs, regarding ethanol-induced behavioral sensitization. Although the mesocorticolimbic dopamine system plays an important role in EBS, we provide evidence of the involvement of other neurotransmitter systems, mainly the glutamatergic, GABAergic, and opioidergic systems. This review also analyses the neural underpinnings (e.g., induction of cellular transcription factors such as cyclic adenosine monophosphate response element binding protein and growth factors, such as the brain-derived neurotrophic factor) and other factors that influence the phenomenon, including age, sex, dose, and protocols of drug administration. One of the reasons that make EBS an attractive phenomenon is the assumption, firmly based on empirical evidence, that EBS and addiction-related processes have common molecular and neural basis. Therefore, EBS has been used as a model of addiction processes. We discuss the association between different measures of ethanol-induced reward and EBS. Parallels between the pharmacological basis of EBS and acute motor effects of ethanol are also discussed.
Collapse
Affiliation(s)
- Rosana Camarini
- Departamento de Farmacologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, SP, Brazil.
| | - Ricardo Marcos Pautassi
- Instituto de Investigaciones Médicas M. y M. Ferreyra, Córdoba (IMMF-CONICET-Universidad Nacional de Córdoba), Universidad Nacional de Córdoba, Argentina
| |
Collapse
|
8
|
Epigenetically modified nucleotides in chronic heroin and cocaine treated mice. Toxicol Lett 2014; 229:451-7. [PMID: 25064621 DOI: 10.1016/j.toxlet.2014.07.023] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2014] [Revised: 07/21/2014] [Accepted: 07/22/2014] [Indexed: 12/19/2022]
Abstract
Epigenetic changes include the addition of a methyl group to the 5' carbon of the cytosine ring, known as DNA methylation, which results in the generation of the fifth DNA base, namely 5-methylcytosine. During active or passive demethylation, an intermediate modified base is formed, 5-hydroxymethylcytosine. We have currently quantified 5-methylcytosine and 5-hydroxymethylcytosine in the liver and brain of mice treated with cocaine or heroin, using liquid chromatography/tandem mass spectrometry (LC-MS/MS). Our results show that global 5-methylcytosine levels are not affected by heroin or cocaine administration, neither in the liver nor in the brain. However, 5-hydroxymethylcytosine levels are reduced in the liver following cocaine administration, while they are not affected by cocaine in the brain or by heroin administration in the liver and the brain. Elucidation of the epigenetic phenomena that takes place with respect to drug abuse and addiction, via quantitative analysis of different modified bases, may enable a better understanding of the underlying mechanisms and may lead to more personalized and effective treatment options.
Collapse
|
9
|
Teodorov E, Camarini R, Bernardi M, Felicio L. Treatment with steroid hormones and morphine alters general activity, sexual behavior, and opioid gene expression in female rats. Life Sci 2014; 104:47-54. [DOI: 10.1016/j.lfs.2014.03.021] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2013] [Revised: 02/13/2014] [Accepted: 03/18/2014] [Indexed: 12/21/2022]
|
10
|
Influence of pre-exposure to morphine on cannabinoid-induced impairment of spatial memory in male rats. Behav Brain Res 2013; 256:157-64. [DOI: 10.1016/j.bbr.2013.07.054] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2013] [Revised: 07/28/2013] [Accepted: 07/30/2013] [Indexed: 11/23/2022]
|
11
|
Fragou D, Zanos P, Kouidou S, Njau S, Kitchen I, Bailey A, Kovatsi L. Effect of chronic heroin and cocaine administration on global DNA methylation in brain and liver. Toxicol Lett 2013; 218:260-5. [DOI: 10.1016/j.toxlet.2013.01.022] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Revised: 01/22/2013] [Accepted: 01/25/2013] [Indexed: 12/11/2022]
|
12
|
Li JX, Shah AP, Patel SK, Rice KC, France CP. Modification of the behavioral effects of morphine in rats by serotonin 5-HT₁A and 5-HT₂A receptor agonists: antinociception, drug discrimination, and locomotor activity. Psychopharmacology (Berl) 2013; 225:791-801. [PMID: 22993050 PMCID: PMC3549012 DOI: 10.1007/s00213-012-2870-2] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/16/2012] [Accepted: 08/28/2012] [Indexed: 11/29/2022]
Abstract
RATIONALE Indirect-acting serotonin (5-HT) receptor agonists can enhance the antinociceptive effects of morphine; however, the specific 5-HT receptor subtype(s) mediating this enhancement is not established. OBJECTIVE This study examined interactions between morphine and both 5-HT(1A) and 5-HT(2A) receptor agonists in rats using measures of antinociception (radiant heat tail flick and warm water tail withdrawal), drug discrimination (3.2 mg/kg morphine versus saline), and locomotion. METHODS Male Sprague-Dawley rats (n = 7-8 per group) were used to examine the effects of morphine alone and in combination with DOM (5-HT(2A) agonist) and 8-OH-DPAT (5-HT(1A) agonist). RESULTS DOM did not modify antinociceptive or discriminative stimulus effects while modestly attenuating locomotor-stimulating effects of morphine; the effect of DOM (0.32 mg/kg) on morphine-induced locomotion was prevented by the 5-HT(2A) receptor-selective antagonist MDL 100907. In contrast, 8-OH-DPAT (0.032-0.32 mg/kg) fully attenuated the antinociceptive effects (both procedures), did not modify the discriminative stimulus effects, and enhanced (0.32 mg/kg) the locomotor-stimulating effects of morphine. These effects of 8-OH-DPAT were prevented by the 5-HT(1A) receptor-selective antagonist WAY100635. CONCLUSION Agonists acting at 5-HT(1A) or 5-HT(2A) receptors do not modify all effects of mu opioid receptor agonists in a similar manner. Moreover, interactions between 5-HT and opioid receptor agonists vary significantly between rats and nonhuman primates, underscoring the value of comparing drug interactions across a broad range of conditions and in multiple species.
Collapse
Affiliation(s)
- Jun-Xu Li
- Corresponding author: Charles P France, Department of Pharmacology, The University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229-3900,
| | | | | | | | | |
Collapse
|
13
|
Smith MA, Cole KT, Iordanou JC, Kerns DC, Newsom PC, Peitz GW, Schmidt KT. The mu/kappa agonist nalbuphine attenuates sensitization to the behavioral effects of cocaine. Pharmacol Biochem Behav 2013; 104:40-6. [PMID: 23305678 DOI: 10.1016/j.pbb.2012.12.026] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/19/2012] [Revised: 12/07/2012] [Accepted: 12/28/2012] [Indexed: 02/01/2023]
Abstract
Sensitization refers to an increase in sensitivity to a drug and is believed to play a role in the etiology of substance use disorders. The purpose of the present study was to evaluate the ability of the mixed mu/kappa agonist nalbuphine to modulate sensitization to the locomotor and positive reinforcing effects of cocaine. Rats were habituated to a locomotor activity chamber and treated with saline (1.0 ml/kg, ip), cocaine (10 mg/kg, ip), or cocaine+nalbuphine (10 mg/kg, ip) every day for 10 days. Following locomotor activity testing, rats were implanted with intravenous catheters and cocaine self-administration was examined on fixed ratio (FR) and progressive ratio (PR) schedules of reinforcement. Rats treated with cocaine exhibited a progressive increase in locomotor activity over the 10-day treatment period, and this effect was significantly reduced in rats treated with cocaine+nalbuphine. In self-administration tests, rats treated with cocaine exhibited significantly higher levels of responding at a threshold dose of cocaine (0.03 mg/kg/infusion) on both FR and PR schedules than rats treated with saline. This increase in responding at a threshold dose of cocaine was blocked completely in rats treated with cocaine+nalbuphine. These data suggest that nalbuphine attenuates the development of sensitization to the behavioral effects of cocaine.
Collapse
Affiliation(s)
- M A Smith
- Department of Psychology, Davidson College, Davidson, NC 28035, USA.
| | | | | | | | | | | | | |
Collapse
|
14
|
Effects of repeated oxycodone administration on its analgesic and subjective effects in normal, healthy volunteers. Behav Pharmacol 2012; 23:271-9. [PMID: 22495183 DOI: 10.1097/fbp.0b013e3283536d6f] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Tolerance to the analgesic effects of opioids has been demonstrated in laboratory animals after repeated drug administration; yet, this effect has been studied less frequently under controlled laboratory conditions in humans. This within-subject, double-blind, placebo-controlled study was designed to determine whether tolerance developed to the analgesic, subjective, and physiological effects of the commonly prescribed opioid oxycodone when it was administered daily for 5 days. The effects of oxycodone (0, 5, and 20 mg/70 kg, orally) were compared, using a within-session cumulative dosing procedure, on the first and fifth days of the 'daily' dosing phase to assess for tolerance; active oxycodone was administered on the second and fourth days of the daily dosing phase. Changes in the effects of oxycodone were also compared when the medication was only administered on the first and the fifth day of a 5-day 'intermittent' dosing phase; placebo medication was administered on the second and fourth days of the intermittent dosing phase. A 9-day 'washout' period occurred between phases during which no medication was administered. Healthy volunteers (N=10) with no history of drug dependence or current drug use participated in this outpatient study. Analgesia was assessed using the cold pressor test, pain and drug effects were measured using a variety of questionnaires, and pupil diameter was monitored as an index of physiological effects. When administered daily, no differences were observed in oxycodone-induced analgesia between the first and the fifth days, but tolerance did develop to some of the positive subjective effects of oxycodone. In contrast, oxycodone-induced analgesia and participant ratings of some positive subjective drug effects were greater on the fifth compared with the first day of the intermittent dosing phase. No differences in the miotic effects of oxycodone between the first and the fifth days of either dosing phase were detected. Although obtained under limited experimental conditions, these findings suggest that tolerance may not develop to the analgesic effects of therapeutic doses of oxycodone under short-term daily dosing conditions, even though some of its subjective effects may decrease. These data also suggest that intermittent administration may enhance the analgesic effects of oxycodone, while also increasing some of the drug's positive subjective effects related to abuse liability.
Collapse
|
15
|
Amnesia induced by morphine in spatial memory retrieval inhibited in morphine-sensitized rats. Eur J Pharmacol 2012; 683:132-9. [DOI: 10.1016/j.ejphar.2012.02.038] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2011] [Revised: 01/20/2012] [Accepted: 02/26/2012] [Indexed: 12/17/2022]
|
16
|
Leri F, Zhou Y, Carmichael B, Cummins E, Kreek MJ. Treatment-like steady-state methadone in rats interferes with incubation of cocaine sensitization and associated alterations in gene expression. Eur Neuropsychopharmacol 2012; 22:143-52. [PMID: 21745729 PMCID: PMC3810140 DOI: 10.1016/j.euroneuro.2011.06.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2011] [Revised: 05/12/2011] [Accepted: 06/14/2011] [Indexed: 01/11/2023]
Abstract
In a previous study, steady-state methadone treatment was found to prevent associative cocaine learning, as well as related decreases in mRNA expression of preprohypocretin/preproorexin (ppHcrt) in the lateral hypothalamus (LH) and dopamine D2 receptor (DR2) in the caudate-putamen (CP), and increases in mu-opioid receptor in the ventral striatum of rats. To investigate whether the same regimen of methadone exposure could prevent the incubation of cocaine sensitization and related alterations in gene expression, male Sprague-Dawley rats received 45 mg/kg/day steady-dose "binge" cocaine administration (IP) for 14 days followed by mini-pumps releasing 30 mg/kg/day methadone (SC). After 14 days of methadone, and a subsequent 10-day drug-free period, all rats were tested for sensitization (cocaine test dose: 15 mg/kg) and brain tissue was collected to quantify mRNA expression. Rats exposed to cocaine displayed cocaine-induced stereotypy at test, as well as enhanced ppHcrt mRNA in the LH and reduced DR2 mRNA in the CP. Importantly, these alterations were significantly reduced in rats treated with methadone following cocaine. These results suggest that steady-state methadone can interfere with the incubation of neuroadaptations underlying changes in behavioral responses to cocaine and cocaine-associated stimuli, and that these effects can be observed even after withdrawal from methadone.
Collapse
|
17
|
Hadjiconstantinou M, Neff NH. Nicotine and endogenous opioids: Neurochemical and pharmacological evidence. Neuropharmacology 2011; 60:1209-20. [DOI: 10.1016/j.neuropharm.2010.11.010] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2010] [Revised: 11/03/2010] [Accepted: 11/11/2010] [Indexed: 10/18/2022]
|
18
|
Abstract
Buprenorphine, an opioid with mixed agonist-antagonist activity at classical opioid receptors, has been approved recently for the treatment of opioid dependency. Buprenorphine is also used as an analgesic. The buprenorphine dose-response curve is sometimes submaximal, or even bell-shaped, in nociceptive assays, depending upon the nature and intensity of the noxious stimulus. Moreover, buprenorphine, when administered with full agonists, such as morphine, antagonizes the action of these drugs. Partial agonism at the mu opioid receptor and, in some cases, antagonism at the kappa or delta opioid receptor have been considered as possible underlying mechanisms for the ceiling effect and bell-shaped dose-response curve of buprenorphine. While ceiling effects can be explained by partial agonist activity of buprenorphine, the bell-shaped dose-response curve cannot be a consequence of this property of the drug. Recently, buprenorphine has been shown to activate the opioid receptor-like (ORL-1; also known as NOP) receptor. Supraspinal activation of the ORL-1 receptor counteracts the antinociceptive and rewarding actions of morphine, raising the possibility that these actions of buprenorphine can also be altered by its ability to concomitantly activate the ORL-1 receptor. The use of molecular biological techniques has advanced our knowledge regarding the role of opioid receptors in modulation of pain and reward. In particular, generation of opioid receptor knockout mice has proven useful in this regard. Indeed, using knockout mice, we have recently shown that the antinociceptive effect of buprenorphine mediated primarily by the mu opioid receptor is attenuated by the ability of the drug to activate the ORL-1 receptor. Thus, the goal of this review is to provide evidence demonstrating that the ORL-1 receptor plays a functional role not only in the antinociceptive effect of buprenorphine but also in other actions of the drug as well.
Collapse
Affiliation(s)
- Kabirullah Lutfy
- Department of Pharmaceutical Sciences, Western University of Health Sciences, 309 East Second Street, Pomona, CA 91766, USA.
| | | |
Collapse
|
19
|
Shafaroodi H, Baradaran N, Moezi L, Dehpour S, Kabiri T, Dehpour AR. Morphine sensitization in the pentylenetetrazole-induced clonic seizure threshold in mice: role of nitric oxide and μ receptors. Epilepsy Behav 2011; 20:602-6. [PMID: 21419715 DOI: 10.1016/j.yebeh.2010.12.020] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/23/2010] [Revised: 09/20/2010] [Accepted: 12/15/2010] [Indexed: 10/18/2022]
Abstract
Behavioral sensitization occurs after repeated administration of μ-opioid receptor agonists following a drug-free period. It seems that the changes in dopaminergic systems induced by μ-opioid receptor agonists play a crucial role in behavioral sensitization to opioids. Nitric oxide also plays a role in some behavioral effects of morphine, including sensitization to the locomotor-stimulating effect. This study investigated whether morphine sensitization appears in seizure threshold and the possible role of μ-opioid receptor and nitric oxide in this sensitization. Sensitization was produced by daily injections of morphine (0.1, 0.5, 1, 5, 15, or 30 mg/kg), followed by a 10-day washout period. Then the challenge test was performed using morphine (0.1, 0.5, 1, 5, 15, or 30 mg/kg) in different groups. To assess clonic seizure threshold, pentylenetetrazole (PTZ) was administered intravenously. Subcutaneous administration of morphine (0.1 and 0.5 mg/kg) induced sensitization in PTZ-induced clonic seizures in mice. Intraperitoneal administration of L-NAME (20 mg/kg), a nonselective inhibitor of nitric oxide synthase, or naltrexone (10 mg/kg), an opioid receptor antagonist, along with morphine inhibited morphine-induced sensitization in PTZ-induced seizure threshold. In conclusion, at low doses, morphine induces sensitization in PTZ-induced clonic seizures in mice probably as a result of the interaction with μ-receptors and nitric oxide.
Collapse
Affiliation(s)
- Hamed Shafaroodi
- Department of Pharmacology and Toxicology, Pharmaceutical Sciences Branch and Pharmaceutical Sciences Research Centre, Islamic Azad University, Tehran, Iran
| | | | | | | | | | | |
Collapse
|
20
|
Bailey A, Metaxas A, Al-Hasani R, Keyworth HL, Forster DM, Kitchen I. Mouse strain differences in locomotor, sensitisation and rewarding effect of heroin; association with alterations in MOP-r activation and dopamine transporter binding. Eur J Neurosci 2010; 31:742-53. [PMID: 20384817 DOI: 10.1111/j.1460-9568.2010.07104.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
There is growing agreement that genetic factors play an important role in the risk to develop heroin addiction, and comparisons of heroin addiction vulnerability in inbred strains of mice could provide useful information on the question of individual vulnerability to heroin addiction. This study examined the rewarding and locomotor-stimulating effects of heroin in male C57BL/6J and DBA/2J mice. Heroin induced locomotion and sensitisation in C57BL/6J but not in DBA/2J mice. C57BL/6J mice developed conditioned place preference (CPP) to the highest doses of heroin, while DBA/2J showed CPP to only the lowest heroin doses, indicating a higher sensitivity of DBA/2J mice to the rewarding properties of heroin vs C57BL/6J mice. In order to investigate the neurobiological substrate underlying some of these differences, the effect of chronic 'intermittent' escalating dose heroin administration on the opioid, dopaminergic and stress systems was explored. Twofold higher mu-opioid receptor (MOP-r)-stimulated [35S]GTPgammaS binding was observed in the nucleus accumbens and caudate of saline-treated C57BL/6J mice compared with DBA/2J. Heroin decreased MOP-r density in brain regions of C57BL/6J mice, but not in DBA/2J. A higher density of dopamine transporters (DAT) was observed in nucleus accumbens shell and caudate of heroin-treated DBA/2J mice compared with heroin-treated C57BL/6J. There were no effects on D1 and D2 binding. Chronic heroin administration decreased corticosterone levels in both strains with no effect of strain. These results suggest that genetic differences in MOP-r activation and DAT expression may be responsible for individual differences in vulnerability to heroin addiction.
Collapse
Affiliation(s)
- Alexis Bailey
- Faculty of Health and Medical Sciences, AY Building, University of Surrey, Guildford, Surrey GU2 7XH, UK.
| | | | | | | | | | | |
Collapse
|
21
|
Nicotine withdrawal and kappa-opioid receptors. Psychopharmacology (Berl) 2010; 210:221-9. [PMID: 19806344 DOI: 10.1007/s00213-009-1674-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/14/2009] [Accepted: 09/08/2009] [Indexed: 10/20/2022]
Abstract
RATIONALE The synthesis and release of dynorphin are increased in the caudate/putamen (CPU) and nucleus accumbens (NAc) of nicotine-withdrawn mice, suggesting a role in the nicotine abstinence syndrome. OBJECTIVES This study aims to investigate the consequences of enhanced dynorphinergic activity on kappa-opioid receptor (KOPr) expression, coupling, and function in CPU and NAc following chronic nicotine administration and withdrawal. METHODS Mice were injected with nicotine-free base 2 mg/kg, or saline, sc, four times daily for 14 days and experiments performed at 24, 48, and 72 h after drug discontinuation. KOPr binding and mRNA were evaluated by [(3)H]-U69,593 autoradiography and in situ hybridization. KOPr coupling and function were investigated by agonist (U69-593)-stimulated [(35)S]GTPgammaS binding autoradiography and inhibition of adenylyl cyclase activity. RESULTS KOPr binding density and mRNA in CPU and NAc were unaltered during nicotine withdrawal; however, KPOr mRNA was increased in midbrain. U69,593-stimulated [(35)S]GTPgammaS binding was attenuated in both striatal regions, especially in NAc. In NAc shell and core, stimulated [(35)S]GTPgammaS binding was significantly decreased by 24 h and further declined over the 72 h observation period. In CPU, significant changes were observed only at 72 h. Basal adenylyl cyclase activity decreased early during nicotine withdrawal and recovered by 48 h. Stimulation with U69,593 failed to inhibit adenylyl cyclase activity at all times studied. CONCLUSIONS These observations suggest that KOPr coupling and function are impaired in NAc and CPU during nicotine withdrawal, and imply receptor desensitization. KOPr desensitization might be a mechanism to ameliorate aversive behavioral symptoms, as nicotine withdrawal evolves.
Collapse
|
22
|
|
23
|
Smith MA, Greene-Naples JL, Lyle MA, Iordanou JC, Felder JN. The effects of repeated opioid administration on locomotor activity: I. Opposing actions of mu and kappa receptors. J Pharmacol Exp Ther 2009; 330:468-75. [PMID: 19403853 DOI: 10.1124/jpet.108.150011] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Repeated administration of many addictive drugs leads to a progressive increase in their locomotor effects. This increase in locomotor activity often develops concomitantly with increases in their positive-reinforcing effects, which are believed to contribute to the etiology of substance use disorders. The purpose of this study was to examine changes in sensitivity to the locomotor effects of opioids after their repeated administration and to determine the role of mu and kappa receptors in mediating these effects. Separate groups of rats were treated with opioid receptor agonists and antagonists every other day for 10 days, and changes in locomotor activity were measured. Repeated administration of the mu agonists, morphine and buprenorphine, produced a progressive increase in locomotor activity during the treatment period, and this effect was blocked by coadministration of the opioid antagonist naltrexone. The kappa agonist spiradoline decreased locomotor activity when administered alone and blocked the progressive increase in locomotor activity produced by morphine. The ability of spiradoline to block morphine-induced increases in locomotor activity was itself blocked by pretreatment with the kappa antagonist nor-binaltorphimine. Repeated administration of high doses, but not low or moderate doses, of the mixed mu/kappa agonists butorphanol, nalbuphine, and nalorphine produced a progressive increase in locomotor activity during the treatment period. Doses of butorphanol, nalbuphine, and nalorphine that failed to produce a progressive increase in locomotor activity when administered alone did so when subjects were pretreated with nor-binaltorphimine. These findings suggest that mu and kappa receptors have functionally opposing effects on opioid-mediated locomotor activity and sensitization-related processes.
Collapse
Affiliation(s)
- Mark A Smith
- Department of Psychology and Program in Neuroscience, Davidson College, Davidson, North Carolina, USA
| | | | | | | | | |
Collapse
|
24
|
Smith MA, Greene-Naples JL, Felder JN, Iordanou JC, Lyle MA, Walker KL. The effects of repeated opioid administration on locomotor activity: II. Unidirectional cross-sensitization to cocaine. J Pharmacol Exp Ther 2009; 330:476-86. [PMID: 19403852 DOI: 10.1124/jpet.108.150037] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Sensitization refers to an increase in sensitivity to the effects of a drug and is believed to play a role in the etiology of substance use disorders. Cross-sensitization has been observed between drugs from different pharmacological classes and may play a role in the escalation of drug use in polydrug-abusing populations. The purpose of this study was to examine cross-sensitization between opioids and cocaine and to determine the extent to which cross-sensitization is mediated by an opioid's selectivity for mu, kappa, and delta receptors. Separate groups of rats were treated with opioid receptor agonists and antagonists every other day for 10 days, and the locomotor effects of cocaine were tested 8 days later. The mu agonists, morphine and buprenorphine, and the delta agonist, BW373U86 [(+/-)-4-[(R(*))-[(2S(*),5R(*))-2,5-dimethyl-4-(2-propenyl)-1-piperazinyl]-(3-hydroxyphenyl)methyl]-N,N-diethylbenzamide hydrochloride], produced cross-sensitization to cocaine, such that repeated administration of these drugs over a 10-day period significantly enhanced cocaine's locomotor effects when tested later. Coadministration of the opioid antagonist naltrexone prevented morphine and buprenorphine from producing cross-sensitization. Coadministration of naltrexone, but not the delta antagonist naltrindole, also prevented BW373U86 from producing cross-sensitization. The kappa agonist spiradoline failed to produce cross-sensitization, but coadministration of spiradoline prevented morphine and buprenorphine from producing cross-sensitization. The ability of spiradoline to block cross-sensitization was itself blocked by the kappa antagonist nor-binaltorphimine. The mixed mu/kappa opioids butorphanol, nalbuphine, and nalorphine did not produce cross-sensitization under any condition examined. These data indicate that agonist activity at mu receptors positively modulates cross-sensitization between opioids and cocaine, whereas agonist activity at kappa receptors negatively modulates this effect.
Collapse
Affiliation(s)
- Mark A Smith
- Department of Psychology, Davidson College, Davidson, North Carolina 28035-7037, USA.
| | | | | | | | | | | |
Collapse
|
25
|
Sahraei H, Etemadi L, Rostami P, Pourmotabbed A, Zarrindast MR, Shams J, Ghoshooni H, Noroozzadeh A, Esfandiari B, Salimi SH. GABAB receptors within the ventral tegmental area are involved in the expression and acquisition of morphine-induced place preference in morphine-sensitized rats. Pharmacol Biochem Behav 2009; 91:409-16. [DOI: 10.1016/j.pbb.2008.08.015] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/17/2007] [Revised: 07/23/2008] [Accepted: 08/12/2008] [Indexed: 11/24/2022]
|
26
|
Sepehrizadeh Z, Bahrololoumi Shapourabadi M, Ahmadi S, Hashemi Bozchlou S, Zarrindast MR, Sahebgharani M. DECREASED AMPA GLuR2, BUT NOT GLuR3, mRNA EXPRESSION IN RAT AMYGDALA AND DORSAL HIPPOCAMPUS FOLLOWING MORPHINE-INDUCED BEHAVIOURAL SENSITIZATION. Clin Exp Pharmacol Physiol 2008; 35:1321-30. [DOI: 10.1111/j.1440-1681.2008.05004.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
27
|
Bailey A, Metaxas A, Yoo JH, McGee T, Kitchen I. Decrease of D2 receptor binding but increase in D2-stimulated G-protein activation, dopamine transporter binding and behavioural sensitization in brains of mice treated with a chronic escalating dose 'binge' cocaine administration paradigm. Eur J Neurosci 2008; 28:759-70. [PMID: 18671743 DOI: 10.1111/j.1460-9568.2008.06369.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Understanding the neurobiology of the transition from initial drug use to excessive drug use has been a challenge in drug addiction. We examined the effect of chronic 'binge' escalating dose cocaine administration, which mimics human compulsive drug use, on behavioural responses and the dopaminergic system of mice and compared it with a chronic steady dose (3 x 15 mg/kg/day) 'binge' cocaine administration paradigm. Male C57BL/6J mice were injected with saline or cocaine in an escalating dose paradigm for 14 days. Locomotor and stereotypy activity were measured and quantitative autoradiographic mapping of D(1) and D(2) receptors, dopamine transporters and D(2)-stimulated [(35)S]GTPgammaS binding was performed in the brains of mice treated with this escalating and steady dose paradigm. An initial sensitization to the locomotor effects of cocaine followed by a dose-dependent increase in the duration of the locomotor effect of cocaine was observed in the escalating but not the steady dose paradigm. Sensitization to the stereotypy effect of cocaine and an increase in cocaine-induced stereotypy score was observed from 3 x 20 to 3 x 25 mg/kg/day cocaine. There was a significant decrease in D(2) receptor density, but an increase in D(2)-stimulated G-protein activity and dopamine transporter density in the striatum of cocaine-treated mice, which was not observed in our steady dose paradigm. Our results document that chronic 'binge' escalating dose cocaine treatment triggers profound behavioural and neurochemical changes in the dopaminergic system, which might underlie the transition from drug use to compulsive drug use associated with addiction, which is a process of escalation.
Collapse
Affiliation(s)
- A Bailey
- Faculty of Health and Medical Sciences, AY Building, University of Surrey, Guildford, Surrey GU2 7XH, UK.
| | | | | | | | | |
Collapse
|
28
|
Isola R, Zhang H, Tejwani GA, Neff NH, Hadjiconstantinou M. Dynorphin and prodynorphin mRNA changes in the striatum during nicotine withdrawal. Synapse 2008; 62:448-55. [PMID: 18361441 DOI: 10.1002/syn.20515] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Nicotine withdrawal causes somatic and negative affective symptoms that contribute to relapse and continued tobacco smoking. So far, the neuronal substrates involved are not fully understood, and an opioid role has been suggested. In this regard, the opioid dynorphin (Dyn) is of interest as it produces aversive states and has been speculated to play a role in the nicotine behavioral syndrome. These studies explore whether Dyn metabolism is altered during withdrawal following chronic administration of nicotine. Mice were administered nicotine, 2 mg/kg, s.c., four times daily for 14 days, and Dyn and prodynorphin (PD) mRNA estimated in selective brain regions at various times (30 min to 96 h) following drug discontinuation. The content of Dyn, estimated by RIA, was decreased in the striatum for a protracted time, from 30 min to over 72 h. In contrast, the mRNA for PD, evaluated by Northern blot, was elevated, appearing by 8 h and lasting over 96 h. Dyn was decreased in both ventral and dorsal striatum, and PD mRNA was differentially increased in the two striatal compartments as demonstrated by in situ hybridization. PD message was predominantly augmented in the nucleus accumbens, rostral pole, core, and shell, and the medial aspects of caudate/putamen. We interpret these data to indicate increased activity of striatal, particularly accumbal, dynorphinergic neurons during nicotine withdrawal resulting in enhanced peptide release and compensatory synthesis. Heightened dynorphinergic tone might be responsible, in part, for the emergence of the negative affective states observed during nicotine withdrawal.
Collapse
Affiliation(s)
- Raffaella Isola
- Department of Psychiatry, College of Medicine, Ohio State University, Columbus, Ohio 43210, USA
| | | | | | | | | |
Collapse
|
29
|
Kotlinska J, Pachuta A, Silberring J. Neuropeptide FF (NPFF) reduces the expression of cocaine-induced conditioned place preference and cocaine-induced sensitization in animals. Peptides 2008; 29:933-9. [PMID: 18295932 DOI: 10.1016/j.peptides.2008.01.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/04/2007] [Revised: 01/10/2008] [Accepted: 01/11/2008] [Indexed: 10/22/2022]
Abstract
The endogenous brain opioid system is believed to play an important role in mediating reward mechanisms. Opioid innervation is high in many limbic regions and reinforcing actions of many drugs of abuse, including cocaine, are thought to be mediated via endogenous opioid system. The aim of the present study was to indicate whether the anti-opioid peptide, neuropeptide FF (NPFF; FLFQPQRF-NH2) was able to modify the rewarding effect of cocaine (5 mg/kg) measured in the expression of conditioned place preference (CPP) test in rats and the expression of sensitization to hyperlocomotor effect of cocaine (10 mg/kg) in mice. Our results indicate that NPFF (5, 10, and 20 nmol) given intracerebroventricularly (i.c.v.) inhibited the expression of cocaine-induced CPP at the dose of 10 nmol (P<0.01) and 20 nmol (P<0.001). Moreover, NPFF inhibited the expression of cocaine-induced sensitization to its hyperlocomotor effect at the dose of 20 nmol (P<0.05) and acute hyperlocomotor effect of cocaine at doses of 5 nmol (P<0.01), 10 nmol (P<0.01), and 20 nmol (P<0.05). Our study suggests that NPFF may participate in a rewarding effect of cocaine measured in the CPP paradigm. On the other hand, our experiments indicate that NPFF is involved in the mechanism of expression of sensitization to cocaine hyperlocomotion but this effect seems to be non-specific because NPFF also inhibited the acute hyperlocomotor effect of cocaine.
Collapse
Affiliation(s)
- Jolanta Kotlinska
- Department of Pharmacology and Pharmacodynamics, Medical University School, Staszica 4, 20-081 Lublin, Poland.
| | | | | |
Collapse
|
30
|
Sepehrizadeh Z, Sahebgharani M, Ahmadi S, Shapourabadi MB, Bozchlou SH, Zarrindast MR. Morphine-induced behavioral sensitization increased the mRNA expression of NMDA receptor subunits in the rat amygdala. Pharmacology 2008; 81:333-43. [PMID: 18391508 DOI: 10.1159/000122959] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2007] [Accepted: 12/02/2007] [Indexed: 01/28/2023]
Abstract
This study was designed to evaluate the effect of repeated morphine treatment on rat behavioral responses. In the genetic section, the mRNA expression of NMDA receptor subunits (NR1 and NR2A) was measured in certain areas of the male rat brain (striatum, prefrontal cortex, hippocampus, hypothalamus and amygdala). In the behavioral section, the effect of repeated morphine treatment on animal models such as locomotion, oral stereotypy, and state-dependent memory in a passive avoidance test was evaluated in the presence or absence of MK801 (NMDA receptor antagonist). Our results showed that chronic morphine treatment, followed by a 7-day (but not 24-hour) washout period, potentiated the effect of test doses of morphine, which is referred to as behavioral sensitization. Meanwhile, pretreatment of animals with MK801 (0.1 and 0.25 mg/kg), 30 min before a test dose of morphine (5 mg/kg), failed to attenuate the locomotion and oral stereotypy in the behavioral sensitization state. Interestingly, a higher dose of MK801 (0.25 mg/kg) decreased memory retrieval induced by morphine (2.5 mg/kg) in state-dependent memory. This effect may be due to the intrinsic motor enhancer property of higher doses of MK801, rather than the blockade of NMDA receptors. It can be concluded that MK801 does not affect morphine-induced behavioral sensitization in the expression phase. In the genetic section of the study, results of quantitative real-time RT-PCR clearly indicated that morphine sensitization increased the expression of NMDA receptor subunits mRNA in the amygdala (NR1 by 104% and NR2A by 85%), while the other areas of the brain were unaffected. Maenwhile, no change in the mRNA levels was observed in non-sensitized animals (chronic morphine treatment followed by a 24-hour washout period). In summary, the present study indicates that repeated morphine treatment followed by long-term (7-day washout) induces behavioral sensitization and causes a delayed increase in mRNA levels of NMDA receptor subunits in the rat amygdala. Meanwhile, it has previously been reported that the amygdala is involved in behavioral sensitization. Thus, it can be concluded that the increase in NMDA receptor expression is associated with morphine-induced behavioral sensitization.
Collapse
Affiliation(s)
- Zargham Sepehrizadeh
- Department of Pharmaceutical Biotechnology, Faculty of Pharmacy, University of Tehran, Tehran, Iran
| | | | | | | | | | | |
Collapse
|
31
|
Boehm SL, Goldfarb KJ, Serio KM, Moore EM, Linsenbardt DN. Does context influence the duration of locomotor sensitization to ethanol in female DBA/2J mice? Psychopharmacology (Berl) 2008; 197:191-201. [PMID: 18049811 PMCID: PMC2279101 DOI: 10.1007/s00213-007-1022-6] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/13/2006] [Accepted: 11/13/2007] [Indexed: 11/29/2022]
Abstract
RATIONALE Repeated exposure to ethanol produces a progressive increase in locomotor sensitivity, referred to as locomotor sensitization. Locomotor sensitization may persist for some time after termination of repeated drug exposure, and context appears to facilitate expression of the behavioral phenomenon. However, many unanswered questions remain concerning the persistence of and degree to which context influences locomotor sensitization to alcohol (ethanol). OBJECTIVES The goal of the present work was to determine the duration of locomotor sensitization to ethanol and the degree to which context dependence positively influences the induction, expression, and persistence of the behavioral phenomenon in female DBA/2J mice. MATERIALS AND METHODS Sensitized (with or without ethanol-paired exposure to the testing chamber) and non-sensitized saline control mice were left undisturbed in their home cages until subsequent ethanol challenge and testing in the locomotor activity testing chambers 7, 14, 21, 28, 42, 56, and/or 70 days after cessation of the ethanol sensitization procedure. Retro-orbital sinus bloods were sampled to determine whether the sensitization procedure had altered blood ethanol clearance rates. RESULTS Locomotor sensitization persisted through post-sensitization day 14, and repeated paring of the drug and testing context prolonged the expression of this phenomenon through at least post-sensitization day 28. Blood ethanol concentrations did not differ. CONCLUSIONS Locomotor sensitization to ethanol persists for some time after cessation of repeated ethanol exposure, and the association of contextual cues with the ethanol experience lengthens this persistence. The present data lay the groundwork for investigations into the neuroadaptive changes that underlie locomotor sensitization to ethanol in mice.
Collapse
Affiliation(s)
- Stephen L Boehm
- Behavioral Neuroscience, Department of Psychology, Binghamton University, Binghamton, NY 13902, USA.
| | | | | | | | | |
Collapse
|
32
|
Triemstra JL, Sato SM, Wood RI. Testosterone and nucleus accumbens dopamine in the male Syrian hamster. Psychoneuroendocrinology 2008; 33:386-94. [PMID: 18249072 PMCID: PMC2275113 DOI: 10.1016/j.psyneuen.2007.12.006] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/19/2007] [Revised: 12/14/2007] [Accepted: 12/17/2007] [Indexed: 11/15/2022]
Abstract
Most drugs of abuse increase dopamine (DA) in nucleus accumbens (Acb). However, the effects of anabolic androgenic steroids (AAS) on Acb DA have not been examined. We determined the effects of subcutaneous (sc) testosterone (T) on Acb DA in male hamsters. The effects of sc amphetamine were also examined for comparison. In addition, Acb DA was evaluated during intracerebroventricular (ICV) T infusion, designed to mimic T intake during ICV T self-administration in drug-naïve and drug-preexposed animals. Acb DA was measured using in vivo microdialysis and HPLC-EC. T (7.5 or 37.5 mg/kg), amphetamine (1 or 5 mg/kg), or vehicle was injected sc and Acb DA monitored for 4h. In the ICV experiment, T (1 or 2 microg/infusion) or vehicle was infused ICV every 6 min for 4h and Acb DA monitored. ICV T preexposure was accomplished by repeating the same ICV T infusion (1 microg/infusion) daily for 14 days, and T infusion was accompanied by microdialysis on 15th day. Neither sc nor ICV T administration increased Acb DA. At high dose (2 microg/infusion), ICV T decreased Acb DA. Likewise, daily ICV infusion of T for 15 days did not alter Acb DA. In contrast, sc amphetamine significantly increased Acb DA at both doses. Therefore, unlike many drugs of abuse, AAS does not increase Acb DA levels. The reduction in DA at high T doses is likely due to autonomic depressant effects of AAS. We suggest that AAS act via mechanism distinct from those of stimulants, but may share neural substrates with other drugs of abuse.
Collapse
Affiliation(s)
| | | | - Ruth I. Wood
- *Address all reprint requests and correspondence to: Ruth I. Wood, Department of Cell and Neurobiology, Keck School of Medicine, University of Southern California, 1333 San Pablo St. BMT 401, Los Angeles, CA 90033, Telephone (323) 442-1980, Fax: (323) 442-3466, e-mail:
| |
Collapse
|
33
|
Carroll ME, Anderson MM, Morgan AD. Higher locomotor response to cocaine in female (vs. male) rats selectively bred for high (HiS) and low (LoS) saccharin intake. Pharmacol Biochem Behav 2007; 88:94-104. [PMID: 17707494 PMCID: PMC3651992 DOI: 10.1016/j.pbb.2007.07.010] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/23/2006] [Revised: 07/09/2007] [Accepted: 07/16/2007] [Indexed: 11/18/2022]
Abstract
Rats selectively bred for high saccharin consumption (HiS) self-administer more oral ethanol and i.v. cocaine than those selectively bred for low saccharin consumption (LoS). Male and female drug-seeking-prone (HiS) and -resistant (LoS) rats were used in the present experiment to test the prediction that cocaine-induced locomotor activity and sensitization varied with sex and their selective breeding status (HiS and LoS). All rats were intermittently exposed over 2 weeks to pairs of sequential saline and cocaine injections, separated by 45 min. The first 5 pairs of injections, each separated by 2-3 days (10-12 days total), were given to examine the development of cocaine-induced locomotor activity and the development of locomotor sensitization, which was determined by comparing the effects of cocaine injection 1 with injection 6 (given 2 weeks after the 5 pairs of intermittent injections). Results indicated that after the first injection pair (saline, cocaine) the HiS and LoS groups did not differ (saline vs. cocaine) in locomotor activity; however, after cocaine injection pairs 1, 5, and 6, HiS females were more active than HiS males and LoS females. There were also significant phenotype differences (HiS>LoS) in locomotor activity after cocaine injections 5 and 6. There was a weak sensitization effect in cocaine-induced locomotor activity in HiS females after cocaine injection 5 (compared to 1); however it was not present after injection 6 or in other groups. The lack of a strong sensitization effect under these temporal and dose conditions was inconsistent with previous reports. However, the results showing HiS>LoS and females>males on cocaine-induced activity measures are consistent with several measures of cocaine-seeking behavior (acquisition, maintenance, escalation, extinction, and reinstatement), and they suggest that cocaine-induced locomotor activity and sensitization are behavioral markers of drug-seeking phenotypes.
Collapse
Affiliation(s)
- Marilyn E Carroll
- Department of Psychiatry, University of Minnesota, MMC 392, Minneapolis, MN 55455, United States.
| | | | | |
Collapse
|
34
|
Zarrindast MR, Asgari-Afshar A, Sahebgharani M. Morphine-induced antinociception in the formalin test: sensitization and interactions with D1 and D2 dopamine receptors and nitric oxide agents. Behav Pharmacol 2007; 18:177-84. [PMID: 17426481 DOI: 10.1097/fbp.0b013e32813c5462] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
In this study, the effects of dopamine receptor antagonists and nitric oxide agents on morphine-induced sensitization in the formalin test in mice have been investigated. Repeated daily intraperitoneal administration of morphine (30 mg/kg for 3 days) followed by a 11-day wash out period increased morphine-induced antinociception in the formalin test, which may be due to sensitization. The antinociceptive response to higher doses of morphine (6 and 9 mg/kg) but not 3 mg/kg was significantly increased in sensitized animals compared with control groups. Pretreatment of animals with an opioid receptor antagonist, naloxone (4 mg/kg), during repeated administration of morphine, attenuated the morphine-induced sensitization. In the second part of the study, the animals received SCH23390 (D1 receptor antagonist), sulpiride (D2 receptor antagonist), L-Arg (nitric oxide precursor) and NG-nitro-L-Arg methylester (nitric oxide synthase inhibitor) during repeated morphine administration, to evaluate the role of dopamine receptor antagonists and nitric oxide agents in this phenomenon. Pretreatment of animals with NG-nitro-L-Arg methylester (20 mg/kg) and sulpiride (100 mg/kg) during morphine sensitization decreased the antinociceptive response to higher doses of morphine in the formalin test. It is concluded that D2 dopamine receptor and nitric oxide mechanisms may be involved at least partly in morphine-induced sensitization in the formalin test.
Collapse
Affiliation(s)
- Mohammad-Reza Zarrindast
- Department of Pharmacology, School of Medicine and Iranian National Center for Addiction Studies, Tehran University of Medical Sciences, Tehran, Iran.
| | | | | |
Collapse
|
35
|
Fichna J, Janecka A, Costentin J, Do Rego JC. The endomorphin system and its evolving neurophysiological role. Pharmacol Rev 2007; 59:88-123. [PMID: 17329549 DOI: 10.1124/pr.59.1.3] [Citation(s) in RCA: 180] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Endomorphin-1 (Tyr-Pro-Trp-Phe-NH2) and endomorphin-2 (Tyr-Pro-Phe-Phe-NH2) are two endogenous opioid peptides with high affinity and remarkable selectivity for the mu-opioid receptor. The neuroanatomical distribution of endomorphins reflects their potential endogenous role in many major physiological processes, which include perception of pain, responses related to stress, and complex functions such as reward, arousal, and vigilance, as well as autonomic, cognitive, neuroendocrine, and limbic homeostasis. In this review we discuss the biological effects of endomorphin-1 and endomorphin-2 in relation to their distribution in the central and peripheral nervous systems. We describe the relationship between these two mu-opioid receptor-selective peptides and endogenous neurohormones and neurotransmitters. We also evaluate the role of endomorphins from the physiological point of view and report selectively on the most important findings in their pharmacology.
Collapse
Affiliation(s)
- Jakub Fichna
- Laboratory of Experimental Neuropsychopharmacology, CNRS FRE 2735, IFRMP 23, Faculty of Medicine & Pharmacy, University of Rouen, 22, Boulevard Gambetta, 76183 Rouen cedex, France
| | | | | | | |
Collapse
|
36
|
Sahraei H, Faghih-Monzavi Z, Fatemi SM, Pashaei-Rad S, Salimi SH, Kamalinejad M. Effects of Papaver rhoeas extract on the acquisition and expression of morphine-induced behavioral sensitization in mice. Phytother Res 2006; 20:737-41. [PMID: 16807881 DOI: 10.1002/ptr.1922] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
In the present study, the effects of a water-alcohol extract of Papaver rhoeas on the acquisition and expression of morphine-induced behavioral sensitization in mice were investigated. The subcutaneous (s.c.) administration of morphine (50 mg/kg) induced locomotor activity in animals, whereas the drug did not show an effect at a dose of 5 mg/kg. On the other hand, intraperitoneal (i.p.) administration of the plant extract (25, 50 and 100 mg/kg) did not show any effect. The locomotor behavioral response was enhanced in mice pretreated with morphine (5 mg/kg, daily x 3 days) alone, indicating that sensitization had developed. Extract (25, 50 and 100 mg/kg, i.p.) administration, 30 min before each of the three daily doses of morphine decreased the development of sensitization. Moreover, intraperitoneal administration of the plant extract (25, 50 and 100 mg/kg) 30 min before the test reduced the expression of morphine-induced behavioral sensitization. The results indicate that administration of the extract of Papaver rhoeas reduced the acquisition and expression of morphine-induced behavioral sensitization in mice.
Collapse
Affiliation(s)
- Hedayat Sahraei
- Department of Physiology and Biophysics, and Behavioral Sciences Research Center (BSRC), School of Medicine, Baqiyatallah, University of Medical Sciences, Tehran, Iran.
| | | | | | | | | | | |
Collapse
|
37
|
Grecksch G, Bartzsch K, Widera A, Becker A, Höllt V, Koch T. Development of tolerance and sensitization to different opioid agonists in rats. Psychopharmacology (Berl) 2006; 186:177-84. [PMID: 16572262 DOI: 10.1007/s00213-006-0365-8] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2005] [Accepted: 01/13/2006] [Indexed: 10/24/2022]
Abstract
RATIONALE Despite numerous investigations, the mechanisms underlying the development of opioid tolerance are far from clear. However, several in vitro studies implicated a protective role of agonist-induced micro-opioid receptor endocytosis in the development of opioid tolerance. Moreover, we have recently demonstrated that the high-efficacy agonist etonitazene promotes rapid endocytosis of micro-opioid receptors, whereas the agonist morphine and the low-efficacy agonist buprenorphine fail to promote detectable receptor endocytosis in micro-opioid receptor expressing HEK293 cells. OBJECTIVES The present study explored the effects of these opioids on the development of tolerance and sensitization in rats in vivo. METHODS The opioid effects were quantified using the hot plate, electric tail root stimulation, and the locomotor activity chamber in male Wistar rats. Dose-response curves were generated for each test drug. To induce tolerance, equieffective doses of etonitazene, morphine, and buprenorphine were administered daily for 29 days. RESULTS We found that chronic treatment with the non-internalizing drugs buprenorphine and morphine resulted in a greater development of tolerance than etonitazene. In addition, the sensitization to the locomotor stimulant effect was high after buprenorphine and morphine, but was lacking after chronic etonitazene application. CONCLUSION The results support a role for the endocytotic potency of agonists in the development of tolerance and addiction during long-term opioid treatment.
Collapse
Affiliation(s)
- Gisela Grecksch
- Institute of Pharmacology and Toxicology, Faculty of Medicine, Otto-von-Guericke-University Magdeburg, Leipziger Str. 44, 39120 Magdeburg, Germany.
| | | | | | | | | | | |
Collapse
|
38
|
Zarrindast MR, Azami BN, Rostami P, Rezayof A. Repeated administration of dopaminergic agents in the nucleus accumbens and morphine-induced place preference. Behav Brain Res 2006; 169:248-55. [PMID: 16472879 DOI: 10.1016/j.bbr.2006.01.011] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2005] [Revised: 01/08/2006] [Accepted: 01/12/2006] [Indexed: 11/19/2022]
Abstract
In the present study, the effects of repeated intra nucleus accumbens (intra-NAc) injections of dopamine receptor agents on morphine-induced conditioned place preference (CPP) in rats were investigated by using an unbiased 3-days schedule of place conditioning design. The animals receiving once daily subcutaneous (s.c.) injections of morphine (0.5-7.5mg/kg) or saline (1.0 ml/kg, s.c.) showed a significant place preference in a dose-dependent manner. The maximum response was observed with 5mg/kg of the opioid. Three days intra-NAc injections of apomorphine (0.5 and 1 microg/rat) followed by 5 days free of the drug, increased or decreased, respectively CPP induced by the lower dose of morphine (0.5mg/kg, s.c.). Morphine-induced CPP was also significantly increased in the animals that had previously received the 3-days intra-NAc injections of SKF 38393 (4 and 8 microg/rat) or quinpirole (2 and 4 microg/rat, intra-NAc). The CPP induced by a higher dose of morphine (5mg/kg, s.c.) was significantly decreased in the animals that had previously received the 3-days SCH 23390 (0.005 and 0.01 microg/rat; intra-NAc). On the other hand, the CPP induced by morphine (5mg/kg, s.c.) was significantly increased in the animals that had previously received the 3-days sulpiride administration (5 microg/rat, intra-NAc). The 3-days administration of apomorphine, SKF 38393 or quinpirole, but not SCH 23390 and sulpiride reduced the locomotor activity in the test session. It is concluded that repeated injections of dopamine receptors agents followed by 5 days free of the drugs in the NAc can affect morphine reward.
Collapse
Affiliation(s)
- Mohammad-Reza Zarrindast
- Department of Pharmacology and Iranian National Center for Addiction Studies, School of Medicine, Tehran University of Medical Sciences, PO Box 13145-784, Tehran, Iran.
| | | | | | | |
Collapse
|
39
|
D'Este L, Casini A, Pontieri FE, Renda TG. Changes in neuropeptide FF and NPY immunohistochemical patterns in rat brain under heroin treatment. Brain Res 2006; 1083:151-8. [PMID: 16529722 DOI: 10.1016/j.brainres.2006.02.009] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2005] [Revised: 01/31/2006] [Accepted: 02/02/2006] [Indexed: 10/24/2022]
Abstract
Immunohistochemical distribution patterns of neuropeptide FF (NPFF) and neuropeptide tyrosine (NPY) were studied in the brain of rats submitted to two different protocols of heroin treatment. In drug-naive rats, acutely injected heroin significantly depleted NPFF-immunoreactive material within the neurons of the nucleus of solitary tract (NTS), significantly decreased the density of NPFF-immunoreactive nerve fibers within the median eminence, pituitary stalk, and neurohypophysis, and markedly increased NPY-immunoreactive neurons and nerve fibers in the thalamic paraventricular nucleus and bed nucleus of stria terminalis. In drug-sensitized rats, heroin significantly increased the number and immunostaining intensity of the NPFF-immunoreactive neurons within the NTS and induced minor changes in the NPFF-immunoreactive nerve fiber network of the median eminence, pituitary stalk, and neurohypophysis and a relatively minor increase in NPY neurons in the thalamic paraventricular nucleus and bed nucleus of stria terminalis. These heroin-induced changes suggest that NPFF is involved in regulating the effects of the heroin injection and in the mechanisms underlying behavioral sensitization. They also add further support to the key role of NPY in any conditions tending to change the animal homeostasis.
Collapse
Affiliation(s)
- Loredana D'Este
- Department of Human Anatomy, Via Borelli 50, 00161 Rome, Italy
| | | | | | | |
Collapse
|
40
|
Heidari P, Sahebgharani M, Riazi G, Zarrindast MR. Influence of Morphine and Dopamine Receptor Sensitization on Locomotor Activity in Mice. Pharmacology 2006; 78:185-92. [PMID: 17063042 DOI: 10.1159/000096428] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2006] [Accepted: 08/23/2006] [Indexed: 11/19/2022]
Abstract
In the present study, the influence of morphine- and dopamine receptor antagonists-induced sensitization on morphine-induced locomotion in mice was investigated. Morphine (30, 40 and 50 mg/kg) increased, while lower doses of the opioid (10 and 20 mg/kg) decreased locomotor activity of mice. Subchronic repeated pretreatment of animals with morphine showed an increase in locomotion induced by the opioid. Clozapine reduced locomotor activity induced by morphine in both the naïve and subchronic morphine-treated animals. Subchronic pretreatment of clozapine also caused an increase in the locomotion induced by morphine. Sulpiride also decreased locomotion induced by morphine and its subchronic administration of the drug caused an increase in morphine- or apomorphine-induced locomotion. Co-administration of clozapine with sulpiride did not elicit potentiation in inhibiting the morphine effect. The D2 receptor mRNA expression was also increased by repeated morphine administration. It may be concluded that morphine-induced sensitization may be due to increase in D2 receptor mRNA expression. Sulpiride and clozapine may induce sensitization and also inhibit morphine-induced locomotion through their dopamine receptor blocking properties.
Collapse
Affiliation(s)
- Parviz Heidari
- Institute of Biochemistry and Biophysics (IBB), University of Tehran, Tehran, Iran
| | | | | | | |
Collapse
|
41
|
Patti CL, Kameda SR, Carvalho RC, Takatsu-Coleman AL, Lopez GB, Niigaki ST, Abílio VC, Frussa-Filho R, Silva RH. Effects of morphine on the plus-maze discriminative avoidance task: role of state-dependent learning. Psychopharmacology (Berl) 2006; 184:1-12. [PMID: 16341847 DOI: 10.1007/s00213-005-0238-6] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/18/2005] [Accepted: 10/20/2005] [Indexed: 10/25/2022]
Abstract
RATIONALE The amnesic effects of morphine may be related to its action on nociception, anxiety, or locomotion. This effect is also suggested to be related to state dependency. OBJECTIVES The aims of this study were to verify the effects of morphine on mice tested in the plus-maze discriminative avoidance task (DAT) that uses light and noise as aversive stimuli and allows the concomitant evaluation of learning, memory, anxiety, and locomotion and also to verify the possible role of state-dependent learning in the effects of morphine. METHODS AND RESULTS The DAT was conducted in a modified elevated plus-maze. In the training, the aversive stimuli were applied when mice entered in one of the enclosed arms, whereas in the test, no stimuli were applied. The main results showed that (1) pretraining morphine (5-20 mg/kg i.p.) induced retrieval deficits (evaluated by the time spent in the aversive arm in the test) but not acquisition deficits (evaluated by the decrease in aversive arm exploration along the training); (2) pretest morphine (5-10 but not 20 mg/kg) counteracted this deficit; (3) morphine induced hypolocomotion (decreased number of entries in the arms), irrespective of memory alterations; and (4) morphine did not alter anxiety-like behavior (evaluated by the time spent in the open arms) during the training. CONCLUSIONS Morphine given before training induces retrieval deficits in mice tested in the DAT, and these deficits could be related to morphine-induced state-dependent learning. Neither the memory deficit induced by pretraining morphine nor the reversal of this deficit by pretest morphine seems to be related to anxiety levels or locomotor alterations.
Collapse
Affiliation(s)
- C L Patti
- Department of Pharmacology, Universidade Federal de São Paulo, Rua Botucatu, 862-Ed. Leal Prado, 04023-062 São Paulo, Brazil
| | | | | | | | | | | | | | | | | |
Collapse
|
42
|
Zarrindast MR, Farajzadeh Z, Rostami P, Rezayof A, Nourjah P. Involvement of the ventral tegmental area (VTA) in morphine-induced memory retention in morphine-sensitized rats. Behav Brain Res 2005; 163:100-6. [PMID: 15913802 DOI: 10.1016/j.bbr.2005.04.006] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2005] [Revised: 04/18/2005] [Accepted: 04/18/2005] [Indexed: 11/27/2022]
Abstract
In the present study, the effects of intra-ventral tegmental area (VTA) injections of morphine on memory retention of a one-trial passive avoidance task have been investigated in morphine-sensitized rats. Retrieval was examined 24h after training and used as memory retention. Sensitization was obtained by subcutaneous (s.c.) injections of morphine, once daily for 3 and 5 days free of the opioid before training. Post-training administration of the both systemic (2.5, 5 and 7.5mg/kg, s.c.) and intra-VTA (5 and 7.5microg/rat) of morphine, dose-dependently decreased memory retention. The response induced by post-training administration of intra-VTA morphine (7.5microg/rat) was significantly reversed in morphine-sensitized rats. The inhibition of morphine-induced amnesia in morphine-sensitized rats was decreased by once daily injections of naloxone (0.5, 1 and 2mg/kg, s.c.), SCH 23390 (0.025, 0.05 and 0.1mg/kg, s.c.) or sulpiride (25, 50 and 100mg/kg, s.c.), during the sensitization. The results suggest that VTA has an important role in morphine-induced amnesia and morphine sensitization affects this process through opioid and dopamine receptors.
Collapse
Affiliation(s)
- Mohammad-Reza Zarrindast
- Department of Pharmacology and Iranian National Center for Addiction Studies, Tehran University of Medical Sciences, P.O. Box 13145-784, Tehran, Iran.
| | | | | | | | | |
Collapse
|
43
|
Lebsanft HB, Kovar KA, Schmidt WJ. 3,4-Methylenedioxymethamphetamine and naloxone in rat rotational behaviour and open field. Eur J Pharmacol 2005; 516:34-9. [PMID: 15899478 DOI: 10.1016/j.ejphar.2005.04.020] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2005] [Revised: 04/13/2005] [Accepted: 04/14/2005] [Indexed: 10/25/2022]
Abstract
It has recently been shown that 3,4-Methylenedioxymethamphetamine (MDMA) has an anti-parkinsonian effect in rodent models of Parkinson's disease. The mechanism of this anti-parkinsonian action is unknown. Opioids have been suggested to play a role in MDMA-induced behaviour. We therefore investigated MDMA and naloxone in the rat rotational behavioural model. Male Sprague-Dawley rats were lesioned unilaterally with 6-hydroxydopamine at the medial forebrain bundle. Administration of R/S-MDMA (5 mg/kg, s.c.) produced ipsilateral rotations. Naloxone (2, 5, 10 mg/kg, s.c.) did not produce rotations on its own but reduced the number of MDMA-induced ipsilateral rotations. This effect was not dose-dependent. In contrast to reports on mice, in unlesioned animals, naloxone (10 mg/kg, s.c.) did not block MDMA (5 mg/kg, s.c.)-induced hyperactivity in an open field in our experiment. It is concluded that endogenous opioids play a role in MDMA's action in the rat rotational behavioural model.
Collapse
Affiliation(s)
- Heike B Lebsanft
- Department Neuropharmacology, Zoological Institute, Faculty of Biology, University of Tuebingen, Auf der Morgenstelle 28 E, 72076 Tuebingen, Germany.
| | | | | |
Collapse
|
44
|
Muller DL, Unterwald EM. D1 dopamine receptors modulate deltaFosB induction in rat striatum after intermittent morphine administration. J Pharmacol Exp Ther 2005; 314:148-54. [PMID: 15772255 DOI: 10.1124/jpet.105.083410] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Induction of the transcription factor deltaFosB was studied to examine neurochemical adaptations produced by repeated opiate administration. The mechanism of this induction was also investigated. The 35- to 37-kDa isoforms of deltaFosB, also referred to as the chronic Fras, were measured in the nucleus accumbens, caudate putamen, and frontal cortex of male Sprague-Dawley rats after either an acute injection of morphine or an escalating dosing schedule of morphine for 10 days. Heroin was also tested to determine whether the findings extend to other opiates. Results from Western blot analysis using an anti-fosB antibody demonstrate that 10-day intermittent escalating dose morphine produced a significant increase in deltaFosB-immunoreactivity in the nucleus accumbens, caudate putamen and frontal cortex, whereas a single injection of morphine had no effect on Fra immunoreactivity. Heroin administered twice daily for 10 days by an intermittent escalating dose schedule also induced deltaFosB in the caudate putamen, but not in the nucleus accumbens or frontal cortex. Daily pretreatment with the selective D1-like dopamine receptor antagonist SCH 23390 [R-(+)-7-chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine hydrochloride] significantly blocked morphine-induced deltaFosB induction in the nucleus accumbens and caudate putamen, but not in the frontal cortex. These results demonstrate that morphine-induced deltaFosB up-regulation in the striatum, but not in the frontal cortex, is modulated by D1 dopamine receptors, suggesting that the mechanisms involved in the up-regulation of these chronic Fras by morphine is brain region-specific.
Collapse
Affiliation(s)
- Daniella L Muller
- Department of Pharmacology, Temple University School of Medicine, 3420 North Broad St., Philadelphia, PA 19140, USA.
| | | |
Collapse
|
45
|
Marin C, Bové J, Serrats J, Cortés R, Mengod G, Tolosa E. The kappa opioid agonist U50,488 potentiates 6-hydroxydopamine-induced neurotoxicity on dopaminergic neurons. Exp Neurol 2005; 191:41-52. [PMID: 15589511 DOI: 10.1016/j.expneurol.2004.08.033] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2003] [Revised: 08/16/2004] [Accepted: 08/19/2004] [Indexed: 11/26/2022]
Abstract
Several observations support the hypothesis that kappa opioid (kappa-opioid) receptor agonism may contribute to neurotoxicity, but other reports have suggested that certain kappa-agonists can attenuate neurological dysfunction. Degeneration of dopaminergic neurons in the substantia nigra is the pathological hallmark of Parkinson's disease. Therefore, it is of particular interest to study whether kappa-opioid receptor agonism has an influence on the progressive degeneration of dopaminergic neurons. We have investigated the effect exerted by the selective kappa-agonist U50,488 on the neurotoxicity induced by intrastriatal 6-hydroxydopamine (6-OHDA) administration on dopaminergic neurons. Male Sprague-Dawley rats received an acute (0.5 mg/kg) or subacute (0.5 mg/kg, twice at day, for 7 days) administration of U50,488, receiving the last dose 30 min before intrastriatal 6-OHDA administration. Acute or subacute U50,488 pretreatment potentiated the 6-OHDA-induced decrease in the number of nigral tyrosine hydroxylase immunoreactive neurons (P < 0.05). Acute U50,488 pretreated animals showed a tendency, although not statistically significant to increase striatal mRNA encoding for enkephalin (PPE mRNA). Subacute U50,488 significantly potentiated the increase in PPE mRNA induced by 6-OHDA (P < 0.05). The present results show a neurotoxic effect of the kappa agonist U50,488 on dopaminergic neurons in rats with a striatal lesion induced by 6-OHDA. This neurotoxic effect is associated to an increase in striatal PPE mRNA levels, suggesting that an increase in the indirect pathway activity and consequently an increase in the activity of the subthalamo-nigral pathway might be involved in this phenomenon.
Collapse
Affiliation(s)
- C Marin
- Laboratori de Neurologia Experimental, Area de Neurociències, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Hospital Clínic, Barcelona, Spain.
| | | | | | | | | | | |
Collapse
|
46
|
Shi XD, Wang GB, Ma YY, Ren W, Luo F, Cui CL, Han JS. Repeated peripheral electrical stimulations suppress both morphine-induced CPP and reinstatement of extinguished CPP in rats: accelerated expression of PPE and PPD mRNA in NAc implicated. ACTA ACUST UNITED AC 2004; 130:124-33. [PMID: 15519683 DOI: 10.1016/j.molbrainres.2004.07.016] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/21/2004] [Indexed: 11/17/2022]
Abstract
Previous studies have shown that peripheral electrical stimulation (PES) can suppress morphine-induced conditioned place preference (CPP) and the reinstatement of extinguished CPP in the rat. The present study was performed to elucidate if preproenkephalin (PPE) and preprodynorphin (PPD) mRNAs in the nucleus accumbens (NAc) play a role in this event. Rats were trained with morphine for 4 days to establish CPP paradigm. They were then given 15-min test once a day for eight consecutive days for extinction trial. Twenty-four hours after the 8th session of extinction trials, rats were given peripheral electrical stimulation (PES) at 2 or 100 Hz once a day for 3 days, then a morphine-priming injection at a dose of 1, 2, or 4 mg/kg to reinstate the extinguished CPP. At the end of the experiment, PPE and PPD mRNA levels in the nucleus acccumbens (NAc) were determined by the semiquantitative RT-PCR technique. The results showed that PES at 2- and 100-Hz administered 30 min a day for 3 days suppressed both the expression of morphine-induced CPP and the reinstatement of extinguished CPP. PES at 2 Hz increased preproenkephalin (PPE) mRNA levels, whereas PES of 100 Hz that of preprodynorphin (PPD) mRNA levels in the NAc. These findings suggest that enkephalin and dynorphin in NAc may play important roles in the mechanisms underlying the inhibitory effect of PES on the expression and reinstatement of morphine-induced CPP in rats.
Collapse
Affiliation(s)
- Xiang-Dang Shi
- Neuroscience Research Institute, Key laboratory for Neuroscience, Peking University, the Ministry of Education, 38 Xueyuan Road, Beijing 100083, PR China
| | | | | | | | | | | | | |
Collapse
|
47
|
Erhardt A, Sillaber I, Welt T, Müller MB, Singewald N, Keck ME. Repetitive transcranial magnetic stimulation increases the release of dopamine in the nucleus accumbens shell of morphine-sensitized rats during abstinence. Neuropsychopharmacology 2004; 29:2074-80. [PMID: 15187982 DOI: 10.1038/sj.npp.1300493] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Recent studies in rodents have shown that withdrawal from chronic drug abuse is associated with a significant decrease in dopamine (DA) release in mesolimbic structures, especially in the shell region of the nucleus accumbens. Since the DA system is known to play an important role in reward processes, a withdrawal-associated impairment in mesolimbic DA-mediated transmission could possibly implicate reward deficit and thus enhance vulnerability to drug craving and relapse. We have previously demonstrated that acute repetitive transcranial magnetic stimulation (rTMS) has a modulatory effect on DA release in several areas of the rat brain, including dorsal striatum, hippocampus, and nucleus accumbens shell. In the present study, we investigated the possible use of rTMS as a tool in re-establishing the dysregulated DA secretion observed during withdrawal in morphine-sensitized male Sprague-Dawley rats. Using intracerebral microdialysis, we monitored the effects of acute rTMS (20 Hz) on the intra-accumbal release-patterns of DA in freely moving animals that were subjected to a morphine sensitization scheme for a period of 8 days. We provide first evidence that acute rTMS (20 Hz) is able to increase DA concentration in the shell region of the nucleus accumbens in both control animals and morphine-sensitized rats during abstinence. The DA release in morphine-sensitized rats was significantly higher than in controls. rTMS, therefore, might gain a potential therapeutic role in the treatment of dysphoric and anhedonic states during drug withdrawal in humans.
Collapse
Affiliation(s)
- A Erhardt
- Max Planck Institute of Psychiatry, Munich, Germany
| | | | | | | | | | | |
Collapse
|
48
|
Tabarelli Z, Rubin MA, Berlese DB, Sauzem PD, Missio TP, Teixeira MV, Sinhorin AP, Martins MAP, Zanatta N, Bonacorso HG, Mello CF. Antinociceptive effect of novel pyrazolines in mice. Braz J Med Biol Res 2004; 37:1531-40. [PMID: 15448875 DOI: 10.1590/s0100-879x2004001000013] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The antinociceptive effect of six novel synthetic pyrazolines (3-ethoxymethyl-5-ethoxycarbonyl-1H-pyrazole (Pz 1) and its corresponding 1-substituted methyl (Pz 2) and phenyl (Pz 3) analogues, and 3-(1-ethoxyethyl)-5-ethoxycarbonyl-1H-pyrazole (Pz 4) and its corresponding 1-substituted methyl (Pz 5) and phenyl (Pz 6) analogues) was evaluated by the tail immersion test in adult male albino mice. The animals (N = 11-12 in each group) received vehicle (5% Tween 80, 10 ml/kg, sc) or 1.5 mmol/kg of each of the pyrazolines (Pz 1-Pz 6), sc. Fifteen, thirty and sixty minutes after drug administration, the mice were subjected to the tail immersion test. Thirty minutes after drug administration Pz 2 and Pz 3 increased tail withdrawal latency (vehicle = 3.4 +/- 0.2; Pz 2 = 5.2 +/- 0.4; Pz 3 = 5.9 +/- 0.4 s; mean +/- SEM), whereas the other pyrazolines did not present antinociceptive activity. Dose-effect curves (0.15 to 1.5 mmol/kg) were constructed for the bioactive pyrazolines. Pz 2 (1.5 mmol/kg, sc) impaired motor coordination in the rotarod and increased immobility in the open-field test. Pz 3 did not alter rotarod performance and spontaneous locomotion, but increased immobility in the open field at the dose of 1.5 mmol/kg. The involvement of opioid mechanisms in the pyrazoline-induced antinociception was investigated by pretreating the animals with naloxone (2.75 micro mol/kg, sc). Naloxone prevented Pz 3- but not Pz 2-induced antinociception. Moreover, naloxone pretreatment did not alter Pz 3-induced immobility. We conclude that Pz 3-induced antinociception involves opioid mechanisms but this is not the case for Pz 2.
Collapse
Affiliation(s)
- Z Tabarelli
- Departamento de Fisiologia, Centro de Ciências da Saúde, Universidade Federal de Santa Maria, 97105-900 Santa Maria, PE, Brazil
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
49
|
Shoaib M, Lowe AS, Williams SCR. Imaging localised dynamic changes in the nucleus accumbens following nicotine withdrawal in rats. Neuroimage 2004; 22:847-54. [PMID: 15193614 DOI: 10.1016/j.neuroimage.2004.01.026] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2003] [Revised: 01/16/2004] [Accepted: 01/20/2004] [Indexed: 11/20/2022] Open
Abstract
This study utilises pharmacological functional magnetic resonance imaging (fMRI) to examine the neurobiological mechanisms through which nicotine produces dependence. Using an established regime to induce physical dependence to nicotine in rats (osmotic minipumps delivering 3.16 mg/kg/day nicotine for 7 days SC), animals were subsequently anaesthetised under urethane and positioned in a stereotaxic frame to allow collection of gradient echo whole brain images with a 4.7-T MRI spectrometer. Rats were initially scanned for 34 min (40 baseline image volumes, 1 volume per 51 s) then challenged with mecamylamine (1.0 mg/kg SC) or saline (1 ml/kg) and scanned for a further 68 min (80 image volumes). Mecamylamine precipitated highly significant positive changes in fMRI blood oxygen level dependent (BOLD) contrast that were predominantly localised to the NAc of nicotine-dependent rats. Saline-treated rats challenged with the same dose of mecamylamine exhibited similar but smaller increases in BOLD contrast although such changes were less defined around the NAc. Precipitated withdrawal also elicited statistically significant negative BOLD contrast changes in widespread cortical regions. These findings are consistent with previous neurochemical reports on decreases in dopamine in the NAc during nicotine withdrawal. This fMRI study further highlights the potential and power to image the neurobiological events during nicotine dependence.
Collapse
Affiliation(s)
- Mohammed Shoaib
- Section of Behavioural Pharmacology, Division of Psychological Medicine, Institute of Psychiatry, Kings College London, London SE5 8AF, UK.
| | | | | |
Collapse
|
50
|
Zarrindast MR, Rezayof A. Morphine state-dependent learning: sensitization and interactions with dopamine receptors. Eur J Pharmacol 2004; 497:197-204. [PMID: 15306205 DOI: 10.1016/j.ejphar.2004.06.041] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2004] [Accepted: 06/22/2004] [Indexed: 10/26/2022]
Abstract
In the present study, the effects of morphine sensitization on impairment of memory formation and the state-dependent learning by morphine have been investigated in mice. Pretraining administration of morphine (0.5, 2.5 and 5 mg/kg) dose dependently decreased the learning of a one-trial passive avoidance task. Pretest administration of morphine (0.5, 2.5 and 5 mg/kg) induced state-dependent retrieval of the memory acquired under pretraining morphine influence. Pretraining or pretest administration of naloxone (0.25, 0.5 and 1 mg/kg) reversed both responses to morphine (5 mg/kg). Amnesia induced by pretraining morphine was significantly reversed in morphine-sensitized mice which had previously received once daily injections of morphine [20 and 30 mg/kg, subcutaneously (s.c.)] for 3 days. Morphine sensitization tended to reverse but did not significantly affect morphine state-dependent memory. The inhibition of morphine-induced amnesia in morphine-sensitized mice was decreased by once daily administration of naloxone (0.5, 1 and 2 mg/kg) 30 min prior to injection of morphine (20 mg/kg/day x 3 days). Three-days administration of 1-phenyl-7,8-dihydroxy-2,3,4,5-tetrahydro-1H-3-benzazepine HCL (SKF 38393; 8, 16 and 32 mg/kg) or SCH 23390; R(+)-7-chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine HCL (0.01, 0.05 and 0.1 mg/kg) before morphine (for 3 days) and during morphine-sensitization, decreased and increased, the amnesia induced by pretraining morphine, respectively. Similar administration of quinpirole (0.5, 1 and 2 mg/kg) or sulpiride (25, 50 and 100 mg/kg) before morphine also decreased and increased the amnesia induced by pretraining morphine, respectively. The results suggest that morphine sensitization affects the impairment of memory formation, but not the facilitation of retrieval induced by morphine and thus it is postulated that dopamine receptors may play an important role in this effect.
Collapse
Affiliation(s)
- Mohammad-Reza Zarrindast
- Department of Pharmacology, School of Medicine Tehran University of Medical Sciences, P. O. Box 13145-784, Tehran, Iran.
| | | |
Collapse
|