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Carboni E, Ibba M, Carboni E, Carta AR. Adolescent stress differentially modifies dopamine and norepinephrine release in the medial prefrontal cortex of adult rats. Prog Neuropsychopharmacol Biol Psychiatry 2024; 134:111055. [PMID: 38879069 DOI: 10.1016/j.pnpbp.2024.111055] [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: 11/23/2023] [Revised: 04/10/2024] [Accepted: 06/11/2024] [Indexed: 06/22/2024]
Abstract
Adolescent stress (AS) has been associated with higher vulnerability to psychiatric disorders such as schizophrenia, depression, or drug dependence. Moreover, the alteration of brain catecholamine (CAT) transmission in the medial prefrontal cortex (mPFC) has been found to play a major role in the etiology of psychiatric disturbances. We investigated the effect of adolescent stress on CAT transmission in the mPFC of freely moving adult rats because of the importance of this area in the etiology of psychiatric disorders, and because CAT transmission is the target of a relevant group of drugs used in the therapy of depression and psychosis. We assessed basal dopamine (DA) and norepinephrine (NE) extracellular concentrations (output) by brain microdialysis in in the mPFC of adult rats that were exposed to chronic mild stress in adolescence. To ascertain the role of an altered release or reuptake, we stimulated DA and NE output by administering either different doses of amphetamine (0.5 and 1.0 mg / kg s.c.), which by a complex mechanism determines a dose dependent increase in the CAT output, or reboxetine (10 mg/kg i.p.), a selective NE reuptake inhibitor. The results showed the following: (i) basal DA output in AS rats was lower than in controls, while no difference in basal NE output was observed; (ii) amphetamine, dose dependently, stimulated DA and NE output to a greater extent in AS rats than in controls; (iii) reboxetine stimulated NE output to a greater extent in AS rats than in controls, while no difference in stimulated DA output was observed between the two groups. These results show that AS determines enduring effects on DA and NE transmission in the mPFC and might lead to the occurrence of psychiatric disorders or increase the vulnerability to drug addiction.
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Affiliation(s)
- Ezio Carboni
- Department of Biomedical Sciences, University of Cagliari, Italy.
| | - Marcello Ibba
- Department of Biomedical Sciences, University of Cagliari, Italy
| | - Elena Carboni
- Unit of Paediatrics, ASST Cremona Maggiore Hospital, Cremona, Italy
| | - Anna R Carta
- Department of Biomedical Sciences, University of Cagliari, Italy
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Lee W, Lee JW, Kim S, Kim JM, Youn DH, Park SH, Kwon CH, Choi SO. Discriminative stimulus and reinforcing effects of diclazepam in rodents. Pharmacol Biochem Behav 2024; 235:173687. [PMID: 38016594 DOI: 10.1016/j.pbb.2023.173687] [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: 05/25/2023] [Revised: 11/22/2023] [Accepted: 11/23/2023] [Indexed: 11/30/2023]
Abstract
Diclazepam, a designer benzodiazepine, is a lesser-known novel anxiolytic substance and a structural analog of diazepam. Although several case studies have reported the adverse effects of diclazepam, their potential impacts remain unknown. Therefore, this study aimed to determine the effects of diclazepam in rodents using drug discrimination, locomotor activity, self-administration (SA), and conditioned place preference (CPP) tests. Sprague-Dawley rats (male, 8 weeks old, weighing 220-450 g, n = 12 per group) and C57BL/6 mice (male, 7 weeks old, weighing 20-25 g, n = 7-8 per group) were administered alprazolam, morphine, and diclazepam. Diclazepam fully elicited alprazolam-appropriate dose-dependent lever responses (>80 %) similar to those of alprazolam. In rats administered 0.5 mg/kg of morphine, a partial substitution (80 %-20 %) was observed. Mice receiving intraperitoneal injections of diclazepam (0.05, 0.2, and 2 mg/kg) showed decreased locomotor activity. In the SA experiment, mice that self-administered intravenous diclazepam (2 μg/kg/infusion) showed significantly higher infusion and active lever responses compared to the vehicle group. No statistically significant rewarding effects of diclazepam at the doses of 0.2 and 2 mg/kg evaluated using the CPP paradigm were found. In conclusion, diclazepam has reinforcing effects and shares the interoceptive effects of alprazolam. Therefore, legal restrictions on the use of diclazepam should be carefully considered.
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Affiliation(s)
- Wonjong Lee
- Pharmacological Research Division, Toxicological Evaluation and Research Department, National Institute of Food and Drug Safety Evaluation, Ministry of Food and Drug Safety, 187 Osong Saengmyeong 2-ro, Heungdeok-gu, Chungju 28159, Republic of Korea
| | - Jung Won Lee
- Division of in Vitro Diagnostic Devices National Institute of Food and Drug Safety Evaluation, Ministry of Food and Drug Safety, 187 Osong Saengmyeong 2-ro, Heungdeok-gu, Chungju 28159, Republic of Korea
| | - Sungsun Kim
- Pharmacological Research Division, Toxicological Evaluation and Research Department, National Institute of Food and Drug Safety Evaluation, Ministry of Food and Drug Safety, 187 Osong Saengmyeong 2-ro, Heungdeok-gu, Chungju 28159, Republic of Korea
| | - Jin Mook Kim
- Pharmacological Research Division, Toxicological Evaluation and Research Department, National Institute of Food and Drug Safety Evaluation, Ministry of Food and Drug Safety, 187 Osong Saengmyeong 2-ro, Heungdeok-gu, Chungju 28159, Republic of Korea
| | - Dong-Hyun Youn
- Pharmacological Research Division, Toxicological Evaluation and Research Department, National Institute of Food and Drug Safety Evaluation, Ministry of Food and Drug Safety, 187 Osong Saengmyeong 2-ro, Heungdeok-gu, Chungju 28159, Republic of Korea
| | - Seong Hye Park
- Pharmacological Research Division, Toxicological Evaluation and Research Department, National Institute of Food and Drug Safety Evaluation, Ministry of Food and Drug Safety, 187 Osong Saengmyeong 2-ro, Heungdeok-gu, Chungju 28159, Republic of Korea
| | - Chan Hyeok Kwon
- Pharmacological Research Division, Toxicological Evaluation and Research Department, National Institute of Food and Drug Safety Evaluation, Ministry of Food and Drug Safety, 187 Osong Saengmyeong 2-ro, Heungdeok-gu, Chungju 28159, Republic of Korea
| | - Sun-Ok Choi
- Pharmacological Research Division, Toxicological Evaluation and Research Department, National Institute of Food and Drug Safety Evaluation, Ministry of Food and Drug Safety, 187 Osong Saengmyeong 2-ro, Heungdeok-gu, Chungju 28159, Republic of Korea.
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Lee W, Lee JW, Kim JM, Hong YK, Kim MS, Choi SO, Kang MS. The abuse potential of prolintane in rodents: Behavioral pharmacology approaches. Neuropharmacology 2021; 205:108917. [PMID: 34896117 DOI: 10.1016/j.neuropharm.2021.108917] [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: 05/09/2021] [Revised: 11/28/2021] [Accepted: 12/05/2021] [Indexed: 10/19/2022]
Abstract
Prolintane (1-Phenyl-2-pyrrolidinylpentane), a synthetic central nervous system (CNS) stimulant, is structurally similar to amphetamine but pharmacologically acts as a dopamine reuptake inhibitor like cocaine. While several case studies reported adverse effects and recreational use of prolintane, the abuse potential of the drug has not been systemically examined yet. In the present study, we evaluated the behavioral effects of prolintane regarding its abuse liability in rodents using locomotor activity, conditioned place preference (CPP), self-administration (SA), and drug discrimination paradigms, as well as in-vivo microdialysis experiment. First, acute prolintane (10 and 20 mg/kg, intraperitoneal injection) increased locomotor activity (distance traveled, cm) in mice but to a lesser degree than methamphetamine (as a positive control). We also found that a single and solitary injection of prolintane (20 mg/kg, IP) significantly increased extracellular dopamine in the striatum. The following result suggests that its stimulatory effects might be associated with the mesolimbic dopaminergic pathway. Further, prolintane produced a significant drug-paired place preference at doses of both 10 and 20 mg/kg. In the SA experiment, the mice that self-administered prolintane intravenously (4 mg/kg/inf) showed a higher infusion and active lever responses but not inactive lever responses. Additionally, cumulative doses of prolintane partially elicited cocaine-appropriate lever responses (38.57% at doses up to 10 mg/kg) in rats. These results implied that prolintane has not only rewarding and reinforcing effects but also interoceptive stimulus properties, which are similar to cocaine at a moderate level. Taken together, this study was the first to show, to our knowledge, that prolintane has a certain level of abuse potential and should be considered carefully as a valuable basis for legal restrictions on use.
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Affiliation(s)
- Wonjong Lee
- Pharmacological Research Division, Toxicological Evaluation and Research Department, National Institute of Food and Drug Safety Evaluation, Ministry of Food and Drug Safety, 187 Osong Saengmyeong 2-ro, Heungdeok-gu, Chungju, 28159, South Korea
| | - Jung Won Lee
- Scientific Officer Division of in Vitro Diagnostic Devices National Institute of Food and Drug Safety Evaluation, Ministry of Food and Drug Safety, 187 Osong Saengmyeong 2-ro, Heungdeok-gu, Chungju, 28159, South Korea
| | - Jin Mook Kim
- Pharmacological Research Division, Toxicological Evaluation and Research Department, National Institute of Food and Drug Safety Evaluation, Ministry of Food and Drug Safety, 187 Osong Saengmyeong 2-ro, Heungdeok-gu, Chungju, 28159, South Korea
| | - Young-Ki Hong
- Pharmacological Research Division, Toxicological Evaluation and Research Department, National Institute of Food and Drug Safety Evaluation, Ministry of Food and Drug Safety, 187 Osong Saengmyeong 2-ro, Heungdeok-gu, Chungju, 28159, South Korea
| | - Mi-Seon Kim
- Pharmacological Research Division, Toxicological Evaluation and Research Department, National Institute of Food and Drug Safety Evaluation, Ministry of Food and Drug Safety, 187 Osong Saengmyeong 2-ro, Heungdeok-gu, Chungju, 28159, South Korea
| | - Sun Ok Choi
- Pharmacological Research Division, Toxicological Evaluation and Research Department, National Institute of Food and Drug Safety Evaluation, Ministry of Food and Drug Safety, 187 Osong Saengmyeong 2-ro, Heungdeok-gu, Chungju, 28159, South Korea
| | - Mi Sun Kang
- Pharmacological Research Division, Toxicological Evaluation and Research Department, National Institute of Food and Drug Safety Evaluation, Ministry of Food and Drug Safety, 187 Osong Saengmyeong 2-ro, Heungdeok-gu, Chungju, 28159, South Korea.
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Gnazzo FG, Mourra D, Guevara C, Beeler JA. Chronic food restriction enhances dopamine-mediated intracranial self-stimulation. Neuroreport 2021; 32:1128-1133. [PMID: 34284450 PMCID: PMC8373704 DOI: 10.1097/wnr.0000000000001700] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Dopamine-mediated reinforcement and behavioral adaptation is essential to survival. Here, we test the effects of food restriction on dopamine-mediated learning and reinforcement using optical intracranial self-stimulation (oICSS), an optogenetic version of conventional electrical ICSS (also known as brain stimulation reward, BSR). Using mouse genetic lines to express channelrhodopsin selectively in midbrain dopamine neurons, we demonstrate that genetically expressed channelrhodopsin can mediate optically evoked dopamine release and support self-stimulation in a lever-pressing paradigm. Using this midbrain dopamine oICSS preparation, we compare acquisition and rate of pressing in ad libitum versus food restricted mice. Food restriction facilitated both more rapid acquisition of self-stimulation behavior and higher rates of responding; reversing food status after acquisition modulated response vigor in already established behavior. These data suggest that food restriction enhances both the acquisition and expression of dopamine-reinforced self-stimulation responding. These data demonstrate the utility of oICSS for examining changes in reinforcement learning concomitant to neuroadaptations induced in dopamine signaling by experimental manipulations such as food restriction.
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Affiliation(s)
- Federico G. Gnazzo
- Department of Psychology, Queens College, City University New York, New York, NY, USA
| | - Devry Mourra
- Department of Psychology, Queens College, City University New York, New York, NY, USA
- CUNY Neuroscience Collaborative, The Graduate Center, City University New York, New York, NY, USA
| | - Christopher Guevara
- Department of Psychology, Queens College, City University New York, New York, NY, USA
- (current ) Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Jeff A. Beeler
- Department of Psychology, Queens College, City University New York, New York, NY, USA
- CUNY Neuroscience Collaborative, The Graduate Center, City University New York, New York, NY, USA
- Biology Program, The Graduate Center, City University New York, New York, NY, USA
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Replacing a Palatable High-Fat Diet with a Low-Fat Alternative Heightens κ-Opioid Receptor Control over Nucleus Accumbens Dopamine. Nutrients 2021; 13:nu13072341. [PMID: 34371851 PMCID: PMC8308677 DOI: 10.3390/nu13072341] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Revised: 06/22/2021] [Accepted: 07/06/2021] [Indexed: 12/04/2022] Open
Abstract
Diet-induced obesity reduces dopaminergic neurotransmission in the nucleus accumbens (NAc), and stressful weight loss interventions could promote cravings for palatable foods high in fat and sugar that stimulate dopamine. Activation of κ-opioid receptors (KORs) reduces synaptic dopamine, but contribution of KORs to lower dopamine tone after dietary changes is unknown. Therefore, the purpose of this study was to determine the function of KORs in C57BL/6 mice that consumed a 60% high-fat diet (HFD) for six weeks followed by replacement of HFD with a control 10% fat diet for one day or one week. HFD replacement induced voluntary caloric restriction and weight loss. However, fast-scan cyclic voltammetry revealed no differences in baseline dopamine parameters, whereas sex effects were revealed during KOR stimulation. NAc core dopamine release was reduced by KOR agonism after one day of HFD replacement in females but after one week of HFD replacement in males. Further, elevated plus-maze testing revealed no diet effects during HFD replacement on overt anxiety. These results suggest that KORs reduce NAc dopamine tone and increase food-related anxiety during dietary weight loss interventions that could subsequently promote palatable food cravings and inhibit weight loss.
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Chen Z, Zhijie C, Yuting Z, Chan L, Shilin X, Qichun Z, Jinying O, Jing L, Chaohua L, Zhixian M. The Ameliorative Effects of Isorhynchophylline on Morphine Dependence Are Mediated Through the Microbiota-Gut-Brain Axis. Front Pharmacol 2021; 12:526923. [PMID: 34168553 PMCID: PMC8218633 DOI: 10.3389/fphar.2021.526923] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Accepted: 02/17/2021] [Indexed: 01/04/2023] Open
Abstract
Morphine abuse is a global public health problem. Increasing evidence has shown that gut microbiota dysbiosis plays an important role in several central nervous system diseases. However, whether there is an association between gut microbiota and morphine dependence remains unclear. In this study, the effects of isorhynchophylline on morphine dependence were evaluated based on the microbiota-gut-brain axis (MGBA). The results showed that isorhynchophylline could reverse the changes in alpha and beta diversity, composition, and richness of the intestinal flora occurring in morphine-dependent zebrafish, as well as the morphine-induced changes in the expression of MGBA-related genes in BV2 cells and the brain and intestine of zebrafish. Based on the results, we then used antibiotics to evaluate whether disrupting the gut microbiota would affect morphine addiction in zebrafish. The results showed that the antibiotic-induced intestinal floral imbalance changed the behavior of morphine-dependent zebrafish, the characteristics of the zebrafish intestinal flora, and the expression of MGBA-related genes in the zebrafish brain and intestine. Importantly, we also show that, following antibiotic administration, the ameliorative effects of isorhynchophylline on morphine addiction were lost. Together, our results indicate that the gut microbiota interacts with the brain, and dysbiosis of the intestinal flora may affect the efficacy of isorhynchophylline in the body. Our findings provide a novel framework for understanding the mechanisms of morphine addiction through the MGBA and may provide new therapeutic strategies for the use of Chinese medicines in the prevention of drug addiction.
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Affiliation(s)
- Zhu Chen
- School of Traditional Chinese Medicine, Southern Medical University, Guangzhou, China.,The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Chen Zhijie
- School of Traditional Chinese Medicine, Southern Medical University, Guangzhou, China
| | - Zhou Yuting
- School of Traditional Chinese Medicine, Southern Medical University, Guangzhou, China
| | - Li Chan
- School of Traditional Chinese Medicine, Southern Medical University, Guangzhou, China
| | - Xiao Shilin
- School of Traditional Chinese Medicine, Southern Medical University, Guangzhou, China
| | - Zhou Qichun
- School of Traditional Chinese Medicine, Southern Medical University, Guangzhou, China
| | - Ou Jinying
- School of Traditional Chinese Medicine, Southern Medical University, Guangzhou, China
| | - Li Jing
- Central Laboratory, Southern Medical University, Guangzhou, China
| | - Luo Chaohua
- School of Traditional Chinese Medicine, Southern Medical University, Guangzhou, China
| | - Mo Zhixian
- School of Traditional Chinese Medicine, Southern Medical University, Guangzhou, China
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Hurel I, Muguruza C, Redon B, Marsicano G, Chaouloff F. Cannabis and exercise: Effects of Δ 9-tetrahydrocannabinol on preference and motivation for wheel-running in mice. Prog Neuropsychopharmacol Biol Psychiatry 2021; 105:110117. [PMID: 32971218 DOI: 10.1016/j.pnpbp.2020.110117] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Revised: 09/11/2020] [Accepted: 09/20/2020] [Indexed: 11/27/2022]
Abstract
Recent surveys have revealed close links between cannabis and exercise. Specifically, cannabis usage before and/or after exercise is an increasingly common habit primarily aimed at boosting exercise pleasure, motivation, and performance whilst facilitating post-exercise recovery. However, whether these beliefs reflect the true impact of cannabis on these aspects of exercise is unknown. This study has thus examined the effects of cannabis' main psychoactive ingredient, namely Δ9-tetrahydrocannabinol (THC), on (i) mouse wheel-running preference and performance and (ii) running motivation and seeking behaviour. Wheel-running preference and performance were investigated using a T-maze with free and locked wheels located at the extremity of either arm. Running motivation and seeking were assessed by a cued-running operant task wherein wheel-running was conditioned by nose poking. Moreover, because THC targets cannabinoid type 1 (CB1) receptors, i.e. receptors previously documented to control running motivation, this study also assessed the role of these receptors in running preference, performance, and craving-like behaviour. Whilst acute blockade or genetic deletion of CB1 receptors decreased running preference and performance in the T-maze, THC proved ineffective on either variable. The failure of THC to affect running variables in the T-maze extended to running motivation, as assessed by cued-running under a progressive ratio (PR) reinforcement schedule. This ineffectiveness of THC was not related to the treatment protocol because it successfully increased motivation for palatable food. Although craving-like behaviour, as indexed by a cue-induced reinstatement of running seeking, was found to depend on CB1 receptors, THC again proved ineffective. Neither running motivation nor running seeking were affected when CB1 receptors were further stimulated by increasing the levels of the endocannabinoid 2-arachidonoylglycerol. These results, which suggest that the drive for running is insensitive to the acute stimulation of CB1 receptors, raise the hypothesis that cannabis is devoid of effect on exercise motivation. Future investigation using chronic administration of THC, with and without other cannabis ingredients (e.g. cannabidiol), is however required before conclusions can be drawn.
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Affiliation(s)
- Imane Hurel
- Endocannabinoids and NeuroAdaptation, NeuroCentre INSERM U1215, 33077 Bordeaux, France; Université de Bordeaux, 33077 Bordeaux, France
| | - Carolina Muguruza
- Endocannabinoids and NeuroAdaptation, NeuroCentre INSERM U1215, 33077 Bordeaux, France; Université de Bordeaux, 33077 Bordeaux, France; Department of Pharmacology, University of the Basque Country UPV/EHU, Leioa, Bizkaia, Spain; Centro de Investigación Biomédica en Red de Salud Mental, CIBERSAM, Spain
| | - Bastien Redon
- Endocannabinoids and NeuroAdaptation, NeuroCentre INSERM U1215, 33077 Bordeaux, France; Université de Bordeaux, 33077 Bordeaux, France
| | - Giovanni Marsicano
- Endocannabinoids and NeuroAdaptation, NeuroCentre INSERM U1215, 33077 Bordeaux, France; Université de Bordeaux, 33077 Bordeaux, France
| | - Francis Chaouloff
- Endocannabinoids and NeuroAdaptation, NeuroCentre INSERM U1215, 33077 Bordeaux, France; Université de Bordeaux, 33077 Bordeaux, France.
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Wallace CW, Loudermilt MC, Fordahl SC. Effect of fasting on dopamine neurotransmission in subregions of the nucleus accumbens in male and female mice. Nutr Neurosci 2020; 25:1338-1349. [PMID: 33297887 DOI: 10.1080/1028415x.2020.1853419] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Diets high in saturated fat (HFD) disrupt dopamine neurotransmission, whereas fasting alters tonic and phasic dopamine release to drive motivation and food consumption. However, functional compartments in the nucleus accumbens (NAc) influencing these effects are not well characterized, and sex comparisons have not been made. This study sought to determine whether consumption of a HFD, sex, or being fed versus fasted altered baseline dopamine release and reuptake throughout NAc subregions. Male and female C57BL/6 mice were fed a control diet or nutrient matched HFD for six weeks. Ex-vivo fast-scan cyclic voltammetry revealed females had significantly slower dopamine reuptake in the NAc core than males when fed ad lib control diet. Fasting enhanced dopamine release and reuptake in the NAc core but not the medioventral shell. Further, being fasted versus fed significantly increased dopamine release throughout the NAc core in control males but specifically promoted release and reuptake in only the ventrolateral core of HF-fed males, effects which were lacking in females. Finally, fasting promoted dopamine release and reuptake in the rostral NAc core of controls and more caudally in HFD groups. These data support that dopamine neurotransmission is heterogeneous in NAc subregions and suggest the ventrolateral core is responsive to energy state. Furthermore, a rostrocaudal gradient in the NAc core might control valence responses to fasting that could promote overeating after chronic HFD consumption.
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Affiliation(s)
- C W Wallace
- Department of Nutrition, UNC Greensboro, Greensboro, NC, USA
| | - M C Loudermilt
- Department of Nutrition, UNC Greensboro, Greensboro, NC, USA
| | - S C Fordahl
- Department of Nutrition, UNC Greensboro, Greensboro, NC, USA
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Godfrey N, Borgland SL. Sex differences in the effect of acute fasting on excitatory and inhibitory synapses onto ventral tegmental area dopamine neurons. J Physiol 2020; 598:5523-5539. [PMID: 32886798 DOI: 10.1113/jp280412] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Accepted: 09/01/2020] [Indexed: 02/06/2023] Open
Abstract
KEY POINTS Fasting can increase motivation for food and can energize reward-seeking. Ventral tegmental area (VTA) dopamine neurons respond to motivationally relevant information and fasting can influence mesolimbic dopamine concentration. An acute overnight fast differentially alters food approach behaviours and excitatory synaptic transmission onto VTA dopamine neurons of male or female mice. While inhibitory synapses onto VTA dopamine neurons are not altered by fasting in male or female mice, male mice had strengthened excitatory synapses whereas female mice had increased endocannabinoid-mediated short-term plasticity at excitatory synapses. These results help us understand how fasting differentially influences excitatory synaptic transmission onto dopamine neurons and may inform different strategies for fasting-induced food seeking by male and female mice. ABSTRACT Dopamine neurons in the ventral tegmental area (VTA) are important for energizing goal-directed behaviour towards food and are sensitive to changes in metabolic states. Fasting increases the incentive motivation for food and the mobilization of energy stores and has sex-dependent effects. However, it is unknown how acute fasting alters excitatory or inhibitory synaptic transmission onto VTA dopamine neurons. An acute 16 h overnight fast induced increased food-seeking behaviour that was more predominant in male mice. Fasting increased miniature excitatory postsynaptic current frequency and amplitude in male, but not female, mice. This effect was not due to altered release probability as there was no change in the paired pulse ratio, nor was it due to an altered postsynaptic response as there was no change in the AMPA receptor/NMDA receptor ratio or response to glutamate uncaging. However, this effect was consistent with an increase in the number of release sites. In addition, depolarization-induced suppression of excitation, a measure of short-term endocannabinoid-mediated plasticity, was enhanced in female but not male fasted mice. There were no fasting-induced changes at inhibitory synapses onto dopamine neurons of male or female mice. Taken together, these results demonstrate that fasting influences excitatory synapses differentially in male and female mice, but preserves inhibitory synapses onto dopamine neurons, indicating that the mesolimbic circuits of male and female mice respond differently to acute energy deprivation.
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Affiliation(s)
- Nathan Godfrey
- Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada
| | - Stephanie L Borgland
- Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada
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Czarna M, Kuchniak K, Chrapusta SJ, Turzyńska D, Płaźnik A, Taracha E. Diverging changes in rat striatal extracellular dopamine and DOPAC levels and in frequency-modulated 50-kHz ultrasonic vocalizations rate during repeated amphetamine treatment. Behav Brain Res 2020; 393:112745. [DOI: 10.1016/j.bbr.2020.112745] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Revised: 05/18/2020] [Accepted: 05/28/2020] [Indexed: 12/27/2022]
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Carr KD. Modulatory Effects of Food Restriction on Brain and Behavioral Effects of Abused Drugs. Curr Pharm Des 2020; 26:2363-2371. [DOI: 10.2174/1381612826666200204141057] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Accepted: 11/19/2019] [Indexed: 12/14/2022]
Abstract
Energy homeostasis is achieved, in part, by metabolic signals that regulate the incentive motivating
effects of food and its cues, thereby driving or curtailing procurement and consumption. The neural underpinnings
of these regulated incentive effects have been identified as elements within the mesolimbic dopamine pathway.
A separate line of research has shown that most drugs with abuse liability increase dopamine transmission in
this same pathway and thereby reinforce self-administration. Consequently, one might expect shifts in energy
balance and metabolic signaling to impact drug abuse risk. Basic science studies have yielded numerous examples
of drug responses altered by diet manipulation. Considering the prevalence of weight loss dieting in Western
societies, and the anorexigenic effects of many abused drugs themselves, we have focused on the CNS and behavioral
effects of food restriction in rats. Food restriction has been shown to increase the reward magnitude of diverse
drugs of abuse, and these effects have been attributed to neuroadaptations in the dopamine-innervated nucleus
accumbens. The changes induced by food restriction include synaptic incorporation of calcium-permeable
AMPA receptors and increased signaling downstream of D1 dopamine receptor stimulation. Recent studies suggest
a mechanistic model in which concurrent stimulation of D1 and GluA2-lacking AMPA receptors enables
increased stimulus-induced trafficking of GluA1/GluA2 AMPARs into the postsynaptic density, thereby increasing
the incentive effects of food, drugs, and associated cues. In addition, the established role of AMPA receptor
trafficking in enduring synaptic plasticity prompts speculation that drug use during food restriction may more
strongly ingrain behavior relative to similar use under free-feeding conditions.
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Affiliation(s)
- Kenneth D. Carr
- Departments of Psychiatry, Biochemistry and Molecular Pharmacology, New York University School of Medicine, 435 East 30th Street, New York, NY 10016, United States
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12
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Fasting may increase incentive signaling for nonfood rewards. Nutr Res 2020; 77:43-53. [PMID: 32315894 DOI: 10.1016/j.nutres.2020.02.013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Revised: 02/21/2020] [Accepted: 02/27/2020] [Indexed: 11/22/2022]
Abstract
During acute energy deprivation, hunger signaling mechanisms support homeostasis by enhancing incentive for food. There is some evidence (primarily based on nonhuman experiments) that fasting heightens incentive signaling for nonfood reward as well. We hypothesized that, consistent with results from research in rodent and nonhuman primates, human participants would evidence increased incentive-related brain activity for nonfood rewards during fast (relative to satiety) and that this increase would be heightened when available rewards were immediate. To assess these possibilities, healthy participants with body mass index between 18 and 29 kg/m2 completed a task which engaged participants in opportunities to win immediate and delayed money (Monetary Incentive Delay Task) during 2 neuroimaging sessions (1 postprandial, 1 fasted). Analyses of participants (N = 18 included, body mass index 22.12± 2.72, age 21.39± 3.52) focused on brain activity during the incentive window of the task. Region of interest, as well as whole-brain analyses, supported the hypothesized increase in incentive signaling during fasting in regions that included caudate and putamen. No evidence of interaction was observed between fasting and the effect of reward immediacy or reward magnitude. Although provisional given the modest sample size, these results suggest that acute fasting can heighten incentive signaling for nonfood rewards.
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Corongiu S, Dessì C, Cadoni C. Adolescence versus adulthood: Differences in basal mesolimbic and nigrostriatal dopamine transmission and response to drugs of abuse. Addict Biol 2020; 25:e12721. [PMID: 30779271 DOI: 10.1111/adb.12721] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Revised: 12/06/2018] [Accepted: 01/08/2019] [Indexed: 12/21/2022]
Abstract
Epidemiological studies have shown that people who begin experimenting drugs of abuse during adolescence are more likely to develop substance use disorders, and the earliest is the beginning of their use, the greatest is the likelihood to become dependent. Understanding the neurobiological changes increasing adolescent vulnerability to drug use is becoming imperative. Although all neurotransmitter systems undergo relevant developmental changes, dopamine system is of particular interest, given its role in a variety of functions related to reward, motivation, and decision making. Thus, in the present study, we investigated differences in mesolimbic and nigrostriatal dopamine transmission between adolescent (5, 6, 7 weeks of age) and adult rats (10-12 weeks of age), in basal conditions and following drug challenge, by using in vivo brain microdialysis. Although no significant difference between adolescents and adults was observed in dopamine basal levels in the nucleus accumbens (NAc)shell and core, reduced DA levels were found in the dorsolateral striatum (DLS) of early and mid-adolescent rats. Adolescent rats showed greater increase of dopamine in the NAc shell following nicotine (0.4 mg/kg), THC (1.0 mg/kg), and morphine (1.0 mg/kg), in the NAc core following nicotine and morphine, and in the DLS following THC, morphine, and cocaine (10 mg/kg). These results, while adding new insight in the development and functionality of the dopamine system during different stages of adolescence, might provide a neurochemical basis for the greater vulnerability of adolescents to drugs of abuse and for the postulated gateway effect of nicotine and THC toward abuse of other illicit substances.
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Affiliation(s)
- Silvia Corongiu
- Department of Biomedical Sciences, Neuropsychopharmacology SectionUniversity of Cagliari Italy
| | - Christian Dessì
- National Research Council of ItalyInstitute of Neuroscience Italy
| | - Cristina Cadoni
- National Research Council of ItalyInstitute of Neuroscience Italy
- Centre of Excellence “Neurobiology of Dependence”University of Cagliari Italy
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Roles of nucleus accumbens shell and core in footshock-induced stress altering behavioral sensitization by methamphetamine in acquisition and testing: Running head: stress, nucleus accumbens, and behavioral sensitization. Behav Brain Res 2019; 380:112434. [PMID: 31846629 DOI: 10.1016/j.bbr.2019.112434] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2019] [Revised: 12/02/2019] [Accepted: 12/13/2019] [Indexed: 12/15/2022]
Abstract
How the subregions of the nucleus accumbens (NAc) shell and core and stress are involved in behavioral sensitization induced by psychostimulants remains unclear. The present study manipulated methamphetamine (MAMPH) injections, lesions of the NAc shell or core, and footshock-treatment-induced stress to address this issue. The present data showed that during the acquisition phase, MAMPH injections, lesions of the NAc shell, and footshock treatments induced hyperactivity for the NAc shell. For the NAc core, MAMPH injections induced hyperactivity; however, lesions of the NAc core did not affect locomotor activity. Footshock treatments disrupted hyperactivity of behavioral sensitization. During the testing phase, MAMPH injections, lesions of the NAc shell, and footshock-treatment-induced stress facilitated hyperactivity for the NAc shell. For the NAc core, MAMPH injections and footshock-treatment-induced stress increased hyperactivity. However, the lesion of the NAc core did not affect locomotor activity. In conclusion, MAMPH injections and footshock-treatment-induced stress play an excitatory role for the NAc shell in acquisition and testing. For the NAc core, footshock-treatment-induced stress plays an inhibitory role in acquisition but an excitatory role in testing. The NAc core was not involved in MAMPH-induced behavioral sensitization in acquisition and testing. The NAc shell plays an inhibitory role in acquisition and testing phases. The present data might provide some insights for drug addiction. The results should be discussed further.
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Jeon SY, Kim YH, Kim SJ, Suh SK, Cha HJ. Abuse potential of 2-(4-iodo-2, 5-dimethoxyphenyl)N-(2-methoxybenzyl)ethanamine (25INBOMe); in vivo and ex vivo approaches. Neurochem Int 2019; 125:74-81. [PMID: 30769030 DOI: 10.1016/j.neuint.2019.02.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2018] [Revised: 01/10/2019] [Accepted: 02/12/2019] [Indexed: 01/08/2023]
Abstract
25INBOMe ("25-I", "N-Bomb"), one of new psychoactive substances (NPSs), is being abused for recreational purpose. However, the liability for abuse or dependence has not been systematically studied yet. The objective of the present study was to evaluate rewarding and reinforcing effects of 25INBOMe using conditioned place preference (CPP) and self-administration (SA) paradigms. In addition, ultrasonic vocalizations (USVs) were measured to investigate relationships between USVs and emotional state regarding dependence on psychoactive substances. To understand molecular mechanism involved in its action, dopamine (DA) level changes were analyzed using synaptosomes extracted from the striatal region of the brain. Expression level changes of SGK1 (serum/glucocorticoid regulated kinase 1) and PER2 (period circadian protein homolog 2), two putative biomarkers for drug dependence, were also analyzed. Results showed that 25INBOMe increased both CPP (0.3 mg/kg) and SA (0.03 mg/kg/infusion) and produced higher frequencies in USVs analysis. It also increased DA levels in the striatal region and changed expression levels of SGK1 and PER2. Results of the present study suggest that 25INBOMe might produce rewarding and reinforcing effects, indicating its dependence liability. In addition, frequencies of USV might be associated with emotional state of mice induced by psychoactive substances regarding substance dependence. This is the first systemic preclinical report on the dependence liability of 25INBOMe and the first attempt to introduce a possible relationship between USVs and emotional state of mice regarding substance dependency. Further studies are needed to clarify the mechanism involved in 25INBOMe dependency and determine the usefulness of USV measurement as a method for evaluating dependence liability.
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Affiliation(s)
- Seo Young Jeon
- National Institute of Drug and Safety Evaluation, Ministry of Food and Drug Safety, Osong, Cheongju, Republic of Korea
| | - Young-Hoon Kim
- National Institute of Drug and Safety Evaluation, Ministry of Food and Drug Safety, Osong, Cheongju, Republic of Korea
| | - Sung Jin Kim
- Cosmetics Policy Division, Ministry of Food and Drug Safety, Osong, Cheongju, Republic of Korea
| | - Soo Kyung Suh
- National Institute of Drug and Safety Evaluation, Ministry of Food and Drug Safety, Osong, Cheongju, Republic of Korea
| | - Hye Jin Cha
- National Institute of Drug and Safety Evaluation, Ministry of Food and Drug Safety, Osong, Cheongju, Republic of Korea.
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Cha HJ, Jeon SY, Jang HJ, Shin J, Kim YH, Suh SK. Rewarding and reinforcing effects of 4-chloro-2,5-dimethoxyamphetamine and AH-7921 in rodents. Neurosci Lett 2018; 676:66-70. [PMID: 29626650 DOI: 10.1016/j.neulet.2018.04.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Revised: 03/30/2018] [Accepted: 04/03/2018] [Indexed: 10/17/2022]
Abstract
New psychoactive substances (NPSs), i.e., newly designed substances with chemical residues that are slightly different from those of known psychoactive substances, have been emerging since the late 2000s, and social problems related to the use of these substances are increasing globally. Two such NPSs are 4-chloro-2,5-dimethoxyamphetamine (DOC), a psychedelic substance that is structurally related to amphetamine, and AH-7921, an opioid analgesic that is used for recreational purposes and has a potency similar to that of morphine. Currently, scientific evidence for the dependence liability or toxicity of NPSs is lacking. Therefore, in this study, we performed animal behavioral tests to evaluate the dependence liability of DOC and AH-7921. The rewarding and reinforcing effects of DOC and AH-7921 were evaluated using the conditioned place preference (CPP) paradigm in mice and the self-administration (SA) procedure in rats. Both DOC and AH-7921 increased the preference for the drug-paired compartment in the CPP test at a dose of 0.3 mg/kg and increased the number of responses to the active lever in the SA test at 0.01 mg/(kg·infusion). Collectively, the data suggest that DOC and AH-7921 may have both rewarding and reinforcing effects. Further studies are needed to confirm the reinforcing effects in broader dose ranges with various schedules.
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Affiliation(s)
- Hye Jin Cha
- Pharmacological Research Division, Toxicological Evaluation and Research Department, National Institute of Food and Drug Safety Evaluation, Ministry of Food and Drug Safety, 187 Osong Saengmyeong 2-ro, Heungdeok-gu, Chungju-shi 28159, Republic of Korea.
| | - Seo Young Jeon
- Pharmacological Research Division, Toxicological Evaluation and Research Department, National Institute of Food and Drug Safety Evaluation, Ministry of Food and Drug Safety, 187 Osong Saengmyeong 2-ro, Heungdeok-gu, Chungju-shi 28159, Republic of Korea
| | - Hwa Jin Jang
- Pharmacological Research Division, Toxicological Evaluation and Research Department, National Institute of Food and Drug Safety Evaluation, Ministry of Food and Drug Safety, 187 Osong Saengmyeong 2-ro, Heungdeok-gu, Chungju-shi 28159, Republic of Korea
| | - Jisoon Shin
- Pharmacological Research Division, Toxicological Evaluation and Research Department, National Institute of Food and Drug Safety Evaluation, Ministry of Food and Drug Safety, 187 Osong Saengmyeong 2-ro, Heungdeok-gu, Chungju-shi 28159, Republic of Korea
| | - Young-Hoon Kim
- Pharmacological Research Division, Toxicological Evaluation and Research Department, National Institute of Food and Drug Safety Evaluation, Ministry of Food and Drug Safety, 187 Osong Saengmyeong 2-ro, Heungdeok-gu, Chungju-shi 28159, Republic of Korea
| | - Soo Kyung Suh
- Pharmacological Research Division, Toxicological Evaluation and Research Department, National Institute of Food and Drug Safety Evaluation, Ministry of Food and Drug Safety, 187 Osong Saengmyeong 2-ro, Heungdeok-gu, Chungju-shi 28159, Republic of Korea
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Enhancement of a visual reinforcer by D-amphetamine and nicotine in adult rats: relation to habituation and food restriction. Psychopharmacology (Berl) 2018; 235:803-814. [PMID: 29199358 DOI: 10.1007/s00213-017-4796-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Accepted: 11/20/2017] [Indexed: 12/11/2022]
Abstract
RATIONALE AND OBJECTIVES Nicotine and D-amphetamine can strengthen reinforcing effects of unconditioned visual stimuli. We investigated whether these reinforcement-enhancing effects reflect a slowing of stimulus habituation and depend on food restriction. METHODS Adult male rats pressed an active lever to illuminate a cue light during daily 60-min sessions. Depending on the experiment, rats were challenged with fixed or varying doses of D-amphetamine (0.25-2 mg/kg IP) and nicotine (0.025-0.2 mg/kg SC) or with the tobacco constituent norharman (0.03-10 μg/kg IV). Experiment 1 tested for possible reinforcement-enhancing effects of D-amphetamine and norharman. Experiment 2 investigated whether nicotine and amphetamine inhibited the spontaneous within-session decline in lever pressing. Experiment 3 assessed the effects of food restriction. RESULTS Amphetamine (0.25-1 mg/kg) and nicotine (0.1 mg/kg) increased active lever pressing specifically (two- to threefold increase). The highest doses of nicotine and amphetamine also affected inactive lever responding (increase and decrease, respectively). With the visual reinforcer omitted, responding was largely extinguished. Neither drug appeared to slow habituation, as assessed by the within-session decline in lever pressing, and reinforcement-enhancing effects still occurred if the drugs were given after this decline had occurred. Food restriction enhanced the reinforcement-enhancing effect of amphetamine but not that of nicotine. CONCLUSIONS Responding remained goal-directed after several weeks of testing. Low doses of D-amphetamine and nicotine produced reinforcement enhancement even in free-feeding subjects, independent of the spontaneous within-session decline in responding. Reinforcement enhancement by amphetamine, but not nicotine, was enhanced by concurrent subchronic food restriction.
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Saszik SM, Smith CM. The impact of stress on social behavior in adult zebrafish (Danio rerio). Behav Pharmacol 2018; 29:53-59. [DOI: 10.1097/fbp.0000000000000338] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Cadoni C. Fischer 344 and Lewis Rat Strains as a Model of Genetic Vulnerability to Drug Addiction. Front Neurosci 2016; 10:13. [PMID: 26903787 PMCID: PMC4746315 DOI: 10.3389/fnins.2016.00013] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Accepted: 01/11/2016] [Indexed: 01/02/2023] Open
Abstract
Today it is well acknowledged that both nature and nurture play important roles in the genesis of psychopathologies, including drug addiction. Increasing evidence suggests that genetic factors contribute for at least 40–60% of the variation in liability to drug dependence. Human genetic studies suggest that multiple genes of small effect, rather than single genes, contribute to the genesis of behavioral psychopathologies. Therefore, the use of inbred rat strains might provide a valuable tool to identify differences, linked to genotype, important in liability to addiction and related disorders. In this regard, Lewis and Fischer 344 inbred rats have been proposed as a model of genetic vulnerability to drug addiction, given their innate differences in sensitivity to the reinforcing and rewarding effects of drugs of abuse, as well their different responsiveness to stressful stimuli. This review will provide evidence in support of this model for the study of the genetic influence on addiction vulnerability, with particular emphasis on differences in mesolimbic dopamine (DA) transmission, rewarding and emotional function. It will be highlighted that Lewis and Fischer 344 rats differ not only in several indices of DA transmission and adaptive changes following repeated drug exposure, but also in hypothalamic-pituitary-adrenal (HPA) axis responsiveness, influencing not only the ability of the individual to cope with stressful events, but also interfering with rewarding and motivational processes, given the influence of corticosteroids on dopamine neuron functionality. Further differences between the two strains, as impulsivity or anxiousness, might contribute to their different proneness to addiction, and likely these features might be linked to their different DA neurotransmission plasticity. Although differences in other neurotransmitter systems might deserve further investigation, results from the reviewed studies might open new vistas in understanding aberrant deviations in reward and motivational functions.
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Affiliation(s)
- Cristina Cadoni
- Institute of Neuroscience, Cagliari Section, Department of Biomedical Sciences, National Research Council of ItalyCagliari, Italy; Centre of Excellence "Neurobiology of Dependence", University of CagliariCagliari, Italy
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Steinglass JE, Walsh BT. Neurobiological model of the persistence of anorexia nervosa. J Eat Disord 2016; 4:19. [PMID: 27195123 PMCID: PMC4870737 DOI: 10.1186/s40337-016-0106-2] [Citation(s) in RCA: 82] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/12/2016] [Accepted: 05/02/2016] [Indexed: 01/01/2023] Open
Abstract
Anorexia Nervosa (AN) is characterized by the maintenance of an undernourished, or starved, state. Persistent restrictive eating, or the recurrent intake of a diet that is inadequate to sustain a healthy weight, is the central behavior maintaining AN. To understand this disturbance, we need to understand the neural mechanisms that allow or promote the persistent choice of inadequate caloric intake. While a range of neural disturbances have been reported in AN, abnormalities in systems relevant to reward processing and the development of habit systems have been consistently described in both structural and functional neuroimaging studies. Most recently, brain and behavior have been directly examined by investigating the neural underpinnings of restrictive food choice. These recent data suggest that, among individuals with AN, dorsal frontostriatal circuits play a greater role in guiding decisions regarding what to eat than among healthy individuals. This line of research attempts to leverage advances in the field of cognitive neuroscience to further our understanding of persistent maladaptive choices of individuals with AN, in the hope that such advances will help in the development of novel treatments for this potentially fatal disorder.
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Central serotonin2B receptor blockade inhibits cocaine-induced hyperlocomotion independently of changes of subcortical dopamine outflow. Neuropharmacology 2015; 97:329-37. [DOI: 10.1016/j.neuropharm.2015.06.012] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Revised: 06/10/2015] [Accepted: 06/16/2015] [Indexed: 12/31/2022]
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Bassareo V, Cucca F, Frau R, Di Chiara G. Differential activation of accumbens shell and core dopamine by sucrose reinforcement with nose poking and with lever pressing. Behav Brain Res 2015; 294:215-23. [PMID: 26275926 DOI: 10.1016/j.bbr.2015.08.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Revised: 08/06/2015] [Accepted: 08/07/2015] [Indexed: 11/30/2022]
Abstract
In order to investigate the role of modus operandi in the changes of nucleus accumbens (NAc) dopamine (DA) transmission in sucrose reinforcement, extracellular DA was monitored by microdialysis in the NAc shell and core of rats trained on a fixed-ratio 1 schedule to respond for sucrose pellets by nose poking and lever pressing respectively. After training, rats were tested on three different sessions: sucrose reinforcement, extinction and passive sucrose presentation. In rats responding by nose poking dialysate DA increased in the shell but not in the core under reinforced as well as under extinction sessions. In contrast, in rats responding by lever pressing dialysate DA increased both in the accumbens shell and core under reinforced and extinction sessions. Response non-contingent sucrose presentation increased dialysate DA in the shell and core of rats trained to respond for sucrose by nose poking as well as in those trained by lever pressing. In rats trained to respond for sucrose by nose poking on a FR5 schedule dialysate DA also increased selectively in the NAc shell during reinforced responding and in both the shell and core under passive sucrose presentation. These findings, while provide an explanation for the discrepancies existing in the literature over the responsiveness of shell and core DA in rats responding for food, are consistent with the notion that NAc shell and core DA encode different aspects of reinforcement.
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Affiliation(s)
- V Bassareo
- Department of Biomedical Sciences, University of Cagliari, Via Ospedale 72, 09124 Cagliari, Italy.
| | - F Cucca
- Department of Biomedical Sciences, University of Cagliari, Via Ospedale 72, 09124 Cagliari, Italy
| | - R Frau
- Department of Biomedical Sciences, University of Cagliari, Via Ospedale 72, 09124 Cagliari, Italy
| | - G Di Chiara
- Department of Biomedical Sciences, University of Cagliari, Via Ospedale 72, 09124 Cagliari, Italy; CNR Institute of Neuroscience, Cagliari Section, Via Ospedale 72, 09124 Cagliari, Italy.
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Harris AC, Mattson C, Shelley D, LeSage MG. Restraint stress attenuates nicotine's locomotor stimulant but not discriminative stimulus effects in rats. Pharmacol Biochem Behav 2014; 124:92-100. [PMID: 24867077 DOI: 10.1016/j.pbb.2014.05.012] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Revised: 05/14/2014] [Accepted: 05/16/2014] [Indexed: 01/07/2023]
Abstract
Stress enhances the locomotor stimulant and discriminative stimulus effects of several addictive drugs (e.g., morphine) in rodents, yet interactions between stress and nicotine's effects in these behavioral models have not been well established. To this end, the current studies examined the effects of restraint stress on nicotine-induced locomotor activity and nicotine discrimination in rats. We used a novel approach in which onset of stress and nicotine administration occurred concurrently (i.e., simultaneous exposure) to simulate effects of stress on ongoing tobacco use, as well as a more traditional approach in which a delay was imposed between stress and nicotine administration (i.e., sequential exposure). Simultaneous exposure to stress reduced the rate of locomotor sensitization induced by daily injections of nicotine (0.4 mg/kg, s.c.). A lower dose of nicotine (0.1mg/kg, s.c.) produced modest effects on activity that were generally unaffected by simultaneous exposure to stress. Sequential exposure to stress and nicotine (0.4 mg/kg, s.c.) slightly suppressed nicotine-induced activity but did not influence rate of locomotor sensitization. Neither simultaneous nor sequential exposure to stress influenced the discriminative stimulus effects of nicotine (0.01-0.2mg/kg, s.c.). These data show that restraint stress reduces nicotine's locomotor stimulant effects, particularly when onset of stress and nicotine exposure occurs simultaneously, but does not influence nicotine discrimination. These findings contrast with the ability of stress to enhance the effects of other drugs in these models. This study also suggests that studying the influence of simultaneous stress exposure on drug effects may be useful for understanding the role of stress in addiction.
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Affiliation(s)
- Andrew C Harris
- Minneapolis Medical Research Foundation, Minneapolis, MN, USA; Department of Medicine, University of Minnesota Medical School, Minneapolis, MN, USA; Department of Psychology, University of Minnesota, Minneapolis, MN, USA.
| | | | - David Shelley
- Minneapolis Medical Research Foundation, Minneapolis, MN, USA
| | - Mark G LeSage
- Minneapolis Medical Research Foundation, Minneapolis, MN, USA; Department of Medicine, University of Minnesota Medical School, Minneapolis, MN, USA; Department of Psychology, University of Minnesota, Minneapolis, MN, USA
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The amphetamine sensitization model of schizophrenia symptoms and its effect on schedule-induced polydipsia in the rat. Psychopharmacology (Berl) 2014; 231:2001-8. [PMID: 24241687 DOI: 10.1007/s00213-013-3345-9] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/08/2013] [Accepted: 10/18/2013] [Indexed: 10/26/2022]
Abstract
RATIONALE Amphetamine enhances dopamine (DA) transmission and induces psychotic states or exacerbates psychosis in at-risk individuals. Amphetamine sensitization of the DA system has been proposed as a rodent model of schizophrenia-like symptoms. In humans, excessive nonphysiologic drinking or primary polydipsia is significantly associated with a diagnosis of schizophrenia. In rodents, nonphysiologic drinking can be induced by intermittent presentation of food in the presence of a drinking spout to a hungry animal; this phenomenon is termed, "schedule-induced polydipsia" (SIP). OBJECTIVE This study aims to determine the effects of amphetamine sensitization on SIP. METHODS We injected rats with amphetamine (1.5 mg/kg) daily for 5 days. Following 4 weeks of withdrawal, animals were food restricted and exposed to the SIP protocol (noncontingent fixed-time 1-min food schedule) for daily 2-h sessions for 24 days. RESULTS Results showed that previously amphetamine-injected animals drank more in the SIP protocol and drank more than controls when the intermittent food presentation schedule was removed. CONCLUSIONS These findings suggest that hyperdopaminergia associated with schizophrenia may contribute to the development of polydipsia in this population. Whether animals that develop SIP have DA dysfunction or aberrant activity of other circuits that modulate DA activity has yet to be clearly defined.
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25
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Food restriction increases glutamate receptor-mediated burst firing of dopamine neurons. J Neurosci 2013; 33:13861-72. [PMID: 23966705 DOI: 10.1523/jneurosci.5099-12.2013] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Restriction of food intake increases the acquisition of drug abuse behavior and enhances the reinforcing efficacy of those drugs. However, the neurophysiological mechanisms responsible for the interactions between feeding state and drug use are largely unknown. Here we show that chronic mild food restriction increases the burst firing of dopamine neurons in the substantia nigra. Dopamine neurons from food-restricted mice exhibited increased burst firing in vivo, an effect that was enhanced by an injection of the psychomotor stimulant cocaine (10 mg/kg, i.p.). Food restriction also enhanced aspartic acid-induced burst firing of dopamine neurons in an ex vivo brain slice preparation, consistent with an adaptation occurring in the somatodendritic compartment and independent of a circuit mechanism. Enhanced burst firing persisted after 10 d of free feeding following chronic food restriction but was not observed following a single overnight fast. Whole-cell patch-clamp recordings indicated that food restriction also increased electrically evoked AMPAR/NMDAR ratios and increased D2 autoreceptor-mediated desensitization in dopamine neurons. These results identify dopamine neurons in the substantia nigra as a convergence point for the interactions between feeding state and drugs of abuse. Furthermore, increased glutamate transmission combined with decreased autoreceptor inhibition could work in concert to enhance drug efficacy in response to food restriction.
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Allen CP, Zhou Y, Leri F. Effect of food restriction on cocaine locomotor sensitization in Sprague-Dawley rats: role of kappa opioid receptors. Psychopharmacology (Berl) 2013; 226:571-8. [PMID: 23212389 DOI: 10.1007/s00213-012-2930-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2012] [Accepted: 11/12/2012] [Indexed: 12/20/2022]
Abstract
RATIONALE The interaction between repeated cocaine exposure and food restriction on sensitization to the stimulatory effects of cocaine has not been characterized. OBJECTIVES To compare cocaine sensitization in rats free fed and food restricted, and begin to explore the role of the stress-responsive dynorphin/kappa opioid system. METHODS Male rats were maintained for 10 days on two feeding conditions: free fed or food restricted (85 % of free fed weight). Test 1 of locomotor reactivity to cocaine (3, 9, or 15 mg/kg, IP) was followed by a sensitizing regimen of cocaine exposure (0 or 30 mg/kg/day × 5 days, IP), by a 10-day drug-free period, and by Test 2 of reactivity to the same cocaine dose. In a second experiment, rats received an injection of norbinaltorphimine (nor-BNI; 0, 5 or 20 mg/kg, SC) 10 days prior to each locomotion test, and plasma corticosterone (CORT) was assessed after Test 2. RESULTS On Test 1, it was found that food restriction enhanced locomotor responses to all doses of cocaine. On Test 2, it was found that free fed and food restricted animals displayed similar sensitized responses to cocaine. This, however, was not observed in nor-BNI-treated rats. Furthermore, 20 mg/kg nor-BNI reduced both the locomotor response to cocaine on Test 2 and the effect of cocaine and food restriction on CORT plasma levels. CONCLUSIONS These results indicate that the interaction between cocaine sensitization and food restriction is not synergistic, and that it involves activation of kappa-opioid receptors.
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Affiliation(s)
- Craig P Allen
- Department of Psychology, University of Guelph, 50 Stone Road East, Guelph, ON, Canada
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Contribution of the mesolimbic dopamine system in mediating the effects of leptin and ghrelin on feeding. Proc Nutr Soc 2012; 71:435-45. [DOI: 10.1017/s0029665112000614] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Feeding behaviour is crucial for the survival of an organism and is regulated by different brain circuits. Among these circuits the mesolimbic dopamine (DA) system is implicated in the anticipation and motivation for food rewards. This system consists of the dopaminergic neurons in the ventral tegmental area (VTA), and their projections to different cortico-limbic structures such as the nucleus accumbens and medial prefrontal cortex. While the importance of this system in motivational drive for different rewards, including drugs of abuse, has been clearly established, its role in energy balance remains largely unexplored. Evidence suggests that peripheral hormones such as leptin and ghrelin are involved in the anticipation and motivation for food and this might be partially mediated through their effects on the VTA. Yet, it remains to be determined whether these effects are direct effects of ghrelin and leptin onto VTA DA neurons, and to what extent indirect effects through other brain areas contribute. Elucidation of the role of leptin and ghrelin signalling on VTA DA neurons in relation to disruptions of energy balance might provide important insights into the role of this neural circuit in obesity and anorexia nervosa.
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Avena NM, Bocarsly ME. Dysregulation of brain reward systems in eating disorders: neurochemical information from animal models of binge eating, bulimia nervosa, and anorexia nervosa. Neuropharmacology 2012; 63:87-96. [PMID: 22138162 PMCID: PMC3366171 DOI: 10.1016/j.neuropharm.2011.11.010] [Citation(s) in RCA: 125] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2011] [Revised: 10/28/2011] [Accepted: 11/18/2011] [Indexed: 01/18/2023]
Abstract
Food intake is mediated, in part, through brain pathways for motivation and reinforcement. Dysregulation of these pathways may underlay some of the behaviors exhibited by patients with eating disorders. Research using animal models of eating disorders has greatly contributed to the detailed study of potential brain mechanisms that many underlie the causes or consequences of aberrant eating behaviors. This review focuses on neurochemical evidence of reward-related brain dysfunctions obtained through animal models of binge eating, bulimia nervosa, or anorexia nervosa. The findings suggest that alterations in dopamine (DA), acetylcholine (ACh) and opioid systems in reward-related brain areas occur in response to binge eating of palatable foods. Moreover, animal models of bulimia nervosa suggest that while bingeing on palatable food releases DA, purging attenuates the release of ACh that might otherwise signal satiety. Animal models of anorexia nervosa suggest that restricted access to food enhances the reinforcing effects of DA when the animal does eat. The activity-based anorexia model suggests alterations in mesolimbic DA and serotonin occur as a result of restricted eating coupled with excessive wheel running. These findings with animal models complement data obtained through neuroimaging and pharmacotherapy studies of clinical populations. Information on the neurochemical consequences of the behaviors associated with these eating disorders will be useful in understanding these complex disorders and may inform future therapeutic approaches, as discussed here. This article is part of a Special Issue entitled 'Central Control of Food Intake'.
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Affiliation(s)
- Nicole M Avena
- University of Florida, College of Medicine, Department of Psychiatry, Gainesville, FL 32608, USA.
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Skibicka KP, Shirazi RH, Hansson C, Dickson SL. Ghrelin interacts with neuropeptide Y Y1 and opioid receptors to increase food reward. Endocrinology 2012; 153:1194-205. [PMID: 22210742 DOI: 10.1210/en.2011-1606] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Ghrelin, a stomach-derived hormone, is an orexigenic peptide that was recently shown to potently increase food reward behavior. The neurochemical circuitry that links ghrelin to the mesolimbic system and food reward behavior remains unclear. Here we examined the contribution of neuropeptide Y (NPY) and opioids to ghrelin's effects on food motivation and intake. Both systems have well-established links to the mesolimbic ventral tegmental area (VTA) and reward/motivation control. NPY mediates the effect of ghrelin on food intake via activation of NPY-Y1 receptor (NPY-Y1R); their connection with respect to motivated behavior is unexplored. The role of opioids in any aspect of ghrelin's action on food-oriented behaviors is unknown. Rats were trained in a progressive ratio sucrose-induced operant schedule to measure food reward/motivation behavior. Chow intake was measured immediately after the operant test. In separate experiments, we explored the suppressive effects of a selective NPY-Y1R antagonist or opioid receptor antagonist naltrexone, injected either intracerebroventricularly or intra-VTA, on ghrelin-induced food reward behavior. The ventricular ghrelin-induced increase in sucrose-motivated behavior and chow intake were completely blocked by intracerebroventricular pretreatment with either an NPY-Y1R antagonist or naltrexone. The intra-VTA ghrelin-induced sucrose-motivated behavior was blocked only by intra-VTA naltrexone. In contrast, the intra-VTA ghrelin-stimulated chow intake was attenuated only by intra-VTA NPY-Y1 blockade. Finally, ghrelin infusion was associated with an elevated VTA μ-opioid receptor expression. Thus, we identify central NPY and opioid signaling as the necessary mediators of food intake and reward effects of ghrelin and localize these interactions to the mesolimbic VTA.
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Affiliation(s)
- Karolina P Skibicka
- Department of Physiology/Endocrinology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at University of Gothenburg, Medicinaregatan 11, P.O. Box 434, SE-405 30 Gothenburg, Sweden.
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Leão RM, Cruz FC, Marin MT, Planeta CDS. Stress induces behavioral sensitization, increases nicotine-seeking behavior and leads to a decrease of CREB in the nucleus accumbens. Pharmacol Biochem Behav 2012; 101:434-42. [PMID: 22330674 DOI: 10.1016/j.pbb.2012.01.025] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2011] [Revised: 01/26/2012] [Accepted: 01/30/2012] [Indexed: 12/17/2022]
Abstract
Experimental evidence shows that exposure to stress engenders behavioral sensitization and increases drug-seeking and leads to intense drug taking. However the molecular mechanisms involved in these processes is not well known yet. The present experiments examined the effects of exposure to variable stress on nicotine-induced locomotor activation, cAMP-response element-binding protein (CREB) and extracellular signal-regulated kinase (ERK) activity and nicotine intravenous self-administration in rats. Male Wistar rats were exposed to variable stress that consisted of the exposure to different stressors twice a day in random order for 10 days. During this period the control group was left undisturbed except for cage cleaning. Ten days after the last stress episode, rats were challenged with either saline or nicotine (0.4 mg/kgs.c.) and the locomotor activity was recorded for 20 min. Immediately after behavioral recordings rats were sacrificed and their brains were removed to posterior western blotting analysis of CREB, phosphoCREB, ERK and phosphoERK in the nucleus accumbens. An independent set of control and stressed animals were subjected to an intravenous nicotine self-administration protocol. The break point during a progressive ratio schedule and nicotine intake patterns during a 24-hour binge was analyzed. Repeated variable stress caused a sensitized motor response to a single challenge of nicotine and decreased CREB in the nucleus accumbens. Furthermore, in the self-administration experiments previous stress exposure caused an increase in the break point and nicotine intake.
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Affiliation(s)
- Rodrigo Molini Leão
- Laboratory of Pharmacology, School of Pharmaceutical Sciences, Univ. Estadual Paulista-UNESP, Rod. Araraquara-Jaú Km 1, 14801-902, Araraquara, São Paulo, Brazil
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Stress-induced cross-sensitization to amphetamine is related to changes in the dopaminergic system. J Neural Transm (Vienna) 2011; 119:415-24. [PMID: 22006016 DOI: 10.1007/s00702-011-0720-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2011] [Accepted: 09/28/2011] [Indexed: 01/21/2023]
Abstract
Repeated stress engenders behavioral sensitization. The mesolimbic dopamine system is critically involved in drug-induced behavioral sensitization. In the present study we examined the differences between adolescent and adult rats in stress-induced behavioral sensitization to amphetamine and changes in dopamine (DA) and its metabolite levels in the mesolimbic system. Adolescent or adult rats were restrained for 2 h, once a day, for 7 days. Three days after the last exposure to stress, the animals were challenged with saline or amphetamine (1.0 mg/kg i.p.) and amphetamine-induced locomotion was recorded for 40 min. Immediately after the behavioral tests, rats were decapitated and the nucleus accumbens (NAcc), ventral tegmental area (VTA) and amygdala (AM) were removed to measure tissue levels of DA and its metabolites by HPLC. Exposure to repeated restraint stress promoted behavioral sensitization to amphetamine in both adult and adolescent rats. In adult rats, amphetamine administration increased DA levels in both the stress and control groups in the NAcc and VTA. In adolescent rats, amphetamine increased DA levels in the NAcc in rats exposed to stress. Furthermore, in the AM of adolescent rats in the control group, amphetamine increased the DA levels; however, amphetamine reduced this neurotransmitter in the rats that were exposed to stress. No alteration was observed in the dopamine metabolite levels. Therefore, stress promoted behavioral sensitization to amphetamine and this may be related to changes in DA levels in the mesolimbic system. These changes appear to be dependent on ontogeny.
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Liu S, Zheng D, Peng XX, Cabeza de Vaca S, Carr KD. Enhanced cocaine-conditioned place preference and associated brain regional levels of BDNF, p-ERK1/2 and p-Ser845-GluA1 in food-restricted rats. Brain Res 2011; 1400:31-41. [PMID: 21640333 DOI: 10.1016/j.brainres.2011.05.028] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2011] [Revised: 04/11/2011] [Accepted: 05/13/2011] [Indexed: 12/18/2022]
Abstract
Previously, a learning-free measure was used to demonstrate that chronic food restriction (FR) increases the reward magnitude of a wide range of abused drugs. Moreover, a variety of striatal neuroadaptations were detected in FR subjects, some of which are known to be involved in synaptic plasticity but have been ruled out as modulators of acute drug reward magnitude. Little is known about effects of FR on drug-conditioned place preference (CPP) and brain regional mechanisms that may enhance CPP in FR subjects. The purpose of the present study was to compare the expression and persistence of a conditioned place preference (CPP) induced by a relatively low dose of cocaine (7.0mg/kg, i.p.) in ad libitum fed (AL) and FR rats and take several brain regional biochemical measures following the first CPP conditioning session to probe candidate mechanisms that may underlie the more robust CPP observed in FR subjects. Behaviorally, AL subjects displayed a CPP upon initial testing which extinguished rapidly over the course of subsequent test sessions while CPP in FR subjects persisted. Despite previous reports of elevated BDNF protein in forebrain regions of FR rats, the FR protocol used in the present study did not alter BDNF levels in dorsal hippocampus, nucleus accumbens or medial prefrontal cortex. On the other hand, FR rats, whether injected with cocaine or vehicle, displayed elevated p-ERK1/2 and p-Ser845-GluA1 in dorsal hippocampus. FR rats also displayed elevated p-ERK1/2 in medial prefrontal cortex and elevated p-ERK1 in nucleus accumbens, with further increases produced by cocaine. The one effect observed exclusively in cocaine-treated FR rats was increased p-Ser845-GluA1 in nucleus accumbens. These findings suggest a number of avenues for continuing investigation with potential translational significance.
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Affiliation(s)
- Shan Liu
- Department of Psychiatry, New York University School of Medicine, USA
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Carr KD. Food scarcity, neuroadaptations, and the pathogenic potential of dieting in an unnatural ecology: binge eating and drug abuse. Physiol Behav 2011; 104:162-7. [PMID: 21530562 DOI: 10.1016/j.physbeh.2011.04.023] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2011] [Accepted: 04/19/2011] [Indexed: 12/31/2022]
Abstract
In the laboratory, food restriction has been shown to induce neuroadaptations in brain reward circuitry which are likely to be among those that facilitate survival during periods of food scarcity in the wild. However, the upregulation of mechanisms that promote foraging and reward-related learning may pose a hazard when food restriction is self-imposed in an ecology of abundant appetitive rewards. For example, episodes of loss of control during weight-loss dieting, use of drugs with addictive potential as diet aids, and alternating fasting with alcohol consumption in order to avoid weight gain, may induce synaptic plasticity that increases the risk of enduring maladaptive reward-directed behavior. In the present mini-review, representative basic research findings are outlined which indicate that food restriction alters the function of mesoaccumbens dopamine neurons, potentiates cellular and behavioral responses to D-1 and D-2 dopamine receptor stimulation, and increases stimulus-induced synaptic insertion of AMPA receptors in nucleus accumbens. Possible mechanistic underpinnings of increased drug reward magnitude, drug-seeking, and binge intake of sucrose in food-restricted animal subjects are discussed and possible implications for human weight-loss dieting are considered.
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Affiliation(s)
- Kenneth D Carr
- Department of Psychiatry, Millhauser Laboratories, New York University School of Medicine, 550 First Ave., New York, NY 10016, USA.
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Bulimia nervosa and evidence for striatal dopamine dysregulation: a conceptual review. Physiol Behav 2011; 104:122-7. [PMID: 21549135 DOI: 10.1016/j.physbeh.2011.04.028] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2011] [Revised: 04/15/2011] [Accepted: 04/20/2011] [Indexed: 01/27/2023]
Abstract
OBJECTIVE This article reviews concepts and evidence, based in particular on the work of Bartley G. Hoebel and colleagues, which suggest that a better understanding of the role of striatal dopamine (DA) in the initiation and/or maintenance of bulimia nervosa (BN) may result in a clearer characterization of mechanisms underlying BN. METHODS Literature review, using PubMed search. RESULTS Several lines of evidence, including the work of Bartley G. Hoebel, implicate the importance of striatal DA in feeding behavior, as well as in the disordered eating behaviors relevant to BN. Preclinical models of 'BN-like' eating behaviors have been associated with changes in striatal DA and DA receptor measures. Emerging clinical research also suggests that striatal DA abnormalities exist in individuals with BN. CONCLUSION Alterations in striatal DA may exist in patients with BN. While the precise relationship between these findings and the etiology and maintenance of bulimic symptomatology remains unclear, further investigation of brain DA systems is a fruitful avenue of future research in BN.
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Peng XX, Ziff EB, Carr KD. Effects of food restriction and sucrose intake on synaptic delivery of AMPA receptors in nucleus accumbens. Synapse 2011; 65:1024-31. [PMID: 21425350 DOI: 10.1002/syn.20931] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2011] [Accepted: 03/05/2011] [Indexed: 11/10/2022]
Abstract
Insertion and removal of AMPA receptors from the synaptic membrane underlie dynamic tuning of synaptic transmission and enduring changes in synaptic strength. Preclinical addiction research suggests that AMPA receptor trafficking plays an important role in nucleus accumbens (NAc) neuroplasticity underlying the compulsive and persistent quality of drug-seeking. Considering the parallels between drug addiction and compulsive eating, plus the supranormal reward properties of sucrose, and the role of dieting as a risk factor in development of binge pathology, the present study used a biochemical subcellular fractionation approach to determine whether brief intake of a 10% sucrose solution increases synaptic delivery of AMPA receptors in NAc of chronically food-restricted (FR) relative to ad libitum fed (AL) rats. FR, alone, produced a small but significant increase in synaptic expression of AMPA receptors. This may contribute to NAc integrative mechanisms that mediate the enhanced behavioral responsiveness of FR subjects to phasic reward stimuli, including food and drugs. Brief intake of sucrose increased GluR1 in the PSD, regardless of dietary condition, though the net effect was greater in FR than AL subjects. A marked increase in GluR2 was also observed, but only in FR rats. This set of results suggests that in FR subjects, sucrose may have primarily increased delivery of GluR1/GluR2 heteromers to the PSD, while in AL subjects sucrose increased delivery of GluR2-lacking channels. The functional consequences of these possible differences in subunit composition of trafficked AMPA receptors between diet groups remain to be determined. Nevertheless, the present set of results suggest a promising new avenue to pursue in the effort to understand synaptic plasticity involved in adaptive and pathological food-directed behavior and the mechanistic basis of severe dieting as a risk factor for the latter.
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Affiliation(s)
- Xing-Xiang Peng
- Department of Psychiatry, New York University School of Medicine, New York 10016, USA
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Modulation of methylphenidate effects on wheel running and acoustic startle by acute food deprivation in commercially and selectively bred rats. Pharmacol Biochem Behav 2011; 97:500-8. [DOI: 10.1016/j.pbb.2010.10.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/20/2010] [Revised: 09/25/2010] [Accepted: 10/23/2010] [Indexed: 11/18/2022]
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Fenu S, Cadoni C, Di Chiara G. Conditioned saccharin avoidance and sensitization to drugs of abuse. Behav Brain Res 2010; 214:248-53. [DOI: 10.1016/j.bbr.2010.05.044] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2010] [Revised: 05/17/2010] [Accepted: 05/21/2010] [Indexed: 10/19/2022]
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Pesic V, Marinkovic P, Janac B, Ignjatovic S, Popic J, Kanazir S, Ruzdijic S. Changes of behavioral parameters during long-term food restriction in middle-aged Wistar rats. Physiol Behav 2010; 101:672-8. [PMID: 20713076 DOI: 10.1016/j.physbeh.2010.08.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2010] [Revised: 07/21/2010] [Accepted: 08/09/2010] [Indexed: 10/19/2022]
Abstract
Food restriction (FR) has a beneficial effect on aging process and exerts a significant effect on the responses of rodents to standard behavioral tasks. The aim of this study was to assess the cumulative influence of FR on the behavioral and biochemical parameters in Wistar rats. Six-month-old rats were subjected to restrictive feeding (50% of the daily food intake, every-other-day feeding regimen) for one month or for six months until ages of 7 and 12months, respectively. We examined the habituation of exploratory movement, amphetamine (AMPH)-induced motor activity, as well as changes in serum corticosterone (CORT) and glucose levels. The results obtained from FR animals were compared with ad libitum (AL)-fed age-matched control rats. Habituation of motor activity was only affected by six months of restrictive feeding. The sensitization of the motor response to AMPH that was observed in animals exposed to FR for one month was not observed in animals that were exposed to the same feeding regimen for six months. Serum CORT was increased and serum glucose was decreased in both FR groups. These results clearly show that despite the similarity of the biochemical changes that were induced by one and six months of FR, the nature of the changes in motor activities in these two groups of animals during habituation and after AMPH treatment was different. Our findings indicate that long-term FR has complex behavioral consequences that need to be carefully evaluated with respect to animal age, duration of FR and severity of the diet.
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Affiliation(s)
- Vesna Pesic
- Institute for Biological Research, Department of Neurobiology, University of Belgrade, Bulevar despota Stefana 142, 11060 Belgrade, Serbia
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Carr KD, Chau LS, Cabeza de Vaca S, Gustafson K, Stouffer M, Tukey DS, Restituito S, Ziff EB. AMPA receptor subunit GluR1 downstream of D-1 dopamine receptor stimulation in nucleus accumbens shell mediates increased drug reward magnitude in food-restricted rats. Neuroscience 2010; 165:1074-86. [PMID: 19931598 PMCID: PMC2821737 DOI: 10.1016/j.neuroscience.2009.11.015] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2009] [Revised: 11/04/2009] [Accepted: 11/05/2009] [Indexed: 11/25/2022]
Abstract
Previous findings suggest that neuroadaptations downstream of D-1 dopamine (DA) receptor stimulation in nucleus accumbens (NAc) are involved in the enhancement of drug reward by chronic food restriction (FR). Given the high co-expression of D-1 and GluR1 AMPA receptors in NAc, and the regulation of GluR1 channel conductance and trafficking by D-1-linked intracellular signaling cascades, the present study examined effects of the D-1 agonist, SKF-82958, on NAc GluR1 phosphorylation, intracranial electrical self-stimulation reward (ICSS), and reversibility of reward effects by a polyamine GluR1 antagonist, 1-NA-spermine, in ad libitum fed (AL) and FR rats. Systemically administered SKF-82958, or brief ingestion of a 10% sucrose solution, increased NAc GluR1 phosphorylation on Ser845, but not Ser831, with a greater effect in FR than AL rats. Microinjection of SKF-82958 in NAc shell produced a reward-potentiating effect that was greater in FR than AL rats, and was reversed by co-injection of 1-NA-spermine. GluR1 abundance in whole cell and synaptosomal fractions of NAc did not differ between feeding groups, and microinjection of AMPA, while affecting ICSS, did not exert greater effects in FR than AL rats. These results suggest a role of NAc GluR1 in the reward-potentiating effect of D-1 DA receptor stimulation and its enhancement by FR. Moreover, GluR1 involvement appears to occur downstream of D-1 DA receptor stimulation rather than reflecting a basal increase in GluR1 expression or function. Based on evidence that phosphorylation of GluR1 on Ser845 primes synaptic strengthening, the present results may reflect a mechanism via which FR normally facilitates reward-related learning to re-align instrumental behavior with environmental contingencies under the pressure of negative energy balance.
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Affiliation(s)
- K D Carr
- Department of Psychiatry, New York University School of Medicine, New York, NY 10016, USA.
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España RA, Oleson EB, Locke JL, Brookshire BR, Roberts DCS, Jones SR. The hypocretin-orexin system regulates cocaine self-administration via actions on the mesolimbic dopamine system. Eur J Neurosci 2009; 31:336-48. [PMID: 20039943 DOI: 10.1111/j.1460-9568.2009.07065.x] [Citation(s) in RCA: 187] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Recent evidence suggests that the hypocretin-orexin system participates in the regulation of reinforcement processes. The current studies examined the extent to which hypocretin neurotransmission regulates behavioral and neurochemical responses to cocaine, and behavioral responses to food reinforcement. These studies used a combination of fixed ratio, discrete trials, progressive ratio and threshold self-administration procedures to assess whether the hypocretin 1 receptor antagonist, SB-334867, reduces cocaine self-administration in rats. Progressive ratio sucrose self-administration procedures were also used to assess the extent to which SB-334867 reduces responding to a natural reinforcer in food-restricted and food-sated rats. Additionally, these studies used microdialysis and in vivo voltammetry in rats to examine whether SB-334867 attenuates the effects of cocaine on dopamine signaling within the nucleus accumbens core. Furthermore, in vitro voltammetry was used to examine whether hypocretin knockout mice display attenuated dopamine responses to cocaine. Results indicate that when SB-334867 was administered peripherally or within the ventral tegmental area, it reduced the motivation to self-administer cocaine and attenuated cocaine-induced enhancement of dopamine signaling. SB-334867 also reduced the motivation to self-administer sucrose in food-sated but not food-restricted rats. Finally, hypocretin knockout mice displayed altered baseline dopamine signaling and reduced dopamine responses to cocaine. Combined, these studies suggest that hypocretin neurotransmission participates in reinforcement processes, likely through modulation of the mesolimbic dopamine system. Additionally, the current observations suggest that the hypocretin system may provide a target for pharmacotherapies to treat cocaine addiction.
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Affiliation(s)
- Rodrigo A España
- Department of Physiology and Pharmacology, Wake Forest University Health Sciences, Winston-Salem, NC 27157, USA.
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Blum K, Chen TJ, Downs BW, Bowirrat A, Waite RL, Braverman ER, Madigan M, Oscar-Berman M, DiNubile N, Gold M. Neurogenetics of dopaminergic receptor supersensitivity in activation of brain reward circuitry and relapse: proposing "deprivation-amplification relapse therapy" (DART). Postgrad Med 2009; 121:176-96. [PMID: 19940429 PMCID: PMC3656125 DOI: 10.3810/pgm.2009.11.2087] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND AND HYPOTHESIS It is well known that after prolonged abstinence, individuals who use their drug of choice experience a powerful euphoria that often precipitates relapse. While a biological explanation for this conundrum has remained elusive, we hypothesize that this clinically observed "supersensitivity" might be tied to genetic dopaminergic polymorphisms. Another therapeutic conundrum relates to the paradoxical finding that the dopaminergic agonist bromocriptine induces stronger activation of brain reward circuitry in individuals who carry the DRD2 A1 allele compared with DRD2 A2 allele carriers. Because carriers of the A1 allele relative to the A2 allele of the DRD2 gene have significantly lower D2 receptor density, a reduced sensitivity to dopamine agonist activity would be expected in the former. Thus, it is perplexing that with low D2 density there is an increase in reward sensitivity with the dopamine D2 agonist bromocriptine. Moreover, under chronic or long-term therapy with D2 agonists, such as bromocriptine, it has been shown in vitro that there is a proliferation of D2 receptors. One explanation for this relates to the demonstration that the A1 allele of the DRD2 gene is associated with increased striatal activity of L-amino acid decarboxylase, the final step in the biosynthesis of dopamine. This appears to be a protective mechanism against low receptor density and would favor the utilization of an amino acid neurotransmitter precursor like L-tyrosine for preferential synthesis of dopamine. This seems to lead to receptor proliferation to normal levels and results in significantly better treatment compliance only in A1 carriers. PROPOSAL AND CONCLUSION We propose that low D2 receptor density and polymorphisms of the D2 gene are associated with risk for relapse of substance abuse, including alcohol dependence, heroin craving, cocaine dependence, methamphetamine abuse, nicotine sensitization, and glucose craving. With this in mind, we suggest a putative physiological mechanism that may help to explain the enhanced sensitivity following intense acute dopaminergic D2 receptor activation: "denervation supersensitivity." Rats with unilateral depletions of neostriatal dopamine display increased sensitivity to dopamine agonists estimated to be 30 to 100 x in the 6-hydroxydopamine (6-OHDA) rotational model. Given that mild striatal dopamine D2 receptor proliferation occurs (20%-40%), it is difficult to explain the extent of behavioral supersensitivity by a simple increase in receptor density. Thus, the administration of dopamine D2 agonists would target D2 sensitization and attenuate relapse, especially in D2 receptor A1 allele carriers. This hypothesized mechanism is supported by clinical trials utilizing amino acid neurotransmitter precursors, enkephalinase, and catechol-O-methyltransferase (COMT) enzyme inhibition, which have resulted in attenuated relapse rates in reward deficiency syndrome (RDS) probands. If future translational research reveals that dopamine agonist therapy reduces relapse in RDS, it would support the proposed concept, which we term "deprivation-amplification relapse therapy" (DART). This term couples the mechanism for relapse, which is "deprivation-amplification," especially in DRD2 A1 allele carriers with natural D2 agonist therapy utilizing amino acid precursors and COMT and enkepalinase inhibition therapy.
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Affiliation(s)
- Kenneth Blum
- Department of Psychiatry, School of Medicine, University of Florida, Gainesville, FL
- Department of Nutrigenomics, LifeGen, Inc., San Diego, CA and Lederach, PA
| | - Thomas J.H. Chen
- Department of Health and Occupational Safety, Chang Jung Christian University, Taiwan, Republic of China
| | - B. William Downs
- Department of Nutrigenomics, LifeGen, Inc., San Diego, CA and Lederach, PA
| | - Abdalla Bowirrat
- Clinical Neuroscience & Population Genetics, Ziv Government Medical Center, Israel
| | - Roger L. Waite
- Department of Nutrigenomics, LifeGen, Inc., San Diego, CA and Lederach, PA
| | - Eric R. Braverman
- Department of Neurosurgery, Weill Cornell College of Medicine, New York, NY
| | - Margaret Madigan
- Department of Nutrigenomics, LifeGen, Inc., San Diego, CA and Lederach, PA
| | | | - Nicholas DiNubile
- Department of Orthopedic Surgery, Hospital of the University of Pennsylvania, Philadelphia, PA
| | - Mark Gold
- Department of Psychiatry, School of Medicine, University of Florida, Gainesville, FL
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Carr KD, Cabeza de Vaca S, Sun Y, Chau LS. Reward-potentiating effects of D-1 dopamine receptor agonist and AMPAR GluR1 antagonist in nucleus accumbens shell and their modulation by food restriction. Psychopharmacology (Berl) 2009; 202:731-43. [PMID: 18841347 PMCID: PMC2805715 DOI: 10.1007/s00213-008-1355-9] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2007] [Accepted: 09/24/2008] [Indexed: 01/21/2023]
Abstract
RATIONALE Previous studies have suggested that chronic food restriction (FR) increases sensitivity of a neural substrate for drug reward. The neuroanatomical site(s) of key neuroadaptations may include nucleus accumbens (NAc) where changes in D-1 dopamine (DA) receptor-mediated cell signaling and gene expression have been documented. OBJECTIVES The purpose of the present study was to begin bridging the behavioral and tissue studies by microinjecting drugs directly into NAc medial shell and assessing behavioral effects in free-feeding and FR subjects. MATERIALS AND METHODS Rats were implanted with microinjection cannulae in NAc medial shell and a subset were implanted with a stimulating electrode in lateral hypothalamus. Reward-potentiating effects of the D-1 DA receptor agonist, SKF-82958, AMPAR antagonist, DNXQ, and polyamine GluR1 antagonist, 1-na spermine, were assessed using the curve-shift method of self-stimulation testing. Motor-activating effects of SKF-82958 were also assessed. RESULTS SKF-82958 (2.0 and 5.0 microg) produced greater reward-potentiating and motor-activating effects in FR than ad libitum fed (AL) rats. DNQX (1.0 microg) and 1-na spermine (1.0 and 2.5 microg) selectively decreased the x-axis intercept of rate-frequency curves in FR subjects, reflecting increased responding for previously subthreshold stimulation. CONCLUSIONS Results suggest that FR may facilitate reward-directed behavior via multiple neuroadaptations in NAc medial shell including upregulation of D-1 DA receptor function involved in the selection and expression of goal-directed behavior, and increased GluR1-mediated activation of cells that inhibit nonreinforced responses.
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Affiliation(s)
- Kenneth D Carr
- Department of Psychiatry, New York University School of Medicine, 550 First Avenue, New York, NY 10016, USA.
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AVENA NM, RADA P, HOEBEL BG. Underweight rats have enhanced dopamine release and blunted acetylcholine response in the nucleus accumbens while bingeing on sucrose. Neuroscience 2008; 156:865-71. [PMID: 18790017 PMCID: PMC4357519 DOI: 10.1016/j.neuroscience.2008.08.017] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2008] [Revised: 07/30/2008] [Accepted: 08/02/2008] [Indexed: 11/17/2022]
Abstract
The present study tested whether rats release more accumbens dopamine (DA) during a sugar binge when they are underweight vs. normal weight. Since acetylcholine (ACh) in the nucleus accumbens (NAc) normally increases as a meal progresses and satiety ensues, we also tested whether ACh release is altered when an animal has lost weight. Rats were maintained on daily 8-h access to chow, with 10% sucrose solution available for the first 2 h. Microdialysis performed on day 21, at normal body weight, revealed an increase in extracellular DA to 122% of baseline in response to drinking sucrose. Extracellular ACh peaked at the end of the meal. Next, the rats were food and sucrose restricted so that by day 28 they were at 85% body weight. When retested, these animals released significantly more DA when drinking sucrose (179%), but ACh release failed to rise. A control group was tested in the same manner but given sugar only on days 1, 21 and 28. At normal body weight, control animals showed a non-significant rise in DA when drinking sucrose on day 21. On day 28, at 85% body weight, the controls showed a small increase (124%) in DA release; however, this was significantly lower than the 179% observed in the underweight rats with daily sugar access. These findings suggest that when an animal binges on sugar and then loses weight, the binge releases significantly more DA and less ACh than when animals are at a normal body weight.
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Affiliation(s)
- N. M. AVENA
- Department of Psychology, Princeton University, Washington Road, Princeton, NJ 08540, USA
| | - P. RADA
- Department of Psychology, Princeton University, Washington Road, Princeton, NJ 08540, USA
- University of Los Andes, Merida, Venezuela, 5101-A
| | - B. G. HOEBEL
- Department of Psychology, Princeton University, Washington Road, Princeton, NJ 08540, USA
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Selective breeding for differential saccharin intake as an animal model of drug abuse. Behav Pharmacol 2008; 19:435-60. [DOI: 10.1097/fbp.0b013e32830c3632] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Cadoni C, Valentini V, Di Chiara G. Behavioral sensitization to Δ9-tetrahydrocannabinol and cross-sensitization with morphine: differential changes in accumbal shell and core dopamine transmission. J Neurochem 2008; 106:1586-93. [DOI: 10.1111/j.1471-4159.2008.05503.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Frank STH, Krumm B, Spanagel R. Cocaine-induced dopamine overflow within the nucleus accumbens measured by in vivo microdialysis: A meta-analysis. Synapse 2008; 62:243-52. [DOI: 10.1002/syn.20489] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Stamp JA, Mashoodh R, van Kampen JM, Robertson HA. Food restriction enhances peak corticosterone levels, cocaine-induced locomotor activity, and ΔFosB expression in the nucleus accumbens of the rat. Brain Res 2008; 1204:94-101. [DOI: 10.1016/j.brainres.2008.02.019] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2007] [Revised: 12/22/2007] [Accepted: 02/03/2008] [Indexed: 10/22/2022]
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Carta AR, Moreno CC, Cadoni C, Tronci E, Di Chiara G. Long-term increase in GAD67 mRNA expression in the central amygdala of rats sensitized by drugs and stress. Eur J Neurosci 2008; 27:1220-30. [DOI: 10.1111/j.1460-9568.2008.06095.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Collins GT, Calinski DM, Newman AH, Grundt P, Woods JH. Food restriction alters N'-propyl-4,5,6,7-tetrahydrobenzothiazole-2,6-diamine dihydrochloride (pramipexole)-induced yawning, hypothermia, and locomotor activity in rats: evidence for sensitization of dopamine D2 receptor-mediated effects. J Pharmacol Exp Ther 2008; 325:691-7. [PMID: 18305018 DOI: 10.1124/jpet.107.133181] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Food restriction enhances sensitivity to the reinforcing effects of a variety of drugs of abuse including opiates, nicotine, and psychostimulants. Food restriction has also been shown to alter a variety of behavioral and pharmacological responses to dopaminergic agonists, including an increased sensitivity to the locomotor stimulatory effects of direct- and indirect-dopamine agonists, elevated extracellular dopamine levels in responses to psychostimulants, as well as suppression of agonist-induced yawning. Behavioral and molecular studies suggest that augmented dopaminergic responses observed in food-restricted animals result from a sensitization of the dopamine D2 receptor; however, little is known about how food restriction affects dopamine D3 receptor function. The current studies were aimed at better defining the effects of food restriction on D2 and D3 receptor function by assessing the capacity of N'-propyl-4,5,6,7-tetrahydrobenzothiazole-2,6-diamine dihydrochloride (pramipexole) to induce yawning, penile erection (PE), hypothermia, and locomotor activity in free-fed and food-restricted rats. Food restriction resulted in a suppression of pramipexole-induced yawning, a sensitized hypothermic response, and an enhanced locomotor response to pramipexole, effects that are suggestive of an enhanced D2 receptor activity; no effect on pramipexole-induced PE was observed. Antagonist studies further supported a food restriction-induced enhancement of the D2 receptor activity because the D2 antagonist 3-[4-(4-chlorophenyl)-4-hydroxypiperidin-l-yl]methyl-1H-indole (L741,626) recovered pramipexole-induced yawning to free-fed levels, whereas yawning and PE were suppressed following pretreatment with the D3 antagonist N-{4-[4-(2,3-dichlorophenyl)-piperazin-1-yl]-trans-but-2-enyl}-4-pyridine-2-yl-benzamide hydrochloride (PG01037). The results of the current studies suggest that food restriction sensitized rats to the D2-mediated effects of pramipexole while having no effect on the D3-mediated effects of pramipexole.
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Affiliation(s)
- Gregory T Collins
- Department of Pharmacology, 1301 Medical Science Research Building III, 1150 W. Medical Center Drive, University of Michigan Medical School, Ann Arbor, MI 48109-0632, USA
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Wand GS, Oswald LM, McCaul ME, Wong DF, Johnson E, Zhou Y, Kuwabara H, Kumar A. Association of amphetamine-induced striatal dopamine release and cortisol responses to psychological stress. Neuropsychopharmacology 2007; 32:2310-20. [PMID: 17342167 DOI: 10.1038/sj.npp.1301373] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Preclinical studies have shown that stress and glucocorticoids increase mesolimbic dopamine (DA) and thereby facilitate psychostimulant self-administration. The relationship between stress-induced cortisol and mesolimbic DA responses to psychostimulants has not been studied in humans. To test the hypotheses that glucocorticoid responses to psychological stress are correlated with DA and subjective responses to psychostimulants in humans, 25 healthy adults (18-29 years) completed the Trier Social Stress Test (TSST) and two positron emission tomography (PET) scans with high-specific [11C]raclopride. The first scan was preceded by intravenous saline and the second by amphetamine (AMPH). Findings showed that stress-induced cortisol levels were positively associated with AMPH-induced DA release in the ventral striatum and other striatal regions. Subjects with higher cortisol responses to stress also reported more positive subjective drug effects with AMPH than subjects with lower responses. The results are consistent with preclinical findings showing an interrelationship between glucocorticoids and mesolimbic DA dynamics, which may influence psychostimulant self-administration in humans.
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Affiliation(s)
- Gary S Wand
- Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
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