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Algallal HE, Jacquemet V, Samaha AN. Intermittent nicotine access is as effective as continuous access in promoting nicotine seeking and taking in rats. Psychopharmacology (Berl) 2024; 241:1135-1149. [PMID: 38326505 DOI: 10.1007/s00213-024-06546-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/09/2024] [Accepted: 01/20/2024] [Indexed: 02/09/2024]
Abstract
RATIONALE Nicotine is a principal psychoactive agent in tobacco, contributing to tobacco's addictive potential. Preclinical studies on the effects of voluntary nicotine intake typically use self-administration procedures that provide continuous nicotine access during each self-administration session. However, many smokers consume cigarettes intermittently rather than continuously throughout each day. For drugs including cocaine and opioids, research in laboratory rats shows that intermittent intake can be more effective than continuous intake in producing patterns of drug use relevant to addiction. OBJECTIVE We determined how intermittent versus continuous nicotine self-administration influences nicotine seeking and taking behaviours. METHODS Female and male rats had continuous (i.e., Long Access; LgA, 6 h/day) or intermittent (IntA; 12 min ON, 60 min OFF, for 6 h/day) access to intravenous nicotine (15 µg/kg/infusion), for 12 daily sessions. We then assessed intake, responding for nicotine under a progressive ratio schedule of drug reinforcement and cue- and nicotine-induced reinstatement of drug seeking. We also estimated nicotine pharmacokinetic parameters during LgA and IntA self-administration. RESULTS Overall, LgA rats took twice more nicotine than did IntA rats, yielding more sustained increases in estimated brain concentrations of the drug. However, the two groups showed similar motivation to seek and take nicotine, as measured using reinstatement and progressive ratio procedures, respectively. CONCLUSIONS Intermittent nicotine use is just as effective as continuous use in producing addiction-relevant behaviours, despite significantly less nicotine exposure. This has implications for modeling nicotine self-administration patterns in human smokers and resulting effects on brain and behaviour.
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Affiliation(s)
- Hajer E Algallal
- Biomedical Sciences, Faculty of Medicine, Université de Montréal, Montreal, QC, Canada
| | - Vincent Jacquemet
- Institute of Biomedical Engineering, Faculty of Medicine, Université de Montréal, Montreal, QC, Canada
- Department of Pharmacology and Physiology, Faculty of Medicine, Université de Montréal, C.P. 6128, Succursale Centre-Ville, Montreal, QC, H3C 3J7, Canada
| | - Anne-Noël Samaha
- Department of Pharmacology and Physiology, Faculty of Medicine, Université de Montréal, C.P. 6128, Succursale Centre-Ville, Montreal, QC, H3C 3J7, Canada.
- Neural Signaling and Circuitry Research Group (SNC), Faculty of Medicine, Université de Montréal, Montreal, QC, Canada.
- Center for Interdisciplinary Research On the Brain and Learning (CIRCA), Université de Montréal, Montreal, QC, Canada.
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Ndiaye NA, Shamleh SA, Casale D, Castaneda-Ouellet S, Laplante I, Robinson MJF, Samaha AN. Relapse after intermittent access to cocaine: Discriminative cues more effectively trigger drug seeking than do conditioned cues. Psychopharmacology (Berl) 2024:10.1007/s00213-024-06614-9. [PMID: 38767684 DOI: 10.1007/s00213-024-06614-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/22/2024] [Accepted: 05/12/2024] [Indexed: 05/22/2024]
Abstract
RATIONALE When people with drug addiction encounter cues associated with drug use, this can trigger cravings and relapse. These cues can include conditioned stimuli (CSs) signaling drug delivery and discriminative stimuli (DSs) signaling drug availability. Compared to CS effects, DS effects are less explored in preclinical studies on cue-induced relapse. OBJECTIVE We compared CS and DS effects on reward seeking following abstinence from intermittent-access cocaine (or sucrose) self-administration. METHODS During 15-20 intermittent-access sessions, rats self-administered i.v. cocaine or sucrose pellets paired with a light-tone CS. Cocaine/sucrose was available for 5-min (signalled by a light; DS+) and unavailable for 25 min (signalled by different lighting conditions; DS-), and this cycled for 4 h/session. Following abstinence, we measured cocaine/sucrose seeking under extinction triggered by CS and DS presentation, and instrumental responding reinforced by these cues. RESULTS Across intermittent-access sessions, rats increased lever pressing for cocaine or sucrose during DS+ periods and decreased responding during DS- periods. On days 2 and 21 of abstinence, only presentation of the DS+ or DS+ and CS combined elicited increased cocaine/sucrose-seeking behaviour (i.e., increased active lever presses). Presenting the DS- alongside the DS+ suppressed the increased cocaine-seeking behaviour otherwise produced by the DS+ . Finally, on day 21 of abstinence, rats showed equivalent levels of lever pressing reinforced by the DS+ , CS and by the DS+ and CS combined, suggesting comparable conditioned reinforcing value. CONCLUSIONS After intermittent self-administration, cocaine-associated DSs and CSs acquire similar conditioned reinforcing properties, but DSs more effectively trigger increases in drug seeking.
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Affiliation(s)
- Ndeye Aissatou Ndiaye
- Department of Neurosciences, Faculty of Medicine, Université de Montréal, Montréal, QC, H3C 3J7, Canada
| | - Sema Abu Shamleh
- Department of Psychology, Concordia University, Montréal, QC, H3G 1M8, Canada
| | - Domiziana Casale
- Department of Psychology, Université de Montréal, Montréal, QC, H3C 3J7, Canada
| | | | - Isabel Laplante
- Department of Pharmacology and Physiology, Faculty of Medicine, Université de Montréal, C.P. 6128, Succursale Centre-Ville Montréal, Montréal, Québec, H3C 3J7, Canada
| | - Mike J F Robinson
- Department of Psychology, Concordia University, Montréal, QC, H3G 1M8, Canada
- Department of Pharmacology and Physiology, Faculty of Medicine, Université de Montréal, C.P. 6128, Succursale Centre-Ville Montréal, Montréal, Québec, H3C 3J7, Canada
| | - Anne-Noël Samaha
- Department of Pharmacology and Physiology, Faculty of Medicine, Université de Montréal, C.P. 6128, Succursale Centre-Ville Montréal, Montréal, Québec, H3C 3J7, Canada.
- Neural Signaling and Circuitry Research Group (SNC), Faculty of Medicine, Université de Montréal, Montréal, QC, H3C 3J7, Canada.
- Center for Interdisciplinary Research On the Brain and Learning (CIRCA), Université de Montréal, Montréal, QC, H3C 3J7, Canada.
- Center for Studies in Behavioral Neurobiology, Department of Psychology, Concordia University, Montréal, QC, H3G 1M8, Canada.
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Robinson MJF, Bonmariage QSA, Samaha AN. Unpredictable, intermittent access to sucrose or water promotes increased reward pursuit in rats. Behav Brain Res 2023; 453:114612. [PMID: 37544370 DOI: 10.1016/j.bbr.2023.114612] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Revised: 07/18/2023] [Accepted: 08/02/2023] [Indexed: 08/08/2023]
Abstract
Reward uncertainty can sensitize reward pathways, promoting increased reward-seeking and -taking behaviours. This is relevant to human conditions such as pathological gambling, eating disorders and drug addiction. In the context of addiction, preclinical self-administration procedures have been developed to model the intermittency of human drug use. These intermittent-access (IntA) procedures involve intermittent but predictable access to drug during self-administration sessions. However, human drug use typically involves intermittent and unpredictable drug access. We introduce a new procedure modeling unpredictable, intermittent access (UIntA) to a reinforcer, and we compare it to procedures that provide predictable reinforcer availability; continuous (ContA) or intermittent (IntA) access. Female rats self-administered water or liquid sucrose in daily hour-long sessions. IntA and ContA rats had access to a fixed volume of water or sucrose (0.1 ml), under a fixed ratio 3 schedule of reinforcement. IntA rats had predictable 5-min reinforcer ON and 25-min reinforcer OFF periods. ContA rats had 60 min of reinforcer access during each session. For UIntA rats, variation in the length of ON and OFF periods (1, 5 or 9 min/period), response requirement (variable ratio 3 schedule of reinforcement), reinforcer probability (50%) and quantity (0, 0.1 or 0.2 ml) introduced reward uncertainty. Following 14 daily self-administration sessions, UIntA rats showed the highest levels of responding for water or sucrose under progressive ratio conditions, responding under extinction conditions, and cue-induced reinstatement of sucrose seeking. Thus, unpredictable, intermittent reward access promotes increased reward pursuit. This has implications for modeling addiction and other disorders of increased reward seeking.
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Affiliation(s)
- Mike J F Robinson
- Department of Pharmacology and Physiology, Faculty of Medicine, Université de Montréal, Montréal, QC H3T 1J4, Canada
| | - Qi Shan A Bonmariage
- Department of Neurosciences, Faculty of Medicine, Université de Montréal, Montréal, QC H3T 1J4, Canada
| | - Anne-Noël Samaha
- Department of Pharmacology and Physiology, Faculty of Medicine, Université de Montréal, Montréal, QC H3T 1J4, Canada; Neural Signaling and Circuitry Research Group (SNC), Faculty of Medicine, Université de Montréal, Montréal, QC H3T 1J4, Canada; Center for Interdisciplinary Research on the Brain and Learning (CIRCA), Université de Montréal, Montréal, QC H3T 1J4, Canada; Neuroscience and Mental Health Strategy of the Université de Montréal (SENSUM), Université de Montréal, Montréal, QC H3T 1J4, Canada.
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Khoo SYS, Samaha AN. Metabotropic glutamate group II receptor activation in the ventrolateral dorsal striatum suppresses incentive motivation for cocaine in rats. Psychopharmacology (Berl) 2023; 240:1247-1260. [PMID: 37060471 DOI: 10.1007/s00213-023-06363-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Accepted: 04/03/2023] [Indexed: 04/16/2023]
Abstract
RATIONALE After a history of intermittent cocaine intake, rats develop patterns of drug use characteristic of substance use disorder. The dorsal striatum is involved in the increased pursuit of cocaine after intermittent drug self-administration experience. Within the dorsal striatum, chronic cocaine use changes metabotropic glutamate type II receptor (mGlu2/3) density and function. OBJECTIVES We examined the extent to which activity at Glu2/3 receptors mediates responding for cocaine after intermittent cocaine use. METHODS Male (n = 11) and female (n = 10) Wistar rats self-administered 0.25 mg/kg/infusion cocaine during 10 daily intermittent access (IntA) sessions (5 min ON/25 min OFF, for 5 h/session). We then examined the effects of microinjections of the mGlu2/3 receptor agonist LY379268 (0, 1, and 3 µg/hemisphere) into the ventrolateral part of the dorsal striatum on cocaine self-administration under a progressive ratio schedule of reinforcement. RESULTS Across 10 IntA sessions, the sexes showed similar levels of cocaine intake. In females only, locomotion significantly increased over sessions, suggesting that female rats developed psychomotor sensitization to self-administered cocaine. After 10 IntA sessions, intra-dorsal striatum LY379268 significantly reduced breakpoints achieved for cocaine, active lever presses, and cocaine infusions earned under progressive ratio. LY379268 had no effects on locomotion or inactive lever presses, indicating no motor effects. CONCLUSIONS These results suggest that mGlu2/3 receptor activation in the ventrolateral dorsal striatum suppresses incentive motivation for cocaine, and this holds promise for new treatments to manage substance use disorder.
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Affiliation(s)
- Shaun Yon-Seng Khoo
- Department of Pharmacology and Physiology, Faculty of Medicine, Université de Montréal, Montréal, QC, H3T 1J4, Canada
- Conduct and Integrity Office, Division of Planning and Assurance, UNSW Sydney, Sydney, NSW, 2052, Australia
| | - Anne-Noël Samaha
- Department of Pharmacology and Physiology, Faculty of Medicine, Université de Montréal, Montréal, QC, H3T 1J4, Canada.
- Research Group on Neural Signaling and Circuits, Faculty of Medicine, Université de Montréal, Montréal, QC, H3T 1J4, Canada.
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Servonnet A, Rompré PP, Samaha AN. Optogenetic activation of basolateral amygdala-to-nucleus accumbens core neurons promotes Pavlovian approach responses but not instrumental pursuit of reward cues. Behav Brain Res 2023; 440:114254. [PMID: 36516942 DOI: 10.1016/j.bbr.2022.114254] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Revised: 12/08/2022] [Accepted: 12/09/2022] [Indexed: 12/14/2022]
Abstract
Reward-associated conditioned stimuli (CSs) can acquire predictive value, evoking conditioned approach behaviours that prepare animals to engage with forthcoming rewards. Such CSs can also acquire conditioned reinforcing value, becoming attractive and pursued. Through their conditioned effects, CSs can promote adaptive (e.g., locating food) but also maladaptive behaviours (e.g., drug use). Basolateral amygdala neurons projecting to the nucleus accumbens core (BLA→NAc core neurons) mediate the response to appetitive CSs, but the extent to which this involves effects on the predictive and/or conditioned reinforcing properties of CSs is unclear. Thus, we examined the effects of optogenetic stimulation of BLA→NAc core neurons on i) CS-triggered approach to the site of reward delivery, a Pavlovian conditioned approach response and ii) the instrumental pursuit of a CS, a measure of conditioned reinforcement. Water-restricted, adult male rats learned that a light-tone compound cue (the CS) predicts water delivery into a receptacle. Pairing optogenetic stimulation of BLA→NAc core neurons with CS presentation potentiated CS-triggered water receptacle visits. This suggests that activity in BLA→NAc core neurons promotes Pavlovian goal-approach behaviour. Next, rats could lever press for CS presentations, without water delivery. Optogenetic stimulation of BLA→NAc core neurons either during instrumental test sessions or during prior CS-water conditioning did not influence lever responding for the CS. This suggests that activity in BLA→NAc core neurons does not influence the instrumental pursuit of a water-paired CS. We conclude that activation of BLA→NAc core neurons promotes cue-induced control over behaviour by increasing conditioned goal-approach responses, without affecting the operant pursuit of reward cues.
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Affiliation(s)
| | | | - Anne-Noël Samaha
- Department of Pharmacology and Physiology (Faculty of Medicine), Canada; Groupe de recherche sur le système nerveux central, Faculty of Medicine, Université de Montréal, 2900 Edouard-Montpetit Boulevard, Montreal H3T 1J4, Quebec, Canada.
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Garceau C, Samaha AN, Cordahi T, Servonnet A, Khoo SYS. Correction to: Metabotropic group II glutamate receptors in the basolateral amygdala mediate cue‑triggered increases in incentive motivation. Psychopharmacology (Berl) 2021; 238:2919-2922. [PMID: 34487191 DOI: 10.1007/s00213-021-05959-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- Caroline Garceau
- Department of Pharmacology and Physiology, Faculty of Medicine, Universite de Montreal, Montreal, QC, H3T 1J4, Canada
| | - Anne-Noël Samaha
- Department of Pharmacology and Physiology, Faculty of Medicine, Universite de Montreal, Montreal, QC, H3T 1J4, Canada.
- CNS Research Group, Faculty of Medicine, Universite de Montreal, Montreal, QC, H3T 1J4, Canada.
| | - Thomas Cordahi
- Department of Neurosciences, Faculty of Medicine, Universite de Montreal, Montreal, QC, H3T 1J4, Canada
| | - Alice Servonnet
- Department of Neurosciences, Faculty of Medicine, Universite de Montreal, Montreal, QC, H3T 1J4, Canada
| | - Shaun Yon-Seng Khoo
- Department of Pharmacology and Physiology, Faculty of Medicine, Universite de Montreal, Montreal, QC, H3T 1J4, Canada
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Garceau C, Samaha AN, Cordahi T, Servonnet A, Khoo SYS. Metabotropic group II glutamate receptors in the basolateral amygdala mediate cue-triggered increases in incentive motivation. Psychopharmacology (Berl) 2021; 238:2905-2917. [PMID: 34223950 DOI: 10.1007/s00213-021-05907-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Accepted: 06/14/2021] [Indexed: 10/20/2022]
Abstract
RATIONALE Reward-associated cues can trigger incentive motivation for reward and invigorate reward-seeking behaviour via Pavlovian-to-instrumental transfer (PIT). Glutamate signaling within the basolateral amygdala (BLA) modulates cue-triggered increases in incentive motivation. However, the role of BLA metabotropic group II glutamate (mGlu2/3) receptors is largely unknown. OBJECTIVES In Experiment 1, we characterized cue-triggered increases in incentive motivation for water reward using the PIT paradigm. In Experiment 2, we assessed the influence of intra-BLA microinjections of the mGlu2/3 receptor agonist LY379268 on this effect. METHODS Water-restricted male Sprague-Dawley rats learned to press a lever for water. Separately, they learned to associate one of two auditory cues with free water. On test days, rats could lever press under extinction conditions (no water), with intermittent, non-contingent CS+ and CS- presentations. In Experiment 1, rats were tested under baseline conditions. In Experiment 2, rats received intra-BLA microinjections of LY379268 (0, 3 and 6 [Formula: see text]g/hemisphere) before testing. RESULTS Across experiments, CS+, but not CS-, presentations increased water-associated lever pressing during testing, even though responding was reinforced neither by water nor the CS+. Intra-BLA LY379268 abolished both CS+ potentiated pressing on the water-associated lever and CS+ evoked conditioned approach to the site of water delivery. LY379268 did not influence locomotion or instrumental and Pavlovian response rates during intervals between CS presentations or during the CS-, indicating no motor effects. CONCLUSIONS mGlu2/3 receptor activity in the BLA mediates cue-triggered potentiation of incentive motivation for reward, suppressing both cue-induced increases in instrumental pursuit of the reward and anticipatory approach behaviour.
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Affiliation(s)
- Caroline Garceau
- Department of Pharmacology and Physiology, Faculty of Medicine, Université de Montréal, Montréal, QC, H3T 1J4, Canada
| | - Anne-Noël Samaha
- Department of Pharmacology and Physiology, Faculty of Medicine, Université de Montréal, Montréal, QC, H3T 1J4, Canada. .,CNS Research Group, Faculty of Medicine, Université de Montréal, Montréal, QC, H3T 1J4, Canada.
| | - Thomas Cordahi
- Department of Neurosciences, Faculty of Medicine, Université de Montréal, Montréal, QC, H3T 1J4, Canada
| | - Alice Servonnet
- Department of Neurosciences, Faculty of Medicine, Université de Montréal, Montréal, QC, H3T 1J4, Canada
| | - Shaun Yon-Seng Khoo
- Department of Pharmacology and Physiology, Faculty of Medicine, Université de Montréal, Montréal, QC, H3T 1J4, Canada
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Robinson TE, Khoo SYS, Ferrario CR, Samaha AN. Studying dopamine in addiction: the cart should follow the horse. Trends Neurosci 2021; 44:595-596. [PMID: 34320335 DOI: 10.1016/j.tins.2021.06.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Accepted: 06/29/2021] [Indexed: 11/16/2022]
Affiliation(s)
- Terry E Robinson
- Department of Psychology (Biopsychology), University of Michigan, Ann Arbor, MI 48109, USA.
| | - Shaun Y-S Khoo
- Department of Pharmacology and Physiology, Faculty of Medicine, Université de Montréal, Montréal, QC H3C 3J7, Canada
| | - Carrie R Ferrario
- Department of Psychology (Biopsychology), University of Michigan, Ann Arbor, MI 48109, USA; Department of Pharmacology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Anne-Noël Samaha
- Department of Pharmacology and Physiology, Faculty of Medicine, Université de Montréal, Montréal, QC H3C 3J7, Canada.
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Servonnet A, Allain F, Gravel-Chouinard A, Hernandez G, Bourdeau Caporuscio C, Legrix M, Lévesque D, Rompré PP, Samaha AN. Dopaminergic mechanisms underlying the expression of antipsychotic-induced dopamine supersensitivity in rats. Neuropharmacology 2021; 197:108747. [PMID: 34364897 DOI: 10.1016/j.neuropharm.2021.108747] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Revised: 07/23/2021] [Accepted: 08/03/2021] [Indexed: 10/20/2022]
Abstract
Antipsychotic treatment can produce a dopamine-supersensitive state, potentiating the response to dopamine receptor stimulation. In both schizophrenia patients and rats, this is linked to tolerance to ongoing antipsychotic treatment. In rodents, dopamine supersensitivity is often confirmed by an exaggerated psychomotor response to d-amphetamine after discontinuation of antipsychotic exposure. Here we examined in rats the dopaminergic mechanisms mediating this enhanced behavioural response, as this could uncover pathophysiological processes underlying the expression of antipsychotic-evoked dopamine supersensitivity. Rats received 0.5 mg/kg/day haloperidol via osmotic minipump for 2 weeks, before treatment was discontinued. After cessation of antipsychotic treatment, rats showed a supersensitive psychomotor response to the D2 agonist quinpirole, but not to the D1 partial agonist SKF38393 or the dopamine reuptake blocker GBR12783. Furthermore, acute D1 receptor blockade (using SCH39166) decreased the exaggerated psychomotor response to d-amphetamine in haloperidol-pretreated rats, whereas acute D2 receptor blockade (using sulpiride) enhanced it. Thus, after discontinuation of antipsychotic treatment, D1- and D2-mediated transmission differentially modulate the expression of a supersensitive response to d-amphetamine. This supersensitive behavioural response was accompanied by enhanced GSK3β activity and suppressed ERK1/2 activity in the nucleus accumbens (but not caudate-putamen), suggesting increased mesolimbic D2 transmission. Finally, after discontinuing haloperidol treatment, neither increasing ventral midbrain dopamine impulse flow nor infusing d-amphetamine into the cerebral ventricles triggered the expression of already established dopamine supersensitivity, suggesting that peripheral effects are required. Thus, while dopamine receptor-mediated signalling regulates the expression of antipsychotic-evoked dopamine supersensitivity, a simple increase in central dopamine neurotransmission is insufficient to trigger this supersensitivity.
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Affiliation(s)
- Alice Servonnet
- Department of Neurosciences, Faculty of Medicine, Université de Montréal, 2900 Edouard-Montpetit boulevard, Montreal, H3T 1J4, Quebec, Canada.
| | - Florence Allain
- Department of Pharmacology and Physiology, Faculty of Medicine, Université de Montréal, 2900 Edouard-Montpetit boulevard, Montreal, H3T 1J4, Quebec, Canada
| | - Alice Gravel-Chouinard
- Department of Neurosciences, Faculty of Medicine, Université de Montréal, 2900 Edouard-Montpetit boulevard, Montreal, H3T 1J4, Quebec, Canada
| | - Giovanni Hernandez
- Department of Neurosciences, Faculty of Medicine, Université de Montréal, 2900 Edouard-Montpetit boulevard, Montreal, H3T 1J4, Quebec, Canada; Faculty of Pharmacy, Université de Montréal, 2900 Edouard-Montpetit boulevard, Montreal, H3T 1J4, Quebec, Canada
| | - Casey Bourdeau Caporuscio
- Department of Pharmacology and Physiology, Faculty of Medicine, Université de Montréal, 2900 Edouard-Montpetit boulevard, Montreal, H3T 1J4, Quebec, Canada
| | - Mathilde Legrix
- Department of Neurosciences, Faculty of Medicine, Université de Montréal, 2900 Edouard-Montpetit boulevard, Montreal, H3T 1J4, Quebec, Canada
| | - Daniel Lévesque
- Faculty of Pharmacy, Université de Montréal, 2900 Edouard-Montpetit boulevard, Montreal, H3T 1J4, Quebec, Canada
| | - Pierre-Paul Rompré
- Department of Neurosciences, Faculty of Medicine, Université de Montréal, 2900 Edouard-Montpetit boulevard, Montreal, H3T 1J4, Quebec, Canada
| | - Anne-Noël Samaha
- Department of Pharmacology and Physiology, Faculty of Medicine, Université de Montréal, 2900 Edouard-Montpetit boulevard, Montreal, H3T 1J4, Quebec, Canada; Groupe de recherche sur le système nerveux central, Faculty of Medicine, Université de Montréal, 2900 Edouard-Montpetit boulevard, Montrea, H3T 1J4, Quebec, Canada.
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Servonnet A, Uchida H, Samaha AN. Continuous versus extended antipsychotic dosing in schizophrenia: Less is more. Behav Brain Res 2020; 401:113076. [PMID: 33345826 DOI: 10.1016/j.bbr.2020.113076] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2020] [Revised: 12/09/2020] [Accepted: 12/11/2020] [Indexed: 11/28/2022]
Abstract
Antipsychotic drugs temper psychotic symptoms by interacting with dopamine D2 receptors to reduce dopamine neurotransmission. Currently, the standard of care involves antipsychotic treatment protocols that achieve steady-state levels of medication. Maintaining patients on continuous treatment is thought to be necessary to keep them stabilised. However, continuous antipsychotic exposure increases the risk of adverse effects over time. These effects include metabolic and cardiovascular disorders, extrapyramidal complications, and dopamine receptor supersensitivity, the latter of which could potentially promote both treatment tolerance and psychosis relapse. In the present review, we describe evidence showing that continuous exposure to antipsychotic drugs can not only worsen long-term outcome, but-past acute phase treatment-it is also unnecessary to effectively manage schizophrenia symptoms. We also describe evidence that regular but extended dosing, allowing predictable periods of lower antipsychotic levels/D2 occupancy, is both safe and effective in patients, and it greatly reduces drug exposure overall. Studies in laboratory animals show that compared to continuous antipsychotic exposure, regular but extended dosing actually has superior antipsychotic-like efficacy, and it also substantially reduces the likelihood of both motor side effects and dopamine receptor supersensitivity. We propose that regular, but extended dosing should be considered in the long-term treatment of people with schizophrenia, because the available evidence suggests it can be just as effective as continuous treatment, while decreasing overall drug exposure and potentially reducing harmful side effects.
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Affiliation(s)
- Alice Servonnet
- Department of Neurosciences, Faculty of Medicine, Université de Montréal, Montreal, Canada
| | - Hiroyuki Uchida
- Department of Neuropsychiatry, Keio University School of Medicine, Tokyo, Japan
| | - Anne-Noël Samaha
- Department of Pharmacology and Physiology, Faculty of Medicine, Université de Montréal, Montreal, Canada; Groupe de recherche sur le système nerveux central, Faculty of Medicine, Université de Montréal, Montreal, Canada.
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Minogianis EA, Samaha AN. Taking Rapid and Intermittent Cocaine Infusions Enhances Both Incentive Motivation for the Drug and Cocaine-induced Gene Regulation in Corticostriatal Regions. Neuroscience 2020; 442:314-328. [PMID: 32682656 DOI: 10.1016/j.neuroscience.2020.05.058] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Revised: 04/21/2020] [Accepted: 05/21/2020] [Indexed: 12/20/2022]
Abstract
A goal in addiction research is to distinguish forms of neuroplasticity that are involved in the transition to addiction from those involved in mere drug taking. Animal models of drug self-administration are essential in this context. Here, we compared in male rats two cocaine self-administration procedures that differ in the extent to which they evoke addiction-like behaviours. We measured both incentive motivation for cocaine using progressive ratio procedures, and cocaine-induced c-fos mRNA expression, a marker of neuronal activity. Rats self-administered intravenous cocaine (0.25 mg/kg/infusion) for seven daily 6-hour sessions. One group had intermittent access (IntA; 6 minutes ON, 26 min OFF × 12) to rapid infusions (delivered over 5 s). This models the temporal kinetics of human cocaine use and produces robust addiction-like behaviour. The other group had Long access (LgA) to slower infusions (90 s). This produces high levels of intake without promoting robust addiction-like behaviour. LgA-90 s rats took twice as much cocaine as IntA-5 s rats did, but IntA-5 s rats showed greater incentive motivation for the drug. Following a final self-administration session, we quantified c-fos mRNA expression in corticostriatal regions. Compared to LgA-90 s rats, IntA-5 s rats had more cocaine-induced c-fos mRNA in the orbitofrontal and prelimbic cortices and the caudate-putamen. Thus, a cocaine self-administration procedure (intermittent intake of rapid infusions) that promotes increased incentive motivation for the drug also enhances cocaine-induced gene regulation in corticostriatal regions. This suggests that increased drug-induced recruitment of these regions could contribute to the neural and behavioural plasticity underlying the transition to addiction.
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Affiliation(s)
- Ellie-Anna Minogianis
- Department of Pharmacology and Physiology, Faculty of Medicine, Université de Montréal, Canada
| | - Anne-Noël Samaha
- Department of Pharmacology and Physiology, Faculty of Medicine, Université de Montréal, Canada; Groupe de recherche sur le système nerveux central (GRSNC), Faculty of Medicine, Université de Montréal, 2900 Édouard-Montpetit Boulevard, Montreal, Quebec H3T 1J4, Canada.
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12
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Allain F, Samaha AN. [Cocaine peaks and troughs. Modeling pathological drug use in rats]. Med Sci (Paris) 2020; 36:212-215. [PMID: 32228836 DOI: 10.1051/medsci/2020034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Florence Allain
- Département de pharmacologie et de physiologie, Groupe de recherche sur le système nerveux central, Faculté de médecine, Université de Montréal, Montréal, QC, H3C 3J7, Canada
| | - Anne-Noël Samaha
- Département de pharmacologie et de physiologie, Groupe de recherche sur le système nerveux central, Faculté de médecine, Université de Montréal, Montréal, QC, H3C 3J7, Canada
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Servonnet A, Hernandez G, El Hage C, Rompré PP, Samaha AN. Optogenetic Activation of the Basolateral Amygdala Promotes Both Appetitive Conditioning and the Instrumental Pursuit of Reward Cues. J Neurosci 2020; 40:1732-1743. [PMID: 31953370 PMCID: PMC7046336 DOI: 10.1523/jneurosci.2196-19.2020] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Revised: 01/06/2020] [Accepted: 01/08/2020] [Indexed: 01/10/2023] Open
Abstract
Reward-associated stimuli can both evoke conditioned responses and acquire reinforcing properties in their own right, becoming avidly pursued. Such conditioned stimuli (CS) can guide reward-seeking behavior in adaptive (e.g., locating food) and maladaptive (e.g., binge eating) ways. The basolateral amygdala (BLA) regulates conditioned responses evoked by appetitive CS, but less is known about how the BLA contributes to the instrumental pursuit of CS. Here we studied the influence of BLA neuron activity on both behavioral effects. Water-restricted male rats learned to associate a light-tone cue (CS) with water delivery into a port. During these Pavlovian conditioning sessions, we paired CS presentations with photo-stimulation of channelrhodopsin-2 (ChR2)-expressing BLA neurons. BLA photo-stimulation potentiated CS-evoked port entries during conditioning, indicating enhanced conditioned approach and appetitive conditioning. Next, new rats received Pavlovian conditioning without photo-stimulation. These rats then received instrumental conditioning sessions where they could press an inactive lever or an active lever that produced CS presentation, without water delivery. Rats pressed more on the active versus inactive lever, and pairing CS presentation with BLA-ChR2 photo-stimulation intensified responding for the CS. This suggests that BLA-ChR2 photo-stimulation enhanced CS incentive value. In a separate experiment, rats did not reliably self-administer BLA-ChR2 stimulations, suggesting that BLA neurons do not carry a primary reward signal. Last, intra-BLA infusions of d-amphetamine also intensified lever-pressing for the CS. The findings suggest that BLA-mediated activity facilitates CS control over behavior by enhancing both appetitive Pavlovian conditioning and instrumental pursuit of CS.SIGNIFICANCE STATEMENT Cues paired with rewards can guide animals to valuable resources such as food. Cues can also promote dysfunctional reward-seeking behavior, as in overeating. Reward-paired cues influence reward seeking through two major mechanisms. First, reward-paired cues evoke conditioned anticipatory behaviors to prepare for impending rewards. Second, reward-paired cues are powerful motivators and they can evoke pursuit in their own right. Here we show that increasing neural activity in the basolateral amygdala enhances both conditioned anticipatory behaviors and pursuit of reward-paired cues. The basolateral amygdala therefore facilitates cue-induced control over behavior by both increasing anticipation of impending rewards and making reward cues more attractive.
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Affiliation(s)
| | - Giovanni Hernandez
- Department of Neurosciences
- Department of Psychiatry, Douglas Mental Health University Institute, McGill University, Montreal H4H 1R3, Quebec, Canada
| | | | | | - Anne-Noël Samaha
- Department of Pharmacology and Physiology,
- Groupe de recherche sur le Système Nerveux Central, Faculty of Medicine, Université de Montréal, Montreal H3T 1J4, Quebec, Canada, and
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Minogianis EA, Servonnet A, Filion MP, Samaha AN. Role of the orbitofrontal cortex and the dorsal striatum in incentive motivation for cocaine. Behav Brain Res 2019; 372:112026. [PMID: 31195036 DOI: 10.1016/j.bbr.2019.112026] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2018] [Revised: 05/30/2019] [Accepted: 06/08/2019] [Indexed: 12/11/2022]
Abstract
Drug addiction involves increased incentive motivation for drug. Intermittent access to cocaine (IntA; 5-6 minutes ON, 25-26 minutes OFF, for 5-6 hours/session) enhances motivation to take the drug. The orbitofrontal cortex (OFC) and the dorsal striatum (DS) are part of a corticolimbic circuit that encodes incentive value and regulates reward-directed behaviour. We predicted that inactivation of the OFC, DS or both suppresses incentive motivation for cocaine after IntA experience. Male Wistar rats had IntA to cocaine (0.25 mg/kg/infusion) for 10 sessions. The rats developed a 'loading' pattern of intake, taking most of their cocaine in the first minute of each drug-available period. They also developed psychomotor sensitization to self-administered cocaine. We then measured incentive motivation for cocaine using a progressive ratio schedule of reinforcement (PR). Before some PR sessions, rats received microinfusions of a baclofen/muscimol cocktail (0.3 and 0.03 nmol/hemisphere, respectively, or saline) to temporarily inactivate the OFC or DS, or to disconnect the two regions. None of these treatments changed spontaneous locomotion in cocaine-naïve rats. However, both baclofen/muscimol and saline infusions influenced cocaine self-administration behaviour. Infusing baclofen/muscimol or saline into the OFC or into the OFC and contralateral DS decreased responding for cocaine under PR, with baclofen/muscimol and saline having similar effects, except that only OFC-DS disconnection with baclofen/muscimol slowed the pace of cocaine intake. Baclofen/muscimol or saline into the DS also reduced responding for cocaine under PR, but baclofen/muscimol was more effective. We conclude that neuronal activity in the OFC and DS might regulate incentive motivation for cocaine.
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Affiliation(s)
- Ellie-Anna Minogianis
- Department of Pharmacology and Physiology, Faculty of Medicine, Université de Montréal, Canada
| | - Alice Servonnet
- Department of Neuroscience, Faculty of Medicine, Université de Montréal, Canada
| | - Marie-Pier Filion
- Department of Pharmacology and Physiology, Faculty of Medicine, Université de Montréal, Canada
| | - Anne-Noël Samaha
- Department of Pharmacology and Physiology, Faculty of Medicine, Université de Montréal, Canada; Central Nervous System Research Group (GRSNC), Faculty of Medicine, Université de Montréal, Canada.
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Abstract
Antipsychotic treatment resistance in schizophrenia remains a major issue in psychiatry. Nearly 30% of patients with schizophrenia do not respond to antipsychotic treatment, yet the underlying neurobiological causes are unknown. All effective antipsychotic medications are thought to achieve their efficacy by targeting the dopaminergic system. Here we review early literature describing the fundamental mechanisms of antipsychotic drug efficacy, highlighting mechanistic concepts that have persisted over time. We then reconsider the original framework for understanding antipsychotic efficacy in light of recent advances in our scientific understanding of the dopaminergic effects of antipsychotics. Based on these new insights, we describe a role for the dopamine transporter in the genesis of both antipsychotic therapeutic response and primary resistance. We believe that this discussion will help delineate the dopaminergic nature of antipsychotic treatment-resistant schizophrenia.
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Affiliation(s)
- Davide Amato
- Department of Neuroscience, Medical University of South Carolina, Charleston, SC, United States
| | - Anna Kruyer
- Department of Neuroscience, Medical University of South Carolina, Charleston, SC, United States
| | - Anne-Noël Samaha
- Department of Pharmacology and Physiology, Faculty of Medicine, Université de Montréal, Montreal, QC, Canada
| | - Andreas Heinz
- Department of Psychiatry, Charité University Medicine Berlin, Campus Charité Mitte, Berlin, Germany
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Minogianis EA, Shams WM, Mabrouk OS, Wong JMT, Brake WG, Kennedy RT, du Souich P, Samaha AN. Varying the rate of intravenous cocaine infusion influences the temporal dynamics of both drug and dopamine concentrations in the striatum. Eur J Neurosci 2018; 50:2054-2064. [PMID: 29757478 DOI: 10.1111/ejn.13941] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Revised: 03/26/2018] [Accepted: 03/27/2018] [Indexed: 11/28/2022]
Abstract
The faster drugs of abuse reach the brain, the greater is the risk of addiction. Even small differences in the rate of drug delivery can influence outcome. Infusing cocaine intravenously over 5 vs. 90-100 s promotes sensitization to the psychomotor and incentive motivational effects of the drug and preferentially recruits mesocorticolimbic regions. It remains unclear whether these effects are due to differences in how fast and/or how much drug reaches the brain. Here, we predicted that varying the rate of intravenous cocaine infusion between 5 and 90 s produces different rates of rise of brain drug concentrations, while producing similar peak concentrations. Freely moving male Wistar rats received acute intravenous cocaine infusions (2.0 mg/kg/infusion) over 5, 45 and 90 s. We measured cocaine concentrations in the dorsal striatum using rapid-sampling microdialysis (1 sample/min) and high-performance liquid chromatography-tandem mass spectrometry. We also measured extracellular concentrations of dopamine and other neurochemicals. Regardless of infusion rate, acute cocaine did not change concentrations of non-dopaminergic neurochemicals. Infusion rate did not significantly influence peak concentrations of cocaine or dopamine, but concentrations increased faster following 5-s infusions. We also assessed psychomotor activity as a function of cocaine infusion rate. Infusion rate did not significantly influence total locomotion, but locomotion increased earlier following 5-s infusions. Thus, small differences in the rate of cocaine delivery influence both the rate of rise of drug and dopamine concentrations, and psychomotor activity. A faster rate of rise of drug and dopamine concentrations might be an important issue in making rapidly delivered cocaine more addictive.
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Affiliation(s)
- Ellie-Anna Minogianis
- Department of Pharmacology and Physiology, Faculty of Medicine, Université de Montréal, C.P. 6128, Succursale Centre-ville, Montreal, QC, H3C 3J7, Canada
| | - Waqqas M Shams
- Department of Psychology, Center for Studies in Behavioral Neurobiology (CSBN), Concordia University, Montreal, QC, Canada
| | - Omar S Mabrouk
- Department of Pharmacology, University of Michigan, Ann Arbor, MI, USA
| | | | - Wayne G Brake
- Department of Psychology, Center for Studies in Behavioral Neurobiology (CSBN), Concordia University, Montreal, QC, Canada
| | - Robert T Kennedy
- Department of Pharmacology, University of Michigan, Ann Arbor, MI, USA.,Department of Chemistry, University of Michigan, Ann Arbor, MI, USA
| | - Patrick du Souich
- Department of Pharmacology and Physiology, Faculty of Medicine, Université de Montréal, C.P. 6128, Succursale Centre-ville, Montreal, QC, H3C 3J7, Canada
| | - Anne-Noël Samaha
- Department of Pharmacology and Physiology, Faculty of Medicine, Université de Montréal, C.P. 6128, Succursale Centre-ville, Montreal, QC, H3C 3J7, Canada.,Groupe de recherche sur le système nerveux central, Faculty of Medicine, Université de Montréal, Montreal, QC, Canada
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Chouinard G, Samaha AN, Chouinard VA, Peretti CS, Kanahara N, Takase M, Iyo M. Antipsychotic-Induced Dopamine Supersensitivity Psychosis: Pharmacology, Criteria, and Therapy. Psychother Psychosom 2018. [PMID: 28647739 DOI: 10.1159/000477313] [Citation(s) in RCA: 145] [Impact Index Per Article: 24.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The first-line treatment for psychotic disorders remains antipsychotic drugs with receptor antagonist properties at D2-like dopamine receptors. However, long-term administration of antipsychotics can upregulate D2 receptors and produce receptor supersensitivity manifested by behavioral supersensitivity to dopamine stimulation in animals, and movement disorders and supersensitivity psychosis (SP) in patients. Antipsychotic-induced SP was first described as the emergence of psychotic symptoms with tardive dyskinesia (TD) and a fall in prolactin levels following drug discontinuation. In the era of first-generation antipsychotics, 4 clinical features characterized drug-induced SP: rapid relapse after drug discontinuation/dose reduction/switch of antipsychotics, tolerance to previously observed therapeutic effects, co-occurring TD, and psychotic exacerbation by life stressors. We review 3 recent studies on the prevalence rates of SP, and the link to treatment resistance and psychotic relapse in the era of second-generation antipsychotics (risperidone, paliperidone, perospirone, and long-acting injectable risperidone, olanzapine, quetiapine, and aripiprazole). These studies show that the prevalence rates of SP remain high in schizophrenia (30%) and higher (70%) in treatment-resistant schizophrenia. We then present neurobehavioral findings on antipsychotic-induced supersensitivity to dopamine from animal studies. Next, we propose criteria for SP, which describe psychotic symptoms and co-occurring movement disorders more precisely. Detection of mild/borderline drug-induced movement disorders permits early recognition of overblockade of D2 receptors, responsible for SP and TD. Finally, we describe 3 antipsychotic withdrawal syndromes, similar to those seen with other CNS drugs, and we propose approaches to treat, potentially prevent, or temporarily manage SP.
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Affiliation(s)
- Guy Chouinard
- Clinical Pharmacology and Toxicology Program, McGill University Montreal, Montreal, QC, Canada
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Servonnet A, Minogianis EA, Bouchard C, Bédard AM, Lévesque D, Rompré PP, Samaha AN. Neurotensin in the nucleus accumbens reverses dopamine supersensitivity evoked by antipsychotic treatment. Neuropharmacology 2017; 123:10-21. [DOI: 10.1016/j.neuropharm.2017.05.015] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Revised: 05/09/2017] [Accepted: 05/13/2017] [Indexed: 12/20/2022]
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19
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Allain F, Roberts DC, Lévesque D, Samaha AN. Intermittent intake of rapid cocaine injections promotes robust psychomotor sensitization, increased incentive motivation for the drug and mGlu2/3 receptor dysregulation. Neuropharmacology 2017; 117:227-237. [DOI: 10.1016/j.neuropharm.2017.01.026] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Revised: 12/15/2016] [Accepted: 01/25/2017] [Indexed: 02/03/2023]
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El Hage C, Bédard AM, Samaha AN. Antipsychotic treatment leading to dopamine supersensitivity persistently alters nucleus accumbens function. Neuropharmacology 2015; 99:715-25. [DOI: 10.1016/j.neuropharm.2015.03.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2014] [Revised: 03/13/2015] [Accepted: 03/14/2015] [Indexed: 10/23/2022]
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Charron A, Hage CE, Servonnet A, Samaha AN. 5-HT2 receptors modulate the expression of antipsychotic-induced dopamine supersensitivity. Eur Neuropsychopharmacol 2015; 25:2381-93. [PMID: 26508706 DOI: 10.1016/j.euroneuro.2015.10.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2015] [Revised: 08/20/2015] [Accepted: 10/05/2015] [Indexed: 10/22/2022]
Abstract
Antipsychotic treatment can produce supersensitivity to dopamine receptor stimulation. This compromises the efficacy of ongoing treatment and increases the risk of relapse to psychosis upon treatment cessation. Serotonin 5-HT2 receptors modulate dopamine function and thereby influence dopamine-dependent responses. Here we evaluated the hypothesis that 5-HT2 receptors modulate the behavioural expression of antipsychotic-induced dopamine supersensitivity. To this end, we first treated rats with the antipsychotic haloperidol using a clinically relevant treatment regimen. We then assessed the effects of a 5-HT2 receptor antagonist (ritanserin; 0.01 and 0.1mg/kg) and of a 5-HT2A receptor antagonist (MDL100,907; 0.025-0.1mg/kg) on amphetamine-induced psychomotor activity. Antipsychotic-treated rats showed increased amphetamine-induced locomotion relative to antipsychotic-naïve rats, indicating a dopamine supersensitive state. At the highest dose tested (0.1mg/kg for both antagonists), both ritanserin and MDL100,907 suppressed amphetamine-induced locomotion in antipsychotic-treated rats, while having no effect on this behaviour in control rats. In parallel, antipsychotic treatment decreased 5-HT2A receptor density in the prelimbic cortex and nucleus accumbens core and increased 5-HT2A receptor density in the caudate-putamen. Thus, activation of either 5-HT2 receptors or of 5-HT2A receptors selectively is required for the full expression of antipsychotic-induced dopamine supersensitivity. In addition, antipsychotic-induced dopamine supersensitivity enhances the ability of 5-HT2/5-HT2A receptors to modulate dopamine-dependent behaviours. These effects are potentially linked to changes in 5-HT2A receptor density in the prefrontal cortex and the striatum. These observations raise the possibility that blockade of 5-HT2A receptors might overcome some of the behavioural manifestations of antipsychotic-induced dopamine supersensitivity.
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Affiliation(s)
- Alexandra Charron
- Department of Pharmacology, Faculty of Medicine, Université de Montréal, Canada
| | - Cynthia El Hage
- Department of Pharmacology, Faculty of Medicine, Université de Montréal, Canada
| | - Alice Servonnet
- Department of Neuroscience, Faculty of Medicine, Université de Montréal, Canada
| | - Anne-Noël Samaha
- Department of Pharmacology, Faculty of Medicine, Université de Montréal, Canada; CNS Research Group, Faculty of Medicine, Université de Montréal, Montréal, QC, Canada.
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Allain F, Minogianis EA, Roberts DC, Samaha AN. How fast and how often: The pharmacokinetics of drug use are decisive in addiction. Neurosci Biobehav Rev 2015; 56:166-79. [DOI: 10.1016/j.neubiorev.2015.06.012] [Citation(s) in RCA: 129] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Revised: 05/28/2015] [Accepted: 06/12/2015] [Indexed: 12/18/2022]
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Bouayad-Gervais K, Minogianis EA, Lévesque D, Samaha AN. The self-administration of rapidly delivered cocaine promotes increased motivation to take the drug: contributions of prior levels of operant responding and cocaine intake. Psychopharmacology (Berl) 2014; 231:4241-52. [PMID: 24752656 DOI: 10.1007/s00213-014-3576-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/11/2013] [Accepted: 04/02/2014] [Indexed: 01/19/2023]
Abstract
RATIONALE Rapid drug delivery to the brain might increase the risk for developing addiction. In rats, increasing the speed of intravenous cocaine delivery (5 vs. 90 s) increases drug intake and the subsequent motivation to self-administer cocaine. Increased motivation for cocaine could result not only from more extensive prior drug intake and operant responding for drug, but also from neuroplasticity evoked by rapid drug uptake. OBJECTIVE We determined the contributions of prior drug intake and operant responding to the increased motivation for cocaine evoked by rapid delivery. We also investigated the effects of cocaine delivery speed on corticostriatal expression of brain-derived neurotrophic factor (BDNF) and tropomyosin receptor kinase B (TrkB) mRNA. METHODS Rats self-administered cocaine (0.25 mg/kg/infusion) delivered over 5 or 90 s during short-access (1 h/session; ShA) or long-access (6 h; LgA) sessions. Motivation for cocaine was then assessed by measuring responding under a progressive ratio schedule of reinforcement. Next, BDNF and TrkB mRNA levels were measured in 5- and 90-s rats. RESULTS Five-second ShA and 5-s-LgA rats were more motivated for cocaine than their 90-s counterparts. This effect was dissociable from previous levels of drug intake or of operant responding for cocaine. In parallel, only rats self-administering rapid cocaine injections had altered BDNF and TrkB mRNA levels in corticostriatal regions. CONCLUSIONS Rapid drug delivery augments the motivation for cocaine independently of effects on the levels of drug intake or operant responding for drug. We suggest that rapid delivery might increase the motivation for drug by promoting neuroplasticity within reward pathways. This neuroplasticity could involve increased regulation of BDNF/TrkB.
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Affiliation(s)
- Karim Bouayad-Gervais
- Department of Pharmacology, Faculty of Medicine, Université de Montréal, C.P. 6128, Succursale Centre-Ville, Montréal, QC, H3C 3J7, Canada
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Samaha AN. Can antipsychotic treatment contribute to drug addiction in schizophrenia? Prog Neuropsychopharmacol Biol Psychiatry 2014; 52:9-16. [PMID: 23793001 DOI: 10.1016/j.pnpbp.2013.06.008] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/22/2013] [Revised: 06/02/2013] [Accepted: 06/11/2013] [Indexed: 12/27/2022]
Abstract
Individuals with schizophrenia are at very high risk for drug abuse and addiction. Patients with a coexisting drug problem fare worse than patients who do not use drugs, and are also more difficult to treat. Current hypotheses cannot adequately account for why patients with schizophrenia so often have a co-morbid drug problem. I present here a complementary hypothesis based on evidence showing that chronic exposure to antipsychotic medications can induce supersensitivity within the brain's dopamine systems, and that this in turn can enhance the rewarding and incentive motivational effects of drugs and reward cues. At the neurobiological level, these effects of antipsychotics are potentially linked to antipsychotic-induced increases in the striatal levels of dopamine D2 receptors and D2 receptors in a high-affinity state for dopamine, particularly at postsynaptic sites. Antipsychotic-induced dopamine supersensitivity and enhanced reward function are not inevitable consequences of prolonged antipsychotic treatment. At least two parameters appear to promote these effects; the use of antipsychotics of the typical class, and continuous rather than intermittent antipsychotic exposure, such that silencing of dopaminergic neurotransmission via D2/3 receptors is unremitting. Thus, by inducing forms of neural plasticity that facilitate the ability of drugs and reward cues to gain control over behaviour, some currently used treatment strategies with typical antipsychotics might contribute to compulsive drug seeking and drug taking behaviours in vulnerable schizophrenia patients.
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Affiliation(s)
- Anne-Noël Samaha
- Department of Pharmacology, Faculty of Medicine, Université de Montréal, Montreal, QC, Canada, H3C 3J7; CNS Research Group, Faculty of Medicine, Université de Montréal, Montreal, QC, Canada, H3C 3J7.
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Affiliation(s)
- Anne-Noël Samaha
- Department of Pharmacology and CNS Research Group, Faculty of Medicine, Université de Montréal, Montreal, QC, Canada.
| | - Stéphane Potvin
- Department of Psychiatry, Faculty of Medicine, Université de Montréal, Montreal, QC, Canada
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Minogianis EA, Lévesque D, Samaha AN. The speed of cocaine delivery determines the subsequent motivation to self-administer the drug. Neuropsychopharmacology 2013; 38:2644-56. [PMID: 23921953 PMCID: PMC3828535 DOI: 10.1038/npp.2013.173] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/20/2013] [Revised: 07/11/2013] [Accepted: 07/15/2013] [Indexed: 12/17/2022]
Abstract
The rapid delivery of drugs of abuse to the brain is associated with an increased likelihood and severity of addiction. Here we evaluated the hypothesis that rapidly delivered cocaine facilitates the addiction process by promoting the development of enhanced motivation for the drug. Rats lever-pressed for cocaine delivered intravenously over 5 or 90 s under fixed ratio (FR) during 6-h sessions. The motivation for cocaine was subsequently assessed using a progressive ratio (PR) schedule, where each successive drug injection cost an exponentially greater number of lever presses, until the cessation of responding. Throughout all self-administration sessions, all rats could only take one injection every 90 s. The 5-s groups self-administered more drug than the 90-s groups across the FR sessions. Under PR, animals that had chronically self-administered rapidly delivered cocaine took more cocaine across a range of doses and regardless of whether the drug was delivered over 5 or 90 s during PR testing. The speed of delivery also determined the long-term neurobiological impact of cocaine. Fourteen days following cocaine withdrawal, caudate-putamen D2 levels were decreased only in the 90-s rats, and quinpirole-mediated Gα(i/o)-protein activation was increased to a greater extent in the 90- vs 5-s rats. Thus, rapid delivery promotes the pursuit of cocaine in the face of rising costs and alters cocaine-induced changes in striatal D2 receptor number and function. As such, rapidly delivered cocaine might facilitate addiction because it more readily alters brain motivation circuits in ways that contribute to the compulsive pursuit of the drug.
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Affiliation(s)
- Ellie-Anna Minogianis
- Department of Pharmacology, Faculty of Medicine, Université de Montréal, Montreal, QC, Canada
| | - Daniel Lévesque
- Faculty of Pharmacy, Université de Montréal, Montreal, QC, Canada,CNS Research Group, Faculty of Medicine, Université de Montréal, Montreal, QC, Canada
| | - Anne-Noël Samaha
- Department of Pharmacology, Faculty of Medicine, Université de Montréal, Montreal, QC, Canada,CNS Research Group, Faculty of Medicine, Université de Montréal, Montreal, QC, Canada,Department of Pharmacology, Faculty of Medicine, Université de Montréal, C.P. 6128, Succursale Centre-ville, Montreal, QC H3C 3J7, Canada, Tel: +514 343 6111 x. 32788, Fax: +514 343 2291, E-mail:
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Bédard AM, Maheux J, Lévesque D, Samaha AN. Prior haloperidol, but not olanzapine, exposure augments the pursuit of reward cues: implications for substance abuse in schizophrenia. Schizophr Bull 2013; 39:692-702. [PMID: 22927669 PMCID: PMC3627770 DOI: 10.1093/schbul/sbs077] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Drug abuse and addiction are excessively common in schizophrenia. Chronic antipsychotic treatment might contribute to this comorbidity by inducing supersensitivity within the brain's dopamine system. Dopamine supersensitivity can enhance the incentive motivational properties of reward cues, and reward cues contribute to the maintenance and severity of drug addiction. We have shown previously that rats withdrawn from continuous haloperidol (HAL) treatment (via subcutaneous minipump) develop dopamine supersensitivity and pursue reward cues more vigorously than HAL-naive rats following an amphetamine (AMPH) challenge. Atypical antipsychotic drugs are thought to be less likely than typicals to produce dopamine supersensitivity. Thus, we compared the effects of HAL and the atypical antipsychotic olanzapine (OLZ) on the pursuit of reward cues. Rats were trained to associate a light-tone cue with water then treated with HAL or OLZ. Following antipsychotic withdrawal, we assessed AMPH-induced enhancement of lever pressing for the cue. Withdrawal from HAL, but not from OLZ, enhanced this effect. HAL, but not OLZ, also enhanced AMPH-induced psychomotor activation and c-fos mRNA expression in the caudate-putamen. Thus, prior HAL, but not OLZ, enhanced conditioned reward following an AMPH challenge, and this was potentially linked to enhanced behavioral sensitivity to AMPH and AMPH-induced engagement of the caudate-putamen. These findings suggest that HAL, but not an atypical like OLZ, modifies reward circuitry in ways that increase responsiveness to reward cues. Because enhanced responsiveness to reward cues can promote drug-seeking behavior, it should be investigated whether atypical antipsychotics might be a preferential option in schizophrenic patients at risk for drug abuse or addiction.
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Affiliation(s)
- Anne-Marie Bédard
- Department of Pharmacology, Faculty of Medicine, Université de MontréalMontreal, QC, Canada
| | - Jérôme Maheux
- Faculty of Pharmacy, Université de MontréalMontreal, QC, Canada
| | - Daniel Lévesque
- Faculty of Pharmacy, Université de MontréalMontreal, QC, Canada
| | - Anne-Noël Samaha
- Department of Pharmacology, Faculty of Medicine, Université de MontréalMontreal, QC, Canada; ,CNS Research Group, Faculty of Medicine, Université de MontréalMontreal, QC, Canada,To whom correspondence should be addressed; C.P. 6128, Succursale Centre-ville, Montreal, Quebec H3C 3J7, Canada; tel: 514-343-6111, ext. 32788, fax: 514-343-2291, e-mail:
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Bédard AM, Maheux J, Lévesque D, Samaha AN. Continuous, but not intermittent, antipsychotic drug delivery intensifies the pursuit of reward cues. Neuropsychopharmacology 2011; 36:1248-59. [PMID: 21326191 PMCID: PMC3079837 DOI: 10.1038/npp.2011.10] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Chronic exposure to antipsychotic medications can persistently change brain dopamine systems. Most studies on the functional significance of these neural changes have focused on motor behavior and few have addressed how long-term antipsychotic treatment might influence dopamine-mediated reward function. We asked, therefore, whether a clinically relevant antipsychotic treatment regimen would alter the incentive motivational properties of a reward cue. We assessed the ability of a Pavlovian-conditioned stimulus to function as a conditioned reward, as well as to elicit approach behavior in rats treated with haloperidol, either continuously (achieved via subcutaneous osmotic minipump) or intermittently (achieved via daily subcutaneous injections). Continuous, but not intermittent, treatment enhanced the ability of amphetamine to potentiate the conditioned reinforcing effects of a cue associated with water. This effect was not related to differences in the ability to attribute predictive value to a conditioned stimulus (as measured by conditioned approach behavior), but was potentially linked to the development of behavioral supersensitivity to amphetamine and to augmented amphetamine-induced immediate early-gene expression (c-fos and Nur77) in dorsal striatopallidal and striatonigral cells. By enhancing the ability of reward cues to control behavior and by intensifying dopamine-mediated striatopallidal and striatonigral cell activity, standard (ie, continuous) antipsychotic treatment regimens might exacerbate drug-seeking and drug-taking behavior in schizophrenia. Achieving regular but transiently high antipsychotic levels in the brain (as modeled in the intermittent condition) might be a viable option to prevent these changes. This possibility should be explored in the clinic.
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Affiliation(s)
- Anne-Marie Bédard
- Department of Pharmacology, Faculty of Medicine, Université de Montréal, Montreal, QC, Canada
| | - Jérôme Maheux
- Faculty of Pharmacy, Université de Montréal, Montreal, QC, Canada
| | - Daniel Lévesque
- Faculty of Pharmacy, Université de Montréal, Montreal, QC, Canada
| | - Anne-Noël Samaha
- Department of Pharmacology, Faculty of Medicine, Université de Montréal, Montreal, QC, Canada,CNS Research Group, Faculty of Medicine, Université de Montréal, Montreal, QC, Canada,Department of Pharmacology, Faculty of Medicine, Université de Montréal, C P 6128, Succursale Centre-ville, Montreal, QC, Canada H3C 3J7. Tel: +1 514 343 6111; Fax: +1 514 343 2291; E-mail:
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Samaha AN, Seeman P, Stewart J, Rajabi H, Kapur S. "Breakthrough" dopamine supersensitivity during ongoing antipsychotic treatment leads to treatment failure over time. J Neurosci 2007; 27:2979-86. [PMID: 17360921 PMCID: PMC6672560 DOI: 10.1523/jneurosci.5416-06.2007] [Citation(s) in RCA: 201] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Antipsychotics often lose efficacy in patients despite chronic continuous treatment. Why this occurs is not known. It is known, however, that withdrawal from chronic antipsychotic treatment induces behavioral dopaminergic supersensitivity in animals. How this emerging supersensitivity might interact with ongoing treatment has never been assessed. Therefore, we asked whether dopamine supersensitivity could overcome the behavioral and neurochemical effects of antipsychotics while they are still in use. Using two models of antipsychotic-like effects in rats, we show that during ongoing treatment with clinically relevant doses, haloperidol and olanzapine progressively lose their efficacy in suppressing amphetamine-induced locomotion and conditioned avoidance responding. Treatment failure occurred despite high levels of dopamine D2 receptor occupancy by the antipsychotic and was at least temporarily reversible by an additional increase in antipsychotic dose. To explore potential mechanisms, we studied presynaptic and postsynaptic elements of the dopamine system and observed that antipsychotic failure was accompanied by opposing changes across the synapse: tolerance to the ability of haloperidol to increase basal dopamine and dopamine turnover on one side, and 20-40% increases in D2 receptor number and 100-160% increases in the proportion of D2 receptors in the high-affinity state for dopamine (D2(High)) on the other. Thus, the loss of antipsychotic efficacy is linked to an increase in D2 receptor number and sensitivity. These results are the first to demonstrate that "breakthrough" supersensitivity during ongoing antipsychotic treatment undermines treatment efficacy. These findings provide a model and a mechanism for antipsychotic treatment failure and suggest new directions for the development of more effective antipsychotics.
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Affiliation(s)
- Anne-Noël Samaha
- Schizophrenia Program, Centre for Addiction and Mental Health, Toronto, Ontario, Canada M5T 1R8
| | - Philip Seeman
- Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada M5T 1R8
- Department of Pharmacology, University of Toronto, Toronto, Ontario, Canada M5S 1A8, and
| | - Jane Stewart
- Centre for Studies in Behavioral Neurobiology, Department of Psychology, Concordia University, Montréal, Quebec, Canada H4B 1R6
| | - Heshmat Rajabi
- Centre for Studies in Behavioral Neurobiology, Department of Psychology, Concordia University, Montréal, Quebec, Canada H4B 1R6
| | - Shitij Kapur
- Schizophrenia Program, Centre for Addiction and Mental Health, Toronto, Ontario, Canada M5T 1R8
- Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada M5T 1R8
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Abstract
It is widely accepted that the more rapidly drugs of abuse reach the brain the greater their potential for addiction. This might be one reason why cocaine and nicotine are more addictive when they are smoked than when they are administered by other routes. Traditionally, rapidly administered drugs are thought to be more addictive because they are more euphorigenic and/or more reinforcing. However, evidence for this is not compelling. We propose an alternative (although not mutually exclusive) explanation based on the idea that the transition to addiction involves drug-induced plasticity in mesocorticolimbic systems, changes that are manifested behaviourally as psychomotor and incentive sensitization. Recent evidence suggests that rapidly administered cocaine or nicotine preferentially engage mesocorticolimbic circuits, and more readily induce psychomotor sensitization. We conclude that rapidly delivered drugs might promote addiction by promoting forms of neurobehavioural plasticity that contribute to the compulsive pursuit of drugs.
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Affiliation(s)
- Anne-Noël Samaha
- Department of Psychology (Biopsychology Program), University of Michigan, Ann Arbor, MI 48109-1109, USA
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Samaha AN, Yau WYW, Yang P, Robinson TE. Rapid delivery of nicotine promotes behavioral sensitization and alters its neurobiological impact. Biol Psychiatry 2005; 57:351-60. [PMID: 15705350 DOI: 10.1016/j.biopsych.2004.11.040] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/09/2004] [Revised: 11/11/2004] [Accepted: 11/23/2004] [Indexed: 11/30/2022]
Abstract
BACKGROUND Nicotine is highly addictive when it is inhaled from tobacco smoke, whereas nicotine replacement products, which usually deliver nicotine orally or transdermally, rarely lead to addiction. It has been proposed that this is due in part to differences in the rate of nicotine delivery to the brain under the two conditions. However, the mechanism by which rapid nicotine delivery facilitates the transition to addiction is not known. The ability of drugs to alter gene regulation and to produce sensitization has been implicated in addiction. We hypothesized, therefore, that varying the rate of nicotine administration may modulate its ability to elicit this form of plasticity. METHODS Animals were treated with repeated intravenous infusions of nicotine over 5, 25, or 100 sec, and their locomotor responses were monitored over treatment days. RESULTS We found that increasing the rate of intravenous nicotine infusion potentiated its ability to produce locomotor sensitization, and to induce c-fos and arc mRNA expression in mesocorticolimbic structures. CONCLUSIONS We suggest that rapid administration may increase vulnerability to addiction by altering the neurobiological impact of nicotine and promoting a form of neurobehavioral plasticity (i.e., sensitization) that can lead to pathological incentive motivation for drugs.
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Affiliation(s)
- Anne-Noël Samaha
- Department of Psychology (Biopsychology Program), University of Michigan, Ann Arbor, Michigan, USA
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Samaha AN, Mallet N, Ferguson SM, Gonon F, Robinson TE. The rate of cocaine administration alters gene regulation and behavioral plasticity: implications for addiction. J Neurosci 2004; 24:6362-70. [PMID: 15254092 PMCID: PMC6729536 DOI: 10.1523/jneurosci.1205-04.2004] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The rapid delivery of drugs of abuse to the brain is thought to promote addiction, but why this occurs is unknown. In the present study, we characterized the influence of rate of intravenous cocaine infusion (5-100 sec) on three effects thought to contribute to its addiction liability: its ability to block dopamine (DA) uptake, to activate immediate early gene expression, and to produce psychomotor sensitization. Rapid infusions potentiated the ability of cocaine to block DA reuptake, to induce c-fos and arc mRNA expression, especially in mesocorticolimbic regions, and to produce psychomotor sensitization. Thus, the rate at which cocaine is delivered influences both its neurobiological impact and its ability to induce a form of drug experience-dependent plasticity implicated in addiction. We propose that rapidly delivered cocaine may be more addictive, in part, because this more readily induces forms of neurobehavioral plasticity that lead to the compulsive pursuit of drugs.
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Affiliation(s)
- Anne-Noël Samaha
- Department of Psychology (Biopsychology Program), University of Michigan, Ann Arbor, Michigan 48109-1109, USA
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Kolb B, Gorny G, Li Y, Samaha AN, Robinson TE. Amphetamine or cocaine limits the ability of later experience to promote structural plasticity in the neocortex and nucleus accumbens. Proc Natl Acad Sci U S A 2003; 100:10523-8. [PMID: 12939407 PMCID: PMC193594 DOI: 10.1073/pnas.1834271100] [Citation(s) in RCA: 156] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2003] [Indexed: 11/18/2022] Open
Abstract
Drugs of abuse and many other kinds of experiences share the ability to alter the morphology of neuronal dendrites and spines, the primary site of excitatory synapses in the brain. We hypothesized, therefore, that exposure to psychostimulant drugs might influence later experience-dependent structural plasticity. We tested this hypothesis by treating rats repeatedly with amphetamine or cocaine and then housing them in either a complex environment or standard laboratory cages for 3-3.5 mo. The brains were processed for Golgi-Cox staining, and the number of dendritic branches and the density of dendritic spines on medium spiny neurons in the nucleus accumbens and pyramidal cells in the parietal cortex were quantified. On most measures, prior treatment with amphetamine or cocaine interfered with the ability of experience in a complex environment to increase dendritic arborization and spine density. We conclude that in some brain regions, repeated exposure to psychomotor-stimulant drugs limits the ability of later experience to produce this form of synaptic plasticity, which may contribute to the persistent behavioral and cognitive deficits associated with drug abuse.
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Affiliation(s)
- Bryan Kolb
- Canadian Centre for Behavioural Neuroscience, University of Lethbridge, Lethbridge, AB, Canada T1K 3M4.
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Kippin TE, Samaha AN, Sotiropoulos V, Pfaus JG. The development of olfactory conditioned ejaculatory preferences in the male rat. II. Parametric manipulation of conditioning session number and duration. Physiol Behav 2001; 73:471-85. [PMID: 11495650 DOI: 10.1016/s0031-9384(01)00485-1] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We have previously demonstrated that repeated pairing of a neutral odor with copulation produces a subsequent conditioned ejaculatory preference (CEP) for females bearing that odor. The present study examines the course of CEP development. In Experiment 1, Long-Evans male rats were allowed access to almond-scented, sexually receptive females for either one, five, or nine conditioning sessions that were 30 min in duration. Males given five or nine sessions displayed significant CEPs. In Experiment 2, male rats were given a single conditioning session with multiple almond-scented females until either a duration (60, 120, 180, or 240 min) or copulatory criterion (two, four, or six ejaculatory series) was satisfied. Males that received 120-, 180-, or 240-min sessions or four ejaculations displayed significant CEPs; males that received two or six ejaculations displayed a trend for CEPs. Analysis of effect size estimates revealed that the strongest CEPs were produced by 120 min of copulation or four ejaculations. In Experiment 3, males receiving nine conditioning sessions each 30 min in duration displayed a more enduring CEP than did males receiving a single conditioning session 240 min in duration. These data suggest that early sexual experiences have particularly powerful influences on subsequent sexual preferences and that the development of sexual preferences are influenced by interactions between CS-UCS pairings and motivational variables.
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Affiliation(s)
- T E Kippin
- Department of Psychology, Center for Studies in Behavioral Neurobiology, Concordia University, Montréal, Québec, Canada.
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Font RL, Samaha AN, Keener MJ, Chevez-Barrios P, Goosey JD. Corneal microsporidiosis. Report of case, including electron microscopic observations. Ophthalmology 2000; 107:1769-75. [PMID: 10964843 DOI: 10.1016/s0161-6420(00)00285-2] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
OBJECTIVE To report a case of corneal stromal infection caused by a protozoon of the genus MICROSPORIDIA:, including clinical, histopathologic, and electron microscopic observations. DESIGN Case report. METHODS Light and electron microscopy studies were performed on keratectomy specimens from a 67-year-old immunocompetent man who had a unilateral chronic stromal keratitis that was refractory to medical treatment. Initial corneal biopsy followed by lamellar and penetrating keratoplasty were performed on the patient. All the specimens were studied histopathologically. RESULTS Light microscopy of the corneal biopsy and the subsequent keratectomy specimens demonstrated myriad small, round to oval microsporidial organisms measuring 3.5 to 5.0 micrometer in length that stained positively with the periodic acid-Schiff, Grocott-methenamine silver, and acid-fast methods and were gram positive. Electron microscopic observations demonstrated viable blastospores that had a thin osmiophilic outer cell wall and contained 11 to 13 coils of the filament. The light and electron microscopic features, the tinctorial characteristics, and the selective corneal stromal involvement are consistent with microsporidial keratitis. CONCLUSIONS Microsporidiosis should be considered in the differential diagnosis of a culture-negative stromal keratitis refractory to medical treatment. The diagnosis can be easily established based on the morphologic features of the protozoa in the keratectomy specimens. No effective medical treatment for the stromal disease is available. Full-thickness keratoplasty is suggested because, in our patient, lamellar keratoplasty did not preclude recurrence of the disease.
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Affiliation(s)
- R L Font
- Department of Ophthalmology, Cullen Eye Institute, Baylor College of Medicine, Houston, Texas, USA.
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Flores C, Samaha AN, Stewart J. Requirement of endogenous basic fibroblast growth factor for sensitization to amphetamine. J Neurosci 2000; 20:RC55. [PMID: 10632621 PMCID: PMC6772396] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/15/2023] Open
Abstract
Repeated exposure to amphetamine produces long-lasting increases in sensitivity to its effects. We reported previously that repeated amphetamine treatment results in increased astrocytic expression of basic fibroblast growth factor (bFGF) in the ventral tegmental area (VTA) and substantia nigra compacta (SNc) and that this effect is prevented by coadministration of a nonspecific glutamate receptor antagonist. Here we show that the development of sensitization to amphetamine is prevented when amphetamine injections are preceded by infusions of a neutralizing antibody to bFGF into the VTA. In addition, we show that astrocytic bFGF expression is increased in the VTA and SNc of animals that exhibit behavioral sensitization and that the number of bFGF-immunoreactive astrocytes in these regions is strongly and positively correlated with the magnitude of sensitization. Cotreatment with an NMDA glutamate receptor antagonist blocks both the development of behavioral sensitization and bFGF induction. These results show that endogenous bFGF is necessary for the development of sensitization to amphetamine and suggest that bFGF mediates the glutamatergic-dopaminergic interaction that initiates the long-term consequences of repeated drug use.
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Affiliation(s)
- C Flores
- Center for Studies in Behavioral Neurobiology Department of Psychology, Concordia University, Montreal, Quebec H3G 1M8, Canada
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Affiliation(s)
- A N Samaha
- Department of Ophthalmology, The American University of Beirut-Medical Center, Lebanon
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Samaha AN, Araj GF, Mroueh SM. Post immunization Hib antigen detection in the CSF of a patient with meningococcal meningitis. J Med Liban 1998; 45:40-2. [PMID: 9421943] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
We report a case of meningococcal meningitis where the cerebrospinal fluid was negative for Neisseria meningitidis but positive for Haemophilus influenzae type b by rapid antigen detection test. We believe that this was due to prior immunization with Haemophilus influenzae type b vaccine. We recommend caution in interpretation of the rapid antigen detection tests especially in patients who had been vaccinated against organisms screened by these tests.
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Affiliation(s)
- A N Samaha
- Department of Pediatrics, American University of Beirut, Lebanon
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