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Nakamura K. The role of the dorsal raphé nucleus in reward-seeking behavior. Front Integr Neurosci 2013; 7:60. [PMID: 23986662 PMCID: PMC3753458 DOI: 10.3389/fnint.2013.00060] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2013] [Accepted: 07/30/2013] [Indexed: 12/22/2022] Open
Abstract
Pharmacological experiments have shown that the modulation of brain serotonin levels has a strong impact on value-based decision making. Anatomical and physiological evidence also revealed that the dorsal raphé nucleus (DRN), a major source of serotonin, and the dopamine system receive common inputs from brain regions associated with appetitive and aversive information processing. The serotonin and dopamine systems also have reciprocal functional influences on each other. However, the specific mechanism by which serotonin affects value-based decision making is not clear. To understand the information carried by the DRN for reward-seeking behavior, we measured single neuron activity in the primate DRN during the performance of saccade tasks to obtain different amounts of a reward. We found that DRN neuronal activity was characterized by tonic modulation that was altered by the expected and received reward value. Consistent reward-dependent modulation across different task periods suggested that DRN activity kept track of the reward value throughout a trial. The DRN was also characterized by modulation of its activity in the opposite direction by different neuronal subgroups, one firing strongly for the prediction and receipt of large rewards, with the other firing strongly for small rewards. Conversely, putative dopamine neurons showed positive phasic responses to reward-indicating cues and the receipt of an unexpected reward amount, which supports the reward prediction error signal hypothesis of dopamine. I suggest that the tonic reward monitoring signal of the DRN, possibly together with its interaction with the dopamine system, reports a continuous level of motivation throughout the performance of a task. Such a signal may provide "reward context" information to the targets of DRN projections, where it may be integrated further with incoming motivationally salient information.
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Affiliation(s)
- Kae Nakamura
- Department of Physiology, Kansai Medical University Hirakata, Japan ; Precursory Research for Embryonic Science and Technology, Japan Science and Technology Agency Kawaguchi, Japan
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Aton SJ, Seibt J, Dumoulin MC, Coleman T, Shiraishi M, Frank MG. The sedating antidepressant trazodone impairs sleep-dependent cortical plasticity. PLoS One 2009; 4:e6078. [PMID: 19568418 PMCID: PMC2699540 DOI: 10.1371/journal.pone.0006078] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2009] [Accepted: 06/02/2009] [Indexed: 01/06/2023] Open
Abstract
Background Recent findings indicate that certain classes of hypnotics that target GABAA receptors impair sleep-dependent brain plasticity. However, the effects of hypnotics acting at monoamine receptors (e.g., the antidepressant trazodone) on this process are unknown. We therefore assessed the effects of commonly-prescribed medications for the treatment of insomnia (trazodone and the non-benzodiazepine GABAA receptor agonists zaleplon and eszopiclone) in a canonical model of sleep-dependent, in vivo synaptic plasticity in the primary visual cortex (V1) known as ocular dominance plasticity. Methodology/Principal Findings After a 6-h baseline period of sleep/wake polysomnographic recording, cats underwent 6 h of continuous waking combined with monocular deprivation (MD) to trigger synaptic remodeling. Cats subsequently received an i.p. injection of either vehicle, trazodone (10 mg/kg), zaleplon (10 mg/kg), or eszopiclone (1–10 mg/kg), and were allowed an 8-h period of post-MD sleep before ocular dominance plasticity was assessed. We found that while zaleplon and eszopiclone had profound effects on sleeping cortical electroencephalographic (EEG) activity, only trazodone (which did not alter EEG activity) significantly impaired sleep-dependent consolidation of ocular dominance plasticity. This was associated with deficits in both the normal depression of V1 neuronal responses to deprived-eye stimulation, and potentiation of responses to non-deprived eye stimulation, which accompany ocular dominance plasticity. Conclusions/Significance Taken together, our data suggest that the monoamine receptors targeted by trazodone play an important role in sleep-dependent consolidation of synaptic plasticity. They also demonstrate that changes in sleep architecture are not necessarily reliable predictors of how hypnotics affect sleep-dependent neural functions.
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Affiliation(s)
- Sara J. Aton
- Department of Neuroscience, School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Julie Seibt
- Department of Neuroscience, School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Michelle C. Dumoulin
- Department of Neuroscience, School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Tammi Coleman
- Department of Neuroscience, School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Mia Shiraishi
- Department of Neuroscience, School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Marcos G. Frank
- Department of Neuroscience, School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- * E-mail:
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Forster GL, Pringle RB, Mouw NJ, Vuong SM, Watt MJ, Burke AR, Lowry CA, Summers CH, Renner KJ. Corticotropin-releasing factor in the dorsal raphe nucleus increases medial prefrontal cortical serotonin via type 2 receptors and median raphe nucleus activity. Eur J Neurosci 2008; 28:299-310. [PMID: 18702701 DOI: 10.1111/j.1460-9568.2008.06333.x] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Interactions between central corticotropin-releasing factor (CRF) and serotonergic systems are believed to be important for mediating fear and anxiety behaviors. Recently we demonstrated that infusions of CRF into the rat dorsal raphe nucleus result in a delayed increase in serotonin release within the medial prefrontal cortex that coincided with a reduction in fear behavior. The current studies were designed to study the CRF receptor mechanisms and pathways involved in this serotonergic response. Infusions of CRF (0.5 microg/0.5 microL) were made into the dorsal raphe nucleus of urethane-anesthetized rats following either inactivation of the median raphe nucleus by muscimol (25 ng/0.25 microL) or antagonism of CRF receptor type 1 or CRF receptor type 2 in the dorsal raphe nucleus with antalarmin (25-50 ng/0.5 microL) or antisauvagine-30 (2 microg/0.5 microL), respectively. Medial prefrontal cortex serotonin levels were measured using in-vivo microdialysis and high-performance liquid chromatography with electrochemical detection. Increased medial prefrontal cortex serotonin release elicited by CRF infusion into the dorsal raphe nucleus was abolished by inactivation of the median raphe nucleus. Furthermore, antagonism of CRF receptor type 2 but not CRF receptor type 1 in the dorsal raphe nucleus abolished CRF-induced increases in medial prefrontal cortex serotonin. Follow-up studies involved electrical stimulation of the central nucleus of the amygdala, a source of CRF afferents to the dorsal raphe nucleus. Activation of the central nucleus increased medial prefrontal cortex serotonin release. This response was blocked by CRF receptor type 2 antagonism in the dorsal raphe. Overall, these results highlight complex CRF modulation of medial prefrontal cortex serotonergic activity at the level of the raphe nuclei.
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Affiliation(s)
- Gina L Forster
- Division of Basic Biomedical Sciences and Neuroscience Group, Sanford School of Medicine, University of South Dakota, 414 E. Clark Street, Vermillion, SD 57069, USA
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Gourley SL, Debold JF, Yin W, Cook J, Miczek KA. Benzodiazepines and heightened aggressive behavior in rats: reduction by GABA(A)/alpha(1) receptor antagonists. Psychopharmacology (Berl) 2005; 178:232-40. [PMID: 15316711 DOI: 10.1007/s00213-004-1987-3] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/24/2004] [Accepted: 07/06/2004] [Indexed: 10/26/2022]
Abstract
RATIONALE Positive modulators of the benzodiazepine/GABA(A) receptor complex can heighten aggressive behavior; the GABA(A)/alpha(1) subunit may play a critical role in benzodiazepine-modulated aggressive behavior. OBJECTIVE The carboline derivatives, beta-CCt and 3-PBC, antagonists with preferential action at the GABA(A) receptors with alpha(1) subunits, may antagonize benzodiazepine-heightened aggression, thus implicating the alpha(1) subunit in heightened aggression. METHODS The GABA(A) receptor agonist 4,5,6,7-tetrahydroisoxazolo[5,4c]-pyridin-3-ol (THIP) (0.01-3.0 mg/kg), and the benzodiazepine receptor agonists midazolam (0.3-3.0 mg/kg) and triazolam (0.003-3.0 mg/kg) were administered to adult male resident rats to assess the drugs' effects on their aggressive behavior toward an intruder. Then beta-CCt (0.3-10.0 mg/kg) and 3-PBC (0.3-17.0 mg/kg) were each administered in conjunction with midazolam. The salient elements of aggressive and non-aggressive behavior were measured by analyzing video recordings and encoding each behavioral act and posture in terms of its frequency and duration of occurrence. RESULTS Midazolam significantly increased the duration of aggressive behaviors at 1.0 and 1.7 mg/kg, and triazolam increased attack bite frequency at 0.03 mg/kg, both implicating GABA(A) receptors with benzodiazepine binding sites in aggressive behavior. In the present dose range, THIP did not affect any behaviors. The broad-spectrum benzodiazepine antagonist, flumazenil (1.0 mg/kg), antagonized the aggression-heightening effects of midazolam. beta-CCt (0.3-10.0 mg/kg) and 3-PBC (0.3-17.0 mg/kg) also antagonized the aggression-heightening effects of midazolam (1.0 mg/kg). CONCLUSIONS These results implicate both the GABA(A) gamma and alpha(1) subunits in benzodiazepine-heightened aggression.
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Affiliation(s)
- Shannon L Gourley
- Department of Psychology, Tufts University, 530 Boston Ave. (Bacon Hall), Medford, MA 02155, USA
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5
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Wegener G, Volke V, Rosenberg R. Endogenous nitric oxide decreases hippocampal levels of serotonin and dopamine in vivo. Br J Pharmacol 2000; 130:575-80. [PMID: 10821785 PMCID: PMC1572107 DOI: 10.1038/sj.bjp.0703349] [Citation(s) in RCA: 130] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/1999] [Revised: 02/29/2000] [Accepted: 03/06/2000] [Indexed: 11/09/2022] Open
Abstract
Nitric oxide (NO) modulates the levels of various neurotransmitters in the CNS. Here we determined whether the specific nitric oxide synthase (NOS) inhibitor 7-nitroindazole (7-NI), the non-selective inhibitor of guanylate cyclase (GC) and NOS, methylene blue (MB), the NO-precursor L-arginine (L-Arg), and the selective soluble GC inhibitor 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) affect extracellular levels of serotonin (5-HT), dopamine (DA), 5-hydroxyindoleacetic acid (5-HIAA), and homovanillic acid (HVA) in the rat ventral hippocampus by using microdialysis in freely moving animals. Local perfusion of 7-NI (1 mM) and MB (1 mM) significantly increased extracellular level of 5-HT, whereas DA was increased by 7-NI only. Systemic administration of 7-NI (50 mg kg(-1)) and MB (30 mg kg(-1)) increased the extracellular levels of 5-HT and DA. Extracellular levels of 5-HIAA was not influenced by local or systemic MB or 7-NI. In contrast, extracellular level of HVA was decreased by systemic MB and retrodialyzed MB, but was not influenced by 7-NI. Retrodialysis of L-Arg (2 mM) decreased the levels of 5-HT, DA, 5-HIAA and HVA in the hippocampus. Systemic administration of L-Arg (250 mg kg(-1)) decreased the level of 5-HT, but failed to influence DA, 5-HIAA and HVA. Local perfusion of ODQ (400 microM) did not affect 5-HT overflow in the hippocampus. We conclude that NOS inhibitors increased extracellular levels of 5-HT and DA in the rat ventral hippocampus after local or systemic administration, whereas the NO precursor L-Arg had the opposite effect. Thus, endogenous NO may exert a negative control over the levels of 5-HT and DA in the hippocampus. However, this effect is probably not mediated by cyclic GMP.
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Affiliation(s)
- G Wegener
- Department of Biological Psychiatry, Institute for Basic Psychiatric Research, Skovagervej 2, DK-8240 Risskov, Denmark.
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Castaneda R, Sussman N, Levy R, O'Malley M, Westreich L. A review of the effects of moderate alcohol intake on psychiatric and sleep disorders. RECENT DEVELOPMENTS IN ALCOHOLISM : AN OFFICIAL PUBLICATION OF THE AMERICAN MEDICAL SOCIETY ON ALCOHOLISM, THE RESEARCH SOCIETY ON ALCOHOLISM, AND THE NATIONAL COUNCIL ON ALCOHOLISM 1998; 14:197-226. [PMID: 9751947 DOI: 10.1007/0-306-47148-5_9] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
In this chapter we discuss the effects of moderate ethanol consumption on the treatment of psychiatric and sleep disorders. A review of the literature on the interactions of ethanol with neurotransmitters and psychotropic medications suggests that although ethanol affects the clinical course of psychiatric and sleep disorders by different mechanisms, it does so principally through perturbations it causes in the balance of central nervous system neurotransmitter systems, which may modify the clinical course of primary psychiatric and sleep disorders and undermine the therapeutic response to psychotropic medications. Neurotransmitter responses may also be manifested clinically by rebound phenomena, akin to a subsyndromal withdrawal, which affect sleep and precipitate anxiety and mood symptoms. In addition, ethanol also modifies the clearance and disposition of a variety of psychotropic metabolites and interferes with their clinical effectiveness. We recommend that most psychiatric patients, and all patients with sleep disorders, should abstain from even moderate ethanol use, as this may adversely affect their clinical course and response to treatment.
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Affiliation(s)
- R Castaneda
- Department of Psychiatry, New York University School of Medicine, Bellevue Hospital Medical Center, New York 10016, USA
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7
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Fernández-Guasti A, López-Rubalcava C. Modification of the anxiolytic action of 5-HT1A compounds by GABA-benzodiazepine agents in rats. Pharmacol Biochem Behav 1998; 60:27-32. [PMID: 9610920 DOI: 10.1016/s0091-3057(97)00482-6] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The general purpose of the present study was to analyze the possible interactions between the GABA benzodiazepine and the serotonin systems in the mediation of the antianxiety actions of 5-HT1A compounds. The anxiolytic effect of buspirone (5 mg/kg), ipsapirone (5 mg/kg), indorenate (5 mg/kg), and 8-OH-DPAT (0.5 mg/kg) was established in the rat burying behavior test. Flumazenil (5 mg/kg), but not bicuculline (2.5 mg/kg), effectively counteracted the reduction in burying behavior produced by buspirone, ipsapirone, and 8-OH-DPAT. These same 5-HT1A compounds, at subthreshold doses, produced an important reduction in burying behavior when combined with diazepam (0.25 mg/kg). The effect of indorenate was not altered by any of the antagonists and, when combined with diazepam it produced large increases in burying behavior latency. Only buspirone alone and in combination with bicuculline or flumazenil impaired motor coordination as tested in the rota rod. Data are discussed on the bases of the interaction between the GABAergic and serotonergic systems, stressing species differences and variations due to the animal model of anxiety.
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Affiliation(s)
- A Fernández-Guasti
- Departamento de Farmacología y Toxicología, CINVESTAV, Instituto Mexicano de Psiquiatría, México DF
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8
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Murphy CA, DiCamillo AM, Haun F, Murray M. Lesion of the habenular efferent pathway produces anxiety and locomotor hyperactivity in rats: a comparison of the effects of neonatal and adult lesions. Behav Brain Res 1996; 81:43-52. [PMID: 8950000 DOI: 10.1016/s0166-4328(96)00041-1] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Recent studies have implicated the habenula in modulating states of arousal and chronic responses to stress. We examined whether lesion of the habenula efferent pathway, the fasciculus retroflexus (FR), at either 3 (P3) or 70 (P70) days of age affects stress-related anxiety (elevated plus-maze test) and activity levels (open-field test) in rats tested as adults. Both P3- and P70-lesioned rats showed chronically elevated plasma levels of corticosterone. Rats receiving FR lesions as neonates (P3) exhibited greater open arm avoidance on the elevated plus-maze than controls 2 months postoperatively, suggesting a heightened state of anxiety. In contrast, P70-lesioned rats behaved similarly to controls on the plus-maze, but showed increased locomotion and increased grooming in the open field, effects not observed in P3-lesioned rats. When an additional stressful condition was imposed (5 days of social isolation plus 24 h food deprivation) before testing, both FR-lesion groups showed an attenuation of the normal behavioral responses (decreased open-arm entries/time in open arms, increased freezing). The effects of FR lesions on activity and behavioral indices of anxiety may be due to disruption of lateral habenular projections to dopaminergic neurons in the ventral tegmentum and/or projections to regions containing high concentrations of benzodiazepine receptors, the median and dorsal raphe and dorsal periaqueductal gray. Behavioral differences observed as a function of lesion age suggest differential capabilities of P3- and P70-lesioned rats to utilize compensatory mechanisms to correct FR lesion-induced deficits.
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Affiliation(s)
- C A Murphy
- Department of Anatomy and Neurobiology, Medical College of Pennsylvania and Hahnemann University, Philadelphia 19129, USA
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9
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Haleem DJ, Batool F. Regionally specific effects of diazepam on brain serotonin metabolism in rats: sustained effects following repeated administration. Life Sci 1996; 59:PL239-46. [PMID: 8845014 DOI: 10.1016/0024-3205(96)00452-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The effects of single (1mg/kg) and repeated (1mg/kg 2* daily for 4 days) diazepam administration are investigated on brain regional 5-hydroxytryptamine (5-HT; serotonin) and 5-hydroxy indoleacetic acid (5-HIAA) concentration in rats. Daily treatment decreased food intakes but body weights did not decrease. Administration of diazepam (1mg/kg) to 4 day saline injected rats on the 5th day decreased 5-HT levels in the hippocampus and increased it in the hypothalamus. 5-HIAA levels were increased in the striatum and decreased in the hypothalamus 4 day diazepam injected rats injected with saline on the 5th day also exhibited similar changes of 5-HT and 5-HIAA. Cortical levels of 5-HIAA were also smaller in these rats. Administration of diazepam to 4 day diazepam injected rats again decreased 5-HT in the hippocampus and 5-HIAA in the hypothalamus. 5-HT and 5-HIAA were both decreased in the striatum. Regionally specific effects of diazepam on brain serotonin metabolism are discussed in relation to their possible functions.
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Affiliation(s)
- D J Haleem
- Department of Biochemistry, University of Karachi, Pakistan
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Swedo SE, Leonard HL, Allen AJ. New developments in childhood affective and anxiety disorders. CURRENT PROBLEMS IN PEDIATRICS 1994; 24:12-38. [PMID: 8174389 DOI: 10.1016/0045-9380(94)90023-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- S E Swedo
- Child Psychiatry Branch, National Institute of Mental Health, Bethesda, Md
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11
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Hascoët M, Bourin M, Todd KG, Coüetoux du Tertre A. Anti-conflict effect of 5-HT1A agonists in rats: a new model for evaluating anxiolytic-like activity. J Psychopharmacol 1994; 8:227-37. [PMID: 22298629 DOI: 10.1177/026988119400800406] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
A new conflict procedure was developed to study the potential anti-punishment effects of 5-HT( 1A) agonists as compared to diazepam. In this paradigm, the opportunity existed for rats to choose during punished periods between immediate, punished reinforcement and delayed, non-punished reinforcement. The results confirm that, for non-sedative doses (1 mg/kg), diazepam increases the number of punished responses. Furthermore, the present paradigm seems sensitive for the detection of 5-HT(1A) activity. Buspirone, gepirone, ipsapirone, zalospirone and 8-OH-DPAT increased responding for immediate but punished reinforcement. 1-(2-pyrimidinyl)piperazine, the common metabolite of the azapirones, does not participate in their anti-conflict effect. NAN 190, a 5-HT(1A) antagonist, was shown to block the 5-HT(1A) agonists. The findings of the present study suggest that benzodiazepines and 5-HT( 1A) agonists reduce the capacity to tolerate delays in reward. Abnormality in serotonin systems may be associated with poor impulse control.
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Affiliation(s)
- M Hascoët
- GIS Médicament, Faculté de Medecine, 44035 Nantes cedex, France
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12
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Wirtshafter D, Stratford TR, Pitzer MR. Studies on the behavioral activation produced by stimulation of GABAB receptors in the median raphe nucleus. Behav Brain Res 1993; 59:83-93. [PMID: 8155296 DOI: 10.1016/0166-4328(93)90154-i] [Citation(s) in RCA: 55] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Injections of the GABAB agonist baclofen into the median raphe nucleus (MR) resulted in marked hyperactivity and in increases in food and water intake by non-deprived animals. The locomotor effects of baclofen were stereospecific and could be antagonized by coinjection of the GABAB antagonist 2-hydroxysaclofen. Hyperactivity was produced by lower doses of baclofen, at shorter latencies, when the drug was injected into the MR than when it applied to the dorsal raphe nucleus (DR) or the ventral tegmental area (VTA). The locomotor response to intra-MR baclofen was unaltered in animals pretreated with the serotonin synthesis inhibitor p-chlorophenylalanine. Finally, intra-MR injections of baclofen produced a large increase in dopamine metabolism in the nucleus accumbens and striatum but failed to alter hippocampal or striatal serotonin metabolism. These findings suggest that baclofen may produce increases in activity and ingestive behavior as a result of an action on non-serotonergic cells in the MR.
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Affiliation(s)
- D Wirtshafter
- Department of Psychology, University of Illinois at Chicago 60680
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Currie PJ, Coscina DV. Paraventricular nucleus injections of idazoxan block feeding induced by paraventricular nucleus norepinephrine but not intra-raphe 8-hydroxy-2-(di-n-propylamino)tetralin. Brain Res 1993; 627:153-8. [PMID: 7904886 DOI: 10.1016/0006-8993(93)90759-g] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Previous work has shown that injection of the 5-hydroxytryptamine (5-HT)1A agonist 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) into the midbrain raphe nuclei activates somatodendritic 5-HT autoreceptors leading to decreased 5-HT synthesis and release in terminal forebrain regions and an increase in feeding behaviour. Since 5-HT is believed to function antagonistically with norepinephrine (NE) in the hypothalamic paraventricular nucleus (PVN) to control feeding, it has been proposed that 8-OH-DPAT elicits food intake by removing the inhibitory influence of 5-HT over PVN alpha 2-adrenergic feeding mechanisms. This hypothesis was tested by examining the ability of PVN injection of the alpha 2-adrenoceptor antagonist idazoxan (IDAZ) to attenuate the feeding stimulant action induced by raphe injection of 8-OH-DPAT. In the first series of experiments the dose-response effects of dorsal and median raphe injection of 8-OH-DPAT in addition to PVN NE on feeding were examined. Injection of NE (5-40 nmol) and 8-OH-DPAT (0.4-1.6 nmol) both elicited reliable dose-dependent increases in 1 h food intake compared to saline control. Similar doses of 8-OH-DPAT injected into the PVN failed to alter baseline feeding. A second series of experiments examined the effects of IDAZ on 8-OH-DPAT and NE-stimulated food intake in rats implanted with dorsal or median raphe cannulae as well as cannulae aimed at the PVN.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- P J Currie
- Section of Biopsychology, Clarke Institute of Psychiatry, Toronto, ON, Canada
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López-Rubalcava C, Saldívar A, Fernández-Guasti A. Interaction of GABA and serotonin in the anxiolytic action of diazepam and serotonergic anxiolytics. Pharmacol Biochem Behav 1992; 43:433-40. [PMID: 1359576 DOI: 10.1016/0091-3057(92)90173-d] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The general purpose of the present study was to analyze the possible interactions between the GABA-benzodiazepine and the serotonergic (5-HT) systems in the anxiolytic action of diazepam and the 5-HT1A agonists, ipsapirone, indorenate, and 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT). The effect of the benzodiazepine receptor antagonist, flumazenil (10.0 mg/kg), on the anxiolytic action of ipsapirone (5.0 mg/kg), indorenate (5.0 mg/kg), and 8-OH-DPAT (0.125 mg/kg) was examined on the avoidance exploratory behavior paradigm in mice. The effect of the 5-HT1 blockers, methiotepin (0.31 mg/kg), pindolol (3.1 mg/kg), and alprenolol (5.0 mg/kg), on the anxiolytic action of diazepam (0.5 mg/kg) was also studied. In the last part of this work, the putative potentiation between diazepam (0.25 mg/kg) and each of the serotonergic anxiolytics was investigated. The antianxiety effect of diazepam, ipsapirone, indorenate, and 8-OH-DPAT was prevented by flumazenil. The serotonergic/beta-blocker, alprenolol, partially antagonized the diazepam effect. Finally, a potentiation of suboptimal doses of diazepam and ipsapirone, but not with indorenate or 8-OH-DPAT, was observed. The findings suggest an interaction between both systems on the anxiolytic action of diazepam and the 5-HT1A agonists.
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Abstract
This review details the neural systems that are important in anxiety-related behaviours. In particular, the role of the amygdaloid complex, Papez circuit, septohippocampal formation and raphe nuclei are described and discussed. Evidence is gathered from a variety of experimental approaches. These include behavioural assessment of anxiety in animals after intracerebral injection of pharmacological agents and following lesions of discrete brain nuclei and selective neurotransmitter pathways. Further evidence is provided by functional brain mapping studies applied to animals and humans. It is proposed that the neural systems recruited in different experimental conditions of anxiety may differ, supporting the notion that clinical anxiety exists in several forms. This has implications for the identification of new anxiolytic treatments. In particular, the findings suggest that approaches aimed at identifying new anxiolytic agents must take into account both the distribution of receptors for the drug and the neuronal systems activated by the experimental protocol.
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Affiliation(s)
- J A Pratt
- Department of Physiology and Pharmacology, University of Strathclyde, Glasgow, U.K
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Morales A, Torres C, Megías JL. Sistemas neurales de relevancia en el contexto de la psicobiología de la ansiedad: una revisión. STUDIES IN PSYCHOLOGY 1992. [DOI: 10.1080/02109395.1992.10821176] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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Bruhwyler J, Chleide E, Liégeois JF, Delarge J, Mercier M. Anxiolytic potential of sulpiride, clozapine and derivatives in the open-field test. Pharmacol Biochem Behav 1990; 36:57-61. [PMID: 2349269 DOI: 10.1016/0091-3057(90)90125-2] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Recently acquired data question the sharp dichotomy between anxiolytics and neuroleptics, since disinhibitory effects have been measured in the rat with very low doses of haloperidol and higher doses of atypical neuroleptics in FI and DRL schedules, but also in the open-field test. That the DA transmission in certain brain regions is involved in some aspects of anxiety has recently been suggested. The present study confirms this hypothesis particularly with high doses of sulpiride (80 mg/kg) and clozapine (24 mg/kg) when tested in the open-field test. Moreover, the results show how a slight chemical modification of clozapine can give a direction to pharmacological activity with one derivative still resembling clozapine and the second one resembling haloperidol. As neuroleptics do not seem to influence the synthesis and utilization of GABA, the higher entry score observed with them would seem to depend above all on DA antagonism in the mesolimbic system.
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Affiliation(s)
- J Bruhwyler
- Department of Psychology, Faculty of Medicine, F.N.D.P. Namur, Belgium
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18
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Curzon G, Kennett GA. m-CPP: a tool for studying behavioural responses associated with 5-HT1c receptors. Trends Pharmacol Sci 1990; 11:181-2. [PMID: 2188399 DOI: 10.1016/0165-6147(90)90109-l] [Citation(s) in RCA: 75] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- G Curzon
- Institute of Neurology, Queen Square, London, UK
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19
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Boix F, Fernández Teruel A, Escorihuela RM, Tobeña A. Handling-habituation prevents the effects of diazepam and alprazolam on brain serotonin levels in rats. Behav Brain Res 1990; 36:209-15. [PMID: 1690010 DOI: 10.1016/0166-4328(90)90059-n] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
In two different experiments, serotonin (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) levels were measured in rats, using HPLC with electrochemical detection, in 3 brain regions (hippocampus, cerebral cortex and hypothalamus) after acute i.p. treatment with diazepam (4 mg/kg), alprazolam (1.25 mg/kg) or vehicle. In the first experiment, rats received the acute treatment 30 min before they were sacrificed. In the second, the animals were previously habituated to handling (involving the maneuvers of injecting and sacrificing at the guillotine) daily for 15 days, before the acute administration of the drugs. Results of the acute treatment alone showed a significant increase in 5-HT levels in hippocampus and cerebral cortex, and a decrease in hypothalamus, but not differences in 5-HIAA levels, for the diazepam- and alprazolam-treated groups. After handling-habituation, no effect in the monoamine or metabolite levels appeared when the rats were treated with diazepam or alprazolam. The results are discussed in relation to the emotional changes induced by the handling procedure, and for possible connections between the mechanisms of action of handling-habituation and benzodiazepine treatments at CNS level.
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Affiliation(s)
- F Boix
- Dept. de Farmacologia i Psiquiatria, Facultat de Medicina, Universitat Autónoma de Barcelona, Catalonia, Spain
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20
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Whitton P, Curzon G. Anxiogenic-like effect of infusing 1-(3-chlorophenyl) piperazine (mCPP) into the hippocampus. Psychopharmacology (Berl) 1990; 100:138-40. [PMID: 2296623 DOI: 10.1007/bf02245806] [Citation(s) in RCA: 75] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
1-(3-Chlorophenyl) piperazine (mCPP) was previously shown to have an anxiogenic-like effect, i.e., it decreased total interaction in a rat social interaction test. Evidence indicated mediation by activation of 5-HT1C receptors with an ED50 of approximately 500 micrograms/kg IP (Kennett et al. 1989). A comparable effect is now shown on infusing 4 micrograms of the drug ICV or infusing 0.5 microgram into the hippocampus. Both responses were dose dependent. Infusion of 1 microgram mCPP into the amygdala had no effect. None of the above treatments significantly reduced locomotion. Results are consistent with the postulated role of the hippocampus in anxiety.
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Affiliation(s)
- P Whitton
- Department of Neurochemistry, Institute of Neurology, London, UK
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21
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Sakurai-Yamashita Y, Kataoka Y, Yamashita K, Miyazaki A, Ushio M, Mine K, Niwa M, Ueki S. Conflict behavior and dynamics of monoamines of various brain nuclei in rats. Neuropharmacology 1989; 28:1067-73. [PMID: 2478922 DOI: 10.1016/0028-3908(89)90119-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The present study was an attempt to clarify the role of noradrenaline (NA) and of the 5-hydroxytryptamine (5-HT) system in various nuclei in brain, as a component of a proposed neural circuit in the mediation of conflict behavior and the anticonflict action of anxiolytics. The authors investigated changes in the concentrations of NA, 3-methoxy-4-hydroxyphenylethyleneglycol, 5-HT and 5-hydroxyindoleacetic acid in discrete regions of the brain in rats, in correlation with conflict behavior and also the effects of diazepam and suriclone. Noradrenergic neural activity diminished with a conflict situation, in the frontal cortex, central amygdala, mammillary body and dorsal hippocampus. 5-Hydroxytryptaminergic neural activity increased with a conflict situation in the frontal cortex, central amygdala, basolateral amygdala and medial septum. These changes in the frontal cortex, central amygdala, mammillary body and dorsal hippocampus were not observed when diazepam 20 mg/kg (p.o.) and suriclone 40 mg/kg (p.o.) produced anticonflict action. Suriclone normalized the increased 5-HT-ergic activity in the medial septum. The suppression of NA-ergic and the activation of 5-HT-ergic (except for the mammillary body) neural activity in the frontal cortex, central amygdala, mammillary body and dorsal hippocampus seemed to be linked to the mediation of conflict behavior. The facilitatory and inhibitory action on NA and 5-HT (except for the mammillary body) neurons, respectively, in these regions of the brain, may be involved in mechanisms underlying the anticonflict action of anxiolytics (diazepam or suriclone).
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22
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Abstract
Our understanding of the biological basis of anxiety is far from complete, although our knowledge of both the neuropharmacologic and molecular basis of anxiety has increased. This article reviews our current knowledge of the possible biological basis of generalized anxiety disorder and panic disorder.
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Affiliation(s)
- M H Teicher
- Harvard Medical School, Boston, Massachusetts
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23
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Gardner CR. Functional in vivo correlates of the benzodiazepine agonist-inverse agonist continuum. Prog Neurobiol 1988; 31:425-76. [PMID: 2849142 DOI: 10.1016/0301-0082(88)90011-1] [Citation(s) in RCA: 61] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- C R Gardner
- Roussel Laboratories, Swindon, Wiltshire, U.K
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24
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25
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Manchon M, Kopp N, Rouzioux JJ, Lecestre D, Deluermoz S, Miachon S. Benzodiazepine receptor and neurotransmitter studies in the brain of suicides. Life Sci 1987; 41:2623-30. [PMID: 2892103 DOI: 10.1016/0024-3205(87)90276-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The characteristics of benzodiazepine binding sites (affinity, number heterogeneity) were studied on frozen sections of hippocampus of 7 suicides and 5 controls subjects, using biochemical and autoradiographic techniques. 3H flunitrazepam was used as ligand, clonazepam and CL 218,872 as displacing agents. Some neurotransmitters or their derivatives (GABA, catecholamines, hydroxy-indols) were evaluated quantitatively in parallel in the hippocampal tissue by liquid chromatography. We observed mainly an increase in the Ki of CL 218,872 subtype I binding sites in suicides, (7.48 +/- 1.7 to 17.24 +/- 1.7 nM, P less than 0.01), (m +/- SEM) and an increase in % of type I binding sites (30 +/- 4.2 to 42 +/- 2.5, P = 0.01). Among neurotransmitters, only norepinephrine differed significantly between controls and suicides (11.34 +/- 1.9 to 24.34 ng/g tissue, P = 0.02).
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Affiliation(s)
- M Manchon
- INSERM U 171, Laboratoire de Neurochimie Fonctionnelle, Hôpital Ste Eugénie, St Genis Laval, France
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26
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Bowling AC, DeLorenzo RJ. Photoaffinity labeling of a novel benzodiazepine binding protein in rat brain. Eur J Pharmacol 1987; 135:97-100. [PMID: 3032662 DOI: 10.1016/0014-2999(87)90763-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Photoaffinity labeling experiments were conducted with [3H]clonazepam to investigate the possible existence of a benzodiazepine binding site that is distinct from the central- and peripheral-type benzodiazepine binding sites. These studies demonstrate the presence of a novel benzodiazepine binding protein in rat brain with a relative mobility of 65,000 daltons that binds benzodiazepines stereoselectivity in the high nanomolar-low micromolar concentration range.
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27
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Healy D. Rhythm and blues. Neurochemical, neuropharmacological and neuropsychological implications of a hypothesis of circadian rhythm dysfunction in the affective disorders. Psychopharmacology (Berl) 1987; 93:271-85. [PMID: 3124158 DOI: 10.1007/bf00187243] [Citation(s) in RCA: 68] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Current views on the organisation and functions of the circadian rhythm system are outlined. Evidence is presented supportive of the notion that the pathophysiology of the affective disorders involves a disruption of circadian rhythms and that the primary locus of action of agents effective in the affective disorders is on the circadian rhythm system. Potential disruptions of this system are enumerated. Such a hypothesis, it is argued, might potentially unite the disparate neurochemical and neuroendocrinological findings emerging in both depression and mania. There are in addition neuropsychological and nosological implications of such a framework, which may help bridge the divide between molecular and behavioural approaches to research on the affective disorders which are outlined.
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Affiliation(s)
- D Healy
- University of Cambridge Clinical School, Department of Psychiatry, Addenbrooke's Hospital, UK
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