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Renda B, Leri F. The anxiogenic drug yohimbine is a reinforcer in male and female rats. Neuropsychopharmacology 2024:10.1038/s41386-024-01985-1. [PMID: 39289489 DOI: 10.1038/s41386-024-01985-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/26/2024] [Revised: 08/26/2024] [Accepted: 08/28/2024] [Indexed: 09/19/2024]
Abstract
The indole alkaloid yohimbine is an anxiogenic drug that activates stress-responsive systems in the brain. However, because yohimbine also elicits approach behaviors, this study employed male and female Sprague-Dawley rats to explore its potential reinforcing effects. Thus, it was first determined if intravenous (IV) infusions of yohimbine (0.25 mg/kg/infusion) could maintain lever pressing, whether intake could be modulated by dose/infusion, and if lever pressing would persist in the absence of yohimbine or yohimbine-paired cues. Next, to assess yohimbine's effect on memory consolidation, 0.3, 1.25 or 3 mg/kg yohimbine was administered post-training using an object recognition memory task. Finally, place conditioning assessed whether doses of yohimbine that elevate blood serum corticosterone levels (1.25 or 3 mg/kg) could elicit a conditioned place preference. It was found that both sexes acquired yohimbine IV self-administration, that intake was modulated by dose/infusion, and that lever pressing persisted during extinction and in the absence of the yohimbine-paired cue. As well, post-training injections of 1.25 mg/kg yohimbine enhanced consolidation of object memory, and 1.25 and 3 mg/kg elevated corticosterone levels and elicited a place preference in both sexes. Finally, in behavioral tests of psychomotor functions, acute yohimbine increased lever pressing for a visual cue and elevated locomotor activity. These findings reveal a profile of yohimbine's behavioral effects that is consistent with that of psychostimulant reinforcing drugs.
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Affiliation(s)
- Briana Renda
- Department of Psychology and Collaborative Neuroscience Program, University of Guelph, Guelph, ON, Canada
| | - Francesco Leri
- Department of Psychology and Collaborative Neuroscience Program, University of Guelph, Guelph, ON, Canada.
- Department of Psychology, University of Toronto, Scarborough, ON, Canada.
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Redfern WS, Dymond A, Strang I, Storey S, Grant C, Marks L, Barnard C, Heys C, Moyser K, Greenwood K, Cobey D, Moore N, Karp NA, Prior H. The functional observational battery and modified Irwin test as global neurobehavioral assessments in the rat: Pharmacological validation data and a comparison of methods. J Pharmacol Toxicol Methods 2019; 98:106591. [DOI: 10.1016/j.vascn.2019.106591] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Revised: 05/07/2019] [Accepted: 05/25/2019] [Indexed: 12/15/2022]
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Willadsen M, Best LM, Wöhr M, Clarke PBS. Effects of anxiogenic drugs on the emission of 22- and 50-kHz ultrasonic vocalizations in adult rats. Psychopharmacology (Berl) 2018; 235:2435-2445. [PMID: 29909426 DOI: 10.1007/s00213-018-4942-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Accepted: 06/04/2018] [Indexed: 12/27/2022]
Abstract
RATIONALE Adult rat 22-kHz vocalizations are often associated with alarm or distress, whereas a subset of 50-kHz calls is preferentially emitted in response to amphetamine and other rewarding stimuli. Whether any 50-kHz calls reflect anxiety is unknown. OBJECTIVE To determine the effects of anxiogenic drugs on 50-kHz call rate and call subtype profile, in comparison with D-amphetamine. METHODS Adult male rats received systemic amphetamine (1 mg/kg) three times several days before testing. Ultrasonic vocalizations were then recorded after acute intraperitoneal injection of amphetamine or one of five anxiogenic drugs: yohimbine (2.5 mg/kg), N-methyl-β-carboline-3-carboxamide (FG 7142, 5 mg/kg), pentylenetetrazol (PTZ, 20 mg/kg), m-chlorophenylpiperazine (mCPP, 1 mg/kg), caffeine (25 mg/kg), or vehicle. RESULTS The duration of immobility was increased by FG 7142, PTZ, and mCPP; this measure was unchanged by yohimbine and reduced by the locomotor stimulant drugs amphetamine and caffeine. Conversely, the 50-kHz call rate was reduced by FG 7142, PTZ and mCPP, and increased by caffeine and amphetamine. Overall, the most common 50-kHz call subtypes were flat, trill, step-up, and complex. Consistent with previous reports, amphetamine increased the relative prevalence of trill calls while reducing the relative prevalence of flat calls. Yohimbine and caffeine reduced flat call prevalence, whereas mCPP reduced trill call prevalence. No other shifts in the call profile were observed, and no anxiogenic drug induced 22-kHz calls. CONCLUSION Anxiogenic drugs, as a class, did not uniformly alter the 50-kHz call rate or subtype profile. Amphetamine-induced effects on 50-kHz call rate and profile do not reflect anxiety.
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Affiliation(s)
- Maria Willadsen
- Behavioral Neuroscience, Experimental and Biological Psychology, Philipps-University of Marburg, Gutenbergstr. 18, 35032, Marburg, Germany
| | - Laura M Best
- Department of Pharmacology and Therapeutics, McGill University, McIntyre Medical Building Rm. 1325, 3655 Promenade Sir William Osler, Montreal, QC, H3G 1Y6, Canada
| | - Markus Wöhr
- Behavioral Neuroscience, Experimental and Biological Psychology, Philipps-University of Marburg, Gutenbergstr. 18, 35032, Marburg, Germany
- Center for Mind, Brain and Behavior (CMBB), Philipps-University of Marburg, Hans-Meerwein-Str. 6, 35032, Marburg, Germany
| | - Paul B S Clarke
- Department of Pharmacology and Therapeutics, McGill University, McIntyre Medical Building Rm. 1325, 3655 Promenade Sir William Osler, Montreal, QC, H3G 1Y6, Canada.
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Cai L, Bakalli H, Rinaman L. Yohimbine anxiogenesis in the elevated plus maze is disrupted by bilaterally disconnecting the bed nucleus of the stria terminalis from the central nucleus of the amygdala. Neuroscience 2012; 223:200-8. [PMID: 22890081 DOI: 10.1016/j.neuroscience.2012.08.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2012] [Revised: 08/02/2012] [Accepted: 08/06/2012] [Indexed: 11/24/2022]
Abstract
The α2 adrenergic receptor antagonist yohimbine (YO) is a sympathomimetic drug that crosses the blood-brain barrier after systemic administration. YO promotes increased transmitter release from noradrenergic (NA) axon terminals in the central nucleus of the amygdala (CEA), bed nucleus of the stria terminalis (BST), hypothalamus, and other brain regions implicated in physiological and behavioral responses to stressful and threatening stimuli. YO is potently anxiogenic in humans and experimental animals, including rats. To determine whether direct connections between the CEA and anterolateral group of BST nuclei (algBST) are necessary for YO anxiogenesis in rats, neurotoxic ibotenate lesions of the CEA in one hemisphere and the ipsi- or contralateral algBST were conducted to disrupt CEA-algBST communication uni- or bilaterally. Sham-lesioned controls received microinjections of vehicle into the CEA and algBST. Two weeks later, behavior was assessed in the elevated plus maze (EPMZ) in rats after i.p. saline or YO (1.0mg/kg). Central ibotenate lesion placement and extent was assessed post-mortem in NeuN-immunolabeled tissue sections. The ability of YO to increase anxiety-like behavior in the EPMZ was similarly robust in rats with sham lesions or ipsilateral CEA-algBST lesions. Conversely, YO anxiogenesis in the EPMZ was disrupted in rats with asymmetric lesions designed to bilaterally disconnect the CEA and algBST, whereas neither unilateral nor bilateral disconnecting lesions altered EPMZ behavior in rats after i.p. saline. We conclude that the anxiogenic effects of increased NA signaling in rats after YO require direct CEA-algBST interactions that do not shape EPMZ behavior under baseline conditions.
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Affiliation(s)
- L Cai
- Department of Neuroscience, University of Pittsburgh, Pittsburgh, PA 15260, United States
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Davis AR, Shields AD, Brigman JL, Norcross M, McElligott ZA, Holmes A, Winder DG. Yohimbine impairs extinction of cocaine-conditioned place preference in an alpha2-adrenergic receptor independent process. Learn Mem 2008; 15:667-76. [PMID: 18772254 DOI: 10.1101/lm.1079308] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Extinction, a form of learning that has the ability to reshape learned behavior based on new experiences, has been heavily studied utilizing fear learning paradigms. Mechanisms underlying extinction of positive-valence associations, such as drug self-administration and place preference, are poorly understood yet may have important relevance to addiction treatment. Data suggest a major role for the noradrenergic system in extinction of fear-based learning. Employing both pharmacological and genetic approaches, we investigated the role of the alpha(2)-adrenergic receptor (alpha(2)-AR) in extinction of cocaine-conditioned place preference (CPP) and glutamatergic transmission in the bed nucleus of the stria terminalis (BNST). We found that pre-extinction systemic treatment with the alpha(2)-AR antagonist yohimbine impaired cocaine CPP extinction in C57BL/6J mice, an effect that was not mimicked by the more selective alpha(2)-AR antagonist, atipamezole. Moreover, alpha(2A)-AR knockout mice exhibited similar cocaine CPP extinction and exacerbated extinction impairing effects of yohimbine. Using acute brain slices and electrophysiological approaches, we found that yohimbine produces a slowly evolving depression of glutamatergic transmission in the BNST that was not mimicked by atipamezole. Further, this action was extant in slices from alpha(2A)-AR knockout mice. Our data strongly suggest that extinction-modifying effects of yohimbine are unlikely to be due to actions at alpha(2A)-ARs.
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Affiliation(s)
- Adeola R Davis
- Vanderbilt Brain Institute, Vanderbilt University Medical Center, Nashville, Tennessee 37232-0615, USA
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Abstract
Fear is an adaptive component of the acute "stress" response to potentially-dangerous (external and internal) stimuli which threaten to perturb homeostasis. However, when disproportional in intensity, chronic and/or irreversible, or not associated with any genuine risk, it may be symptomatic of a debilitating anxious state: for example, social phobia, panic attacks or generalized anxiety disorder. In view of the importance of guaranteeing an appropriate emotional response to aversive events, it is not surprising that a diversity of mechanisms are involved in the induction and inhibition of anxious states. Apart from conventional neurotransmitters, such as monoamines, gamma-amino-butyric acid (GABA) and glutamate, many other modulators have been implicated, including: adenosine, cannabinoids, numerous neuropeptides, hormones, neurotrophins, cytokines and several cellular mediators. Accordingly, though benzodiazepines (which reinforce transmission at GABA(A) receptors), serotonin (5-HT)(1A) receptor agonists and 5-HT reuptake inhibitors are currently the principle drugs employed in the management of anxiety disorders, there is considerable scope for the development of alternative therapies. In addition to cellular, anatomical and neurochemical strategies, behavioral models are indispensable for the characterization of anxious states and their modulation. Amongst diverse paradigms, conflict procedures--in which subjects experience opposing impulses of desire and fear--are of especial conceptual and therapeutic pertinence. For example, in the Vogel Conflict Test (VCT), the ability of drugs to release punishment-suppressed drinking behavior is evaluated. In reviewing the neurobiology of anxious states, the present article focuses in particular upon: the multifarious and complex roles of individual modulators, often as a function of the specific receptor type and neuronal substrate involved in their actions; novel targets for the management of anxiety disorders; the influence of neurotransmitters and other agents upon performance in the VCT; data acquired from complementary pharmacological and genetic strategies and, finally, several open questions likely to orientate future experimental- and clinical-research. In view of the recent proliferation of mechanisms implicated in the pathogenesis, modulation and, potentially, treatment of anxiety disorders, this is an opportune moment to survey their functional and pathophysiological significance, and to assess their influence upon performance in the VCT and other models of potential anxiolytic properties.
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Affiliation(s)
- Mark J Millan
- Psychopharmacology Department, Centre de Rescherches de Croissy, Institut de Recherches (IDR) Servier, 125 Chemin de Ronde, 78290 Croissy-sur-Seine, Paris, France.
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Millan MJ, Brocco M. The Vogel conflict test: procedural aspects, gamma-aminobutyric acid, glutamate and monoamines. Eur J Pharmacol 2003; 463:67-96. [PMID: 12600703 DOI: 10.1016/s0014-2999(03)01275-5] [Citation(s) in RCA: 111] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
A multitude of mechanisms are involved in the control of emotion and in the response to stress. These incorporate mediators/targets as diverse as gamma-aminobutyric acid (GABA), excitatory amino acids, monoamines, hormones, neurotrophins and various neuropeptides. Behavioural models are indispensable for characterization of the neuronal substrates underlying their implication in the etiology of anxiety, and of their potential therapeutic pertinence to its management. Of considerable significance in this regard are conflict paradigms in which the influence of drugs upon conditioned (trained) behaviours is examined. For example, the Vogel conflict test, which was introduced some 30 years ago, measures the ability of drugs to release the drinking behaviour of water-deprived rats exposed to a mild aversive stimulus ("punishment"). This model, of which numerous procedural variants are discussed herein, has been widely used in the evaluation of potential anxiolytic agents. In particular, it has been exploited in the characterization of drugs interacting with GABAergic, glutamatergic and monoaminergic networks, the actions of which in the Vogel conflict test are summarized in this article. More recently, the effects of drugs acting at neuropeptide receptors have been examined with this model. It is concluded that the Vogel conflict test is of considerable utility for rapid exploration of the actions of anxiolytic (and anxiogenic) drugs. Indeed, in view of its clinical relevance, broader exploitation of the Vogel conflict test in the identification of novel classes of anxiolytic agents, and in the determination of their mechanisms of action, would prove instructive.
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Affiliation(s)
- Mark J Millan
- Psychopharmacology Department, Institut de Recherches Servier, Centre de Recherches de Croissy, 125 Chemin de Ronde, 78290 Croissy/Seine, Paris, France.
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Clarke RW, Harris J. RX 821002 as a tool for physiological investigation of alpha(2)-adrenoceptors. CNS DRUG REVIEWS 2002; 8:177-92. [PMID: 12177687 PMCID: PMC6741674 DOI: 10.1111/j.1527-3458.2002.tb00222.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
RX 821002 is the 2-methoxy congener of idazoxan. In binding and tissue studies it behaves as a selective antagonist of alpha(2)-adrenoceptors, with at least 5 times greater affinity for these receptors than any other binding site. It does not select between the different types of alpha(2)-receptor. Although this drug probably has no future as a therapeutic agent, it remains a good probe for physiological activity at alpha(2)-adrenoceptors in animal experiments. A particularly useful feature of this compound is its lack of binding at I(1) and I(2) imidazoline receptors. However, it has relatively high affinity for 5-HT(1A) receptors (at which it acts as an antagonist) and a tendency to behave as an inverse agonist at alpha(2A)-adrenoceptors in some cell culture systems. These potential drawbacks may be overcome by careful design of experiments, and the greater selectivity of RX 821002 renders it much superior to yohimbine or idazoxan as a tool for probing physiological actions at alpha(2)-receptors. It can be compared favorably with other selective antagonists such as atipamezole. In physiological studies, RX 821002 augments norepinephrine release in the frontal cortex and increases drinking behavior in rat. In rabbit, intrathecal administration of this drug enhances somatic and autonomic motor outflows, showing that tonic adrenergic descending inhibition of withdrawal reflexes and sympathetic pre-ganglionic neurons is strong in this species. The potentiation of reflexes may be considered a pro-nociceptive action. In the same model, RX 821002 antagonizes the inhibitory effects of the mu opioid fentanyl, indicating that exogenous opioids synergize with endogenously released norepinephrine in the spinal cord. Thus, the careful use of RX 821002 has revealed several aspects of the physiological activity of alpha(2)-adrenoceptors in rabbit spinal cord and rat brain. We recommend that RX 821002 and/or compounds with similar selectivity for alpha(2)-adrenoceptors (atipamezole, MK-912, RS-79948) should be used in preference to yohimbine or idazoxan in all future studies of this type.
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Affiliation(s)
- R W Clarke
- Division of Animal Physiology, School of Biosciences, Sutton Bonington Campus, University of Nottingham, Loughborough LE12 5RD, UK.
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Millan MJ, Newman-Tancredi A, Audinot V, Cussac D, Lejeune F, Nicolas JP, Cogé F, Galizzi JP, Boutin JA, Rivet JM, Dekeyne A, Gobert A. Agonist and antagonist actions of yohimbine as compared to fluparoxan at alpha(2)-adrenergic receptors (AR)s, serotonin (5-HT)(1A), 5-HT(1B), 5-HT(1D) and dopamine D(2) and D(3) receptors. Significance for the modulation of frontocortical monoaminergic transmission and depressive states. Synapse 2000; 35:79-95. [PMID: 10611634 DOI: 10.1002/(sici)1098-2396(200002)35:2<79::aid-syn1>3.0.co;2-x] [Citation(s) in RCA: 144] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Herein, we evaluate the interaction of the alpha(2)-AR antagonist, yohimbine, as compared to fluparoxan, at multiple monoaminergic receptors and examine their roles in the modulation of adrenergic, dopaminergic and serotonergic transmission in freely-moving rats. Yohimbine displays marked affinity at human (h)alpha(2A)-, halpha(2B)- and halpha(2C)-ARs, significant affinity for h5-HT(1A), h5-HT(1B), h5-HT(1D), and hD(2) receptors and weak affinity for hD(3) receptors. In [(35)S]GTPgammaS binding protocols, yohimbine exerts antagonist actions at halpha(2A)-AR, h5-HT(1B), h5-HT(1D), and hD(2) sites, yet partial agonist actions at h5-HT(1A) sites. In vivo, agonist actions of yohimbine at 5-HT(1A) sites are revealed by WAY100,635-reversible induction of hypothermia in the rat. In guinea pigs, antagonist actions of yohimbine at 5-HT(1B) receptors are revealed by blockade of hypothermia evoked by the 5-HT(1B) agonist, GR46,611. In distinction to yohimbine, fluparoxan shows only modest partial agonist actions at h5-HT(1A) sites versus marked antagonist actions at halpha(2)-ARs. While fluparoxan selectively enhances hippocampal noradrenaline (NAD) turnover, yohimbine also enhances striatal dopamine (DA) turnover and suppresses striatal turnover of 5-HT. Further, yohimbine decreases firing of serotonergic neurones in raphe nuclei, an action reversed by WAY100,635. Fluparoxan increases extracellular levels of DA and NAD, but not 5-HT, in frontal cortex. In analogy, yohimbine enhances FCX levels of DA and NAD, yet suppresses those of 5-HT, the latter effect being antagonized by WAY100,635. The induction by fluoxetine of FCX levels of 5-HT, DA, and NAD is potentiated by fluparoxan. Yohimbine likewise facilitates the influence of fluoxetine upon DA and NAD levels, but not those of 5-HT. In conclusion, the alpha(2)-AR antagonist properties of yohimbine increase DA and NAD levels both alone and in association with fluoxetine. However, in contrast to the selective alpha(2)-AR antagonist, fluparoxan, the 5-HT(1A) agonist actions of yohimbine suppress 5-HT levels alone and underlie its inability to augment the influence of fluoxetine upon 5-HT levels.
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MESH Headings
- Adrenergic alpha-2 Receptor Agonists
- Adrenergic alpha-2 Receptor Antagonists
- Adrenergic alpha-Antagonists/pharmacology
- Animals
- Antidepressive Agents/pharmacology
- Body Temperature/drug effects
- Frontal Lobe/drug effects
- Frontal Lobe/physiology
- Guinea Pigs
- Hippocampus/drug effects
- Hippocampus/physiology
- Humans
- Mice
- Neurons/drug effects
- Neurons/physiology
- Piperoxan/analogs & derivatives
- Piperoxan/pharmacology
- Pyrroles/pharmacology
- Rats
- Receptor, Serotonin, 5-HT1B
- Receptor, Serotonin, 5-HT1D
- Receptors, Dopamine D2/drug effects
- Receptors, Dopamine D2/physiology
- Receptors, Dopamine D3
- Receptors, Serotonin/drug effects
- Receptors, Serotonin/physiology
- Receptors, Serotonin, 5-HT1
- Swine
- Synaptic Transmission/drug effects
- Synaptic Transmission/physiology
- Yohimbine/pharmacology
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Affiliation(s)
- M J Millan
- Psychopharmacology Department, Institut de Recherches Servier, Centre de Recherches de Croissy, 125, Chemin de Ronde, 78290-Croissy-sur-Seine, Paris, France
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Jenck F, Martin JR, Moreau JL. The 5-HT1A receptor agonist flesinoxan increases aversion in a model of panic-like anxiety in rats. J Psychopharmacol 1999; 13:166-70. [PMID: 10475723 DOI: 10.1177/026988119901300209] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Acute systemic administration of the selective serotonin (5-HT)1A receptor full agonist flesinoxan enhanced the sensitivity of rats to the panic-like aversion elicited by local stimulation of the dorsolateral periaqueductal grey (dPAG). This experimental paradigm in rats has previously been validated as a simulation of acute anxiety with particular relevance to panic disorder. The dose-dependent decrease in threshold for acute fear responses recorded in rats following intraperitoneal administration of flesinoxan (1-10 mg/kg) was similar to that induced by the panic precipitating agent yohimbine and opposite to the threshold increase induced by the antipanic drug alprazolam. The proaversive effect of flesinoxan observed in rats is consistent with the reported aggravation of the condition of panic patients following oral flesinoxan treatment. Thus, the model adequately detects drug-induced panicogenic-like properties. Data suggest that selective activation of 5-HT1A receptors (pre- and/or post-synaptic in brain and/or periphery) following systemic administration of 5-HT1A receptor full agonists exacerbates aversion in animals or patients with panic anxiety; activation of these receptor subtypes may probably mediate the panicogenic action reported under certain circumstances with non-selective 5-HT mimetics.
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Affiliation(s)
- F Jenck
- ROCHE Pharma Division, Preclinical CNS Research, Basel, Switzerland.
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Spedding M, Newman-Tancredi A, Millan MJ, Dacquet C, Michel AN, Jacoby E, Vickery B, Tallentire D. Interaction of the anxiogenic agent, RS-30199, with 5-HT1A receptors: modulation of sexual activity in the male rat. Neuropharmacology 1998; 37:769-80. [PMID: 9707291 DOI: 10.1016/s0028-3908(98)00065-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
RS-30199 has been shown previously to have atypical interactions at 5-HT1A receptors. RS-30199 and RS-64459, an analogue of buspirone with a buspirone side chain, were compared with the classic, partial agonist at 5-HT1A receptors, 8-hydroxy-2 (di-n-propylamino) tetralin (8-OH-DPAT) and buspirone. At human (h) 5-HT1A receptors in CHO cells, RS-30199-193 (racemate) and its enantiomers (-197, -198) inhibited [3H]-8-OH-DPAT binding (RS-30199-198, ki, 29.7 +/- 11.7 nM; RS-30199-197, ki, 74.1 +/- 11.7 nM) as did RS-64459 (ki, 24.9 +/- 6.0 nM), but RS-30199-197 and -198 were almost full agonists in a [35S]-GTPgammaS binding assay, whereas RS-64459 was a partial agonist, resembling buspirone and 8-OH-DPAT. RS-64459 and the enantiomers of RS-30199 had weaker affinity for 5-HT2C and 5-HT7 receptors. These compounds did not induce the 5-HT behavioural syndrome in male rats. However, in a model where naive male rats were introduced to estrogen-progesterone primed, sexually receptive female rats, RS-30199-197 (0.1, 1, 10 mg/kg, s.c.) had a profound inhibitory effect on sexual behaviour score. Neither buspirone nor 8-OH-DPAT reduced the sexual behaviour score. Unlike 8-OH-DPAT, which shortens intromission latency, RS-30199 prolonged intromission latency. RS-30199 (10 mg/kg s.c.) fully inhibited the facilitation of sexual behaviour caused by the alpha2-adrenoceptor antagonist, delequamine (0.1 mg/kg, p.o.). In contrast, RS-64459 (100, 250, 1000 and 4000 microg/kg, s.c.) failed to modify the sexual behaviour score and did not modify intromission latency. The differences between the effects of RS-30199 and RS-64459 in binding and functional experiments are supported by molecular models of the receptor-ligand interaction, where the compounds interact in different ways with the receptor; a model is proposed for the allosteric interaction of different agents with the receptor, resulting in different functional profiles. RS-30199 can be considered an atypical agonist at 5-HT1A receptors.
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Affiliation(s)
- M Spedding
- Institut de Internationales, Servier, Croissy Research Centre, Paris, France.
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Gobert A, Rivet JM, Audinot V, Newman-Tancredi A, Cistarelli L, Millan MJ. Simultaneous quantification of serotonin, dopamine and noradrenaline levels in single frontal cortex dialysates of freely-moving rats reveals a complex pattern of reciprocal auto- and heteroreceptor-mediated control of release. Neuroscience 1998; 84:413-29. [PMID: 9539213 DOI: 10.1016/s0306-4522(97)00565-4] [Citation(s) in RCA: 162] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
In the present study, a novel and exceptionally sensitive method of high-performance liquid chromatography coupled to coulometric detection, together with concentric dialysis probes, was exploited for an examination of the role of autoreceptors and heteroceptors in the modulation of dopamine, noradrenaline and serotonin levels in single samples of the frontal cortex of freely-moving rats. The selective D3/D2 receptor agonist, CGS 15855A [(+/-)-trans-1,3,4,4a,5,10b-hexahydro-4-propyl-2H-[1]benzopyrano[3 ,4-b]-pyridin-9-ol], and antagonist, raclopride, respectively decreased (-50%) and increased (+60%) levels of dopamine without significantly modifying those of serotonin and noradrenaline. The selective alpha2-adrenergic receptor agonist, dexmedetomidine, markedly decreased noradrenaline levels (-100%) and likewise suppressed those of serotonin and dopamine by -55 and -45%, respectively. This effect was mimicked by the preferential alpha2-adrenergic receptor agonist, guanabenz (-100%, -60% and -50%). Furthermore, the alpha2-adrenergic receptor antagonist, RX 821,002 [2(2-methoxy-1,4-benzodioxan-2-yl)-2-imidazoline], and the preferential alpha2A-adrenergic receptor antagonist, BRL 44408 [2-(2H-(1-methyl-1,3-dihydroisoindole)methyl)-4,5-dihydroimidaz ole], both evoked a pronounced elevation in levels of noradrenaline (+212%, +109%) and dopamine (+73%, +85%). In contrast, the preferential alpha(2B/2C)-adrenergic receptor antagonist, prazosin, did not modify noradrenaline and dopamine levels. RX 821,002 and BRL 44408 did not significantly modify levels of serotonin, whereas prazosin decreased these levels markedly (-55%), likely due to its alpha1-adrenergic receptor antagonist properties. The selective serotonin-1A receptor agonist, 8-hydroxy-2-(di-n-propylamino)-tetralin (8-OH-DPAT), reduced serotonin levels (-65%) and increased those of dopamine and noradrenaline by +100%), and +175%, respectively. The selective serotonin-1A antagonist, WAY 100,635 [N-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-N-(2-pyridinyl)cyclo- hexanecarboxamide], which had little affect on monoamine levels alone, abolished the influence of 8-OH-DPAT upon serotonin and dopamine levels and significantly attenuated its influence upon noradrenaline levels. Finally, the selective serotonin-1B agonist, GR 46611 [3-[3-(2-dimethylaminoethyl)-1H-indol-5-yl]-N-(4-methoxybenzyl)acrylamid e], decreased serotonin levels (-49%) and the serotonin-1B antagonist, GR 127,935 [N-[4-methoxy-3-(4-methylpiperazin-1-yl)phenyl]-2'-methyl-4'-(5-me thyl-1,2,4-oxadiazol-3-yl)-biphenyl-4-carboxamide], which did not significantly modify serotonin levels alone, abolished this action of GR 46611. Levels of dopamine and noradrenaline were not affected by GR 46611 or GR 127,935. In conclusion, there is a complex pattern of reciprocal autoreceptor and heteroceptor control of monoamine release in the frontal cortex. Most notably, activation of alpha2-adrenergic receptors inhibits the release of noradrenaline, dopamine and serotonin in each case, while stimulation of serotonin-1A receptors suppresses serotonin, yet facilitates noradrenaline and dopamine release. In addition, dopamine D2/D3 autoreceptors restrain dopamine release while (terminal-localized) serotonin-1B receptors reduce serotonin release. Control of serotonin release is expressed phasically and that of noradrenaline and dopamine release tonically.
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Affiliation(s)
- A Gobert
- Institut de Recherches Servier, Psychopharmacology Department, Croissy-sur-Seine, France
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Cao BJ, Rodgers RJ. Comparative behavioural profiles of buspirone and its metabolite 1-(2-pyrimidinyl)-piperazine (1-PP) in the murine elevated plus-maze. Neuropharmacology 1997; 36:1089-97. [PMID: 9294974 DOI: 10.1016/s0028-3908(97)00094-4] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
It has been suggested that in vivo formation of the metabolite 1-(2-pyrimidinyl)-piperazine (1-PP) may be a major drawback in the use of buspirone as an anti-anxiety agent. To test this hypothesis, the effects of buspirone, alone or with proadifen (an inhibitor of liver microsomal enzymes) pretreatment, were contrasted with those of 1-PP in the murine elevated plus-maze test of anxiety. At 3.0 mg/kg (but not lower doses), buspirone per se had modest anxiolytic-like effects (increased percentage of open arm entries; reduced stretched-attend postures and flatback approach) that were associated with increased grooming and immobility. However, in proadifen-pretreated mice, buspirone produced behavioural depression only, with marked effects evident both at 1.0 and 3.0 mg/kg. As proadifen blocks the biotransformation of buspirone to 1-PP, these data suggest that any anxiolytic activity of buspirone in the murine plus-maze may be attributable to its principal active metabolite. Consistent with this hypothesis, 1-PP (0.5-13.5 mg/kg) produced dose-dependent anti-anxiety effects on both conventional and ethological measures that were not confounded by motoric impairment. Results are discussed in relation to biochemical and electrophysiological studies suggesting that 1-PP has a direct action at 5-HT1A receptors.
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Affiliation(s)
- B J Cao
- Department of Psychology, University of Leeds, U.K
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Tallentire D, McRae G, Spedding M, Clark R, Vickery B. Modulation of sexual behaviour in the rat by a potent and selective alpha 2-adrenoceptor antagonist, delequamine (RS-15385-197). Br J Pharmacol 1996; 118:63-72. [PMID: 8733577 PMCID: PMC1909492 DOI: 10.1111/j.1476-5381.1996.tb15367.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
1. The contributions of alpha 2-adrenoceptors and 5-HT1A receptors to sexual behaviour in the rat have been re-evaluated by use of a highly potent and selective alpha 2-adrenoceptor antagonist, delequamine (RS-15385-197), yohimbine, idazoxan and the partial agonist at 5-HT1A receptors, 8-hydroxy-2(di-n-propylamino)-tetralin (8-OH-DPAT). 2. In a model where naive male rats were introduced to oestrogen-progesterone primed, sexually receptive female rats, delequamine (0.4-6.4 mg kg-1, p.o.) dose-relatedly increased the sexual behaviour score over the entire dose-range whereas yohimbine was effective at only one dose, 2 mg kg-1, p.o.. Idazoxan was active only at 2.5 and 5 mg kg-1, p.o. Yohimbine, but neither delequamine nor idazoxan, decreased ejaculation latency. 8-OH-DPAT (0.1 and 0.25 mg kg-1, s.c.) reduced the time, and the number of intromissions to ejaculation without affecting other parameters. A combination of delequamine (0.4 mg kg-1, p.o.) and 8-OH-DPAT (0.1 mg kg-1 s.c.) increased the percentage of rats mounting, intromitting and ejaculating, and reduced ejaculation latency and the number of intromissions. 3. In orchidectomized, sexually experienced rats exposed to sexually receptive females, delequamine, idazoxan and yohimbine increased the number of rats mounting, and there was a tendency to increase the number of animals intromitting, but no effect on ejaculatory behaviour. 4. In ovariectomized female rats brought to low level receptivity by priming with low dose injections of oestradiol benzoate and progesterone, delequamine, at 1.6 and 6.4 mg kg-1 p.o., increased lordosis, while yohimbine, at 2, 4 and 8 mg kg-1 p.o., reduced lordotic responses to sexually experienced males in a dose-dependent manner. 8-OH-DPAT at 0.1, 0.25 mg kg-1, s.c. reduced lordosis in a dose-dependent manner. 5. These findings may be explained on the basis that yohimbine is an alpha 2-adrenoceptor antagonist with affinity for 5-HT1A receptors and that the effects of 5-HT1A receptors may modulate the sexual behaviour responses to alpha 2-receptor antagonism in some models. Thus, in contrast to yohimbine, the highly-selective alpha 2-adrenoceptor antagonist, delequamine, was very effective in increasing the behavioural score in male and female rats over a wide dose-range.
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Affiliation(s)
- D Tallentire
- Syntex Research, Palo Alto, California 94304, USA
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