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Groenink L, Verdouw PM, Zhao Y, Ter Heegde F, Wever KE, Bijlsma EY. Pharmacological modulation of conditioned fear in the fear-potentiated startle test: a systematic review and meta-analysis of animal studies. Psychopharmacology (Berl) 2023; 240:2361-2401. [PMID: 36651922 PMCID: PMC10593622 DOI: 10.1007/s00213-022-06307-1] [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] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Accepted: 12/21/2022] [Indexed: 01/19/2023]
Abstract
RATIONALE AND OBJECTIVES Fear conditioning is an important aspect in the pathophysiology of anxiety disorders. The fear-potentiated startle test is based on classical fear conditioning and over the years, a broad range of drugs have been tested in this test. Synthesis of the available data may further our understanding of the neurotransmitter systems that are involved in the expression of conditioned fear. METHODS Following a comprehensive search in Medline and Embase, we included 68 research articles that reported on 103 drugs, covering 56 different drug classes. The systematic review was limited to studies using acute, systemic drug administration in naive animals. RESULTS Qualitative data synthesis showed that most clinically active anxiolytics, but not serotonin-reuptake inhibitors, reduced cued fear. Anxiogenic drugs increased fear potentiation in 35% of the experiments, reduced fear potentiation in 29% of the experiments, and were without effect in 29% of the experiments. Meta-analyses could be performed for five drug classes and showed that benzodiazepines, buspirone, 5-HT1A agonists, 5-HT1A antagonists, and mGluR2,3 agonists reduced cued conditioned fear. The non-cued baseline startle response, which may reflect contextual anxiety, was only significantly reduced by benzodiazepines and 5-HT1A antagonists. No associations were found between drug effects and methodological characteristics, except for strain. CONCLUSIONS The fear-potentiated startle test appears to have moderate to high predictive validity and may serve as a valuable tool for the development of novel anxiolytics. Given the limited available data, the generally low study quality and high heterogeneity additional studies are warranted to corroborate the findings of this review.
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Affiliation(s)
- Lucianne Groenink
- Division of Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Universiteitsweg 99, 3584 CG, Utrecht, The Netherlands.
| | - P Monika Verdouw
- Division of Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Universiteitsweg 99, 3584 CG, Utrecht, The Netherlands
| | - Yulong Zhao
- Division of Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Universiteitsweg 99, 3584 CG, Utrecht, The Netherlands
| | - Freija Ter Heegde
- Division of Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Universiteitsweg 99, 3584 CG, Utrecht, The Netherlands
| | - Kimberley E Wever
- Department of Anaesthesiology, Pain and Palliative Medicine, Radboud Institute for Health Sciences, Radboud University Medical Center, Geert Grooteplein 10, 6525 GA, Nijmegen, The Netherlands
| | - Elisabeth Y Bijlsma
- Division of Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Universiteitsweg 99, 3584 CG, Utrecht, The Netherlands
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Heesbeen EJ, Bijlsma EY, Verdouw PM, van Lissa C, Hooijmans C, Groenink L. The effect of SSRIs on fear learning: a systematic review and meta-analysis. Psychopharmacology (Berl) 2023; 240:2335-2359. [PMID: 36847831 PMCID: PMC10593621 DOI: 10.1007/s00213-023-06333-7] [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] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Accepted: 01/31/2023] [Indexed: 03/01/2023]
Abstract
RATIONALE Selective serotonin reuptake inhibitors (SSRIs) are considered first-line medication for anxiety-like disorders such as panic disorder, generalized anxiety disorder, and post-traumatic stress disorder. Fear learning plays an important role in the development and treatment of these disorders. Yet, the effect of SSRIs on fear learning are not well known. OBJECTIVE We aimed to systematically review the effect of six clinically effective SSRIs on acquisition, expression, and extinction of cued and contextual conditioned fear. METHODS We searched the Medline and Embase databases, which yielded 128 articles that met the inclusion criteria and reported on 9 human and 275 animal experiments. RESULTS Meta-analysis showed that SSRIs significantly reduced contextual fear expression and facilitated extinction learning to cue. Bayesian-regularized meta-regression further suggested that chronic treatment exerts a stronger anxiolytic effect on cued fear expression than acute treatment. Type of SSRI, species, disease-induction model, and type of anxiety test used did not seem to moderate the effect of SSRIs. The number of studies was relatively small, the level of heterogeneity was high, and publication bias has likely occurred which may have resulted in an overestimation of the overall effect sizes. CONCLUSIONS This review suggests that the efficacy of SSRIs may be related to their effects on contextual fear expression and extinction to cue, rather than fear acquisition. However, these effects of SSRIs may be due to a more general inhibition of fear-related emotions. Therefore, additional meta-analyses on the effects of SSRIs on unconditioned fear responses may provide further insight into the actions of SSRIs.
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Affiliation(s)
- Elise J Heesbeen
- Division of Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, Netherlands
| | - Elisabeth Y Bijlsma
- Division of Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, Netherlands
| | - P Monika Verdouw
- Division of Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, Netherlands
| | - Caspar van Lissa
- Department of Methodology, Tilburg University, Tilburg, Netherlands
| | - Carlijn Hooijmans
- Department of Anaesthesiology, Pain and Palliative Care, Radboud University Medical Center, Nijmegen, Netherlands
| | - Lucianne Groenink
- Division of Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, Netherlands.
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Zhao Y, Bijlsma EY, Verdouw PM, Garssen J, Groenink L. The contribution of contextual fear in the anxiolytic effect of chlordiazepoxide in the fear-potentiated startle test. Behav Brain Res 2018; 353:57-61. [PMID: 29969605 DOI: 10.1016/j.bbr.2018.06.035] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [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: 05/14/2018] [Revised: 06/28/2018] [Accepted: 06/29/2018] [Indexed: 10/28/2022]
Abstract
This study evaluated the extent to which a reduction in contextual fear contributes to the anxiolytic effect of benzodiazepines in the fear-potentiated startle response. To this end, chlordiazepoxide, an anxiolytic often used as positive control in preclinical drug studies, and zolpidem, known to have sedative properties and to be devoid of anxiolytic effects, were tested in two contexts: the same context as training had taken place and an alternative context. In addition, the level of muscle relaxation was assessed in a grip strength test. Chlordiazepoxide (2.5-10 mg/kg) decreased the fear-potentiated startle response, confirming its anxiolytic activity. In addition, it dose-dependently decreased the overall startle response in the same, but not the alternative context, and did not affect grip strength, indicating that chlordiazepoxide inhibits contextual fear in the absence of non-specific drug effects. Zolpidem (1.0-10 mg/kg) reduced the overall startle response in both contexts equally and decreased grip strength, indicating that its effects on fear-potentiated startle are due to non-specific drug effects, and not anxiolytic effects. The present findings show that chlordiazepoxide reduces contextual conditioned fear in the absence of non-specific drug effects. In addition, they show that training and testing rats in different contexts makes it possible to distinguish between cued, contextual and non-specific drug effects. As exaggerated contextual fear conditioning contributes to the fear generalization processes implicated in pathological anxiety, focus in screening of anxiolytic effects could be directed more towards the suppression of contextual fear and, therefore, this approach would be a valuable addition to standard preclinical screening.
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Affiliation(s)
- Yulong Zhao
- Division of Pharmacology, Utrecht Institute for Pharmaceutical Sciences (UIPS), Utrecht University, Universiteitsweg 99, 3584 CG, Utrecht, Netherlands
| | - Elisabeth Y Bijlsma
- Division of Pharmacology, Utrecht Institute for Pharmaceutical Sciences (UIPS), Utrecht University, Universiteitsweg 99, 3584 CG, Utrecht, Netherlands.
| | - P Monika Verdouw
- Division of Pharmacology, Utrecht Institute for Pharmaceutical Sciences (UIPS), Utrecht University, Universiteitsweg 99, 3584 CG, Utrecht, Netherlands
| | - Johan Garssen
- Division of Pharmacology, Utrecht Institute for Pharmaceutical Sciences (UIPS), Utrecht University, Universiteitsweg 99, 3584 CG, Utrecht, Netherlands
| | - Lucianne Groenink
- Division of Pharmacology, Utrecht Institute for Pharmaceutical Sciences (UIPS), Utrecht University, Universiteitsweg 99, 3584 CG, Utrecht, Netherlands
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Verdouw PM, van Esterik JC, Peeters BW, Millan MJ, Groenink L. CRF1 but not glucocorticoid receptor antagonists reduce separation-induced distress vocalizations in guinea pig pups and CRF overexpressing mouse pups. A combination study with paroxetine. Pharmacol Biochem Behav 2017; 154:11-19. [DOI: 10.1016/j.pbb.2017.01.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/27/2016] [Revised: 01/05/2017] [Accepted: 01/09/2017] [Indexed: 01/04/2023]
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Abstract
Described in this unit is the ultrasonic distress vocalization test in rat pups. This test is a reliable method for detecting anxiolytic properties of test compounds. In this test, ultrasonic vocalizations (30 to 50 kHz) are elicited by separating rat pups of 9 to 11 days of age from their mother and littermates for a brief period of time. The test can be performed under two different stress conditions. Pups are placed in isolation in either a warm (37°C) or cold (18°C) environment for 5 min. The total number and duration of ultrasonic calls emitted by the pups during this period is used as an index of anxiety. Established anxiolytic compounds, including benzodiazepines, serotonin(1A) receptor agonists, and selective serotonin reuptake inhibitors (SSRIs), consistently reduce the number and cumulative duration of these ultrasonic distress vocalizations.
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Affiliation(s)
- Lucianne Groenink
- Psychopharmacology, Department of Pharmaceutical Sciences, Utrecht Institute for Pharmaceutical Sciences and Rudolf Magnus Institute of Neuroscience, Utrecht, The Netherlands
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Veening JG, Böcker KBE, Verdouw PM, Olivier B, De Jongh R, Groenink L. Activation of the septohippocampal system differentiates anxiety from fear in startle paradigms. Neuroscience 2009; 163:1046-60. [PMID: 19580851 DOI: 10.1016/j.neuroscience.2009.06.064] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2008] [Revised: 06/26/2009] [Accepted: 07/29/2009] [Indexed: 12/18/2022]
Abstract
It has been suggested that different brain areas are involved in the modulation and expression of fear and anxiety. In the present study we investigated these potential differences by using the fear-potentiated-startle (FPS) and light-enhanced-startle (LES) paradigms to differentiate between fear and anxiety, respectively. Male Wistar rats were tested in the FPS and LES paradigm and perfused 1 h after the test session. Fos immunoreactivity (IR) was quantified in 21 brain areas and compared between FPS, LES and four control conditions. Both FPS and LES procedures significantly enhanced the acoustic startle response. A principal component analysis of Fos-IR-data showed that 70% of the changes in Fos-IR could be explained by three independent components: an arousal-component, identifying brain areas known to be activated under conditions of vigilance, arousal and stress, a LES- and an FPS-component. The LES component comprised the septohippocampal system and functionally interrelated areas including nucleus accumbens, anterior cingulate cortex, lateral habenula and supramammillary areas, but not the dorsolateral part of the bed nucleus of the stria terminalis. The central amygdaloid nucleus and the dorsolateral part of the bed nucleus of the stria terminalis loaded exclusively on the FPS component. Analysis of the separate brain areas revealed significantly higher Fos-IR in LES relative to FPS in the anterior cingulate cortex, nucleus accumbens shell, lateral septum, lateral habenula and area postrema. We conclude that the neural circuitry activated during FPS and LES shows clear differences. In anxiety as induced by LES, activation of the septohippocampal system and related areas seems to play a major role. In fear as induced by FPS, the central amygdaloid nucleus and the dorsolateral part of the bed nucleus of the stria terminalis loaded on the same component, but Fos-IR observed in these brain regions did not differentiate between anxiety and fear. Furthermore, principal-component analysis appears a useful tool in detecting and describing correlated changes in patterns of neuronal activity.
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Affiliation(s)
- J G Veening
- Department of Anatomy, 109 UMC St Radboud, University of Nijmegen, Geert Grooteplein N 21, Nijmegen, The Netherlands.
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Groenink L, Dirks A, Verdouw PM, de Graaff M, Peeters BW, Millan MJ, Olivier B. CRF1 not glucocorticoid receptors mediate prepulse inhibition deficits in mice overexpressing CRF. Biol Psychiatry 2008; 63:360-8. [PMID: 17716630 DOI: 10.1016/j.biopsych.2007.06.002] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/23/2007] [Revised: 05/29/2007] [Accepted: 06/04/2007] [Indexed: 10/22/2022]
Abstract
BACKGROUND Both corticotropin-releasing factor (CRF) and glucocorticoid receptors (GR) are implicated in the psychotic symptoms of psychiatric disorders. Correspondingly, it is of interest to determine their respective involvement in the sensorimotor gating deficits displayed by transgenic mice overexpressing CRF. These mice reveal lifelong elevations of CRF and corticosterone levels. METHODS Effects of the GR antagonists ORG34517 (5-45 mg/kg by mouth [PO]) and mifepristone (5-45 mg/kg PO) and the CRF(1) receptor antagonists CP154,526 (20-80 mg/kg intraperitoneally [IP]) and DMP695 (2.5-40.0 mg/kg IP) on prepulse inhibition (PPI) of the acoustic startle response were studied in mice overexpressing CRF and in their wild-type littermates. In addition, PPI was measured in both genotypes 2 weeks after adrenalectomy with or without exogenous corticosterone administration via subcutaneous pellet implant (20 mg corticosterone). RESULTS ORG34517 and mifepristone did not influence perturbation of PPI in mice overexpressing CRF; reducing corticosterone levels by adrenalectomy likewise did not improve PPI. Further, elevation in corticosterone levels by pellet implantation did not disrupt PPI in wild-type mice. Conversely, both CRF(1) receptor antagonists, CP154,526 (40-80 mg/kg IP) and DMP695 (40 mg/kg IP), significantly restored PPI in CRF-overexpressing mice. CONCLUSIONS Sustained overactivation of CRF(1) receptors rather than excessive GR receptor stimulation underlies impaired sensorimotor gating in CRF-overexpressing mice. CRF(1) receptors thus may play a role in the expression of psychotic features in stress-related psychiatric disorders.
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Affiliation(s)
- Lucianne Groenink
- Psychopharmacology, Department of Pharmaceutical Sciences, Rudolf Magnus Institute of Neuroscience and Utrecht Institute of Pharmaceutical Sciences, Utrecht, the Netherlands.
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Dirks A, Groenink L, Westphal KGC, Olivier JDA, Verdouw PM, van der Gugten J, Geyer MA, Olivier B. Reversal of startle gating deficits in transgenic mice overexpressing corticotropin-releasing factor by antipsychotic drugs. Neuropsychopharmacology 2003; 28:1790-8. [PMID: 12865891 DOI: 10.1038/sj.npp.1300256] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Chronically elevated levels of corticotropin-releasing factor (CRF) in transgenic mice overexpressing CRF in the brain (CRF-OE) appear to be associated with alterations commonly associated with major depressive disorder, as well as with sensorimotor gating deficits commonly associated with schizophrenia. In the present study, we tested the hypothesis that antipsychotics may be effective in normalizing prepulse inhibition (PPI) of acoustic startle in CRF-OE mice, which display impaired sensorimotor gating compared to wild-type (WT) mice. The typical antipsychotic haloperidol and atypical antipsychotic risperidone improved PPI in the CRF-OE mice, but were ineffective in WT mice. The atypical antipsychotic clozapine did not influence PPI in CRF-OE mice, but reduced gating in WT mice. This effect of clozapine in the CRF-OE mice may thus be regarded as a relative improvement, consistent with the observed effect of haloperidol and risperidone. As expected, the anxiolytic, nonantipsychotic chlordiazepoxide was devoid of any effect. All four compounds dose-dependently reduced the acoustic startle response irrespective of genotype. These results indicate that antipsychotic drugs are effective in improving startle gating deficits in the CRF-OE mice. Hence, the CRF-OE mouse model may represent an animal model for certain aspects of psychotic depression, and could be a valuable tool for research addressing the impact of chronically elevated levels of CRF on information processing.
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MESH Headings
- Acoustic Stimulation
- Animals
- Antipsychotic Agents/pharmacology
- Behavior, Animal
- Body Weight/drug effects
- Corticotropin-Releasing Hormone/biosynthesis
- Corticotropin-Releasing Hormone/genetics
- Depression
- Disease Models, Animal
- Dose-Response Relationship, Drug
- Inhibition, Psychological
- Male
- Mice
- Mice, Inbred Strains
- Mice, Transgenic
- Reflex, Acoustic/drug effects
- Reflex, Startle/drug effects
- Reflex, Startle/physiology
- Stimulation, Chemical
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Affiliation(s)
- Anneloes Dirks
- Department of Psychopharmacology, Utrecht Institute of Pharmaceutical Sciences, Utrecht University, Utrecht, The Netherlands.
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Groenink L, Dirks A, Verdouw PM, Schipholt ML, Veening JG, van der Gugten J, Olivier B. HPA axis dysregulation in mice overexpressing corticotropin releasing hormone. Biol Psychiatry 2002; 51:875-81. [PMID: 12022960 DOI: 10.1016/s0006-3223(02)01334-3] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
BACKGROUND Hypersecretion of corticotropin-releasing hormone (CRH) in the brain has been implicated in stress-related human pathologies. We developed a transgenic mouse line overexpressing CRH (CRH-OE) exclusively in neural tissues to assess the effect of long-term CRH overproduction on regulation of the hypothalamic-pituitary-adrenal (HPA) axis. METHODS Male transgenic CRH-OE(2122) mice on a C57BL/6J background were used. Littermate wildtype mice served as control animals. Basal plasma corticotropin and corticosterone concentrations were measured, and adrenal gland weight was determined. A dexamethasone suppression test measured the effects of long-term CRH hypersecretion on negative feedback control. Additionally, we measured plasma corticosterone concentrations in reaction to stress. RESULTS CRH-OE(2122) mice showed elevated basal plasma corticosterone concentrations, hypertrophy of the adrenal gland, and dexamethasone nonsuppression. Basal plasma ACTH concentrations of wildtype and CRH-OE(2122) mice did not differ significantly. In reaction to stress, CRH-OE(2122) mice showed a normal corticosterone response. CONCLUSIONS The HPA axis abnormalities observed in CRH-OE(2122) mice suggest that long-term hypersecretion of CRH in the brain can be a main cause of HPA axis dysregulation. The alterations in HPA axis regulation are reminiscent of changes reported in major depressive disorder. As such, these CRH -OE(2122) mice may model the neuroendocrine changes observed in major depressive disorder.
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Affiliation(s)
- Lucianne Groenink
- Department of Psychopharmacology, Utrecht University, Utrecht, The Netherlands
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Groenink L, Van der Gugten J, Verdouw PM, Maes RA, Olivier B. The anxiolytic effects of flesinoxan, a 5-HT1A receptor agonist, are not related to its neuroendocrine effects. Eur J Pharmacol 1995; 280:185-93. [PMID: 7589185 DOI: 10.1016/0014-2999(95)00209-4] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [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: 01/26/2023]
Abstract
The effects of flesinoxan, a selective 5-HT1A receptor agonist, were studied under basal non-stress conditions and in the shock-probe burying paradigm. Flesinoxan (1 and 3 mg/kg s.c.) significantly reduced burying and freezing behaviour, indicating clear anxiolytic properties. Under non-stress conditions, injection of 3 mg/kg flesinoxan significantly enhanced plasma corticosterone and glucose levels, whereas prolactin secretion was significantly enhanced after both 1 mg/kg and 3 mg/kg flesinoxan. Flesinoxan (1 and 3 mg/kg) did not suppress shock-probe stress-induced rises in plasma corticosterone and glucose levels. The enhanced plasma prolactin levels induced by flesinoxan were not further affected by shock-probe exposure. Our data show that the anxiolytic effects of flesinoxan in the shock-probe burying paradigm are not related to increases in plasma corticosterone and glucose levels.
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Affiliation(s)
- L Groenink
- Department of Psychopharmacology, Faculty of Pharmacy, Rudolf Magnus Institute for Neurosciences, Utrecht University, Netherlands
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