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Zwanzger P, Singewald N, Bandelow B. [Pharmacotherapy of anxiety disorders-Guideline-conform treatment and new developments]. Nervenarzt 2021; 92:433-440. [PMID: 33502576 DOI: 10.1007/s00115-020-01051-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 12/11/2020] [Indexed: 01/07/2023]
Abstract
Besides cognitive behavioral therapy (CBT), psychopharmacotherapy belongs to the first-line treatment approaches for anxiety disorders according to all national and international guidelines. According to studies and meta-analyses, modern antidepressants in particular have been proven to be effective. Depending on the substance, there are approvals for panic disorder, generalized anxiety disorder and social phobia. There are also approvals for other substance groups, e.g. anticonvulsants for generalized anxiety disorder. Benzodiazepines should be used with caution in view of the risk of dependency. Although effective and well-tolerated medications are available, up to 30% of patients still do not respond or do not respond adequately to treatment. Consequently, research efforts to develop new substances are important. Based on a better understanding of the complex neurobiological mechanisms underlying anxiety disorders, a large number of substances are currently undergoing clinical trials. Modulators of current and new transmitter systems, in particular the glutamatergic and the endocannabinoid systems as well as neuropeptides, are being discussed as innovative substances. Strategies are also being investigated which, in combination with psychotherapy, aim at optimizing fear extinction memory. First studies are also underway on the use of psychedelic agents in combination with psychotherapy for anxiety.
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Affiliation(s)
- P Zwanzger
- Fachbereich Psychosomatische Medizin, Kompetenzschwerpunkt Angst, kbo-Inn-Salzach-Klinikum, Gabersee 7, 83512, Wasserburg am Inn, Deutschland. .,Klinik für Psychiatrie und Psychotherapie, Ludwig-Maximilians-Universität München, München, Deutschland.
| | - N Singewald
- Center for Molecular Biosciences Innsbruck (CMBI), Department of Pharmacology and Toxicology, Institute of Pharmacy, Leopold-Franzens-Universität Innsbruck, Innsbruck, Österreich
| | - B Bandelow
- Klinik für Psychiatrie und Psychotherapie, Universitätsmedizin Göttingen, Göttingen, Deutschland
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Pierre A, Regin Y, Van Schuerbeek A, Fritz EM, Muylle K, Beckers T, Smolders IJ, Singewald N, De Bundel D. Effects of disrupted ghrelin receptor function on fear processing, anxiety and saccharin preference in mice. Psychoneuroendocrinology 2019; 110:104430. [PMID: 31542636 DOI: 10.1016/j.psyneuen.2019.104430] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Revised: 08/26/2019] [Accepted: 09/03/2019] [Indexed: 02/07/2023]
Abstract
BACKGROUND Obesity is a risk factor for stress-related mental disorders such as post-traumatic stress disorder. The underlying mechanism through which obesity affects mental health remains poorly understood but dysregulation of the ghrelin system may be involved. Stress increases plasma ghrelin levels, which stimulates food intake as a potential stress-coping mechanism. However, diet-induced obesity induces ghrelin resistance which in turn may have deleterious effects on stress-coping. In our study, we explored whether disruption of ghrelin receptor function though high-fat diet or genetic ablation affects fear processing, anxiety-like behavior and saccharin preference in mice. METHODS Adult male C57BL6/J mice were placed on a standard diet or high-fat diet for a total period of 8 weeks. We first established that high-fat diet exposure for 4 weeks elicits ghrelin resistance, evidenced by a blunted hyperphagic response following administration of a ghrelin receptor agonist. We then carried out an experiment in which we subjected mice to auditory fear conditioning after 4 weeks of diet exposure and evaluated effects on fear extinction, anxiety-like behavior and saccharin preference. To explore whether fear conditioning as such may influence the effect of diet exposure, we also subjected mice to auditory fear conditioning prior to diet onset and 4 weeks later we investigated auditory fear extinction, anxiety-like behavior and saccharin preference. In a final experiment, we further assessed lack of ghrelin receptor function by investigating auditory fear processing, anxiety-like behavior and saccharin preference in ghrelin receptor knockout mice and their wild-type littermates. RESULTS High-fat diet exposure had no significant effect on auditory fear conditioning and its subsequent extinction or on anxiety-like behavior but significantly lowered saccharin preference. Similarly, ghrelin receptor knockout mice did not differ significantly from their wild-type littermates for auditory fear processing or anxiety-like behavior but showed significantly lower saccharin preference compared to wild-type littermates. CONCLUSION Taken together, our data suggest that disruption of ghrelin receptor function per se does not affect fear or anxiety-like behavior but may decrease saccharin preference in mice.
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Affiliation(s)
- A Pierre
- Department of Pharmaceutical Sciences, Research Group Experimental Pharmacology, Center for Neurosciences (C4N), Vrije Universiteit Brussel, Laarbeeklaan 103, 1090 Brussels, Belgium
| | - Y Regin
- Department of Pharmaceutical Sciences, Research Group Experimental Pharmacology, Center for Neurosciences (C4N), Vrije Universiteit Brussel, Laarbeeklaan 103, 1090 Brussels, Belgium
| | - A Van Schuerbeek
- Department of Pharmaceutical Sciences, Research Group Experimental Pharmacology, Center for Neurosciences (C4N), Vrije Universiteit Brussel, Laarbeeklaan 103, 1090 Brussels, Belgium
| | - E M Fritz
- Department of Pharmacology and Toxicology, Institute of Pharmacy and CMBI, University of Innsbruck, Innrain 80/82, Innsbruck, Austria
| | - K Muylle
- Department of Pharmaceutical Sciences, Research Group Experimental Pharmacology, Center for Neurosciences (C4N), Vrije Universiteit Brussel, Laarbeeklaan 103, 1090 Brussels, Belgium
| | - T Beckers
- Departement of Psychology and Leuven Brain Institute, KU Leuven, Tiensestraat 102 box 3712, 3000, Leuven, Belgium
| | - I J Smolders
- Department of Pharmaceutical Sciences, Research Group Experimental Pharmacology, Center for Neurosciences (C4N), Vrije Universiteit Brussel, Laarbeeklaan 103, 1090 Brussels, Belgium
| | - N Singewald
- Department of Pharmacology and Toxicology, Institute of Pharmacy and CMBI, University of Innsbruck, Innrain 80/82, Innsbruck, Austria
| | - D De Bundel
- Department of Pharmaceutical Sciences, Research Group Experimental Pharmacology, Center for Neurosciences (C4N), Vrije Universiteit Brussel, Laarbeeklaan 103, 1090 Brussels, Belgium.
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Fritz EM, Kreuzer M, Singewald N, Fenzl T. Fundamental sleep architecture in mice holds the potential to predict high-fear phenotype after fear conditioning. Sleep Med 2019. [DOI: 10.1016/j.sleep.2019.11.307] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Murphy CP, Singewald N. Potential of microRNAs as novel targets in the alleviation of pathological fear. Genes, Brain and Behavior 2017; 17:e12427. [DOI: 10.1111/gbb.12427] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Revised: 09/20/2017] [Accepted: 10/05/2017] [Indexed: 12/16/2022]
Affiliation(s)
- C. P. Murphy
- Department of Pharmacology and Toxicology, Institute of Pharmacy, Center for Molecular Biosciences Innsbruck; University of Innsbruck; Innsbruck Austria
| | - N. Singewald
- Department of Pharmacology and Toxicology, Institute of Pharmacy, Center for Molecular Biosciences Innsbruck; University of Innsbruck; Innsbruck Austria
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Sosulina L, Strippel C, Romo-Parra H, Walter AL, Kanyshkova T, Sartori SB, Lange MD, Singewald N, Pape HC. Substance P excites GABAergic neurons in the mouse central amygdala through neurokinin 1 receptor activation. J Neurophysiol 2015; 114:2500-8. [PMID: 26334021 DOI: 10.1152/jn.00883.2014] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [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: 11/07/2014] [Accepted: 08/19/2015] [Indexed: 11/22/2022] Open
Abstract
Substance P (SP) is implicated in stress regulation and affective and anxiety-related behavior. Particularly high expression has been found in the main output region of the amygdala complex, the central amygdala (CE). Here we investigated the cellular mechanisms of SP in CE in vitro, taking advantage of glutamic acid decarboxylase-green fluorescent protein (GAD67-GFP) knockin mice that yield a reliable labeling of GABAergic neurons, which comprise 95% of the neuronal population in the lateral section of CE (CEl). In GFP-positive neurons within CEl, SP caused a membrane depolarization and increase in input resistance, associated with an increase in action potential firing frequency. Under voltage-clamp conditions, the SP-specific membrane current reversed at -101.5 ± 2.8 mV and displayed inwardly rectifying properties indicative of a membrane K(+) conductance. Moreover, SP responses were blocked by the neurokinin type 1 receptor (NK1R) antagonist L-822429 and mimicked by the NK1R agonist [Sar(9),Met(O2)(11)]-SP. Immunofluorescence staining confirmed localization of NK1R in GFP-positive neurons in CEl, predominantly in PKCδ-negative neurons (80%) and in few PKCδ-positive neurons (17%). Differences in SP responses were not observed between the major types of CEl neurons (late firing, regular spiking, low-threshold bursting). In addition, SP increased the frequency and amplitude of GABAergic synaptic events in CEl neurons depending on upstream spike activity. These data indicate a NK1R-mediated increase in excitability and GABAergic activity in CEl neurons, which seems to mostly involve the PKCδ-negative subpopulation. This influence can be assumed to increase reciprocal interactions between CElon and CEloff pathways, thereby boosting the medial CE (CEm) output pathway and contributing to the anxiogenic-like action of SP in the amygdala.
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Affiliation(s)
- L Sosulina
- Institute of Physiology I, Westfälische Wilhelms-Universität Münster, Münster, Germany; Neuronal Networks Group, Deutsches Zentrum für Neurodegenerative Erkrankungen (DZNE), Bonn, Germany
| | - C Strippel
- Institute of Physiology I, Westfälische Wilhelms-Universität Münster, Münster, Germany
| | - H Romo-Parra
- Institute of Physiology I, Westfälische Wilhelms-Universität Münster, Münster, Germany
| | - A L Walter
- Institute of Physiology I, Westfälische Wilhelms-Universität Münster, Münster, Germany
| | - T Kanyshkova
- Institute of Physiology I, Westfälische Wilhelms-Universität Münster, Münster, Germany
| | - S B Sartori
- Department of Pharmacology and Toxicology, Institute of Pharmacy, and Centre for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Insbruck, Austria; and
| | - M D Lange
- Institute of Physiology I, Westfälische Wilhelms-Universität Münster, Münster, Germany
| | - N Singewald
- Department of Pharmacology and Toxicology, Institute of Pharmacy, and Centre for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Insbruck, Austria; and
| | - H-C Pape
- Institute of Physiology I, Westfälische Wilhelms-Universität Münster, Münster, Germany;
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Fitzgerald PJ, Pinard CR, Camp MC, Feyder M, Sah A, Bergstrom HC, Graybeal C, Liu Y, Schlüter OM, Grant SGN, Singewald N, Xu W, Holmes A. Durable fear memories require PSD-95. Mol Psychiatry 2015; 20:913. [PMID: 25824301 DOI: 10.1038/mp.2015.44] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Singewald N, Schmuckermair C, Whittle N, Holmes A, Ressler KJ. Pharmacology of cognitive enhancers for exposure-based therapy of fear, anxiety and trauma-related disorders. Pharmacol Ther 2014; 149:150-90. [PMID: 25550231 PMCID: PMC4380664 DOI: 10.1016/j.pharmthera.2014.12.004] [Citation(s) in RCA: 269] [Impact Index Per Article: 26.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2014] [Accepted: 12/24/2014] [Indexed: 12/20/2022]
Abstract
Pathological fear and anxiety are highly debilitating and, despite considerable advances in psychotherapy and pharmacotherapy they remain insufficiently treated in many patients with PTSD, phobias, panic and other anxiety disorders. Increasing preclinical and clinical evidence indicates that pharmacological treatments including cognitive enhancers, when given as adjuncts to psychotherapeutic approaches [cognitive behavioral therapy including extinction-based exposure therapy] enhance treatment efficacy, while using anxiolytics such as benzodiazepines as adjuncts can undermine long-term treatment success. The purpose of this review is to outline the literature showing how pharmacological interventions targeting neurotransmitter systems including serotonin, dopamine, noradrenaline, histamine, glutamate, GABA, cannabinoids, neuropeptides (oxytocin, neuropeptides Y and S, opioids) and other targets (neurotrophins BDNF and FGF2, glucocorticoids, L-type-calcium channels, epigenetic modifications) as well as their downstream signaling pathways, can augment fear extinction and strengthen extinction memory persistently in preclinical models. Particularly promising approaches are discussed in regard to their effects on specific aspects of fear extinction namely, acquisition, consolidation and retrieval, including long-term protection from return of fear (relapse) phenomena like spontaneous recovery, reinstatement and renewal of fear. We also highlight the promising translational value of the preclinial research and the clinical potential of targeting certain neurochemical systems with, for example d-cycloserine, yohimbine, cortisol, and L-DOPA. The current body of research reveals important new insights into the neurobiology and neurochemistry of fear extinction and holds significant promise for pharmacologically-augmented psychotherapy as an improved approach to treat trauma and anxiety-related disorders in a more efficient and persistent way promoting enhanced symptom remission and recovery.
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Affiliation(s)
- N Singewald
- Department of Pharmacology and Toxicology, Institute of Pharmacy and CMBI, Leopold-Franzens University of Innsbruck, Innrain 80-82, A-6020 Innsbruck, Austria.
| | - C Schmuckermair
- Department of Pharmacology and Toxicology, Institute of Pharmacy and CMBI, Leopold-Franzens University of Innsbruck, Innrain 80-82, A-6020 Innsbruck, Austria
| | - N Whittle
- Department of Pharmacology and Toxicology, Institute of Pharmacy and CMBI, Leopold-Franzens University of Innsbruck, Innrain 80-82, A-6020 Innsbruck, Austria
| | - A Holmes
- Laboratory of Behavioral and Genomic Neuroscience, National Institute on Alcohol Abuse and Alcoholism, NIH, Bethesda, MD, USA
| | - K J Ressler
- Department of Psychiatry and Behavioral Sciences, Emory University School of Medicine, Atlanta, GA, USA
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8
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Sotnikov SV, Markt PO, Malik V, Chekmareva NY, Naik RR, Sah A, Singewald N, Holsboer F, Czibere L, Landgraf R. Bidirectional rescue of extreme genetic predispositions to anxiety: impact of CRH receptor 1 as epigenetic plasticity gene in the amygdala. Transl Psychiatry 2014; 4:e359. [PMID: 24518397 PMCID: PMC3944631 DOI: 10.1038/tp.2013.127] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2013] [Accepted: 12/07/2013] [Indexed: 12/05/2022] Open
Abstract
The continuum of physiological anxiety up to psychopathology is not merely dependent on genes, but is orchestrated by the interplay of genetic predisposition, gene x environment and epigenetic interactions. Accordingly, inborn anxiety is considered a polygenic, multifactorial trait, likely to be shaped by environmentally driven plasticity at the genomic level. We here took advantage of the extreme genetic predisposition of the selectively bred high (HAB) and low anxiety (LAB) mouse model exhibiting high vs low anxiety-related behavior and tested whether and how beneficial (enriched environment) vs detrimental (chronic mild stress) environmental manipulations are capable of rescuing phenotypes from both ends of the anxiety continuum. We provide evidence that (i) even inborn and seemingly rigid behavioral and neuroendocrine phenotypes can bidirectionally be rescued by appropriate environmental stimuli, (ii) corticotropin-releasing hormone receptor 1 (Crhr1), critically involved in trait anxiety, shows bidirectional alterations in its expression in the basolateral amygdala (BLA) upon environmental stimulation, (iii) these alterations are linked to an increased methylation status of its promoter and, finally, (iv) binding of the transcription factor Yin Yang 1 (YY1) to the Crhr1 promoter contributes to its gene expression in a methylation-sensitive manner. Thus, Crhr1 in the BLA is critically involved as plasticity gene in the bidirectional epigenetic rescue of extremes in trait anxiety.
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Affiliation(s)
- S V Sotnikov
- Behavioral Neuroendocrinology, Max Planck Institute of Psychiatry, Munich, Germany,Department of Normal Physiology, Sechenov First Moscow State Medical University, Moscow, Russia,Behavioral Neuroendocrinology, Max Planck Institute of Psychiatry, Kraepelinstr. 2, 80804 Munich, Germany. E-mail: or
| | - P O Markt
- Behavioral Neuroendocrinology, Max Planck Institute of Psychiatry, Munich, Germany,Behavioral Neuroendocrinology, Max Planck Institute of Psychiatry, Kraepelinstr. 2, 80804 Munich, Germany. E-mail: or
| | - V Malik
- Behavioral Neuroendocrinology, Max Planck Institute of Psychiatry, Munich, Germany
| | - N Y Chekmareva
- Department of Normal Physiology, Sechenov First Moscow State Medical University, Moscow, Russia
| | - R R Naik
- Behavioral Neuroendocrinology, Max Planck Institute of Psychiatry, Munich, Germany
| | - A Sah
- Department of Pharmacology and Toxicology, Institute of Pharmacy and Centre for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck, Austria
| | - N Singewald
- Department of Pharmacology and Toxicology, Institute of Pharmacy and Centre for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck, Austria
| | - F Holsboer
- Behavioral Neuroendocrinology, Max Planck Institute of Psychiatry, Munich, Germany
| | - L Czibere
- Behavioral Neuroendocrinology, Max Planck Institute of Psychiatry, Munich, Germany
| | - R Landgraf
- Behavioral Neuroendocrinology, Max Planck Institute of Psychiatry, Munich, Germany
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Ebner K, Muigg P, Singewald N. Inhibitory function of the dorsomedial hypothalamic nucleus on the hypothalamic-pituitary-adrenal axis response to an emotional stressor but not immune challenge. J Neuroendocrinol 2013; 25:48-55. [PMID: 22861486 PMCID: PMC3549560 DOI: 10.1111/j.1365-2826.2012.02369.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2012] [Revised: 07/24/2012] [Accepted: 07/27/2012] [Indexed: 11/28/2022]
Abstract
Accumulating evidence implicates the dorsomedial hypothalamic nucleus (DMH) in the regulation of autonomic and neuroendocrine stress responses. However, although projections from the DMH to the paraventricular hypothalamic nucleus (PVN), which is the critical site of the neuroendocrine stress axis, have been described, the impact of DMH neurones in the modulation of hypothalamic-pituitary-adrenal (HPA) axis activation during stress is not fully understood. The present study aimed to investigate the role of the DMH in HPA axis responses to different types of stimuli. Male Sprague-Dawley rats fitted with a chronic jugular venous catheter were exposed to either an emotional stressor (elevated platform-exposure) or immune challenge (systemic interleukin-1β administration). Bilateral electrolytic lesions of the DMH disinhibited HPA axis responses to the emotional stressor, as indicated by higher plasma adrenocorticotrophic hormone levels during and after elevated platform exposure in lesioned animals compared to sham-lesioned controls. Moreover, DMH-lesioned animals showed increased neuronal activation in the PVN, as indicated by a higher c-Fos expression after elevated-platform exposure compared to controls. By contrast, DMH-lesions had no effects on HPA axis responses to immune challenge. Taken together, our data suggest an inhibitory role of DMH neurones on stress-induced HPA axis activation that is dependent upon the nature of the stimulus being important in response to an emotional stressor but not to immune challenge.
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Affiliation(s)
- K Ebner
- Department of Pharmacology and Toxicology, Institute of Pharmacy and Center for Molecular Biosciences Innsbruck (CMBI), Leopold-Franzens-University of Innsbruck, Innsbruck, Austria.
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Franklin M, Bermudez I, Hlavacova N, Babic S, Murck H, Schmuckermair C, Singewald N, Gaburro S, Jezova D. Aldosterone increases earlier than corticosterone in new animal models of depression: is this an early marker? J Psychiatr Res 2012; 46:1394-7. [PMID: 22901774 DOI: 10.1016/j.jpsychires.2012.07.010] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2012] [Revised: 07/13/2012] [Accepted: 07/16/2012] [Indexed: 11/26/2022]
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Sah A, Schmuckermair C, Sartori SB, Gaburro S, Kandasamy M, Irschick R, Klimaschewski L, Landgraf R, Aigner L, Singewald N. Anxiety- rather than depression-like behavior is associated with adult neurogenesis in a female mouse model of higher trait anxiety- and comorbid depression-like behavior. Transl Psychiatry 2012; 2:e171. [PMID: 23047242 PMCID: PMC3565824 DOI: 10.1038/tp.2012.94] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Adult neurogenesis has been implicated in affective disorders and the action of antidepressants (ADs) although the functional significance of this association is still unclear. The use of animal models closely mimicking human comorbid affective and anxiety disorders seen in the majority of patients should provide relevant novel information. Here, we used a unique genetic mouse model displaying higher trait anxiety (HAB) and comorbid depression-like behavior. We demonstrate that HABs have a lower rate of hippocampal neurogenesis and impaired functional integration of newly born neurons as compared with their normal anxiety/depression-like behavior (NAB) controls. In HABs, chronic treatment with the AD fluoxetine alleviated their higher depression-like behavior and protected them from relapse for 3 but not 7 weeks after discontinuation of the treatment without affecting neurogenesis. Similar to what has been observed in depressed patients, fluoxetine treatment induced anxiogenic-like effects during the early treatment phase in NABs along with a reduction in neurogenesis. On the other hand, treatment with AD drugs with a particularly strong anxiolytic component, namely the neurokinin-1-receptor-antagonist L-822 429 or tianeptine, increased the reduced rate of neurogenesis in HABs up to NAB levels. In addition, challenge-induced hypoactivation of dentate gyrus (DG) neurons in HABs was normalized by all three drugs. Overall, these data suggest that AD-like effects in a psychopathological mouse model are commonly associated with modulation of DG hypoactivity but not neurogenesis, suggesting normalization of hippocampal hypoactivity as a neurobiological marker indicating successful remission. Finally, rather than to higher depression-related behavior, neurogenesis seems to be linked to pathological anxiety.
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Affiliation(s)
- A Sah
- Department of Pharmacology and Toxicology, Institute of Pharmacy and Centre for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck, Austria,Max-Planck-Institute of Psychiatry, Kraepelinstrasse, Munich,Germany
| | - C Schmuckermair
- Department of Pharmacology and Toxicology, Institute of Pharmacy and Centre for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck, Austria
| | - S B Sartori
- Department of Pharmacology and Toxicology, Institute of Pharmacy and Centre for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck, Austria
| | - S Gaburro
- Department of Pharmacology and Toxicology, Institute of Pharmacy and Centre for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck, Austria
| | - M Kandasamy
- Institut für Molekulare Regenerative Medizin, Paracelsus Medizinische Privatuniversität, Strubergasse, Salzburg, Austria
| | - R Irschick
- Division of Neuroanatomy, Department of Anatomy, Histology and Embryology, Innsbruck, Austria
| | - L Klimaschewski
- Division of Neuroanatomy, Department of Anatomy, Histology and Embryology, Innsbruck, Austria
| | - R Landgraf
- Max-Planck-Institute of Psychiatry, Kraepelinstrasse, Munich,Germany
| | - L Aigner
- Institut für Molekulare Regenerative Medizin, Paracelsus Medizinische Privatuniversität, Strubergasse, Salzburg, Austria,Spinal Cord Injury and Tissue Regeneration Center Salzburg, Paracelsus Medical University, Strubergasse, Salzburg, Austria
| | - N Singewald
- Department of Pharmacology and Toxicology, Institute of Pharmacy and Centre for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck, Austria,Department of Pharmacology and Toxicology, CCB - Center for Chemistry and Biomedicine, University of Innsbruck, Innrain 80/82, 3rd floor, A-6020 Innsbruck, Austria. E-mail:
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Sah A, Markt P, Sotnikov SV, Koehl C, Landgraf R, Singewald N. Adult neurogenesis in a mouse model of affective behavior: pharmacological and non-pharmacological interventions. Pharmacopsychiatry 2011. [DOI: 10.1055/s-0031-1292536] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Sartori SB, Whittle N, Hetzenauer A, Singewald N. Magnesium deficiency induces anxiety and HPA axis dysregulation: modulation by therapeutic drug treatment. Neuropharmacology 2011; 62:304-12. [PMID: 21835188 PMCID: PMC3198864 DOI: 10.1016/j.neuropharm.2011.07.027] [Citation(s) in RCA: 91] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2011] [Revised: 07/16/2011] [Accepted: 07/18/2011] [Indexed: 01/12/2023]
Abstract
Preclinical and some clinical studies suggest a relationship between perturbation in magnesium (Mg2+) homeostasis and pathological anxiety, although the underlying mechanisms remain largely unknown. Since there is evidence that Mg2+ modulates the hypothalamic-pituitary adrenal (HPA) axis, we tested whether enhanced anxiety-like behaviour can be reliably elicited by dietary Mg2+ deficiency and whether Mg2+ deficiency is associated with altered HPA axis function. Compared with controls, Mg2+ deficient mice did indeed display enhanced anxiety-related behaviour in a battery of established anxiety tests. The enhanced anxiety-related behaviour of Mg2+ deficient mice was sensitive to chronic desipramine treatment in the hyponeophagia test and to acute diazepam treatment in the open arm exposure test. Mg2+ deficiency caused an increase in the transcription of the corticotropin releasing hormone in the paraventricular hypothalamic nucleus (PVN), and elevated ACTH plasma levels, pointing to an enhanced set-point of the HPA axis. Chronic treatment with desipramine reversed the identified abnormalities of the stress axis. Functional mapping of neuronal activity using c-Fos revealed hyper-excitability in the PVN of anxious Mg2+ deficient mice and its normalisation through diazepam treatment. Overall, the present findings demonstrate the robustness and validity of the Mg2+ deficiency model as a mouse model of enhanced anxiety, showing sensitivity to treatment with anxiolytics and antidepressants. It is further suggested that dysregulations in the HPA axis may contribute to the hyper-emotionality in response to dietary induced hypomagnesaemia. This article is part of a Special Issue entitled ‘Anxiety and Depression’.
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Affiliation(s)
- S B Sartori
- Department of Pharmacology and Toxicology, Institute of Pharmacy, and Centre for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Peter-Mayr-Strasse 1, A-6020 Innsbruck, Austria.
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Tasan RO, Bukovac A, Peterschmitt YN, Sartori SB, Landgraf R, Singewald N, Sperk G. Altered GABA transmission in a mouse model of increased trait anxiety. Neuroscience 2011; 183:71-80. [PMID: 21458543 PMCID: PMC3092983 DOI: 10.1016/j.neuroscience.2011.03.051] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2011] [Revised: 03/21/2011] [Accepted: 03/24/2011] [Indexed: 12/21/2022]
Abstract
Anxiety disorders are the most prevalent central nervous system diseases imposing a high social burden to our society. Emotional processing is particularly controlled by GABA-ergic transmission in the amygdala. Using in situ hybridization and immunohistochemistry we now investigated changes in the expression of GABA synthesizing enzymes (GAD65 and GAD67), GABAA (α1–5, β1–3, γ1–2) and GABAB receptor subunits (GBBR1, GBBR2) in amygdaloid nuclei of high anxiety-related behavior (HAB) mice in comparison to mice selected for normal anxiety-related behavior (NAB). Levels of GAD65 and GAD67 mRNAs and protein, as well as those of GABA were increased in the amygdala of HAB mice. Relative to NAB controls, mRNA expression of the GABAA receptor subunits β1, β2 and γ2 was specifically increased in the basolateral amygdala of HAB mice while transcription of α5 and γ1 subunits was reduced in the central and medial amygdala. On the protein level, increases in β2 and γ2 subunit immunoreactivities were evident in the basolateral amygdala of HAB mice. No change in GABAB receptor expression was observed. These findings point towards an imbalanced GABA-ergic neurotransmission in the amygdala of HAB mice. On the other hand, FosB, a marker for neuronal activity, was increased in principal neurons of the basolateral amygdala in HAB mice, reflecting activation of excitatory neurons, possibly as a consequence of reduced GABA-ergic tonic inhibition through α5 and γ1 containing receptors. Ultimately these mechanisms may lead to the compensatory activation of GABA transmission, as indicated by the increased expression of GAD65/67 in HAB mice.
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Affiliation(s)
- R O Tasan
- Department of Pharmacology, Medical University Innsbruck, 6020 Innsbruck, Austria.
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15
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Yen YC, Sartori SB, Steiner A, Singewald N, Landgraf R. Pharmacology of neuropeptide S in a mouse model of extremes in anxiety-related behavior. Pharmacopsychiatry 2009. [DOI: 10.1055/s-0029-1240257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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16
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Camp M, Norcross M, Whittle N, Feyder M, D'Hanis W, Yilmazer-Hanke D, Singewald N, Holmes A. Impaired Pavlovian fear extinction is a common phenotype across genetic lineages of the 129 inbred mouse strain. Genes Brain Behav 2009; 8:744-52. [PMID: 19674120 DOI: 10.1111/j.1601-183x.2009.00519.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Fear extinction is impaired in psychiatric disorders such as post-traumatic stress disorder and schizophrenia, which have a major genetic component. However, the genetic factors underlying individual variability in fear extinction remain to be determined. By comparing a panel of inbred mouse strains, we recently identified a strain, 129S1/SvImJ (129S1), that exhibits a profound and selective deficit in Pavlovian fear extinction, and associated abnormalities in functional activation of a key prefrontal-amygdala circuit, as compared with C57BL/6J. The first aim of the present study was to assess fear extinction across multiple 129 substrains representing the strain's four different genetic lineages (parental, steel, teratoma and contaminated). Results showed that 129P1/ReJ, 129P3/J, 129T2/SvEmsJ and 129X1/SvJ exhibited poor fear extinction, relative to C57BL/6J, while 129S1 showed evidence of fear incubation. On the basis of these results, the second aim was to further characterize the nature and specificity of the extinction phenotype in 129S1, as an exemplar of the 129 substrains. Results showed that the extinction deficit in 129S1 was neither the result of a failure to habituate to a sensitized fear response nor an artifact of a fear response to (unconditioned) tone per se. A stronger conditioning protocol (i.e. five x higher intensity shocks) produced an increase in fear expression in 129S1, relative to C57BL/6J, due to rapid rise in freezing during tone presentation. Taken together, these data show that impaired fear extinction is a phenotypic feature common across 129 substrains, and provide preliminary evidence that impaired fear extinction in 129S1 may reflect a pro-fear incubation-like process.
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Affiliation(s)
- M Camp
- Section on Behavioral Science and Genetics, Laboratory for Integrative Neuroscience, National Institute on Alcoholism and Alcohol Abuse, NIH, Bethesda, MD, USA.
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17
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Singewald GM, Nguyen NK, Neumann ID, Singewald N, Reber SO. Effect of chronic psychosocial stress-induced by subordinate colony (CSC) housing on brain neuronal activity patterns in mice. Stress 2009; 12:58-69. [PMID: 19116889 DOI: 10.1080/10253890802042082] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.6] [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: 10/21/2022] Open
Abstract
Chronic subordinate colony (CSC) housing has been recently validated as a murine model of chronic psychosocial stress which induces alterations of stress-related parameters including decreased body-weight gain and an increased level of anxiety in comparison with single housed control (SHC) mice. By using immunohistochemical immediate early gene (IEG) mapping we investigated whether CSC housing causes alterations in neuronal activation patterns in limbic areas including the amygdala, hippocampus, septum and the periaqueductal gray (PAG) and hypothalamic paraventricular nucleus (PVN). While CSC housing increased basal Zif-268 expression in the nucleus accumbens shell compared to SHC, IEG responses to subsequent open arm (OA) exposure were attenuated in the ventral and intermediate sub-regions of the lateral septum, parvocellular PVN and the dorsal CA3 region of the hippocampus of CSC compared with SHC mice. In contrast, a potentiated c-Fos response in CSC mice was observed in the dorsomedial PAG after OA exposure. Confirming previous findings obtained on the elevated plus-maze, an enhanced anxiety-related behavior in CSC compared with SHC mice was also observed during OA exposure. In order to investigate the appropriate control conditions for CSC housing, group housed control (GHC) mice were additionally included in the behavioral testing. Interestingly, GHC as well as CSC mice showed significantly less risk assessment/exploratory behavior during OA exposure compared with SHC mice indicating that group housing itself is stressful for mice and not an adequate control for the CSC paradigm. Overall, CSC housing is an ethologically relevant chronic psychosocial stressor which results in an elevated sensitivity to a subsequent novel, aversive challenge. However, the CSC-induced increase in anxiety-related behavior was accompanied by differences in neuronal activation, compared with SHC, in defined sub-regions of brain areas known to be involved in the processing of emotionality and stress responses.
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Affiliation(s)
- G M Singewald
- Department of Pharmacology and Toxicology, Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Austria.
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18
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Tasan RO, Lin S, Hetzenauer A, Singewald N, Herzog H, Sperk G. Increased novelty-induced motor activity and reduced depression-like behavior in neuropeptide Y (NPY)-Y4 receptor knockout mice. Neuroscience 2008; 158:1717-30. [PMID: 19121371 DOI: 10.1016/j.neuroscience.2008.11.048] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2008] [Revised: 10/29/2008] [Accepted: 11/20/2008] [Indexed: 01/16/2023]
Abstract
There is growing evidence that neuropeptide Y (NPY) acting through Y1 and Y2 receptors has a prominent role in modulating anxiety- and depression-like behavior in rodents. However, a role of other Y-receptors like that of Y4 receptors in this process is poorly understood. We now investigated male Y2, Y4 single and Y2/Y4 double knockout mice in behavioral paradigms for changes in motor activity, anxiety and depression-like behavior. Motor activity was increased in Y2, Y4 and Y2/Y4 knockout mice under changing and stressful conditions, but not altered in a familiar environment. Y4 and Y2 knockout mice revealed an anxiolytic phenotype in the light/dark test, marble burying test and in stress-induced hyperthermia, and reduced depression-like behavior in the forced swim and tail suspension tests. In Y2/Y4 double knockout mice, the response in the light/dark test and in the forced swim test was further enhanced compared with Y4 and Y2 knockout mice, respectively. High levels of Y4 binding sites were observed in brain stem nuclei including nucleus of solitary tract and area postrema. Lower levels were found in the medial amygdala and hypothalamus. Peripheral administration of pancreatic polypeptide (PP) induced Y4 receptor-dependent c-Fos expression in brain stem, hypothalamus and amygdala. PP released peripherally from the pancreas in response to food intake, may act not only as a satiety signal but also modulate anxiety-related locomotion.
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Affiliation(s)
- R O Tasan
- Department of Pharmacology, Medical University Innsbruck, Peter-Mayr-Strasse 1a, A-6020 Innsbruck, Austria.
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19
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Painsipp E, Wultsch T, Edelsbrunner ME, Tasan RO, Singewald N, Herzog H, Holzer P. Reduced anxiety-like and depression-related behavior in neuropeptide Y Y4 receptor knockout mice. Genes Brain Behav 2008; 7:532-42. [PMID: 18221379 DOI: 10.1111/j.1601-183x.2008.00389.x] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Neuropeptide Y (NPY) acting through Y1 receptors reduces anxiety- and depression-like behavior in rodents, whereas Y2 receptor stimulation has the opposite effect. This study addressed the implication of Y4 receptors in emotional behavior by comparing female germ line Y4 knockout (Y4-/-) mice with control and germ line Y2-/- animals. Anxiety- and depression-like behavior was assessed with the open field (OF), elevated plus maze (EPM), stress-induced hyperthermia (SIH) and tail suspension tests (TST), respectively. Learning and memory were evaluated with the object recognition test (ORT). In the OF and EPM, both Y4-/- and Y2-/- mice exhibited reduced anxiety-related behavior and enhanced locomotor activity relative to control animals. Locomotor activity in a familiar environment was unchanged in Y4-/- but reduced in Y2-/- mice. The basal rectal temperature exhibited diurnal and genotype-related alterations. Control mice had temperature minima at noon and midnight, whereas Y4-/- and Y2-/- mice displayed only one temperature minimum at noon. The magnitude of SIH was related to time of the day and genotype in a complex manner. In the TST, the duration of immobility was significantly shorter in Y4-/- and Y2-/- mice than in controls. Object memory 6 h after initial exposure to the ORT was impaired in Y2-/- but not in Y4-/- mice, relative to control mice. These results show that genetic deletion of Y4 receptors, like that of Y2 receptors, reduces anxiety-like and depression-related behavior. Unlike Y2 receptor knockout, Y4 receptor knockout does not impair object memory. We propose that Y4 receptors play an important role in the regulation of behavioral homeostasis.
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Affiliation(s)
- E Painsipp
- Research Unit of Translational Neurogastroenterology, Institute of Experimental and Clinical Pharmacology, Medical University of Graz, Graz, Austria
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20
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Lu A, Steiner MA, Whittle N, Vogl AM, Walser SM, Ableitner M, Refojo D, Ekker M, Rubenstein JL, Stalla GK, Singewald N, Holsboer F, Wotjak CT, Wurst W, Deussing JM. Conditional mouse mutants highlight mechanisms of corticotropin-releasing hormone effects on stress-coping behavior. Mol Psychiatry 2008; 13:1028-42. [PMID: 18475271 DOI: 10.1038/mp.2008.51] [Citation(s) in RCA: 118] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Hypersecretion of central corticotropin-releasing hormone (CRH) has been implicated in the pathophysiology of affective disorders. Both, basic and clinical studies suggested that disrupting CRH signaling through CRH type 1 receptors (CRH-R1) can ameliorate stress-related clinical conditions. To study the effects of CRH-R1 blockade upon CRH-elicited behavioral and neurochemical changes we created different mouse lines overexpressing CRH in distinct spatially restricted patterns. CRH overexpression in the entire central nervous system, but not when overexpressed in specific forebrain regions, resulted in stress-induced hypersecretion of stress hormones and increased active stress-coping behavior reflected by reduced immobility in the forced swim test and tail suspension test. These changes were related to acute effects of overexpressed CRH as they were normalized by CRH-R1 antagonist treatment and recapitulated the effect of stress-induced activation of the endogenous CRH system. Moreover, we identified enhanced noradrenergic activity as potential molecular mechanism underlying increased active stress-coping behavior observed in these animals. Thus, these transgenic mouse lines may serve as animal models for stress-elicited pathologies and treatments that target the central CRH system.
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Affiliation(s)
- A Lu
- Max Planck Institute of Psychiatry, Munich, Germany
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21
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Lu A, Steiner MA, Whittle N, Vogl AM, Walser SM, Ableitner M, Refojo D, Ekker M, Rubenstein JL, Stalla GK, Singewald N, Holsboer F, Wotjak CT, Wurst W, Deussing JM. Conditional CRH overexpressing mice: an animal model for stress-elicited pathologies and treatments that target the central CRH system. Mol Psychiatry 2008; 13:989. [PMID: 18936754 DOI: 10.1038/mp.2008.107] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- A Lu
- Max Planck Institute of Psychiatry, Kraepelinstrasse, Munich, Germany
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22
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Bunck M, Czibere L, Schmidt MV, Rafael J, Muigg P, Panhuysen M, Pütz B, Deussing JM, Singewald N, Holsboer F, Wigger A, Landgraf R. Expressing emotions: Avp and Crh are involved in the phenotype of mice bred for extremes in anxiety-related behavior. Pharmacopsychiatry 2007. [DOI: 10.1055/s-2007-991794] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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23
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Striessnig J, Koschak A, Sinnegger-Brauns MJ, Hetzenauer A, Nguyen NK, Busquet P, Pelster G, Singewald N. Role of voltage-gated L-type Ca2+ channel isoforms for brain function. Biochem Soc Trans 2006; 34:903-9. [PMID: 17052224 DOI: 10.1042/bst0340903] [Citation(s) in RCA: 133] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Voltage-gated LTCCs (L-type Ca2+ channels) are established drug targets for the treatment of cardiovascular diseases. LTCCs are also expressed outside the cardiovascular system. In the brain, LTCCs control synaptic plasticity in neurons, and DHP (dihydropyridine) LTCC blockers such as nifedipine modulate brain function (such as fear memory extinction and depression-like behaviour). Voltage-sensitive Ca2+ channels Cav1.2 and Cav1.3 are the predominant brain LTCCs. As DHPs and other classes of organic LTCC blockers inhibit both isoforms, their pharmacological distinction is impossible and their individual contributions to defined brain functions remain largely unknown. Here, we summarize our recent experiments with two genetically modified mouse strains, which we generated to explore the individual biophysical features of Cav1.2 and Cav1.3 LTCCs and to determine their relative contributions to various physiological peripheral and neuronal functions. The results described here also allow predictions about the pharmacotherapeutic potential of isoform-selective LTCC modulators.
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Affiliation(s)
- J Striessnig
- Department of Pharmacology and Toxicology, Institute for Pharmacy, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Peter-Mayrstr. 1/I, A-6020 Innsbruck, Austria.
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24
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Bruening S, Oh E, Hetzenauer A, Escobar-Alvarez S, Westphalen RI, Hemmings HC, Singewald N, Shippenberg T, Toth M. The anxiety-like phenotype of 5-HT receptor null mice is associated with genetic background-specific perturbations in the prefrontal cortex GABA-glutamate system. J Neurochem 2006; 99:892-9. [PMID: 16925594 DOI: 10.1111/j.1471-4159.2006.04129.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A deficit in the serotonin 5-HT(1A) receptor has been found in panic and post-traumatic stress disorders, and genetic inactivation of the receptor results in an anxiety-like phenotype in mice on both the C57Bl6 and Swiss-Webster genetic backgrounds. Anxiety is associated with increased neuronal activity in the prefrontal cortex and here we describe changes in glutamate and GABA uptake of C57Bl6 receptor null mice. Although these alterations were not present in Swiss-Webster null mice, we have previously reported reductions in GABA(A) receptor expression in these but not in C57Bl6 null mice. This demonstrates that inactivation of the 5-HT(1A) receptor elicits different and genetic background-dependent perturbations in the prefrontal cortex GABA/glutamate system. These perturbations can result in a change in the balance between excitation and inhibition, and indeed both C57Bl6 and Swiss-Webster null mice show signs of increased neuronal excitability. Because neuronal activity in the prefrontal cortex controls the extent of response to anxiogenic stimuli, the genetic background-specific perturbations in glutamate and GABA neurotransmission in C57Bl6 and Swiss-Webster 5-HT(1A) receptor null mice may contribute to their shared anxiety phenotype. Our study shows that multiple strains of genetically altered mice could help us to understand the common and individual features of anxiety.
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MESH Headings
- Animals
- Anxiety/genetics
- Anxiety/psychology
- Behavior, Animal/physiology
- Blotting, Western
- Chromatography, High Pressure Liquid
- Excitatory Amino Acid Transporter 3/metabolism
- Genes, fos/genetics
- Glutamic Acid/physiology
- Immunohistochemistry
- In Vitro Techniques
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Microdialysis
- Phenotype
- Potassium Chloride/pharmacology
- Prefrontal Cortex/metabolism
- Receptor, Serotonin, 5-HT1A/genetics
- Receptor, Serotonin, 5-HT1A/physiology
- Sodium/physiology
- Stress, Psychological/metabolism
- Stress, Psychological/psychology
- Synaptosomes/drug effects
- Synaptosomes/metabolism
- gamma-Aminobutyric Acid/metabolism
- gamma-Aminobutyric Acid/physiology
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Affiliation(s)
- S Bruening
- Department of Pharmacology, Weill Medical College of Cornell University, New York, New York, USA
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25
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Abstract
Substance P (SP) is one of the most abundant peptides in the central nervous system and has been implicated in a variety of physiological and pathophysiological processes including stress regulation, as well as affective and anxiety-related behaviour. Consistent with these functions, SP and its preferred neurokinin 1 (NK1) receptor has been found within brain areas known to be involved in the regulation of stress and anxiety responses. Aversive and stressful stimuli have been shown repeatedly to change SP brain tissue content, as well as NK1 receptor binding. More recently it has been demonstrated that emotional stressors increase SP efflux in specific limbic structures such as amygdala and septum and that the magnitude of this effect depends on the severity of the stressor. Depending on the brain area, an increase in intracerebral SP concentration (mimicked by SP microinjection) produces mainly anxiogenic-like responses in various behavioural tasks. Based on findings that SP transmission is stimulated under stressful or anxiety-provoking situations it was hypothesised that blockade of NK1 receptors may attenuate stress responses and exert anxiolytic-like effects. Preclinical and clinical studies have found evidence in favour of such an assumption. The status of this research is reviewed here.
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Affiliation(s)
- K Ebner
- Department of Pharmacology and Toxicology, Institute of Pharmacy, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck, Austria.
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26
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Hetzenauer A, Sinnegger-Brauns MJ, Striessnig J, Singewald N. Brain activation pattern induced by stimulation of L-type Ca2+-channels: Contribution of CaV1.3 and CaV1.2 isoforms. Neuroscience 2006; 139:1005-15. [PMID: 16542784 DOI: 10.1016/j.neuroscience.2006.01.059] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2005] [Revised: 01/25/2006] [Accepted: 01/27/2006] [Indexed: 10/24/2022]
Abstract
Ca(V)1.2 and Ca(V)1.3, are the main dihydropyridine-sensitive L-type calcium channel isoforms in the brain. To reveal the contribution of each isoform to the neuronal activation pattern elicited by the dihydropyridine L-type calcium channel activator BayK 8644, we utilized Fos expression as a marker of neuronal activation in mutant mice (Ca(V)1.2(DHP-/-) mice) expressing dihydropyridine-insensitive Ca(V)1.2 L-type calcium channels. BayK 8644-treated wildtype mice displayed intense and widespread Fos expression throughout the neuroaxis in 77 of 80 brain regions quantified. The Fos response in Ca(V)1.2(DHP-/-) mice was greatly attenuated or absent in most of these areas, suggesting that a major part of the widespread Fos induction including most cortical areas was mediated by Ca(V)1.2 L-type calcium channels. BayK 8644-induced Fos expression in Ca(V)1.2(DHP-/-) mice indicating predominantly Ca(V)1.3 L-type calcium channel-mediated activation was noted in more restricted neuronal populations (20 of 80), in particular in the central amygdala, the bed nucleus of the stria terminalis, paraventricular hypothalamic nucleus, lateral preoptic area, locus coeruleus, lateral parabrachial nucleus, central nucleus of the inferior colliculus, and nucleus of the solitary tract. Our data indicate that selective stimulation of other than Ca(V)1.2 L-type calcium channels, mostly Ca(V)1.3, causes neuronal activation in a specific set of mainly limbic, hypothalamic and brainstem areas, which are associated with functions including integration of emotion-related behavior. Hence, selective modulation of Ca(V)1.3 L-type calcium channels could represent a novel (pharmacotherapeutic) tool to influence these CNS functions.
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Affiliation(s)
- A Hetzenauer
- Leopold-Franzens-University Innsbruck, Institute of Pharmacy, Department of Pharmacology and Toxicology and Center for Molecular Biosciences Innsbruck, University of Innsbruck, Peter-Mayr-Str. 1, A-6020 Innsbruck, Austria
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27
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Herpfer I, Fiebich BL, Singewald N, Hamke M, Lieb K. Functional downregulation of the neurokinin 1 receptor by antidepressant, neuroleptics and mood stabilizers. Pharmacopsychiatry 2005. [DOI: 10.1055/s-2005-918712] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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28
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Erhardt A, Sillaber I, Welt T, Müller MB, Singewald N, Keck ME. Repetitive transcranial magnetic stimulation increases the release of dopamine in the nucleus accumbens shell of morphine-sensitized rats during abstinence. Neuropsychopharmacology 2004; 29:2074-80. [PMID: 15187982 DOI: 10.1038/sj.npp.1300493] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.4] [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: 11/08/2022]
Abstract
Recent studies in rodents have shown that withdrawal from chronic drug abuse is associated with a significant decrease in dopamine (DA) release in mesolimbic structures, especially in the shell region of the nucleus accumbens. Since the DA system is known to play an important role in reward processes, a withdrawal-associated impairment in mesolimbic DA-mediated transmission could possibly implicate reward deficit and thus enhance vulnerability to drug craving and relapse. We have previously demonstrated that acute repetitive transcranial magnetic stimulation (rTMS) has a modulatory effect on DA release in several areas of the rat brain, including dorsal striatum, hippocampus, and nucleus accumbens shell. In the present study, we investigated the possible use of rTMS as a tool in re-establishing the dysregulated DA secretion observed during withdrawal in morphine-sensitized male Sprague-Dawley rats. Using intracerebral microdialysis, we monitored the effects of acute rTMS (20 Hz) on the intra-accumbal release-patterns of DA in freely moving animals that were subjected to a morphine sensitization scheme for a period of 8 days. We provide first evidence that acute rTMS (20 Hz) is able to increase DA concentration in the shell region of the nucleus accumbens in both control animals and morphine-sensitized rats during abstinence. The DA release in morphine-sensitized rats was significantly higher than in controls. rTMS, therefore, might gain a potential therapeutic role in the treatment of dysphoric and anhedonic states during drug withdrawal in humans.
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Affiliation(s)
- A Erhardt
- Max Planck Institute of Psychiatry, Munich, Germany
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29
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Kaehler ST, Salchner P, Singewald N, Philippu A. Differential amino acid transmission in the locus coeruleus of Wistar Kyoto and spontaneously hypertensive rats. Naunyn Schmiedebergs Arch Pharmacol 2004; 370:381-7. [PMID: 15526108 DOI: 10.1007/s00210-004-0987-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2004] [Accepted: 09/07/2004] [Indexed: 11/25/2022]
Abstract
In addition to differences in their blood pressure, Wistar Kyoto (WKY) and spontaneously hypertensive rats (SHR) are known to differ in their emotional behaviour. The neurochemistry underlying these differences is not well understood. In the present study the release rates of the two main regulatory amino acids in the locus coeruleus, glutamate and gamma-aminobutyric acid (GABA), were monitored in WKY rats and SHR to investigate whether basal and/or challenged neurotransmission differs between these strains. The strains differed in their basal blood pressure (WKY 102+/-2 mmHg, SHR 140+/-4 mmHg), as well as in their emotional behaviour, since WKY rats displayed enhanced anxiety-related behaviour in the open field test (time in centre: WKY 197+/-40 s/30 min, SHR 741+/-93 s/30 min). Basal glutamate and GABA release rates did not differ between WKY rats and SHR. A rise in blood pressure induced by intravenous infusion of noradrenaline for 10 min enhanced GABA release in WKY rats by 60%, while no effect was observed in SHR. Glutamate release did not respond to experimental hypertension in both strains. Intravenous infusion of sodium nitroprusside led to a fall in blood pressure, which was less pronounced and was of shorter duration in WKY rats than in SHR. The depressor response had no effect on amino acid release in the locus coeruleus of both strains. Mild stress induced by noise or tail pinch led to slight rises in arterial blood pressure (10 mmHg and 20 mmHg respectively), which were similar in WKY rats and SHR. Tail pinch enhanced the release rates of glutamate and GABA in the locus coeruleus of WKY rats and SHR; however, no strain differences were noted. Noise stress did not significantly influence amino acid release. These findings demonstrate that SHR and WKY rats differ in GABAergic neurotransmission, which is revealed in response to specific cardiovascular challenges, but not to mild stressors. The observed lack of GABA response to blood pressure elevation in SHR may reflect a disturbed mechanism counteracting high blood pressure, possibly contributing to hypertension in this strain.
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Affiliation(s)
- S T Kaehler
- Department of Pharmacology and Toxicology, University of Innsbruck, Peter-Mayr-Strasse 1, 6020 Innsbruck, Austria.
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Murck H, Sinner C, Singewald N. Magnesium-deficient diet alters depression and anxiety-related behavior in mice – Influence of desipramine and hypericum extract. Pharmacopsychiatry 2004. [DOI: 10.1055/s-2003-825453] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Sartori SB, Burnet PWJ, Sharp T, Singewald N. Evaluation of the effect of chronic antidepressant treatment on neurokinin-1 receptor expression in the rat brain. Neuropharmacology 2004; 46:1177-1183. [PMID: 15111024 DOI: 10.1016/j.neuropharm.2004.02.013] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2003] [Revised: 01/23/2004] [Accepted: 02/11/2004] [Indexed: 12/27/2022]
Abstract
Clinically effective antidepressants are thought to exert their therapeutic effects by facilitating central monoamine neurotransmission. However, recent data showing that neurokinin-1 receptor (NK1R) antagonists have antidepressant properties in both animal and clinical studies raise the possibility that classical antidepressants may also influence NK1R expression in the brain. To test this hypothesis, rats were treated with desipramine, paroxetine, venlafaxine, tranylcypromine or vehicle for 14-42 days. NK1R binding sites and mRNA were determined in a wide variety of brain areas using in situ hybridization and quantitative receptor autoradiography. In all areas examined, the abundance of NK1R binding sites was unchanged after 14 days of treatment. None of the treatments altered the number of NK1R binding sites following 42 days treatment with the exception that an increase was found in the locus coeruleus with tranylcypromine. Taken together, we report that repeated treatment with antidepressants of different classes does not cause significant changes in NK1R expression.
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Affiliation(s)
- S B Sartori
- Department of Pharmacology and Toxicology, Institute of Pharmacy, University of Innsbruck, Peter-Mayr-Strasse 1, A-6020 Innsbruck, Austria
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Salchner P, Lubec G, Engelmann M, Orlando GF, Wolf G, Sartori SB, Hoeger H, Singewald N. Genetic functional inactivation of neuronal nitric oxide synthase affects stress-related Fos expression in specific brain regions. Cell Mol Life Sci 2004; 61:1498-506. [PMID: 15197473 DOI: 10.1007/s00018-004-4140-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
To identify neuronal substrates involved in NO/stress interactions we used Fos expression as a marker and examined the pattern of neuronal activation in response to swim stress in nNOS knock-out (nNOS-/-) and wild-type (WT) mice. Forced swimming enhanced Fos expression in WT and nNOS-/- mice in several brain regions, including cortical, limbic and hypothalamic regions. Differences in the Fos response between the two groups were observed in a limited set (6 out of 42) of these brain areas only: nNOS-/- mice displayed increased stressor-induced Fos expression in the medial amygdala, periventricular hypothalamic nucleus, supraoptic nucleus, CA1 field of the hippocampus, dentate gyrus and infralimbic cortex. No differences were observed in regions including the septum, central amygdala, periaqueductal grey and locus coeruleus. During forced swimming, nNOS-/- mice displayed reduced immobility duration, while no differences in general locomotor activity were observed between the groups in the home cage and during the open field test. The findings indicate that deletion of nNOS alters stress-coping ability during forced swimming and leads to an altered pattern of neuronal activation in response to this stressor in specific parts of the limbic system, hypothalamus and the medial prefrontal cortex.
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Affiliation(s)
- P Salchner
- Department of Pharmacology and Toxicology, University of Innsbruck, Peter-Mayr-Str. 1, 6020 Innsbruck, Austria
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Abstract
Microdialysis for measurement of serotonin in the paraventricular nucleus of the hypothalamus (PVN) and the dorsal hippocampus was performed under both basal and stimulated conditions, known to elicit differential behavioral and neuroendocrine responses in rats with inborn high (HAB) or low (LAB) anxiety-related behavior. We studied the release of hypothalamic and hippocampal serotonin in response to elevated platform exposure and forced swim stress, a mild emotional and a combined emotional and physical stressor, respectively. The data suggest that serotonin release patterns may depend on the inborn level of anxiety, the brain area dialyzed, and the stressor the animals were exposed to. Under basal conditions, no differences in serotonin release in either the PVN or dorsal hippocampus were observed between HAB and LAB rats. While in the PVN open platform exposure failed to change the release of serotonin, forced swim stress induced an increase in both HAB (p = 0.0001) and LAB (p = 0.01) rats with a significantly greater effect in the former (p = 0.027). In the dorsal hippocampus, only LABs, but not HABs, responded to the elevated platform exposure by enhancing the release of serotonin (p = 0.01). Also, forced swim stress increased hippocampal serotonin only in LAB (p = 0.002), but not HAB, rats probably indicating an involvement of hippocampal serotonin in locomotion and active stress coping. It remains to be shown to what extent the differences in serotonin release contribute to neuroendocrine and behavioral differences between HAB and LAB rats.
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Affiliation(s)
- A E Umriukhin
- Institute of Normal Physiology of PK Anokhin, Moscow 103009, Russia.
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Engelmann M, Ludwig M, Singewald N, Ebner K, Sabatier N, Lubec G, Landgraf R, Wotjak CT. Taurine selectively modulates the secretory activity of vasopressin neurons in conscious rats. Eur J Neurosci 2001; 14:1047-55. [PMID: 11683896 DOI: 10.1046/j.0953-816x.2001.01729.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Previous experiments have shown that a 10-min forced swimming session triggers the release of vasopressin from somata and dendrites, but not axon terminals, of neurons of the hypothalamic-neurohypophysial system. To further investigate regulatory mechanisms underlying this dissociated release, we forced male Wistar rats to swim in warm (20 degrees C) water and monitored release of the potentially inhibitory amino acids gamma amino butyric acid (GABA) and taurine into the hypothalamic supraoptic nucleus using microdialysis. Forced swimming caused a significant increase in the release of taurine (up to 350%; P < 0.05 vs. prestress release), but not GABA. To reveal the physiological significance of centrally released taurine, the specific taurine antagonist 6-aminomethyl-3-methyl-4H-1,2,4-benzothiadiazine-1,1-dioxide was administered into the supraoptic nucleus via retrodialysis. Administration of this antagonist caused a significant increase in the release of vasopressin within the supraoptic nucleus and into the blood both under basal conditions and during stress (up to 800%; P < 0.05 vs. basal values), without affecting hypothalamic or plasma oxytocin. Local administration of the GABA(A) receptor antagonist bicuculline, in contrast, failed to influence vasopressin secretion at either time point. In a separate series of in vivo electrophysiological experiments, administration of the same dosage of the taurine antagonist into the supraoptic nucleus via microdialysis resulted in an increased electrical activity of identified vasopressinergic, but not oxytocinergic, neurons. Taken together our data demonstrate that taurine is released within the supraoptic nucleus during physical/emotional stress. Furthermore, at the level of the supraoptic nucleus, taurine inhibits not only the electrical activity of vasopressin neurons but also acts as an inhibitor of both central and peripheral vasopressin secretion during different physiological states.
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Affiliation(s)
- M Engelmann
- Institut für Medizinische Neurobiologie, Otto-von-Guericke-Universität Magdeburg, Leipziger Str. 44. D-39120 Magdeburg, Germany.
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Sinner C, Kaehler ST, Philippu A, Singewald N. Role of nitric oxide in the stress-induced release of serotonin in the locus coeruleus. Naunyn Schmiedebergs Arch Pharmacol 2001; 364:105-9. [PMID: 11534849 DOI: 10.1007/s002100100428] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Serotonergic mechanisms within the locus coeruleus (LC) are thought to be important in various functions including the stress response. In this study we investigated a possible role of nitric oxide (NO) as an intermediary messenger in the regulation of the serotonin (5-HT) neurotransmission within the LC. Using the push-pull superfusion technique coupled with HPLC and electrochemical detection, the in vivo release of 5-HT was determined in time periods of 10 min in the LC of freely moving rats. Superfusion with three different NO donors, SIN-1 (linsidomine), S-nitroso-N-penicillamine (SNAP) or 3-(2-hydroxy-2-nitroso-1-propylhydrazino)-1-propanamine (PAPANO) increased 5-HT release in the LC. Superfusion with the precursor of NO, L-arginine, for 1 h led to a sustained increase in 5-HT release. On the other hand, the NOS inhibitor N-methyl-L-arginine methyl ester (L-NAME) did not significantly change the release of 5-HT. Infusion of N-methyl-D-aspartate (NMDA) or kainic acid, as well as exposure of rats to noise stress or tail pinch increased the release of 5-HT in the LC. Superfusion with L-NAME prevented the increase in 5-HT outflow by all these procedures, while the inactive isomer D-NAME had no effect. Taken together, the results of this study suggest that the release of 5-HT in the LC is facilitated by NO. Under resting conditions inhibition of NOS does not appear to substantially influence the release of 5-HT in the LC. However, there seems to be a facilitatory nitrergic influence on serotonergic responses evoked by excitatory amino acid receptor stimulation or various stress stimuli.
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Affiliation(s)
- C Sinner
- Department of Pharmacology and Toxicology, University of Innsbruck, Austria
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Seidl R, Cairns N, Singewald N, Kaehler ST, Lubec G. Differences between GABA levels in Alzheimer's disease and Down syndrome with Alzheimer-like neuropathology. Naunyn Schmiedebergs Arch Pharmacol 2001; 363:139-45. [PMID: 11218066 DOI: 10.1007/s002100000346] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Down syndrome (DS) is a genetic disease with developmental brain abnormalities resulting in early mental retardation and precocious, age-dependent Alzheimer-type neurodegeneration. Furthermore, non-cognitive symptoms may be a cardinal feature of functional decline in adults with DS. A number of amino acids [glutamate, aspartate, gamma-aminobutyrate (GABA), glycine, taurine, glutamine, serine, arginine] were investigated in post-mortem tissue samples from temporal, occipital cortex, thalamus, caudate nucleus, and cerebellum of adult patients with Down syndrome (DS) exhibiting Alzheimer-like neuropatholgy, Alzheimer's disease (AD) and from controls by use of high performance liquid chromatography (HPLC). In DS, no significant differences from control values could be observed in any of the brain regions. In AD, significant loss of GABA content was found in the temporal cortex (0.5+/-0.2 micromol/g vs. 1.3+/-0.8 micromol/g wet weight tissue, P<0.01), occipital cortex (0.8+/-0.2 micromol/g vs. 1.4+/-0.6 micromol/g, P<0.05) and cerebellum (1.1+/-0.3 micromol/g vs. 1.8+/-0.5 micromol/g, P<0.05). Glutamate and aspartate concentrations were significantly reduced in the caudate nucleus of AD subjects (glutamate: 6.1+/-3.4 micromol/g vs. 14.7+/-1.8 micromol/g; aspartate: 1.5+/-0.3 micromol/g vs. 3.3+/-0.4 micromol/g, P<0.05). The results of this study confirm previous findings in late stage AD and provide further information with respect to DS which may be relevant to understanding different pathogenesis of cognitive and non-cognitive (behavioral) features in DS and AD.
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Affiliation(s)
- R Seidl
- Department of Pediatrics, University of Vienna, Austria
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Keck ME, Sillaber I, Ebner K, Welt T, Toschi N, Kaehler ST, Singewald N, Philippu A, Elbel GK, Wotjak CT, Holsboer F, Landgraf R, Engelmann M. Acute transcranial magnetic stimulation of frontal brain regions selectively modulates the release of vasopressin, biogenic amines and amino acids in the rat brain. Eur J Neurosci 2000; 12:3713-20. [PMID: 11029641 DOI: 10.1046/j.1460-9568.2000.00243.x] [Citation(s) in RCA: 127] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Using intracerebral microdialysis in urethane-anaesthetized adult male Wistar rats, we monitored the effects of acute repetitive transcranial magnetic stimulation (rTMS; 20 trains of 20 Hz, 2.5 s) on the intrahypothalamic release of arginine vasopressin (AVP) and selected amino acids (glutamate, glutamine, aspartate, serine, arginine, taurine, gamma-aminobutyric acid) and the intrahippocampal release of monoamines (dopamine, noradrenaline, serotonin) and their metabolites (homovanillic acid, 3,4-dihydroxyphenylacetic acid, 5-hydroxyindoleacetic acid). The stimulation parameters were adjusted according to the results of accurate computer reconstructions of the current density distributions induced by rTMS in the rat and human brains, ensuring similar stimulation patterns in both cases. There was a continuous reduction in AVP release of up to 50% within the hypothalamic paraventricular nucleus in response to rTMS. In contrast, the release of taurine, aspartate and serine was selectively stimulated within this nucleus by rTMS. Furthermore, in the dorsal hippocampus the extracellular concentration of dopamine was elevated in response to rTMS. Taken together, these data provide the first in vivo evidence that acute rTMS of frontal brain regions has a differentiated modulatory effect on selected neurotransmitter/neuromodulator systems in distinct brain areas.
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Affiliation(s)
- M E Keck
- Max Planck Institute of Psychiatry, Munich, Germany.
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38
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Abstract
It is speculated that specific hindbrain transmitter pathways centred on the periaqueductal gray and locus coeruleus are an important integrative neural substrate for the expression of anxiety and the somatic symptoms and cardiovascular changes that accompany severe anxiety states, such as in panic disorder. Here we investigated the effects of various drugs, known to induce panic in humans and to be anxiogenic in animals, on Fos expression in the periaqueductal gray, locus coeruleus and other parts of the rat hindbrain. The drugs tested were the benozodiazepine inverse agonist FG-7142, the alpha(2)-adrenoceptor antagonist yohimbine, the non-selective 5-hydroxytryptamine(2C) receptor agonist m-chlorophenyl piperazine, the adenosine antagonist caffeine and the cholecystokinin analogue BOC-CCK(4). A clear-cut finding was that administration of each anxiogenic drug caused a striking region-specific pattern of Fos expression within the hindbrain. In particular, the drugs commonly increased Fos-like immunoreactivity in the periaqueductal gray and locus coeruleus. Increased Fos expression in the periaqueductal gray was specific to the rostral dorsolateral and caudal ventrolateral regions. All the anxiogenic drugs also increased Fos-like immunoreactivity in the lateral parabrachial nucleus and nucleus of the solitary tract and all but one (BOC-CCK(4)) increased Fos in the dorsal raphe nucleus. Rats habituated to the test environment and injected with saline vehicle displayed little or no Fos-like immunoreactivity in the hindbrain areas investigated. In summary, each of the anxiogenic drugs tested (FG-7142, yohimbine, m-chlorophenyl piperazine, caffeine and BOC-CCK(4)) increased Fos expression in a restricted number of hindbrain regions, including the periaqueductal gray and locus coeruleus. Previous Fos studies have found that these same regions are activated by various fearful environmental stimuli. Therefore, a specific set of hindbrain circuits may be commonly involved in the processing of anxiety-related information evoked by pharmacological and environmental manipulation. The present findings also raise the possibility that measurement of the effect of anxiogenic drugs on Fos expression might be a useful way to model hindbrain pathways activated by anxiety and possibly panic.
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Affiliation(s)
- N Singewald
- University Department of Clinical Pharmacology, Radcliffe Infirmary, Woodstock Road, Oxford, UK.
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Singewald N, Kouvelas D, Kaehler ST, Sinner C, Philippu A. Peripheral chemoreceptor activation enhances 5-hydroxytryptamine release in the locus coeruleus of conscious rats. Neurosci Lett 2000; 289:17-20. [PMID: 10899398 DOI: 10.1016/s0304-3940(00)01241-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Intravenous bolus injection of KCN (40 microg) elicited brief but pronounced tachypnea, bradycardia and pressor response, and led to a 37% increase in 5-hydroxytryptamine (serotonin) (5-HT) release in the locus coeruleus (LC) of freely moving rats. Slow infusion of KCN (15 microg/min) for 10 min induced only a slight pressor response, but increased the respiration rate (+39 breaths/min), as well as 5-HT release in the LC (+60%) throughout the infusion. In rats with transected chemoreceptor afferents, neither injection or infusion of KCN changed 5-HT release, suggesting that in intact animals, the effect on extracellular 5-HT was due to activation of peripheral chemoreceptors. In summary, we report that peripheral chemoreceptor activation enhances 5-HT release in the LC, indicating that 5-HT might be involved in the modulation of LC activity by ascending chemosensory information.
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Affiliation(s)
- N Singewald
- Department of Pharmacology and Toxicology, Institute of Pharmacy, University of Innsbruck, Peter-Mayr-Strasse 1, A-6020, Innsbruck, Austria.
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Singewald N, Kouvelas D, Mostafa A, Sinner C, Philippu A. Release of glutamate and GABA in the amygdala of conscious rats by acute stress and baroreceptor activation: differences between SHR and WKY rats. Brain Res 2000; 864:138-41. [PMID: 10793197 DOI: 10.1016/s0006-8993(00)02172-7] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
To reveal the functional importance of amino acid neurotransmission in the amygdala (AMY) of conscious spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats, the in vivo release of glutamate (GLU) and GABA in this brain structure was studied using the push-pull superfusion technique. Basal GLU and GABA release rates in the AMY were comparable in SHR and WKY rats, although arterial blood pressure (BP) in SHR (152+/-6 mmHg) was higher than in WKY rats (102+/-4 mmHg). Neuronal depolarization by superfusion with veratridine enhanced the release of GLU and GABA to a similar extent in both rat strains. On the other hand, exposure to noise stress (95 dB) for 3 min led to a tetrodotoxin-sensitive increase in GLU release in the AMY of SHR, but not WKY rats. The concurrent pressor response to noise was enhanced in SHR as compared to WKY rats. A rise in BP induced by intravenous infusion of phenylephrine for 9 min had no effect on amino acid release in the AMY of both strains. The data suggest an exaggerated stress response of glutamatergic neurons in the AMY of SHR as compared with WKY rats, which might be of significance for the strain differences in the cardiovascular and behavioural responses to stress. The results also show that, in both rat strains, glutamatergic and GABAergic neurons in the AMY are not modulated by baroreceptor activation. Moreover, hypertension in adult SHR does not seem to be linked to a disturbed synaptic regulation of glutamatergic or GABAergic transmission in the AMY.
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Affiliation(s)
- N Singewald
- Department of Pharmacology and Toxicology, University of Innsbruck, Peter-Mayr-Strasse 1, A-6020, Innsbruck, Austria.
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Seidl R, Kaehler ST, Prast H, Singewald N, Cairns N, Gratzer M, Lubec G. Serotonin (5-HT) in brains of adult patients with Down syndrome. J Neural Transm Suppl 2000; 57:221-32. [PMID: 10666678 DOI: 10.1007/978-3-7091-6380-1_14] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Down syndrome (DS) is a genetic disease with developmental brain abnormalities resulting in early mental retardation and precocious, age dependent Alzheimer-type neurodegeneration. Furthermore, non-cognitive symptoms may be a cardinal feature of functional decline in adults with DS. As the serotonergic system plays a well known role in integrating emotion, cognition and motor function, serotonin (5-HT) and its main metabolite, 5-hydroxyindol-3-acetic acid (5-HIAA) were investigated in post-mortem tissue samples from temporal cortex, thalamus, caudate nucleus, occipital cortex and cerebellum of adult patients with DS, Alzheimer's disease (AD) and controls by use of high performance liquid chromatography (HPLC). In DS, 5-HT was found to be age-dependent significantly decreased in caudate nucleus by 60% (DS: mean +/- SD 58.6 +/- 28.2 vs. Co: 151.7 +/- 58.4 pmol/g wet tissue weight) and in temporal cortex by about 40% (196.8 +/- 108.5 vs. 352.5 +/- 183.0 pmol/g), insignificantly reduced in the thalamus, comparable to controls in cerebellum, whereas occipital cortex showed increased levels (204.5 +/- 138.0 vs. 82.1 +/- 39.1 pmol/g). In all regions of DS samples, alterations of 5-HT were paralleled by levels of 5-HIAA, reaching significance compared to controls in thalamus and caudate nucleus. In AD, 5-HT was insignificantly reduced in temporal cortex and thalamus, unchanged in cerebellum, but significantly elevated in caudate nucleus (414.3 +/- 273.7 vs. 151.7 +/- 58.4 pmol/g) and occipital cortex (146.5 +/- 76.1 vs. 82.1 +/- 39.1 pmol/g). The results of this study confirm and extend putatively specific 5-HT dysfunction in basal ganglia (caudate nucleus) of adult DS, which is not present in AD. These findings may be relevant to the pathogenesis and treatment of cognitive and non-cognitive (behavioral) features in DS.
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Affiliation(s)
- R Seidl
- Department of Pediatrics, University of Vienna, Austria
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Abstract
The aim of the present study was to investigate the importance of the serotonergic transmission in the locus coeruleus (LC) to conditioned fear. Rats were conditioned to fear by exposing them to noise signal (N), light signal (L) and electric foot shock (S) for 4 days. Control rats were exposed to the same events without receiving S. The LC was superfused with artificial cerebrospinal fluid (aCSF) through a push-pull cannula, and the release of 5-hydroxytryptamine (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) was determined in the superfusate. Motility, blood pressure (BP) and heart rate (HR) were telemetrically recorded. (1) The process of moving animals from their home cage into the grid-floor chamber transiently increased the release rate of 5-HT and the outflow of 5-HIAA in control and naive rats. In conditioned rats, 5-HT release was similarly increased during transfer but was permanently decreased in the grid-floor chamber. Control rats showed phases of enhanced motility in the chamber, while conditioned animals displayed continuous immobility. In naive rats, enhanced motility persisted in the novel environment. (2) Exposure of rats to N+L+S increased the release of 5-HT and the outflow of 5-HIAA to the same extent in conditioned and naive rats. These changes were associated with elevated motility, rise in BP and tachycardia. (3) In conditioned subjects, exposure to N+L in the fifth day led to a pronounced and sustained decrease in the release rate of 5-HT and to tachycardia, while no effects were observed in control rats or naive rats. The findings suggest that conditioned fear attenuates serotonergic neurotransmission within the LC. Telemetric recording of HR proves to be a valuable index for fear and stress processes.
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Affiliation(s)
- S T Kaehler
- Department of Pharmacology, University of Innsbruck, Peter-Mayr Strasse 1, Innsbruck, Austria
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Abstract
Previous experiments have shown that arginine vasopressin (AVP) released within the septal brain area of adult male rats in response to defined stressor exposure is involved in emotionality-related behavior. We report here that a 10-min forced swimming session stimulated the release of glutamate, aspartate, arginine, gamma-aminobutyric acid (GABA) and taurine but not alanine and serine in the medio-lateral part of this brain structure. Local administration of the AVP V1 receptor antagonist d(CH2)5Tyr(Me)AVP by inverse microdialysis caused a significant increase in the concentration of taurine in microdialysates under resting conditions that was further potentiated during forced swimming. In contrast, the release of alanine, arginine, GABA and serine was unaffected by antagonist treatment. Taken together with previous data, our results suggest that the effects of intraseptally released AVP on stress-coping strategies might be mediated at least in part via its influence on the local release of taurine.
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Affiliation(s)
- N Singewald
- Universität Innsbruck, Institut für Pharmakologie and Toxikologie, Austria
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Kaehler ST, Singewald N, Philippu A. The release of catecholamines in hypothalamus and locus coeruleus is modulated by peripheral chemoreceptors. Naunyn Schmiedebergs Arch Pharmacol 1999; 360:428-34. [PMID: 10551280 DOI: 10.1007/s002109900094] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
To investigate whether impulses from chemoreceptors influence the release of catecholamines in the hypothalamus and the locus coeruleus, the two brain areas were superfused simultaneously and bilaterally with artificial cerebrospinal fluid through push-pull cannulae. The release of catecholamines was determined in the superfusate before and during chemoreceptor stimulation by bicarbonate solution saturated with carbon dioxide (CO2-NaHCO3) or KCN. Experiments were carried out on intact cats after carotid body denervation (CD). Intracarotid infusion of CO2-NaHCO3 increased arterial blood pressure and enhanced the release of noradrenaline but not dopamine in the posterior hypothalamus and the locus coeruleus. Following CD, the enhancing effect of CO2-NaHCO3 on the noradrenaline release in the posterior hypothalamus was abolished, while the effect on blood pressure was slightly enhanced. CD reversed the NaHCO3-induced release of noradrenaline in the locus coeruleus to a decreased noradrenaline outflow. Intracarotid infusion of KCN led to a fall in blood pressure. KCN increased the release rates of noradrenaline and, to a lesser extent, that of dopamine in the posterior hypothalamus, as well as the release of noradrenaline in the locus coeruleus. CD abolished the KCN-induced fall of blood pressure and the increased release of noradrenaline and dopamine in the posterior hypothalamus. Similar to CO2-NaHCO3, the enhancing effect of KCN on the noradrenaline release in the locus coeruleus was reversed following CD to a reduced noradrenaline outflow. Superfusion of the posterior hypothalamus and the locus coeruleus with KCN did not influence either blood pressure or the release rates of noradrenaline and dopamine in these brain areas. The findings show that impulses originating from chemoreceptors of the carotid body increase the release rates of the catecholamines in the posterior hypothalamus and the locus coeruleus, thus underlining the importance of catecholaminergic neurons of these brain areas in cardiovascular control.
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Affiliation(s)
- S T Kaehler
- Institut für Pharmakologie und Toxikologie der Universität Innsbruck, Austria
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Abstract
To investigate the effect of nitric oxide (NO) on the release of serotonin and its main metabolite, 5-hydroxyindoleacetic acid (5-HIAA), the posterior hypothalamus of the conscious rat was superfused through a push-pull cannula with drugs which either liberate NO, or inhibit NO synthase (NOS). The NO donors, linsidomine, diethylamine/nitric oxide (DEA/NO), S-nitroso-N-acetylpenicillamine (SNAP), S-nitroso-glutathione (SNOG) and sodium nitroprusside influenced the release of serotonin in a biphasic way. Low concentrations of drugs diminished, while higher concentrations of these compounds enhanced the outflow of serotonin. The NOS inhibitors N(G)-methyl-L-arginine methyl ester (L-NAME) and 7-nitroindazole (7-NINA) enhanced the serotonin release. A high concentration of L-NAME slightly diminished the outflow of serotonin. Inhibition of the guanylyl cyclase by oxodiazolo[4, 3]quinoxaline-one (ODQ) abolished the changes in serotonin outflow induced by both low and high concentrations of linsidomine. The extracellular concentration of the 5-HIAA was not influenced by the compounds used. These data suggest that endogenous NO modulates the release of serotonin in a biphasic and cGMP-dependent way.
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Affiliation(s)
- S T Kaehler
- Department of Pharmacology and Toxicology, University of Innsbruck, Peter-Mayr-Strasse 1, Innsbruck A-6020, Austria
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Kohlhauser C, Kaehler S, Mosgoeller W, Singewald N, Kouvelas D, Prast H, Hoeger H, Lubec B. Histological changes and neurotransmitter levels three months following perinatal asphyxia in the rat. Life Sci 1999; 64:2109-24. [PMID: 10372653 DOI: 10.1016/s0024-3205(99)00160-5] [Citation(s) in RCA: 44] [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] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The involvement of excitatory amino acids (EAA) in the pathogenesis of hypoxic-ischemic states is well-documented. Information on the role of overexcitation by EAA in perinatalasphyxia (PA), however, is limited and data from adult models cannot be directly extrapolated to immature systems. Moreover, most adult models of ischemia are representing stroke rather than PA. We decided to study long term effects in a non-invasive rat model of PA resembling the clinical situation three months following the asphyctic insult. Morphometry on Nissl - stained sections was used to determine neuronal death in frontal cortex, striatum, hippocampus CA1, hypothalamus and cerebellum L1, and the amino acids glutamate, glutamine, aspartate, GABA, taurine, arginine as well as histamine, serotonin and 5-hydroxy-indoleacetic acid were determined in several brain regions and areas. Morphometry revealed that neuronal loss was present in the hippocampal area CA1 in all groups with PA and that morphological alterations were significantly higher in the cerebellar granular layer. The prominent light microscopical finding in all areas of asphyctic rats studied was decreased Nissl-staining, suggesting decreased cellular RNA levels. Glutamate, aspartate and glutamine were significantly elevated in the hypothalamus of asphyctic rats probably indicating overstimulation by EAA. Excitotoxicity in this area would be compatible with findings of emotional / behavioral deficits observed in a parallel study in our model of PA. Our observations point to and may help to explain behavioral and emotional deficits in Man with a history of perinatal asphyxia.
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Affiliation(s)
- C Kohlhauser
- University of Vienna, Dpt of Pediatrics, Austria
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Kaehler ST, Singewald N, Philippu A. Release of serotonin in the locus coeruleus of normotensive and spontaneously hypertensive rats (SHR). Naunyn Schmiedebergs Arch Pharmacol 1999; 359:460-5. [PMID: 10431756 DOI: 10.1007/pl00005376] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The aim of the present work was to clarify whether differences exist between the release of endogenous serotonin in the locus coeruleus of normotensive and hypertensive rats. The locus coeruleus was superfused with artificial cerebrospinal fluid (aCSF) through a push-pull cannula and serotonin and its metabolite 5-hydroxyindoleacetic acid (5-HIAA) were determined in the superfusate by HPLC combined with electrochemical detection. Compared with normotensive Wistar-Kyoto (WKY) rats, the basal release rate of serotonin in the locus coeruleus of spontaneously hypertensive rats (SHR) was increased more than twofold. Intravenous infusion of noradrenaline (4 microg/kg min) increased mean arterial blood pressure to the same extent in hypertensive and normotensive rats. The pressor response was associated with an increased serotonin release. In WKY rats, the release of serotonin in the locus coeruleus evoked by noradrenaline infusion was more pronounced than in SHR. In WKY rats, intravenous infusion of sodium nitroprusside (150 microg/kg min) led to a fall in blood pressure which was less pronounced and lasted shorter than in SHR. The depressor response was associated with decreased serotonin release. In WKY rats, the decrease in serotonin release evoked by sodium nitroprusside was more pronounced and lasted longer than in SHR. Neither noradrenaline nor sodium nitroprusside influenced the outflow of 5-HIAA. The sensory stimuli noise and tail pinch led to a slight rise in arterial blood pressure which was similar in WKY rats and SHR. These stimuli enhanced the release rate of serotonin and the outflow of 5-HIAA to the same extent in the locus coeruleus of normotensive and hypertensive rats. The findings suggest that the enhanced release of serotonin in the locus coeruleus of genetically hypertensive rats reflects a mechanism counteracting the disturbed blood pressure homeostasis. Stressors influence blood pressure and release of serotonin in the locus coeruleus of SHR and WKY rats to the same extent.
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Affiliation(s)
- S T Kaehler
- Institut für Pharmakologie und Toxikologie der Universität Innsbruck, Austria
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Singewald N, Kaehler ST, Philippu A. Noradrenaline release in the locus coeruleus of conscious rats is triggered by drugs, stress and blood pressure changes. Neuroreport 1999; 10:1583-7. [PMID: 10380985 DOI: 10.1097/00001756-199905140-00035] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The in vivo release of noradrenaline (NA) in the locus coeruleus (LC) of conscious rats was enhanced by local superfusion of pargyline, idazoxan, bicuculline, AMPA as well as by experimentally induced hypotension. Noise stress considerably enhanced NA release in the LC and this response was promoted after local alpha2-adrenoceptor blockade by idazoxan. Air jet stress and noise stress elicited comparable increases in NA release in the LC and the simultaneously superfused amygdala. The NA responses in both areas did not change during a second exposure to each of the stressors. It is concluded that NA release at the somatodendritic level of LC neurons is triggered by high LC activity and most likely serves to limit LC activation to excitatory stimuli by feedback inhibition via alpha2-adrenoceptors.
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Affiliation(s)
- N Singewald
- Department of Pharmacology and Toxicology, University of Innsbruck, Austria
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Kaehler ST, Singewald N, Philippu A. Dependence of serotonin release in the locus coeruleus on dorsal raphe neuronal activity. Naunyn Schmiedebergs Arch Pharmacol 1999; 359:386-93. [PMID: 10498288 DOI: 10.1007/pl00005365] [Citation(s) in RCA: 49] [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] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The serotonergic innervation of the locus coeruleus paetly derives from the dorsal raphe nucleus (DRN). Using the push-pull superfusion technique, we investigated whether and to what extent the release of serotonin and the extracellular concentration of its metabolite 5-hydroxyindoleacetic acid (5-HIAA) in the locus coeruleus are influenced by the neuronal activity of the DRN. In anaesthetized rats, a push-pull cannula was inserted into the locus coeruleus, which was continuously superfused with artificial cerebrospinal fluid (aCSF). Serotonin and 5-HIAA levels in the superfusate were determined by HPLC combined with electrochemical detection. Electrical stimulation (5 Hz, 300 microA, 1 ms) of the DRN for 5 min, or its chemical stimulation by microinjection of glutamate (3.5 nmol, 50 nl), led to an increased release of serotonin in the locus coeruleus and to a slight (2 mmHg) decrease in blood pressure. Superfusion of the locus coeruleus with tetrodotoxin (1 microM) abolished the increase in the release rate of serotonin evoked by electrical stimulation of the DRN, while the slight fall in blood pressure was not influenced. Thermic lesion (75 degrees C, 1 min) of the DRN elicited a pronounced decline in serotonin release rate within the locus coeruleus, the maximum decrease being 52%. The decrease in the release of serotonin was associated with a long-lasting rise in blood pressure. Microinjection of the serotonin neurotoxin 5,7-dihydroxytryptamine (5 microg, 250 nl) into the DRN led to an initial increase in the serotonin release rate that coincided with a short-lasting fall in blood pressure. Subsequently, the release of serotonin was permanently reduced and was associated with hypertension. Microinjection of the 5-HT1A receptor agonist (+/-)-8-hydroxy-dipropylaminotetralin (8-OH-DPAT; 7.5 nmol, 50 nl) into the DRN led to a long-lasting reduction of the release rate of serotonin in the locus coeruleus. Microinjection of 8-OH-DPAT into the DRN also slightly lowered blood pressure (3 mmHg). Neither stimulations nor lesion of the DRN, nor microinjection of 8-OH-DPAT into this raphe nucleus, altered the extracellular concentration of 5-HIAA. Judging from the present biochemical results it appears that the serotonergic afferents to the locus coeruleus originate to more than 50% from cell bodies located in the DRN. The neuronal serotonin release in the locus coeruleus is modulated by 5-HT1A receptors lying within the DRN. Changes in blood pressure and release of serotonin elicited by stimulating or lesioning the DRN point to the importance of serotonergic neurons extending between this raphe nucleus and the locus coeruleus in central cardiovascular control.
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Affiliation(s)
- S T Kaehler
- Institut für Pharmakologie und Toxikologie der Universität Innsbruck, Austria
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Kaehler ST, Philippu A, Singewald N. Effects of local MAO inhibition in the locus coeruleus on extracellular serotonin and 5-HIAA during exposure to sensory and cardiovascular stimuli. Naunyn Schmiedebergs Arch Pharmacol 1999; 359:187-93. [PMID: 10208305 DOI: 10.1007/pl00005341] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Previously, we have shown that in the presence of pargyline the release of serotonin (5-HT) in the locus coeruleus is modulated by various sensory stimuli and blood pressure fluctuations. The aim of the present study was to investigate whether local inhibition of monoamine oxidase (MAO) influences basal and stimulus-induced release of 5-HT in the locus coeruleus. For this purpose, the locus coeruleus was superfused in the absence and in the presence of the MAO inhibitor pargyline. Additionally, we examined whether the release of the 5-HT metabolite 5-hydroxy-indole acetic acid (5-HIAA) in the locus coeruleus is altered in response to stimuli. The locus coeruleus of the conscious rat was superfused through a push-pull cannula with artificial cerebrospinal fluid (CSF). 5-HT and 5-HIAA were determined in the superfusate. The basal release rate of 5-HT and the basal outflow of 5-HIAA averaged 2.0 fmol/min and 69 fmol/min, respectively. The basal release rate of 5-HT and the 5-HIAA outflow were tetrodotoxin (TTX)-sensitive. In the absence of pargyline, the sensory stimuli noise stress or tail pinch, applied for 10 min, increased 5-HT and 5-HIAA outflow by 50-70%. In contrast, an experimentally induced rise in blood pressure for 10 min enhanced 5-HT release by 50%, but had no effect on 5-HIAA outflow. The release of 5-HT and/or 5-HIAA elicited by sensory stimuli or a blood pressure rise was abolished by TTX. Addition of pargyline to the CSF enhanced 5-HT release fourfold and slightly decreased 5-HIAA outflow. These levels remained stable throughout the entire observation period of 8 h. In the presence of pargyline, 5-HT release elicited by noise, tail pinch and increase in blood pressure was enhanced. It is concluded that superfusion with pargyline enhances 5-HT release and reduces 5-HIAA outflow in the locus coeruleus. Furthermore, the ability of sensory stimuli and baroreceptor activation to enhance 5-HT release is preserved during a prolonged pargyline-induced increase in extracellular 5-HT. Since sensory stimuli enhanced, while baroreceptor activation did not influence 5-HIAA outflow, 5-HIAA is not a reliable index for short-term changes in the activity of serotonergic neurons in the locus coeruleus.
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Affiliation(s)
- S T Kaehler
- Institut für Pharmakologie und Toxikologie der Universität Innsbruck, Austria
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