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P.4.013 Assessing CRH-mediated anxiogenic and anxiolytic effects using region-and neurotransmitter-specific CRH overexpressing mice
Depression: towards new drug targets +/− mice, CSDS led to significantly higher adrenal gland and reduced thymus weights, as well as to a significantly increased corticosterone response to an acute stressor. Furthermore, WT mice showed increased anxiety-related behavior evidenced by a significant decrease in open arm time in the elevated plus-maze test. Interestingly, we also observed a significant increase in corticosterone response levels and in anxiety-related behavior in the EPM in Fkbp52 +/− mice under basal conditions compared to wild type animals, pointing to a more vulnerable phenotype of this mouse line. In contrast, only chronically stressed wild type animals showed a significantly decreased stresscoping behavior in the forced swim test as well as significantly increased CRH mRNA levels in the PVN, while these chronic stress effects were not observed in Fkbp52 +/− mice. Taken together, our data emphasize a more vulnerable phenotype of this mouse line in distinct parameters, while other parameters point to a lower vulnerability. This complex phenotype might underline brain region specific roles of GR signaling and might be in line with other studies, showing that FKBP4 does not contribute to all branches of GR signaling [3]. Our results support the important role of this co-chaperone in regulating stress vulnerability and resilience. Reference(s) [1] Binder, E., B., 2009 The role of FKBP5, a cochaperone of the glucocorticoid receptor in the pathogenesis and therapy of affective and anxiety disorders. Psychoneuroendocrinology 34, 186–195. [2] Hartmann J., Wagner K., V., Liebl C., Scharf S., H., Wang X., D., Wolf M., Hausch F., Rein T., Schmidt U., Touma C., Cheung-Flynn J., Cox M., B., Smith D., F., Holsboer F., M¨uller M., B., Schmidt M., V., 2012 The involvement of FK506-binding protein 51 (FKBP5) in the behavioral and neuroendocrine effects of chronic social defeat stress. Neuropharmacology 62, 332–339. [3] Wolf I., M., Periyasamy S., Hinds T., Yong W., Shou W., Sanchez E., R., 2009 Targeted ablation reveals a novel role of FKBP52 in gene-specific regulation of glucocorticoid receptor transcriptional activity. J Steroid Biochem Mol Biol 113, 36−45.
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P.4.013 Assessing CRH-mediated anxiogenic and anxiolytic effects using regionand neurotransmitter-specific CRH overexpressing mice N. Dedic1 ° , M. Ableitner1 , C. Touma2 , X.D. Wang3 , C. K¨uhne1 , M.V. Schmidt3 , W. Wurst1 , F. Holsboer4 , D. Refojo5 , J.M. Deussing1 . 1 Max Planck Institute of Psychiatry, Molecular Neurogenetics, Munich, Germany; 2 Max Planck Institute of Psychiatry, Psychoneuroendocrinology, Munich, Germany; 3 Max Planck Institute of Psychiatry, Neurobiology of Stress, Munich, Germany; 4 Max Planck Institute of Psychiatry, Munich, Germany; 5 Max Planck Institute of Psychiatry, Molecular Neurobiology, Munich, Germany The corticotropin-releasing hormone (CRH) plays a major role in the adjustment of neuroendocrine, autonomic, and behavioural adaptations to stress. Dysregulated and/or hyperactive CRH circuits were shown to be involved in neuroendocrine disturbances in the context of stressrelated disorders such as anxiety and depression. So far little was known about the brain regions and specific CRH-controlled neurotransmitter circuits which modulate anxiety and depression-like behaviour. In this regard, we were recently able to provide a clearer understanding of the interaction of CRH and other neurotransmitter systems by unraveling the identity of anxiety-modulating CRHR1-positive glutamatergic and dopaminergic neurons [1]. Our results provide substantial evidence that anxiety-related behaviour is generated by an imbalance between CRHR1-controlled anxiogenic glutamatergic and anxiolytic dopaminergic systems. However, the identity of CRH-releasing neurons and sites of CRH action have not been fully established yet. We could recently show that CRH overexpression specifically in the forebrain enhances anxiety-related behaviour. In addition, CRH expression in the hippocampus has been assigned to GABAergic interneurons [2] and was shown to increase GABA release in the amygdala and striatum while also affecting excitatory glutamatergic transmission. To assess the effects of CRH hypersecretion specifically in GABAergic neurons of the forebrain we applied a conditional strategy [3] to generate a transgenic mouse model overxpressing CRH selectively in these neurons (CRHCOEGABA ). We investigated neuroendocrine and gene expression alterations and performed a comprehensive behavioural screen of CRH-COEGABA mice. Interestingly, CRH-COEGABA mice displayed significantly decreased anxiety-related behaviour in the open field, elevated plus-maze, and dark-light box test compared to control littermates. These effects were not caused by altered
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Depression: towards new drug targets
basal HPA axis activity, since morning and afternoon corticosterone levels were indistinguishable between CRH-COEGABA and respective control mice. However, CRH overexpression in GABAergic neurons led to a significantly elevated corticosterone response following 10 min of immobilization stress. This might be mediated by the observed increase in endogenous CRH mRNA expression within the central amygdala of CRH-COEGABA mice, which is known to indirectly affect HPA axis activity via the PVN. Additionaly, we detected exogenous CRH expression within the locus coeruleus by means of double in situ hybridization. However, the effects of CRH on anxiety-related behaviour are most likely not mediated by the noradrenergic system since the additional analysis of mice overexpressing CRH only in the mid-/hindbrain area (CRH-COEEn1 ) did not reveal any differences in emotional behaviour. A significant increase in CRH R1 and R2 expression was detected in the hippocampus of CRH-COEGABA mice, which also showed mild deficits in spatial learning evident in prolonged escape latencies during the Morris water-maze task. Future microdialysis experiments will clearify whether CRH overexpression in GABAergic neurons is associated with alterd neurotransmitter release. Although we could show that CRH overexpression in GABAergic neurons leads to decreased anxiety-like behaviour, it remains to be determined which CRH-containing neurons are mediating the anxiogenic effects observed in forebrainspecific CRH overexpressing mice. In conclusion, our results strengthen the hypothesis that CRH hyperactivity, observed in many patients suffering from emotional disorders, might not be general but rather restricted to particular neuronal circuits. Reference(s) [1] Refojo, D., Schweizer, M., Kuehne, C., Ehrenberg, S., Thoeringer, C., Vogl, A.M., Dedic, N., Schumacher, M., von, W.G., Avrabos, C., Touma, C., Engblom, D., Schutz, G., Nave, K.A., Eder, M., Wotjak, C.T., Sillaber, I., Holsboer, F., Wurst, W., and Deussing, J.M., 2011 Glutamatergic and dopaminergic neurons mediate anxiogenic and anxiolytic effects of CRHR1. Science 333, 1903–1907. [2] Chen, Y., Brunson, K.L., Adelmann, G., Bender, R.A., Frotscher, M., and Baram, T.Z., 2004 Hippocampal corticotropin releasing hormone: pre- and postsynaptic location and release by stress. Neuroscience 126, 533– 540. [3] Lu, A., Steiner, M.A., Whittle, N., Vogl, A.M., Walser, S.M., Ableitner, M., Refojo, D., Ekker, M., Rubenstein, J.L., Stalla, G.K., Singewald, N., Holsboer, F., Wotjak, C.T., Wurst, W., and Deussing, J.M.,
2008 Conditional mouse mutants highlight mechanisms of corticotropin-releasing hormone effects on stress-coping behavior. Mol. Psychiatry 13, 1028– 1042.
P.4.014 Deep brain stimulation in treatmentresistant depression in mice C. Dournes1 ° , S. Beesk´e1 , C. Belzung2 , G. Griebel1 . Sanofi Recherche & D´eveloppement, Exploratory Unit, Chilly-Mazarin, France; 2 INSERM U-930, Universit´e Fran¸cois Rabelais UFR Sciences et Techniques, Tours, France
1
Major depressive disorder is a widespread and costly illness, with a prevalence of about 10% worldwide. A variety of treatments is available, but a significant proportion of patients do not achieve sustained symptomatic remission. Indeed, current antidepressants have limited therapeutic efficacy as approximately 30% of patients are treatment-resistant. Deep Brain Stimulation (DBS), which is successfully used in patients with Parkinson’s disease has recently been suggested to represent a possible therapeutic strategy for treatment-resistant depression [1]. It was notably shown that chronic electrical stimulation of white matter tracts adjacent to the subgenual cingulate gyrus resulted in a striking and sustained remission of depression. In this study, we used a modified version of the unpredictable chronic mild stress (UCMS) test, a naturalistic model of depression, to validate highfrequency electrical stimulation of the subgenual cingulate cortex (sgCC, i.e. Brodmann area 25) as a possible treatment to improve behavioral symptoms associated with a depressive-like state (e.g. anxiety, aggressiveness). Male BALB/c mice were subjected to UCMS, which consisted of the sequential and unpredictable application of a variety of mild stressors for a total of 8 weeks. We evaluated on a weekly basis the fur coat, an index of depressive-like state in these animals. From week 3 until the end of week 5 mice received either a saline injection or were treated with the antidepressant fluoxetine. These latter were then subdivided into two groups, i.e. the most responsive to fluoxetine and the less sensitive to the drug, based on their fur coat state. The latter were considered as ‘treatment-resistant’ and were subsequently used for bilateral DBS (at two frequencies 80 or 120 Hz) or were treated with the CRF1 receptor antagonist, SSR125543, based on the idea that the blockade of this receptor may be a possible therapeutic strategy for treatment-resistant patients [2]. Following two weeks of daily 1-h DBS or SSR125543 treatment, mice were tested in a variety
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P.4.013 Assessing CRH-mediated anxiogenic and anxiolytic effects using regionand neurotransmitter-specific CRH overexpressing mice N. Dedic1 ° , M. Ableitner1 , C. Touma2 , X.D. Wang3 , C. K¨uhne1 , M.V. Schmidt3 , W. Wurst1 , F. Holsboer4 , D. Refojo5 , J.M. Deussing1 . 1 Max Planck Institute of Psychiatry, Molecular Neurogenetics, Munich, Germany; 2 Max Planck Institute of Psychiatry, Psychoneuroendocrinology, Munich, Germany; 3 Max Planck Institute of Psychiatry, Neurobiology of Stress, Munich, Germany; 4 Max Planck Institute of Psychiatry, Munich, Germany; 5 Max Planck Institute of Psychiatry, Molecular Neurobiology, Munich, Germany The corticotropin-releasing hormone (CRH) plays a major role in the adjustment of neuroendocrine, autonomic, and behavioural adaptations to stress. Dysregulated and/or hyperactive CRH circuits were shown to be involved in neuroendocrine disturbances in the context of stressrelated disorders such as anxiety and depression. So far little was known about the brain regions and specific CRH-controlled neurotransmitter circuits which modulate anxiety and depression-like behaviour. In this regard, we were recently able to provide a clearer understanding of the interaction of CRH and other neurotransmitter systems by unraveling the identity of anxiety-modulating CRHR1-positive glutamatergic and dopaminergic neurons [1]. Our results provide substantial evidence that anxiety-related behaviour is generated by an imbalance between CRHR1-controlled anxiogenic glutamatergic and anxiolytic dopaminergic systems. However, the identity of CRH-releasing neurons and sites of CRH action have not been fully established yet. We could recently show that CRH overexpression specifically in the forebrain enhances anxiety-related behaviour. In addition, CRH expression in the hippocampus has been assigned to GABAergic interneurons [2] and was shown to increase GABA release in the amygdala and striatum while also affecting excitatory glutamatergic transmission. To assess the effects of CRH hypersecretion specifically in GABAergic neurons of the forebrain we applied a conditional strategy [3] to generate a transgenic mouse model overxpressing CRH selectively in these neurons (CRHCOEGABA ). We investigated neuroendocrine and gene expression alterations and performed a comprehensive behavioural screen of CRH-COEGABA mice. Interestingly, CRH-COEGABA mice displayed significantly decreased anxiety-related behaviour in the open field, elevated plus-maze, and dark-light box test compared to control littermates. These effects were not caused by altered
S94
Depression: towards new drug targets
basal HPA axis activity, since morning and afternoon corticosterone levels were indistinguishable between CRH-COEGABA and respective control mice. However, CRH overexpression in GABAergic neurons led to a significantly elevated corticosterone response following 10 min of immobilization stress. This might be mediated by the observed increase in endogenous CRH mRNA expression within the central amygdala of CRH-COEGABA mice, which is known to indirectly affect HPA axis activity via the PVN. Additionaly, we detected exogenous CRH expression within the locus coeruleus by means of double in situ hybridization. However, the effects of CRH on anxiety-related behaviour are most likely not mediated by the noradrenergic system since the additional analysis of mice overexpressing CRH only in the mid-/hindbrain area (CRH-COEEn1 ) did not reveal any differences in emotional behaviour. A significant increase in CRH R1 and R2 expression was detected in the hippocampus of CRH-COEGABA mice, which also showed mild deficits in spatial learning evident in prolonged escape latencies during the Morris water-maze task. Future microdialysis experiments will clearify whether CRH overexpression in GABAergic neurons is associated with alterd neurotransmitter release. Although we could show that CRH overexpression in GABAergic neurons leads to decreased anxiety-like behaviour, it remains to be determined which CRH-containing neurons are mediating the anxiogenic effects observed in forebrainspecific CRH overexpressing mice. In conclusion, our results strengthen the hypothesis that CRH hyperactivity, observed in many patients suffering from emotional disorders, might not be general but rather restricted to particular neuronal circuits. Reference(s) [1] Refojo, D., Schweizer, M., Kuehne, C., Ehrenberg, S., Thoeringer, C., Vogl, A.M., Dedic, N., Schumacher, M., von, W.G., Avrabos, C., Touma, C., Engblom, D., Schutz, G., Nave, K.A., Eder, M., Wotjak, C.T., Sillaber, I., Holsboer, F., Wurst, W., and Deussing, J.M., 2011 Glutamatergic and dopaminergic neurons mediate anxiogenic and anxiolytic effects of CRHR1. Science 333, 1903–1907. [2] Chen, Y., Brunson, K.L., Adelmann, G., Bender, R.A., Frotscher, M., and Baram, T.Z., 2004 Hippocampal corticotropin releasing hormone: pre- and postsynaptic location and release by stress. Neuroscience 126, 533– 540. [3] Lu, A., Steiner, M.A., Whittle, N., Vogl, A.M., Walser, S.M., Ableitner, M., Refojo, D., Ekker, M., Rubenstein, J.L., Stalla, G.K., Singewald, N., Holsboer, F., Wotjak, C.T., Wurst, W., and Deussing, J.M.,
2008 Conditional mouse mutants highlight mechanisms of corticotropin-releasing hormone effects on stress-coping behavior. Mol. Psychiatry 13, 1028– 1042.
P.4.014 Deep brain stimulation in treatmentresistant depression in mice C. Dournes1 ° , S. Beesk´e1 , C. Belzung2 , G. Griebel1 . Sanofi Recherche & D´eveloppement, Exploratory Unit, Chilly-Mazarin, France; 2 INSERM U-930, Universit´e Fran¸cois Rabelais UFR Sciences et Techniques, Tours, France
1
Major depressive disorder is a widespread and costly illness, with a prevalence of about 10% worldwide. A variety of treatments is available, but a significant proportion of patients do not achieve sustained symptomatic remission. Indeed, current antidepressants have limited therapeutic efficacy as approximately 30% of patients are treatment-resistant. Deep Brain Stimulation (DBS), which is successfully used in patients with Parkinson’s disease has recently been suggested to represent a possible therapeutic strategy for treatment-resistant depression [1]. It was notably shown that chronic electrical stimulation of white matter tracts adjacent to the subgenual cingulate gyrus resulted in a striking and sustained remission of depression. In this study, we used a modified version of the unpredictable chronic mild stress (UCMS) test, a naturalistic model of depression, to validate highfrequency electrical stimulation of the subgenual cingulate cortex (sgCC, i.e. Brodmann area 25) as a possible treatment to improve behavioral symptoms associated with a depressive-like state (e.g. anxiety, aggressiveness). Male BALB/c mice were subjected to UCMS, which consisted of the sequential and unpredictable application of a variety of mild stressors for a total of 8 weeks. We evaluated on a weekly basis the fur coat, an index of depressive-like state in these animals. From week 3 until the end of week 5 mice received either a saline injection or were treated with the antidepressant fluoxetine. These latter were then subdivided into two groups, i.e. the most responsive to fluoxetine and the less sensitive to the drug, based on their fur coat state. The latter were considered as ‘treatment-resistant’ and were subsequently used for bilateral DBS (at two frequencies 80 or 120 Hz) or were treated with the CRF1 receptor antagonist, SSR125543, based on the idea that the blockade of this receptor may be a possible therapeutic strategy for treatment-resistant patients [2]. Following two weeks of daily 1-h DBS or SSR125543 treatment, mice were tested in a variety