P.2.a. Mood disorders and treatment − Affective disorders (basic) P.2.a.007 5-HT1B receptors play a key role in modulation of pattern separation performance and hedonic state of old mice D. Felice1 ° , J.P. Guilloux1 , Y. Li2 , A.L. Pehrson2 , I. MendezDavid1 , A.M. Gardier1 , C. S´anchez2 , D.J. David1 1 Universit´e Paris-Sud EA 3544, Facult´e de Pharmacie, Chatenay-Malabry Cedex F-92296, France; 2 Lundbeck Research USA, Inc. 215 College Road 07652, Paramus NJ, USA Purpose: Even though the association of depression and anxiety disorders with cognitive impairment is a common health problem in the elderly population, few preclinical investigations have focused on integrated studies of depression/anxiety-related behaviors and cognitive functions in old animals. Rodent studies indicate that the 5-HT1B receptor is implicated in aging [1], depression [2] and adult hippocampal neurogenesis, the later being a candidate mechanism for antidepressant action and cognitive function [3]. The pattern separation (PS) paradigm is a neurogenesisdependent cognitive task. The aim of the present study is to investigate the effects of the 5-HT1B receptor agonist, CP94253, in anxiety/depression related behaviors and performance in the PS paradigm of old mice and to compare the behavioral phenotype of old to young mice. Methods: 18-months old C57 male mice administered with CP94253 (20 mg/kg/day, p.o. for 3 weeks, n = 7) or vehicle (n = 10) were tested in anxiety/depression related behaviors (open field, OF; elevated plus maze, EPM; novelty suppressed feeding, NSF, saccharin preference test, SPT) and the PS paradigm. In the PS paradigm, mice were trained to discriminate between two similar contexts (A and B). The shock associated training context A and the similar (no-shock) context B shared many features. A group of ten 2-months old mice was used as control. The level of 5-HT1B receptor occupancy after chronic treatment with CP94253 was determined 24 hrs after last dose administration by means of ex vivo autoradiography displacing 3H-GR125743. Results: Aged mice were more anxious than young mice in the OF (center/total distance; p < 0.05) and EPM (time in open arms, p < 0.05) tests. There were no differences in the NSF and SPT tests. In PS, young mice discriminated context A from context B from Day 6, whereas old mice discriminated from Day 12. Chronic treatment with CP94253 induced an anhedoniclike behavior measured as decreased preference for saccharin consumption (p < 0.001, SPT test); had no effects in the OF, EPM and NSF tests. Interestingly, CP94253 improved age-induced PS deficits with significant discrimination from Day 9 (p < 0.05). The ex vivo autoradiography study showed that this pharmacologically active dose of CP94253 corresponded to approximately 50% occupancy of the 5-HT1B receptors. Conclusion: Our study showed an anxious phenotype and impaired performance in a neurogenesis-dependent PS task of old compared to young mice. Chronic treatment with CP94253 reversed age-induced deficits in PS, suggesting a key role of 5-HT1B receptors in this task and therefore, possibly also for neurogenesis. Moreover, our results suggest a role of 5-HT1B receptors in anhedonia, a core symptom of depression. However, further studies are needed to substantiate these findings (e.g. behavioral effects of CP94253 in young mice and effect on hippocampal neurogenesis). Ongoing experiments are evaluating the effect of 5-HT1B receptor deletion in knockout mice in pattern separation. This study furthers our understanding of
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depression/anxiety disorders and dementia in aged population and can bring new insights that can impact drug development. References [1] David DJ, Bourin M, Hascoet M, Colombel MC, Baker GB, Jolliet P (2001) Comparison of antidepressant activity in 4- and 40-week-old male mice in the forced swimming test: involvement of 5-HT1A and 5-HT1B receptors in old mice. Psychopharmacology (Berl) 153:443– 449. [2] Sibille E, Su J, Leman S, Le Guisquet AM, Ibarguen-Vargas Y, JoeyenWaldorf J, Glorioso C, Tseng GC, Pezzone M, Hen R, Belzung C (2007) Lack of serotonin1B receptor expression leads to age-related motor dysfunction, early onset of brain molecular aging and reduced longevity. Mol Psychiatry 12:1042–1056, 1975. [3] Xia L, Delomenie C, David I, Rainer Q, Marouard M, Delacroix H, David DJ, Gardier AM, Guilloux JP (2012) Ventral hippocampal molecular pathways and impaired neurogenesis associated with 5-HT(1)A and 5-HT(1)B receptors disruption in mice. Neuroscience letters 521:20−25. Disclosure statement: This abstract is financially supported by Lundbeck Research USA, Inc.
P.2.a.008 Correlation between levels of Akt1/GSK-3b signaling pathway proteins and severity of depressive symptoms N.A. Bokhan1 ° , I.S. Losenkov2 , N.M. Vyalova2 , G.G. Simutkin3 , S.A. Ivanova2 1 Mental Health Research Institute, Addictive States Department, Tomsk, Russia; 2 Mental Health Research Institute, Biological Psychiatry Department, Tomsk, Russia; 3 Mental Health Research Institute, Affective States Department, Tomsk, Russia Purpose of the study: Akt1/GSK-3b signaling pathway is an important part of neuron functioning involved in regulation of various cell processes such as serotonin and dopamine signal transduction, neurodegeneration, synaptic plasticity, growth and death of neurons, forming neuronal polarity [1,2]. Since discovering ability of lithium to inhibit GSK-3, great number of studies was dedicated to investigation of the involvement of Akt1/GSK-3b signaling pathway proteins in affective disorders pathogenesis. However, there is a small data concerning its role in clinical polymorphism of affective pathology [3]. The purpose of our study was to investigate correlation between severity of depression and levels of total Akt1and total GSK-3b, phospho-serine-473 Akt1 and phospho-serine-9 GSK-3b in peripheral blood mononuclear cells (PBMCs) of patients with depressive disorders. Methods: Group of 44 patients with depressive disorders [26 with depressive episode (ICD-10: F32) and 18 with recurrent depressive disorder (ICD-10: F33)] was included into the study. Severity of depressive symptoms was evaluated using SIGH-SAD scale (contained 17 items for typical and 7 items for atypical symptoms) at baseline and after 14 and 28 days of treatment with SSRIs. Venous blood was taken at baseline and then used for PBMCs extraction. Immublotting was used for detection of total Akt1, total GSK-3b, phospho-serine-473 Akt1 and phosphoserine-9 GSK-3b in cells. Levels of total GSK-3b and total GSK-3b were calculated in ratio to b-actin. Levels of phosphoserine-473 Akt1and phospho-serine-9 GSK-3b were calculated in ratio to total levels of Akt1 and GSK-3b, respectively. Statistical analysis was performed using SPSS software (v. 20.0), significance was set at p < 0.05. Mann–Whitney U-test was used for comparison between groups. Spearman’s rank correlation test was used for correlation assessment.
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Results: The study showed difference in total GSK-3b between two groups of patients. Level of this protein was higher in cells of recurrent depressive disorder patients than in group of patients with depressive episode (P = 0.042). No difference between levels of total Akt1, phospho-serine-473 Akt1 and phospho-serine-9 GSK-3b was observed (p < 0.01). Also no difference was observed between groups in SIGH-SAD total score, score for typical and for atypical symptoms at baseline, after 14 and 28 days of treatment (p < 0.01). Several significant correlations were found. Patients with recurrent depression showed correlation of total GSK-3b level with total score at baseline (r = 0.601, p = 0.039). Correlation between total score at 14 of therapy and levels of phospho-serine-9 GSK-3b was found (r = −0.441, p = 0.035) in the group of patients with depressive episode. For total Akt1 levels no correlation was observed. Levels of phospho-serine-473 Akt1 were negatively correlated with score for typical symptoms for the patients with depressive episode (r = −0.622, p = 0.001) after 14 days of therapy and for the patients with recurrent depression (r = −0.880, p = 0.021) after 28 days of therapy. Conclusions: Thus, our study demonstrated that levels of Akt1/GSK-3b signaling pathway proteins in PMBCs of patients with depressive disorders correlate with SIGH-SAD score as at baseline and after therapy. Also it was found that patients with recurrent depressive disorder have higher total GSK-3b. References [1] Beaulieu, J.M., 2011 A role for Akt and glycogen synthase kinase-3 as integrators of dopamine and serotonin neurotransmission in mental health. Journal of Psychiatry Neuroscience 37, 9−16. [2] Salcedo-Tello, P., Ortiz-Matamoros A., Arias C., 2011 GSK3 function in the brain during development, neuronal plasticity, and neurodegeneration. International Journal of Alzheimer’s Disease 11, 1−12. [3] Li, X., Jope R., 2010 Is glycogen synthase kinase-3 a central modulator in mood regulation? Neuropsychopharmacology 35, 2143–2154.
P.2.a.009 Disturbances of circadian rhythm in a rat chronic mild stress model of depression
In our hands, the CMS model has additional features that enhance its validity. Thus rats show a graduated response to stress; a substantial fraction of animals submitted to stress are resilient and do not become anhedonia-like, but do have stress-induced cognitive impairments [2]. Furthermore antidepressant administration reverses stress-induced anhedonia only in approximately 50% of the treated animals, which mirrors clinical treatment refraction and is thus adding additional translational value to the CMS model. Depression-like and control rats were terminated by decapitation in a 24 h timespan and the brain removed from skull. Quantification and visualization of CGs in the brain were established by the in situ hybridization method. Results: We studied three of the most essential clock genes, Per1, Per2 and Bmal1, and found that depression-like animals showed an abnormal CR in subregions of the rat brains related to depression; Expression of Per1 showed a significantly robust CR in the SCN, the hippocampus and the pineal gland. In the SCN a significantly robust CR of Per1, Per2 and Bmal1 is shown. As for Per2 and Bmal1, a shift in phase has been observed in the SCN. Furthermore, a significantly different expression of Per1 and Per2 is measured between CMS susceptible rats and control rats in the hippocampus. Expression of clock genes in the Pineal gland are not affected by stress induced depression. Conclusion: We conclude that abnormalities in CRs are related to depression-like state in the CMS model. However, the effect of chronic stress is selective; Per1 expresses a robust CR in the master clock and in two other brain structures related to depression. However, Per2 and Bmal1 expression might be more susceptible and responsive to chronic stress induced depression. References [1] Wiborg, O., 2013. Chronic mild stress for modeling anhedonia. Cell & Tissue Research Special Issue, 354, 155−69. [2] Henningsen, K, Woldbye DPD, Wiborg, O., 2013. Electroconvulsive stimulation reverses anhedonia and cognitive impairments in rats exposed to chronic mild stress. Eur. Neuropsychopharm., 23, 1789−94.
O. Wiborg1 ° , S. Christiansen1 , K. Højgaard1 , J. Fahrenkrug2 , E.V. Bouzinova1 1 Aarhus University, Clinical Medicine, Aarhus, Denmark; 2 Bispebjerg Hospital, Clinical Biochemistry, Copenhagen NV, Denmark
P.2.a.010 Buprenorphine in combination with samidorphan (ALKS 33) results in antidepressive-like effects in two distinct rat models
Objectives: It has been suggested that abnormalities in circadian rhythm (CR) may be a causal factor in the development of major depressive disorder (MDD). Blunted or abnormal CR has been found in depressed individuals in a variety of body functions including sleep/wake pattern, body temperature and hormone secretion. The suprachiasmatic nucleus (SCN) is well known for its function as the master clock and regulates several circadian systems by clock genes (CG) expression. In addition to central expression, peripheral CGs have been found. The aim of this project is to provide new insights into the pathology and etiology of (MDD) and to find new molecular targets focusing on the CR. Methods: The study is based on an extensively validated animal model of depression, the chronic mild stress model (CMS). Chronic mild stress model is a valid rat model of depression. Chronic exposure to mild and unpredictable stressors induces an anhedonic-like state, which is monitored as a reduced intake of a sucrose solution. Anhedonic-like behavior can be reversed by chronic treatment with antidepressant drugs [1].
M.S. Todtenkopf1 ° , R.L. Dean1 , D.J. Eyerman1 , J.I. Cunningham1 , D.R. Deaver1 1 Alkermes Inc., Life Sciences and Toxicology, Waltham, USA ALKS 5461 represents a novel treatment for depression that combines buprenorphine (a partial mu agonist) with samidorphan (a potent full mu antagonist), formerly referred to as ALKS 33. In a recent phase 2 clinical trial in Major Depressive Disorder, ALKS 5461 was superior to placebo on a range of depressive symptoms. There is a substantial body of nonclinical and pharmacologic research indicating that endogenous opioid systems regulate mood and are dysregulated in patients with depressive illness [1,2]. Additionally, opioid receptors and their endogenous ligands are expressed in areas of the brain that have been associated with regulating mood and depression, including the nucleus accumbens, prefrontal cortex, hippocampus, thalamus, caudate and amygdala [3]. Unfortunately, the use of mu opioid agonists for the treatment of CNS diseases and mood disorders such as Major Depressive Disorder has been hampered by their abuse liability