S 47445 counteracts the behavioral manifestations and hippocampal neuroplasticity changes in bulbectomized mice

S 47445 is a positive allosteric modulator of glutamate AMPA-type receptors that possesses procognitive, neurotrophic and enhancing synaptic plasticity properties. Its chronic administration promotes antidepressant- and anxiolytic-like effects in different rodent models of depression. We have evaluated the behavioral effects of S 47445 in the bilateral olfactory bulbectomy mice model (OB) and the adaptive changes in those proteins associated to brain neuroplasticity (BDNF and mTOR pathway). Following OB surgery, adult C57BL/6J male mice were chronically administered S 47445 (1, 3 and 10?mg/kg/day; i.p.) and fluoxetine (18?mg/kg/day; i.p.), and then behaviorally tested in the open field test. Afterwards, the expression levels of BDNF, mTOR, phospho-mTOR, 4EBP1 and phospho-4EBP1 were evaluated in hippocampus and prefrontal cortex. Both drugs reduced the OB-induced locomotor activity, a predictive outcome of antidepressant efficacy, with a similar temporal pattern of action. S 47445, but not fluoxetine, showed an anxiolytic effect as reflected by an increased central activity. Chronic administration of S 47445 reversed OB-induced changes in BDNF and phopho-mTOR expression in hippocampus but not in prefrontal cortex. The chronic administration of S 47445 induced antidepressant- and anxiolytic-like effects at low-medium doses (1 and 3?mg/kg/day, i.p.) associated with the reversal of OB-induced changes in hippocampal BDNF and mTOR signaling pathways.Funding: This work was supported by the Institut de Recherches Internationales Servier and the Spanish Ministry of Economy and Competitiveness (MINECO/FEDER) (grant number SAF2015-67457-R)

Modulation of neuroplasticity pathways and antidepressant-like behavioural responses following the short-term (3 and 7 days) administration of the 5-HT₄ receptor agonist RS67333.

It has been recently suggested that activation of 5-HT4 receptors might exert antidepressant-like effects in rats after 3 d treatment, suggesting a new strategy for developing faster-acting antidepressants. We studied the effects of 3 d and 7 d treatment with the 5-HT4 receptor partial agonist RS67333 (1.5 mg/kg.d) in behavioural tests of chronic efficacy and on neuroplastic-associated changes, such as adult hippocampal neurogenesis, expression of CREB, BDNF, b-catenin, AKT and 5-HT4 receptor functionality. RS67333 treatment up-regulated hippocampal cell proliferation, b-catenin expression and pCREB/CREB ratio after 3 d treatment. This short-term treatment also reduced immobility time in the forced swim test (FST), together with a partial reversion of the anhedonic-like state (sucrose consumption after chronic corticosterone). Administration of RS67333 for 7 d resulted in a higher increase in the rate of hippocampal cell proliferation, a significant desensitization of 5-HT4 receptor-coupled adenylate cyclase activity and a more marked increase in the expression of neuroplasticity-related proteins (BDNF, CREB, AKT): these changes reached the same magnitude as those observed after 3 wk administration of classical antidepressants. Consistently, a positive behavioural response in the novelty suppressed feeding (NSF) test and a complete reversion of the anhedonic-like state (sucrose consumption) were also observed after 7 d treatment. These results support the antidepressant-like profile of RS67333 with a shorter onset of action and suggest that this time period of administration (3–7 d) could be a good approximation to experimentally predict the onset of action of this promising strategy

The absence of 5-HT4 receptors modulates depression- and anxiety-like responses and influences the response of fluoxetine in olfactory bulbectomised mice: Adaptive changes in hippocampal neuroplasticity markers and 5-HT1A autoreceptor

reclinical studies support a critical role of 5-HT4 receptors (5-HT4Rs) in depression and anxiety, but their influence in depression- and anxiety-like behaviours and the effects of antidepressants remain partly unknown. We evaluated 5-HT4R knockout (KO) mice in different anxiety and depression paradigms and mRNA expression of some neuroplasticity markers (BDNF, trkB and Arc) and the functionality of 5-HT1AR. Moreover, the implication of 5-HT4Rs in the behavioural and molecular effects of chronically administered fluoxetine was assessed in naïve and olfactory bulbectomized mice (OBX) of both genotypes. 5-HT4R KO mice displayed few specific behavioural impairments including reduced central activity in the open-field (anxiety), and decreased sucrose consumption and nesting behaviour (anhedonia). In these mice, we measured increased levels of BDNF and Arc mRNA and reduced levels of trkB mRNA in the hippocampus, and a desensitization of 5-HT1A autoreceptors. Chronic administration of fluoxetine elicited similar behavioural effects in WT and 5-HT4R KO mice on anxiety-and depression-related tests. Following OBX, locomotor hyperactivity and anxiety were similar in both genotypes. Interestingly, chronic fluoxetine failed to reverse this OBX-induced syndrome in 5-HT4R KO mice, a response associated with differential effects in hippocampal neuroplasticity biomarkers. Fluoxetine reduced hippocampal Arc and BDNF mRNA expressions in WT but not 5-HT4R KO mice subjected to OBX. These results demonstrate that the absence of 5-HT4Rs triggers adaptive changes that could maintain emotional states, and that the behavioural and molecular effects of fluoxetine under pathological depression appear to be critically dependent on 5-HT4RsThis research was supported by Spanish Ministry of Economy and Competitiveness (SAF2011-25020), and Centro de Investigación Biomédica en Red de Salud Mental (CIBERSAM)

Neural plasticity and proliferation in the generation of antidepressant effects: hippocampal implication

It is widely accepted that changes underlying depression and antidepressant-like effects involve not only alterations in the levels of neurotransmitters as monoamines and their receptors in the brain, but also structural and functional changes far beyond. During the last two decades, emerging theories are providing new explanations about the neurobiology of depression and the mechanism of action of antidepressant strategies based on cellular changes at the CNS level. The neurotrophic/plasticity hypothesis of depression, proposed more than a decade ago, is now supported by multiple basic and clinical studies focused on the role of intracellular-signalling cascades that govern neural proliferation and plasticity. Herein, we review the state-of-the-art of the changes in these signalling pathways which appear to underlie both depressive disorders and antidepressant actions. We will especially focus on the hippocampal cellularity and plasticity modulation by serotonin, trophic factors as brain-derived neurotrophic factor (BDNF), and vascular endothelial growth factor (VEGF) through intracellular signalling pathways-cAMP, Wnt/ β -catenin, and mTOR. Connecting the classic monoaminergic hypothesis with proliferation/neuroplasticity-related evidence is an appealing and comprehensive attempt for improving our knowledge about the neurobiological events leading to depression and associated to antidepressant therapies

Enhanced Stress Response in 5-HT1AR Overexpressing Mice: Altered HPA Function and Hippocampal Long-Term Potentiation

Postsynaptic 5-HT1A receptors (5-HT1AR) play an important role in anxiety and stress, although their contribution is still controversial. Previous studies report that mice overexpressing postsynaptic 5-HT1ARs show no changes in basal anxiety, though the influence of stress conditions has not been addressed yet. In this study, we used this animal model to evaluate the role of 5-HT1ARs in anxiety response after pre-exposure to an acute stressor. Under basal conditions, 5-HT1AR overexpressing animals presented high corticosterone levels and a lower mineralocorticoid/ glucocorticoid receptor ratio. After pre-exposure to a single stressor, they showed a high anxiety-like response, associated with a blunted increase in corticosterone levels and higher c-Fos activation in the prefrontal cortex. Moreover, these mice also presented a lack of downregulation of hippocampal long-term potentiation after stress exposure. Therefore, higher postsynaptic 5-HT1AR activation might predispose to a high anxious phenotype and an impaired stress coping behavior.Funding sources: This research was supported by Spanish Ministry of Economy and Competitiveness (SAF2011-25020 and SAF2015-67457-R), Instituto de Salud Carlos III (FIS Grant PI13-00038) co-funded by the European Regional Development Fund (‘A way to buildEurope’) and Centro de Investigacion Biomedica en Red de Salud Mental(CIBERSAM)

Dopaminergic control of ADAMTS2 expression through cAMP/CREB and ERK: molecular effects of antipsychotics

A better understanding of the molecular mechanisms that participate in the development and clinical manifestations of schizophrenia can lead to improve our ability to diagnose and treat this disease. Previous data strongly associated the levels of deregulated ADAMTS2 expression in peripheral blood mononuclear cells (PBMCs) from patients at first episode of psychosis (up) as well as in clinical responders to treatment with antipsychotic drugs (down). In this current work, we performed an independent validation of such data and studied the mechanisms implicated in the control of ADAMTS2 gene expression. Using a new cohort of drug-naïve schizophrenia patients with clinical follow-up, we confirmed that the expression of ADAMTS2 was highly upregulated in PBMCs at the onset (drug-naïve patients) and downregulated, in clinical responders, after treatment with antipsychotics. Mechanistically, ADAMTS2 expression was activated by dopaminergic signalling (D1-class receptors) and downstream by cAMP/CREB and mitogen-activated protein kinase (MAPK)/ERK signalling. Incubation with antipsychotic drugs and selective PKA and MEK inhibitors abrogated D1-mediated activation of ADAMTS2 in neuronal-like cells. Thus, D1 receptors signalling towards CREB activation might participate in the onset and clinical responses to therapy in schizophrenia patients, by controlling ADAMTS2 expression and activity. The unbiased investigation of molecular mechanisms triggered by antipsychotic drugs may provide a new landscape of novel targets potentially associated with clinical efficacy.Acknowledgements: We are highly indebted to the participants and their families for their cooperation in this study. We also thank IDIVAL biobank (Inés Santiuste and Jana Arozamena) for clinical samples and data as well as the PAFIP members (Marga Corredera) for the data collection. This work was supported by: SAF2016-76046-R and SAF2013-46292-R (MINECO and FEDER) to B.C.F., PI16/00156 (isciii and FEDER) to J.P.V., LUCHAMOS POR LA VIDA project to F.R.J. and J.P.V., SAF2017-83702-R (MINECO and FEDER), Red TERCEL RD12/0019/0024 (ISCIII) and GVA-PROMETEO 2018/041 (Generalitat Valenciana) to S.M. J.P.V. is supported by the RyC research programme (RYC-2013-14097) and F.R.J. by the predoctoral research programme (BES-2014-070615), from MINECO and FEDER

Dopaminergic control of ADAMTS2 expression through cAMP/CREB and ERK: molecular effects of antipsychotics

© The Author(s) 2019.A better understanding of the molecular mechanisms that participate in the development and clinical manifestations of schizophrenia can lead to improve our ability to diagnose and treat this disease. Previous data strongly associated the levels of deregulated ADAMTS2 expression in peripheral blood mononuclear cells (PBMCs) from patients at first episode of psychosis (up) as well as in clinical responders to treatment with antipsychotic drugs (down). In this current work, we performed an independent validation of such data and studied the mechanisms implicated in the control of ADAMTS2 gene expression. Using a new cohort of drug-naïve schizophrenia patients with clinical follow-up, we confirmed that the expression of ADAMTS2 was highly upregulated in PBMCs at the onset (drug-naïve patients) and downregulated, in clinical responders, after treatment with antipsychotics. Mechanistically, ADAMTS2 expression was activated by dopaminergic signalling (D1-class receptors) and downstream by cAMP/CREB and mitogen-activated protein kinase (MAPK)/ERK signalling. Incubation with antipsychotic drugs and selective PKA and MEK inhibitors abrogated D1-mediated activation of ADAMTS2 in neuronal-like cells. Thus, D1 receptors signalling towards CREB activation might participate in the onset and clinical responses to therapy in schizophrenia patients, by controlling ADAMTS2 expression and activity. The unbiased investigation of molecular mechanisms triggered by antipsychotic drugs may provide a new landscape of novel targets potentially associated with clinical efficacy.This work was supported by: SAF2016-76046-R and SAF2013-46292-R (MINECO and FEDER) to B.C.F., PI16/00156 (isciii and FEDER) to J.P.V., LUCHAMOS POR LA VIDA project to F.R.J. and J.P.V., SAF2017-83702-R (MINECO and FEDER), Red TERCEL RD12/0019/0024 (ISCIII) and GVA-PROMETEO 2018/041 (Generalitat Valenciana) to S.M. J.P.V. is supported by the RyC research programme (RYC-2013-14097) and F.R.J. by the predoctoral research programme (BES-2014-070615), from MINECO and FEDER

Chronic treatment with the opioid antagonist naltrexone favours the coupling of spinal cord μ-opioid receptors to Gα z protein subunits

Trabajo presentado a la II Reunión Científica Conjunta de la Red de Trastornos Adictivos-Sociedad Española de Neurociencia-Cibersam celebrada en Salamanca del 27 al 28 de septiembre de 2011.-- El pdf es el manuscrito de autor.-- et al.Sustained administration of opioid antagonists to rodents results in an enhanced antinociceptive response to agonists. We investigated the changes in spinal μ-opioid receptor signalling underlying this phenomenon. Rats received naltrexone (120 μg/h; 7 days) via osmotic minipumps. The antinociceptive response to the μ-agonist sufentanil was tested 24 h after naltrexone withdrawal. In spinal cord samples, we determined the interaction of μ-receptors with Gα proteins (agonist-stimulated [ 35S] GTPγS binding and immunoprecipitation of [ 35S]GTPγS- labelled Gα subunits) as well as μ-opioid receptor-dependent inhibition of the adenylyl cyclase (AC) activity. Chronic naltrexone treatment augmented DAMGO-stimulated [ 35S]GTPγS binding, potentiated the inhibitory effect of DAMGO on the AC/cAMP pathway, and increased the inverse agonist effect of naltrexone on cAMP accumulation. In control rats, the inhibitory effect of DAMGO on cAMP production was antagonized by pertussis toxin (PTX) whereas, after chronic naltrexone, the effect became resistant to the toxin, suggesting a coupling of μ-receptors to PTX-insensitive Gα z subunits. Immunoprecipitation assays confirmed the transduction switch from Gα i/o to Gα z proteins. The consequence was an enhancement of the antinociceptive response to sufentanil that, in consonance with the neurochemical data, was prevented by Gα z-antisense oligodeoxyribonucleotides but not by PTX. Such changes in opioid receptor signalling can be a double-edged sword. On the one hand, they may have potential applicability to the optimisation of the analgesic effects of opioid drugs for the control of pain. On the other hand, they represent an important homeostatic dysregulation of the endogenous opioid system that might account for undesirable effects in patients chronically treated with opioid antagonists. © 2011 Elsevier Ltd. All rights reserved.This work was supported by grants from: Instituto de Salud Carlos III (RTICS: RD06/001/1016 and RD06/001/1006) and Ministerio de Ciencia e Innovación (SAF2007/65451, SAF2007/61862 and SAF2010/16894).Peer reviewe

Long-term efficacy of antidepressants: Analyzing brain adaptive modifications

The regulatory changes induced by chronic antidepressants oil the different brain signalling process has been the subject of study ill Our group. We here review some of the results oil this topic. On one side, our efforts have been addressed to the Study of the coupling of 5-HT(1) receptors to G proteins: we have demonstrated that 5-HT(1A) autoreceptors tire selectively desensitized by chronic fluoxetine, suggesting that this could be one of the reasons of the delayed response antidepressants. A functional desensitization of 5-HT(1B) receptors has been also found. Oil the other hand, we have focused oil the mechanisms involved in neural proliferation. studying two possible new targets: a) the endocannabinoid system, as we have observed a functional up-regulation of CB(1) receptor functionality in all animal model of depression (olfactory bulbectomy), reversed by fluoxetine and b) the Wnt-beta-catenin pathway: an up-regulation of the expression of beta-catenin in hippocampus. in parallel with,in increase of cell proliferation. has been observed in the hippocampus of rats treated with venlafaxine. Taken together, these results provide valuable information about the involvement of transductional pathways in the mediation of the effects of antidepressant drugs.The results reviewed in this contribution have been supported by the Spaniard Ministry of Science (SAF04-00941 and SAF07-61862).Peer Reviewe

TGF-β and opioid receptor signaling crosstalk results in improvement of endogenous and exogenous opioid analgesia under pathological pain conditions

Transforming growth factor-β1 (TGF-β1) protects against neuroinflammatory events underlying neuropathic pain. TGF-β signaling enhancement is a phenotypic characteristic of mice lacking the TGF-β pseudoreceptor BAMBI (BMP and activin membrane-bound inhibitor), which leads to an increased synaptic release of opioid peptides and to a naloxone-reversible hypoalgesic/antiallodynic phenotype. Herein, we investigated the following: (1) the effects of BAMBI deficiency on opioid receptor expression, functional efficacy, and analgesic responses to endogenous and exogenous opioids; and (2) the involvement of the opioid system in the antiallodynic effect of TGF-β1. BAMBI-KO mice were subjected to neuropathic pain by sciatic nerve crash injury (SNI). Gene (PCR) and protein (Western blot) expressions of μ- and δ-opioid receptors were determined in the spinal cord. The inhibitory effects of agonists on the adenylyl cyclase pathway were investigated. Two weeks after SNI, wild-type mice developed mechanical allodynia and the functionality of μ-opioid receptors was reduced. By this time, BAMBI-KO mice were protected against allodynia and exhibited increased expression and function of opioid receptors. Four weeks after SNI, when mice of both genotypes had developed neuropathic pain, the analgesic responses induced by morphine and RB101 (an inhibitor of enkephalin-degrading enzymes, which increases the synaptic levels of enkephalins) were enhanced in BAMBI-KO mice. Similar results were obtained in the formalin-induced chemical-inflammatory pain model. Subcutaneous TGF-β1 infusion prevented pain development after SNI. The antiallodynic effect of TGF-β1 was naloxone-sensitive. In conclusion, modulation of the endogenous opioid system by TGF-β signaling improves the analgesic effectiveness of exogenous and endogenous opioids under pathological pain conditions.This work was supported by Ministerio de Ciencia e Innovacio´n Grant SAF2010-16894, Fundacio´ La Marato´ de TV3 Grant 072131, Instituto de Salud Carlos III Grant RTICS:RD06/001/1016, and Sociedad Espan˜ola de Farmacología and Laboratorios Almirall-Prodesfarm