Article

Identification of a low-molecular weight TrkB antagonist with anxiolytic and antidepressant activity in mice

Neurobiology and Molecular Pharmacology, Centre de Psychiatrie et Neurosciences, UMR-894 INSERM/Université Paris Descartes, Paris, France.
The Journal of clinical investigation (Impact Factor: 13.22). 05/2011; 121(5):1846-57. DOI: 10.1172/JCI43992
Source: PubMed

ABSTRACT

The neurotrophin brain-derived neurotrophic factor (BDNF) and its receptor tropomyosin-related kinase B (TrkB) have emerged as key mediators in the pathophysiology of several mood disorders, including anxiety and depression. However, therapeutic compounds that interact with TrkB receptors have been difficult to develop. Using a combination of structure-based in silico screening and high-capacity functional assays in recombinant and neuronal cells, we identified a low-molecular weight TrkB ligand (ANA-12) that prevented activation of the receptor by BDNF with a high potency. ANA-12 showed direct and selective binding to TrkB and inhibited processes downstream of TrkB without altering TrkA and TrkC functions. KIRA-ELISA analysis demonstrated that systemic administration of ANA-12 to adult mice decreased TrkB activity in the brain without affecting neuronal survival. Mice administered ANA-12 demonstrated reduced anxiety- and depression-related behaviors on a variety of tests predictive of anxiolytic and antidepressant properties in humans. This study demonstrates that structure-based virtual screening strategy can be an efficient method for discovering potent TrkB-selective ligands that are active in vivo. We further propose that ANA-12 may be a valuable tool for studying BDNF/TrkB signaling and may constitute a lead compound for developing the next generation of therapeutic agents for the treatment of mood disorders.

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Available from: Maxime Cazorla
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    • "As previously described, the newly developed TrkB inhibitor Ana-12 displayed antidepressant properties in the TST when injected acutely (Cazorla et al., 2011), and we found here a comparable effect after chronic administration. These findings with a TrkB antagonist are rather provocative because most of the literature indicated the opposite results after peripheral administration of agonists or central agonist injection directly into the hippocampus (Liu et al., 2010;Shirayama et al., 2002). "
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    ABSTRACT: Growing evidence indicates that impairment of the stress response, in particular the negative feedback regulation mechanism exerted by the hypothalamo-pituitary-adrenal (HPA) axis, might be responsible for the hippocampal atrophy observed in depressed patients. Antidepressants, possibly through the activation of BDNF signaling, may enhance neuroplasticity and restore normal hippocampal functions. In this context, glucocorticoid receptor-impaired (GR-i) mice-a transgenic mouse model of reduced GR-induced negative feedback regulation of the HPA axis-were used to investigate the role of BDNF/TrkB signaling in the behavioral and neurochemical effects of the new generation antidepressant drug, agomelatine. GR-i mice exhibited marked alterations in depressive-like and anxiety-like behaviors, together with a decreased cell proliferation and altered levels of neuroplastic and epigenetic markers in the hippocampus. GR-i mice and their wild-type littermates were treated for 21 days with vehicle, agomelatine (50mg/kg/day; i.p) or the TrkB inhibitor Ana-12 (0.5mg/kg/day, i.p) alone, or in combination with agomelatine. Chronic treatment with agomelatine resulted in antidepressant-like effects in GR-i mice and reversed the deficit in hippocampal cell proliferation and some of the alterations of mRNA plasticity markers in GR-i mice. Ana-12 blocked the effect of agomelatine on motor activity as well as its ability to restore a normal hippocampal cell proliferation and expression of neurotrophic factors. Altogether, our findings indicate that agomelatine requires TrkB signaling to reverse some of the molecular and behavioral alterations caused by HPA axis impairment.
    Full-text · Article · Nov 2015 · European neuropsychopharmacology: the journal of the European College of Neuropsychopharmacology
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    • "A total of 169 Sprague–Dawley rats from 32 L were used. The animals were divided into six groups: (a) normal untreated controls for electrophysiological analyses of NTS VL neuronal development at postnatal days P10-11 (before the critical period), P12-13 (during the critical period), and P14-15 (after the critical period); (b) intraperitoneally (i.p.) injected with 7,8-DHF (dissolved first in 100% DMSO, then diluted in 10% DMSO with 0.1 mol/L phosphate buffer; 5 mg/kg, once a day for 2 days and recorded on the third day before the critical period (P10-11), during the critical period (P12-13), and after the critical period (P14-15); the chosen dosage was based on published work (Jang et al. 2010); (c) littermates of b were i.p. injected with a comparable volume of vehicle (10% DMSO) once a day for 2 days and followed the same regimen as in b; (d) i.p. injected with ANA-12 (dissolved first in 100% DMSO, then diluted sequentially to 10% DMSO with 0.1 mol/L phosphate buffer; 2.46 mmol/kg, once a day at P7, P11, P12, or P15, and the HMs recorded a day after each injection); the chosen dosage was based on published report (Cazorla et al. 2011); (e) littermates of d were i.p. injected with a comparable volume of vehicle following the same regimen ; and (f) electrophysiological study of NTS VL neurons subjected to acute hypoxia (95% N 2 and 5% CO 2 for 5– 6 min) in brain slices at P11 (before the critical period), P13 (during the critical period), and P15 (after the critical period). Hypoxia was 5 min for EPSC and 6 min for IPSC recordings because the peak of IPSCs lagged about 1 min behind that of EPSCs, so the extra min allowed for comparable elapse time after the peak response. "
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    ABSTRACT: The critical period of respiratory development in rats is a narrow window toward the end of the second postnatal week (P12-13), when abrupt neurochemical, electrophysiological, and ventilatory changes occur, when inhibition dominates over excitation, and when the animals' response to hypoxia is the weakest. The goal of this study was to further test our hypothesis that a major mechanism underlying the synaptic imbalance during the critical period is a reduced expression of brain-derived neurotrophic factor (BDNF) and its TrkB receptors. Our aims were to determine (1) that the inhibitory dominance observed in hypoglossal motoneurons during the critical period was also demonstrable in a key respiratory chemosensor, NTSVL; (2) if in vivo application of a TrkB agonist, 7,8-DHF, would prevent, but a TrkB antagonist, ANA-12, would accentuate the synaptic imbalance; and (3) if hypoxia would also heighten the imbalance. Our results indicate that (1) the synaptic imbalance was evident in the NTSVL during the critical period; (2) intraperitoneal injections of 7,8-DHF prevented the synaptic imbalance during the critical period, whereas ANA-12 in vivo accentuated such an imbalance; and (3) acute hypoxia induced the weakest response in both the amplitude and frequency of sEPSCs during the critical period, but it increased the frequency of sIPSCs during the critical period. Thus, our findings are consistent with and strengthen our hypothesis that BDNF and TrkB play a significant role in inducing a synaptic imbalance during the critical period of respiratory development in the rat.
    Preview · Article · Nov 2015
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    • "Animals (n = 5) were sacrificed after 2 h of drug treatment on the 10th day. For the experiments using ANA-12 (0.5 mg/kg; i.p), a TrkB receptor antagonist [19] to verify the role of TrkB in MLT or NAS mediated signalling, following groups were used: (i) only ANA-12 group, 1% ethanol and 50% DMSO (30 min after 50% DMSO treatment) were treated for 9 days and on the 10th day, ANA-12 was injected after 30 min of 1% ethanol; (ii) NAS + ANA-12 group, NAS and 50% DMSO (30 min after NAS treatment) were injected for 9 day and ANA-12 was injected once after 30 min of NAS treatment on the 10th day; (iii) MLT + ANA-12 group, MLT and 50% DMSO (30 min after MLT treatment) were injected for 9 day and ANA-12 was injected once after 30 min of MLT treatment on the 10th day. Animals (n = 5) were sacrificed 4 h of post ANA-12 treatment on the 10th day. "
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    ABSTRACT: Though growing evidence implicates both melatonin (MLT) and its immediate precursor N -acetylserotonin (NAS) in the regulation of hippocampal neurogenesis, their comparative mechanistic relationship with core behavioural correlates of psychiatric disorders is largely unknown. To address this issue, we investigated the ability of these indoleamines to mitigate the behavioral phenotypes associated with NMDA-receptor (NMDAR) hypofunction in mice. We demonstrated that exogenous MLT and NAS treatments attenuated the NMDAR antagonist (ketamine) induced immobility in the forced swim test (FST) but not the classical striatum-related hyperlocomotor activity phenotype. The MLT/NAS-mediated protection of the phenotype in FST could be correlated to the ability of these indoleamines to counteract the deleterious effects of chronic ketamine on pro-survival molecular events by restoring the activities in MEK-ERK and PI3K-AKT pathways in the hippocampus. MLT seems to modulate these pathways by promoting accumulation of the mature form of BDNF above the control (vehicle-treated) levels, perhaps via MLT receptor-dependent mechanisms and in the process overcoming the ketamine-induced down-regulation of BDNF. In contrast, NAS appears to partly restore the ketamine-induced decrease of BDNF to the control levels. In spite of this fundamental difference in modulating BDNF levels in the upstream events, both MLT and NAS seem to overlap in the TrkB-induced downstream pro-survival mechanisms in the hippocampus, providing protection against NMDAR-hypofunction related cellular events. Perhaps, this also signifies the physiological importance of robust MLT synthesizing machinery that converts serotonin to MLT, in ensuring positive impact on hippocampus-related symptoms in psychiatric disorders.
    Full-text · Article · Oct 2015 · Behavioural brain research
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