50 years of hurdles and hope in anxiolytic drug discovery

Griebel, Guy; Holmes, Andrew

doi:10.1038/nrd4075

Cited by 383 publications

(365 citation statements)

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“…In the search for better antidepressants, much attention has focused on neuropeptides and their receptors, the most diverse neurotransmitter system in the brain (8,(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21), which includes galanin. As yet, however, there is no compelling evidence of efficacy of the neuropeptide approach or that particular peptides are involved in the pathogenesis of MDD.…”

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confidence: 99%

Brain galanin system genes interact with life stresses in depression-related phenotypes

Juhász

Hullám

Eszlári

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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Galanin is a stress-inducible neuropeptide and cotransmitter in serotonin and norepinephrine neurons with a possible role in stress-related disorders. Here we report that variants in genes for galanin (GAL) and its receptors (GALR1, GALR2, GALR3), despite their disparate genomic loci, conferred increased risk of depression and anxiety in people who experienced childhood adversity or recent negative life events in a European white population cohort totaling 2,361 from Manchester, United Kingdom and Budapest, Hungary. Bayesian multivariate analysis revealed a greater relevance of galanin system genes in highly stressed subjects compared with subjects with moderate or low life stress. Using the same method, the effect of the galanin system genes was stronger than the effect of the well-studied 5-HTTLPR polymorphism in the serotonin transporter gene (SLC6A4). Conventional multivariate analysis using general linear models demonstrated that interaction of galanin system genes with life stressors explained more variance (1.7%, P = 0.005) than the life stress-only model. This effect replicated in independent analysis of the Manchester and Budapest subpopulations, and in males and females. The results suggest that the galanin pathway plays an important role in the pathogenesis of depression in humans by increasing the vulnerability to early and recent psychosocial stress. Correcting abnormal galanin function in depression could prove to be a novel target for drug development. The findings further emphasize the importance of modeling environmental interaction in finding new genes for depression.galanin receptors | mood disorders | network-based analysis | neurogenesis | transmitter coexistence M ajor depressive disorder (MDD) is a common and serious disease afflicting more women than men, and a leading cause of disability worldwide, associated with much suffering and major costs for society (1, 2). Environmental psychosocial stressors are important in pathogenesis, because episodes are usually preceded by adverse life events, and early childhood experiences of physical and emotional abuse and parental neglect are important vulnerability factors (3, 4). Genetic vulnerability is significant with a heritability of about 35% (5). We remain ignorant about the brain processes that translate these genetic and environmental influences into depressive symptoms or risk. A major clue is that effective antidepressant drugs act directly or indirectly to enhance neurotransmission in serotonin (5-HT) and norepinephrine monoamine pathways, proving the monoamine hypothesis of depression (6-8). Many other candidate mechanisms have been identified in anatomical, pharmacological, and behavioral studies of stress in rodents. However, the demonstration of stateor trait-related abnormalities in human monoamine or other neural systems remains frustratingly elusive, despite modern brain-imaging methods. To determine whether the neuropeptide galanin has a role in depression, we used a unique Bayesian systems-based analysis to dissect out the influ...

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confidence: 99%

Brain galanin system genes interact with life stresses in depression-related phenotypes

Juhász

Hullám

Eszlári

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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“…Therefore, there is an ongoing search for new medications targeting mood disorders, such as MD and anxiety. Here, neuropeptides and their receptors, the most diverse family of neurotransmitters in the brain (7), have been extensively explored (5,(8)(9)(10)(11)(12)(13)(14)(15)(16)(17), including galanin and its three receptors.Galanin is a 29-aa (30-aa in humans) neuropeptide (18) with a wide distribution in the rat brain (19,20), where it is coexpressed with noradrenaline/norepinephrine (NA) in locus coeruleus (LC) neurons and with 5-hydroxytryptamine (5-HT) in dorsal raphe nucleus (DR) neurons (21-25). There are three galanin receptors, GALR1-GALR3, which all belong to the family of seven transmembrane-spanning, G protein-coupled receptors (26-29).…”

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confidence: 99%

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confidence: 99%

Depression-like behavior in rat: Involvement of galanin receptor subtype 1 in the ventral periaqueductal gray

Wang

Barde

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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The neuropeptide galanin coexists in rat brain with serotonin in the dorsal raphe nucleus and with noradrenaline in the locus coeruleus (LC), and it has been suggested to be involved in depression. We studied rats exposed to chronic mild stress (CMS), a rodent model of depression. As expected, these rats showed several endophenotypes relevant to depression-like behavior compared with controls. All these endophenotypes were normalized after administration of a selective serotonin reuptake inhibitor. The transcripts for galanin and two of its receptors, galanin receptor 1 (GALR1) and GALR2, were analyzed with quantitative real-time PCR using laser capture microdissection in the following brain regions: the hippocampal formation, LC, and ventral periaqueductal gray (vPAG). Only Galr1 mRNA levels were significantly increased, and only in the latter region. After knocking down Galr1 in the vPAG with an siRNA technique, all parameters of the depressive behavioral phenotype were similar to controls. Thus, the depression-like behavior in rats exposed to CMS is likely related to an elevated expression of Galr1 in the vPAG, suggesting that a GALR1 antagonist could have antidepressant effects.dorsal raphe | neuropeptide | siRNA | stress | transmitter coexistence T he indoleamine hypothesis of depression was formulated some five decades ago (1, 2), in parallel with the catecholamine hypothesis (3, 4), and has been supported by the success of selective serotonin reuptake inhibitors (SSRIs) for treatment of major depression (MD) (5). However, in a considerable number of cases, SSRIs are associated with side effects or lack of efficacy. For example, after treatment with SSRIs, only one-third of patients obtain full remission of symptoms (6). Therefore, there is an ongoing search for new medications targeting mood disorders, such as MD and anxiety. Here, neuropeptides and their receptors, the most diverse family of neurotransmitters in the brain (7), have been extensively explored (5,(8)(9)(10)(11)(12)(13)(14)(15)(16)(17), including galanin and its three receptors.Galanin is a 29-aa (30-aa in humans) neuropeptide (18) with a wide distribution in the rat brain (19,20), where it is coexpressed with noradrenaline/norepinephrine (NA) in locus coeruleus (LC) neurons and with 5-hydroxytryptamine (5-HT) in dorsal raphe nucleus (DR) neurons (21-25). There are three galanin receptors, GALR1-GALR3, which all belong to the family of seven transmembrane-spanning, G protein-coupled receptors (26-29). They are found in many areas of the rat brain, as first shown with autoradiographic ligand-binding methodology (30, 31), and later with in situ hybridization (ISH)/quantitative real-time PCR (qPCR) (32-36). The galanin system has been associated with numerous physiological and pathophysiological functions (29), including depression-and anxiety-like behaviors.There is early evidence from studies on the rat that central administration of galanin influences mood-related behavior in a region-specific way (37, 38), and also that galanin is prodepres...

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“…The test battery employed here showed to be adequate, since the classical anxiolytic, diazepam, exhibited its typical effects in the Openfield and Elevated plus-maze tests which are best experimental methods for the measurement of anxiety, because they are typically assessed by measuring the repeated decrease in a fear-related behavior in a context environmental -for example, freezing and elevation to the floor (Griebel & Holmes, 2013;Mansouri et al, 2014).…”

Section: Discussionmentioning

confidence: 99%

Anxiolytic-like effect of Citrus limon (L.) Burm f. essential oil inhalation on mice

Viana

Cardoso

Silva

et al. 2016

Rev. bras. plantas med.

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Experimental in vivo study aimed to characterize the anxiolytic-like effect of the Citrus limon fruit peel's essential oil (CLEO) in animal models of anxiety, besides evaluating the viability J774.A1 cells in vitro through the MTT reduction method at the concentrations of 10 and 100 µg/mL. The anxiolytic behavior was evaluated in Swiss mice (n = 8) using the methodology of Elevated Plus-Maze (EPM) and Open-Field (OF). CLEO was tested by inhalation at the doses of 100, 200, and 400 µL, and as control, animals were subjected to inhalation of the vehicle (saline solution 0.9% + Tween80®) and intraperitoneal administration of diazepam (1.5 mg/kg). In the cell viability assay, it was observed that none of the concentrations showed cytotoxicity. OF test showed significant anxiolytic activity at all tested doses of OECL, compared to the control group, without changing the motor performance of the animals. Corroborating OF data, the EPM test confirmed anxiolytic activity in at least two doses of the tested oil (200 and 400 µL), justified by the number of entries and increase in the percentage of time in the open arms. The data analysis of this study evidenced that inhalation of OECL was able to induce an anxiolytic behavior in mice; however, further studies are required to ensure its safe use by the population. .A1 através do método de redução do MTT nas concentrações de 10 e 100 µg/mL. O comportamento ansiolítico foi avaliado em camundongos Swiss (n = 8), utilizando a metodologia do Labirinto em Cruz Elevado (LCE) e do Campo Aberto (CA). O OECL foi testado por inalação nas doses de 100, 200 e 400 µL, e como controle, os grupos foram submetidos à inalação do veículo (Solução fisiológica 0,9% + Tween80®) e administração intraperitoneal de diazepam (1,5 mg/kg). No ensaio de viabilidade celular, observou-se que nenhuma das concentrações apresentou citotoxicidade. O teste de CA demonstrou atividade ansiolítica significativa em todas as doses testadas do OECL, comparada ao grupo controle, sem alterar a performance motora dos animais. Corroborando os dados do CA, o teste do LCE confirmou a atividade ansiolítica em pelo menos duas das doses do óleo testadas (200 e 400 µL), justificada pelo número de entradas e aumento na percentagem de tempo nos braços abertos. A análise dos dados deste estudo evidenciou que a inalação do OECL foi capaz de induzir um comportamento ansiolítico em camundongos; entretanto, outros estudos são necessários para garantir o seu uso seguro pela população.Palavras-chave: Ansiolítico. Citrus limon. Óleo essencial. Inalação. Camundongos.

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50 years of hurdles and hope in anxiolytic drug discovery

Cited by 383 publications

References 275 publications

Brain galanin system genes interact with life stresses in depression-related phenotypes

Brain galanin system genes interact with life stresses in depression-related phenotypes

Depression-like behavior in rat: Involvement of galanin receptor subtype 1 in the ventral periaqueductal gray

Anxiolytic-like effect of Citrus limon (L.) Burm f. essential oil inhalation on mice

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