Helplessness-like escape deficits of NIH-HS rats predict passive behavior in the forced swimming test:Relevance for the concurrent validity of rat models of depression

The genetically heterogeneous NIH-HS rat stock has been characterized by its response to anxiety- and fear-inducing situations, thus leading to the conclusion that they are a rather anxious and passive coping type of rats. Taking advantage of these profiles, and knowing that they show very poor performance in the two-way active (shuttle box) escape/avoidance task, we have tested NIH-HS rats (n = 80) in the forced swimming test (FST) as well as we have studied escape response deficits (i.e. response failures) of the same animals in the two-way shuttle box task. They were also tested for anxiety in the elevated zero-maze. The goal of such a study was that of investigating whether there are associations or relationships among helplessness-like or passive coping responses between both models of depression, i.e. the FST and the helplessness-like escape deficits in the shuttle box task. The results for the first time show associations among responses from both depression models and that selecting rats for displaying extreme (active or passive) responses in one of the models predict in a coherent manner (according to the hypothesis) their behaviour in the other model. These findings are discussed in the context of the concurrent validity of both models of depression as well as concerning the possible relevance of NIH-HS rats as a tool for future studies on this field.

Noradrenergic, glutamatergic and dopaminergic systems are implicated in antidepressant-like effect of flavonoids extracted from okra (Abelmoschus esculentus [L.] Moench.) fruit in the forced swimming test

Okra(Abelmoschus esculentus[L.]Moench.)is one of the most frequently used herbals in East or West Africa,and its various biological activities have been widely studied.Flavonoids extracted from many plants are reported to have neurological properties,e.g antidepressant and antifatigue.However,its neurological protect in antidepressant-like effect of flavonoids extracted from okra have not yet been demonstrated.The present study was aimed at investigating the antidepressant-like eff ect of the flavonoids extracted from okra fruit(FOF)using the forced swimming test(FST)pattern and preliminary exploration its potential mechanism.We also used the open fi eld test(OFT)to estimate the spontaneous locomotor activity.We found that oral administration(p.o.)of FOF(300 mg/kg)alone signifi cantly reduced the immobility time in the FST without changes in locomotor activity in the OPT.The experimental data indicated the antidepressant-like eff ect of FOF involved in noradrenergic,glutamatergic and dopaminergic systems.

Evaluation of antidepressant activity of methanolic and hydroalcoholic extracts of Acorus calamus L.rhizome through tail suspension test and forced swimming test of mice

Objective:Acorus calamus(AC)L.(Araceae)is an annual semi-aquatic and aromatic plant found in Europe,North America and Asia.Its rhizomes are often used by Native Americans,Americans,and Chinese as well as by other cultures.Ethnobotanical studies and documents have shown their use in various disease treatments,such as insomnia,mental disorders,diabetes mellitus,epilepsy,inflammation,asthma,neuropathic pain,and diarrhea.In this study,the antidepressant activity of methanolic and hydroalcoholic extracts of the AC rhizome part in mice was investigated.Methods:Three doses of methanolic extract of AC rhizome(MEACR)(25,50 and 100 mg/kg b.wt),three doses of hydroalcoholic extract of AC rhizome(HAACR)(100,200 and 400 mg/kg b.wt),and standards(imipramine,15 mg/kg b.wt and fluoxetine,20 mg/kg b.wt)was daily oral administration to the mice for consecutive 14 days.The extract effect on the immobility time was monitored by a tail suspension test(TST)and a forced swimming test(FST).Monoamine oxidase(MAO)levels were also analyzed using standard methods.Results:The optimum antidepressant activity was viewed at 100 mg/kg b.wt of MEACR extract and400 mg/kg b.wt of HAACR extract with 23.82%and 20.59%immobility period reduction,respectively.Besides,the extracts weakened the FST-induced elevation of MAO activity significantly and returned to near-normal levels of neurotransmitters in the brain.100 mg/kg b.wt or above of MEACR extract significantly prevented the MAO-A and MAO-B activities in mice brain at a dose-dependent fashion.But,just 400 mg/kg b.wt of HAACR extract prevented the activity of MAO-A and MAO-B.Fluoxetine and imipramine showed a tendency to prevent the activity of MAO-A and MAO-B.Conclusion:This study suggests that AC rhizome extract mediated antidepressant activity by modulating the central neurochemical and hypothalamic-pituitary-adrenal(HPA)axis in response to FST and TSTinduced stress.Therefore,AC rhizome extract can be used as a valuable plant supplement to treat depressive disorders.

Orbitofrontal cortex action of 5-hydroxytryptamine and its receptor in an acute forced swimming stress-induced depression model

BACKGROUND： The orbitofrontal cortex （OFC） is a brain region closely associated with emotion. 5-hydroxytryptamine （5-HT） has been shown to be involved in human depression. OBJECTIVE： To investigate OFC actions and mechanisms of 5-HT and 5-HT1A receptor （5-HT1AR） in stress-induced depression.DESIGN, TIME AND SETTING： A randomized, controlled, animal experiment was performed at Laboratory of Neurobiology, College of Life Science, Shaanxi Normal University between May 2006 and March 2008. MATERIALS： 5-HT, p-chlorophenylalanine （PCPA, an inhibitor to tryptophan hydroxylase） and spiperone （5-HT1AR antagonist） were provided by Sigma, USA; rabbit anti-rat 5-HT1AR antibody was provided by Tianjin Haoyang Biological Manufacture. METHODS： A total of 40 male Sprague Dawley rats, aged 3 months, were randomly divided into five groups： control, model, 5-HT, spiperone ＋ 5-HT, and PCPA, with 8 rats in each group. Except for control group, rats in the other four groups were used to establish depression models by forced swimming for 15 minutes. At 30 minutes before forced swimming test, 0.5 pL of 5-HT （12.5 pg/pL）, PCPA （20 pg/pL）, spiperone （1.3 pg/pL） ＋ 5-HT （12.5 pg/pL, 10 minutes later）, and saline were respectively injected into the OFC of 5-HT, PCPA, spiperone ＋ 5-HT, and model groups, respectively. The control group received a saline microinjection into the OFC.MAIN OUTCOME MEASURES： Forced swimming and open field tests were employed to measure animal behaviors, and immunohistochemistry was used to analyze 5-HT1AR expression in the OFC, cingulate cortex, and piriform cortex. RESULTS： （1） Compared with the model group, 5-HT microinjection into the OFC prominently reduced immobility time in the forced swimming test and rearing in open field test （P 〈 0.05）; locomotion and grooming in open field test were increased, although there was no significance （P 〉 0.05）. Furthermore, following PCPA microinjection into the OFC （PCPA ＋ forced swimming stress）, immobility time in forced swimming test increased dramatically （P〈 0.01）, locomotion and rearing in open field test declined （P〈 0.05 and P 〈 0.01, respectively）. Compared with the 5-HT group, 5-HT1AR antagonist （spiperone ＋ 5-HT ＋ forced swimming stress） increased immobility time in forced swimming test （P 〈 0.01）, but decreased locomotion, rearing, and grooming in open field test. （2） Forced swimming stress markedly elevated 5-HT1AR expression in OFC, cingulate cortex, and piriform cortex （P〈 0.05 or P〈 0.01）. CONCLUSION： 5-HT improved stress-induced depression, and 5-HT anti-depression effects are primarily achieved via 5-HT1AR. Stress-induced up regulation of 5-HT1AR expression might be a compensatory mechanism for decreased 5-HT expression.

Chaihu-Shugan-San exerts an antidepressive effect by downregulating miR-124 and releasing inhibition of the MAPK14 and Gria3 signaling pathways

Dysregulation of mi R-124 has been reported to be involved in the pathophysiology of depression. Chaihu-Shugan-San, a traditional Chinese medicine, has antidepressive activity; however, the underlying mechanisms remain unclear. In this study, to generate a rodent model of depression, rats were subjected to a combination of solitary confinement and chronic unpredictable mild stress for 28 days. Rats were intragastrically administered Chaihu-Shugan-San（2.835 m L/kg/d） for 4 weeks, once a day. Real-time reverse-transcription quantitative polymerase chain reaction, mi RNA microarray, western blot assay and transmission electron microscopy demonstrated that ChaihuShugan-San downregulated mi R-124 expression and upregulated the m RNA and protein levels of mitogen-activated protein kinase 14（MAPK14） and glutamate receptor subunit 3（Gria3）. Chaihu-Shugan-San also promoted synapse formation in the hippocampus. The open field test, sucrose consumption test and forced swimming test were used to assess depression-like behavior. After intragastric administration of Chaihu-Shugan-San, sucrose consumption increased, while the depressive behaviors were substantially reduced. Together, these findings suggest that Chaihu-Shugan-San exerts an antidepressant-like effect by downregulating mi R-124 expression and by releasing the inhibition of the MAPK14 and Gria3 signaling pathways.

Neuronal protein-tyrosine phosphatase 1B hinders sensory-motor functional recovery and causes affective disorders in two different focal ischemic stroke models

Ischemic brain injury causes neuronal death and inflammation.Inflammation activates protein-tyrosine phosphatase 1B(PTP1B).Here,we tested the significance of PTP1B activation in glutamatergic projection neurons on functional recovery in two models of stroke:by photothrombosis,focal ischemic lesions were induced in the sensorimotor cortex(SM stroke)or in the peri-prefrontal cortex(peri-PFC stroke).Elevated PTP1B expression was detected at 4 days and up to 6 weeks after stroke.While ablation of PTP1B in neurons of neuronal knockout(NKO)mice had no effect on the volume or resorption of ischemic lesions,markedly different effects on functional recovery were observed.SM stroke caused severe sensory and motor deficits(adhesive removal test)in wild type and NKO mice at 4 days,but NKO mice showed drastically improved sensory and motor functional recovery at 8 days.In addition,peri-PFC stroke caused anxiety-like behaviors(elevated plus maze and open field tests),and depression-like behaviors(forced swimming and tail suspension tests)in wild type mice 9 and 28 days after stroke,respectively,with minimal effect on sensory and motor function.Peri-PFC stroke-induced affective disorders were associated with fewer active(FosB+)neurons in the PFC and nucleus accumbens but more FosB+neurons in the basolateral amygdala,compared to sham-operated mice.In contrast,mice with neuronal ablation of PTP1B were protected from anxiety-like and depression-like behaviors and showed no change in FosB+neurons after peri-PFC stroke.Taken together,our study identifies neuronal PTP1B as a key component that hinders sensory and motor functional recovery and also contributes to the development of anxiety-like and depression-like behaviors after stroke.Thus,PTP1B may represent a novel therapeutic target to improve stroke recovery.All procedures for animal use were approved by the Animal Care and Use Committee of the University of Ottawa Animal Care and Veterinary Service(protocol 1806)on July 27,2018.

What can we learn on rodent fearfulness/anxiety from the genetically heterogeneous NIH-HS rat stock?

The “National Institutes of Health” genetically heterogeneous (NIH-HS) rat stock was created in the 1980s through an eight-way cross of as much as possible separate inbred rat strains (i.e. the MR/N, WN/N, WKY/N, M520/N, F344/N, ACI/N, BN/SsN and BUF/N strains) which were readily available at that time. Hansen and Spuhler [1] developed a more naturalistic, genetically heterogeneous rat stock with the aim of optimizing the distribution of genotypic frequencies and recombination and under the hypothesis that the NIH-HS stock could yield a broad-range distribution of responses (broader than commonly used laboratory rat strains) to experimental conditions, and thus serve as a base population for selection studies. Along the last decade, in a series of studies we have phenotypically characterized the NIH-HS rat stock (a colony exists at our laboratory since 2004) for their anxiety/fearfulness profiles (using a battery of both unconditioned and conditioned tests/tasks), as well as regarding their stress-induced hormonal responses, coping style under inescapable stress and spatial learning ability. We have also compared the phenotypic profiles of NIH-HS rats with those of the low anxious RHA-I and the high anxious RLA-I rat strains. The NIH-HS rat stock is, as a population, a rather anxious type of rat, with predominantly reactive/passive coping style in unlearned and learned anxiety/fear tests, and elevated stress hormone responses (as well as enhanced “depressive” symptoms in the forced swimming test). Genetic studies currently under way have thus far revealed that the genetically heterogeneous NIH-HS rat stock constitutes a unique tool for fine mapping of QTL (for multiple behavioural and biological complex traits) to megabase resolution levels, thus enabling candidate gene identification. We give some examples of this in the present paper, while also highlighting that microarray gene expression studies reveal that HPA-axis- and prolactin-related genes (among others) in the amygdala appear to be related with (or associated to) the coping style and anxiety/fearfulness responses of NIH-HS rats.

Assessment of commonly used tests in experimental depression studies according to behavioral patterns of rodents

Considering the main factor that causes or triggers depression in humans is stress.Several stress factors are applied to form depression-like symptoms in rodents.Depression tests are used to analyze the nature and patterns of depression.Well-founded modeling and versatile evaluation of tests are necessary to investigate a hypothesis that is related to depression.It is impossible to model or test all aspects of depression in humans by using experimental animals.As a result,the aims of the study should be determined specifically in depression models.The correct interpretation of the tests that are suitable for these aims is indispensable for the reliability of the data.To achieve this goal,the biological basis of the depression-related behaviors of animals should be well known.In this review,model and test concepts related to depression are discussed and behavioral patterns of rodents are explained with several examples.

Antidepressant-like effects of the ethanolic extract of XiaobuxinTang,a traditional Chinese herbal prescription in animal models of depression

Background Xiaobuxin-Tang, a traditional Chinese herbal prescription recorded in a silk scroll unearthed from Mogao Caves of Dunhuang has been indicated that it can remit depressive disorder. The present study was designed to investigate its antidepressant effects in various animal depression models.Methods Xiaobuxin-Tang was extracted by 70% alcohol, and then three behavioral despair models and 5-Hydroxytryptophan （HTP）-induced head twitch response model were adopted to assess the antidepressant effects of the ethanolic extract of Xiaobuxin-Tang with the study on spontaneous motor activity. Groups of mice and rats received oral treatment with Xiaobuxin-Tang （150-1200 mg/kg） only once acutely in all tests. The duration of immobility was measured during the last 4 minutes of the 6-minutes test period in mice forced swimming test, rats forced swimming test and mice tail suspension test. In 5-HTP-induced head twitch response, the mice were intraperitoneally administered with 120 mg/kg of L-5-HTP, and then the cumulative number of head twitches was counted in 20 minutes. Spontaneous motor activities of mice were recorded automatically in 10 minutes by VIDEOMEX-V image analytic system.Results The extract at doses of 300 mg/kg （p.o.） and 600 mg/kg （p.o.） significantly decreased the duration of immobility time in a dose dependent manner in mice forced swimming test; also, the extract at dose of 1200 mg/kg （p.o.） significantly decreased the duration of immobility time in rat forced swimming test. Furthermore, the extract at a dose of 600 mg/kg had the same effect in mice tail suspension test. Meanwhile, the extract at the effective doses for behavioral despair models, had no effect on spontaneous motor activity in mice. The extract （300-1200 mg/kg, p.o.） also increased the accumulative number of the 5-HTP-induced head twitch response in mice in 20 minutes.Conclusion Our results suggested that the ethanolic extract of Xiaobuxin-Tang exerts antidepressant-like effect.

Astrocytic GABA_B Receptors in Mouse Hippocampus Control Responses to Behavioral Challenges through Astrocytic BDNF

Major depressive disorder(MDD) is a common mood disorder that affects almost 20% of the global population.In addition,much evidence has implicated altered function of the gamma-aminobutyric acid(GABAergic) system in the pathophysiology of depression.Recent research has indicated that GABA_B receptors(GABA_BRs) are an emerging therapeutic target in the treatment of stress-related disorders such as MDD.However,which cell types with GABA_BRs are involved in this process is unknown.As hippocampal dysfunction is implicated in MDD,we knocked down GABA_BRs in the hippocampus and found that knocking down these receptors in astrocytes,but not in GABAergic or pyramidal neurons,caused a decrease in immobility in the forced swimming test(FST) without affecting other anxiety-and depression-related behaviors.We also generated astrocytespecific GABABR-knockout mice and found decreased immobility in the FST in these mice.Furthermore,the conditional knockout of GABA_BRs in astrocytes selectively increased the levels of brain-derived neurotrophic factor protein in hippocampal astrocytes,which controlled the decrease in immobility in the FST.Taken together,our findings contribute to the current understanding of which cell types expressing GABA_BRs modulate antidepressant activity in the FST,and they may provide new insights into the pathological mechanisms and potential targets for the treatment of depression.

Effects of Liuwei Dihuang Decoction(Yukmijihwang-tang)on Physical Fatigue by Regulating Neurotransmitters in Brain

Objective:To study the effect of Liuwei Dihuang Decoction(六味地黄汤)or Yukmijihwangtang(YJT)on endurance exercise by in vivo experiment.Methods:ICR mice were randomly divided into the control group(distilled water)and the YJT groups(1,10,100 mg/kg),5 animals per group.YJT and distilled water were orally administered.The anti-fatigue effect of YJT was evaluated by open fifiled test(OFT),forced swimming test(FST),and tail suspension test(TST).Results:In the OFT,YJT signifificantly increased the total movement distance in a dose-dependent manner.Additionally,treatment with YJT signifificantly decreased immobility time in the FST and the TST.Various neurotransmitters such as norepinephrine(NE),serotonin(5-HT),dopamine(DA)levels were increased by FST.Administration of YJT down-regulated the expression levels of NE,5-HT,5-hydroxyindole-acetic acid(5-HIAA),and DA in the brain stem and hypothalamus of mice.Moreover,protein expression of HSP70 in mice liver and heart muscles was signifificantly increased in the YJT groups.Conclusions:YJT could ameliorate fatigue and enhance exercise tolerance through suppressing of brain monoamines including NE,5-HT,5-HIAA,and DA in FST mice model.

Astrocyte-Derived Lactate Modulates the Passive Coping Response to Behavioral Challenge in Male Mice

Every organism inevitably experiences stress. In the face of acute, intense stress, for example, periods of passivity occur when an organism's actions fail to overcome the challenge. The occurrence of inactive behavior may indicate that struggling would most likely be fruitless.Repeated serious stress has been associated with mood disorders such as depression. The modulation of passive coping response patterns has been explored with a focus on the circuit level. However, the cellular and molecular mechanisms are largely uncharacterized. Here, we report that lactate is a key factor in the astrocytic modulation of the passive coping response to behavioral challenge in adult mice. We found increased extracellular lactate in the medial prefrontal cortex(mPFC) when mice experienced the forced swimming test(FST). Furthermore, we discovered that disturbing astrocytic glycogenolysis, which is a key step for lactate production in the mPFC, decreased the duration of immobility in the FST. Knocking down monocarboxylate transporter 4(MCT4), which is expressed exclusively in astrocytes and transports lactate from astrocytes to the extracellular space, caused similar results in the FST. The behavioral effect of both the pharmacological disturbance of astrocytic glycogenolysis and viral disruption of MCT4 expression was rescued via the administration of L-lactate. Moreover, we found that both pharmacological and viral modulation of astrocytederived lactate in mPFC slices increased the excitability of layer V pyramidal neurons, and this enhancement was reversed by exogenous L-lactate administration. These results highlight astrocyte-derived lactate as a biological mechanism underlying the passive coping response to behavioral challenge and may provide new strategies to prevent mood disorders.

A Network Pharmacology-Based Study on Antidepressant Effect of Salicornia europaea L.Extract with Experimental Support in Chronic Unpredictable Mild Stress Model Mice

Objective:To investigate the pharmacodynamic material basis,mechanism of actions and targeted diseases of Salicornia europaea L.(SE)based on the network pharmacology method,and to verify the antidepressant-like effect of the SE extract by pharmacological experiments.Methods:Retrieval tools including Chinese medicine(CM),PubMed,PharmMapper,MAS 3.0 and Cytoscape were used to search the components of SE,predict its targets and related therapeutic diseases,and construct the"Component-TargetPathway"network of SE for central nervous system(CNS)diseases.Further,protein-protein interaction(PPI)network,Kyoto Encyclopedia of Genes and Genomes(KEGG)and Gene Ontology(GO)function annotation of depression-related targets were analyzed to predict the antidepressant mechanism of SE.Chronic unpredictable mild stress(CUMS)model was used to construct a mouse model with depression-like symptoms.And the animals were randomly divided into 6 groups(n=10)including the normal group(nonstressed mice administered with distilled water),the CUMS group(CUMS mice administered with distilled water),the venlafaxine group(CUMS mice administered with venlafaxine 9.38 mg/kg),SE high-,medium-,and low-dose groups(CUMS mice administered with SE 1.8,1.35 and 0.9 g/kg,respectively).Then some relevant indicators were determined for experimental verification by the forced swim test(FST),the tail suspension test(TST)and open-field test(OFT).Dopamine(DA)concentration in hippocampus and cerebral cortex,IL-2 and corticosterone(CORT)levels in blood,and nuclear factor E2 related factor 2(Nrf2),kelch-like epichlorohydrin related protein 1(Keap1),NAD(P)H dehydrogenase[quinone]1(NQO1)and heme oxygenase-1(HO-1)levels in mice were measured by enzyme linked immunosorbent assay(ELISA)and Western blot respectively to explore the possible mechanisms.Results:The"target-disease"network diagram predicted by network pharmacology,showed that the potential target of SE involves a variety of CNS diseases,among which depression accounts for the majority.The experimental results showed that SE(1.8,1.35 g/kg)significantly decreased the immobility period,compared with the CUMS group in FST and TST in mice after 3-week treatment,while SE exhibited no significant effect on exploratory behavior in OFT in mice.Compared with CUMS group,the SE group(0.9 g/kg)showed significant differences(P<0.05)in DA levels in the hippocampus and cerebral cortex.In addition,compared with CUMS control group,SE(1.8 g/kg)group showed a significant effect on decreasing the activities of CORT(P<0.05),and serum IL-2level with no statistical significance.Finally,Western blot results showed that compared with the model group,Nrf2,Keap1,NQO1 and HO-1 protein expressions in SE group(1.8 g/kg)were up-regulated(all P<0.01).Conclusion:The SE extract may have an antidepressant effect,which appeared to regulate Nrf2-ARE pathway and increased levels of DA and CORT in the hippocampus and cortex.