Light-dark Box Test Research Articles

Anthocyanins in Lycium ruthenicum Murray reduce nicotine withdrawal-induced anxiety and craving in mice

Lycium ruthenicum Murray is widely used in traditional Chinese medicine and is believed to have antimicrobial, antioxidant, and anti-fatigue effects. Anthocyanins are considered to be one of the main active components. The previous work by our research team found that the anthocyanins in Lycium ruthenicum extract (ALRM) produce a stable anti-anxiety effect. The mechanisms of action include reducing the level of corticotropin-releasing factor (CRF) as well as regulating extracellular signal-regulated kinase/mitogen activation, protein kinase (ERK/MAPK) pathways, and others, all of which are related to the mechanisms of nicotine addiction. To investigate the effects of ALRM on anxiety and craving behavior after nicotine withdrawal, the components of ALRM were analyzed using the UPLC-Orbitrap MS method. The effects of ALRM on anxiety behavior induced by nicotine withdrawal were investigated in mice using the elevated plus maze (EPM) and light–dark box (LDB) tests. The effects of ALRM on craving behavior after nicotine withdrawal were further investigated using the conditional place preference (CPP) test. The EPM and LDB tests demonstrated that ALRM could alleviate the anxiety behavior induced by nicotine withdrawal and reduce nicotine craving in mice. Based on the identified ALRM components, the network pharmacology method was used to predict the mechanism of ALRM alleviating anxiety after nicotine withdrawal in mice. It was speculated that ALRM was involved in the production and transmission of dopamine, choline, and other nervous system functions and exhibited a potential role in treating nicotine addiction.

Assessment of Antidepressant-like, Anxiolytic Effects and Impact on Memory of Pimpinella anisum L. Total Extract on Swiss Albino Mice.

Mental disorders are psychological symptoms that impact multiple areas of an individual’s life. Depression and anxiety are chronic illnesses described as the most prevalent stress-related mood disorders that cause injury and early death. In Morocco, Anise “Pimpinella anisum L.” is one of the most traditionally used condiment plants, which has long been used to cure various illnesses and in phytotherapy. The present study was designed to investigate the antidepressant, anxiolytic, and memory impact of the total extract of Pimpinella anisum (PATE) at the doses of 100 and 200 mg/kg, using the Forced Swimming Test (FST), Tail Suspension Test (TST), Open Field Test (OFT), and Light–Dark Box Test (LDBT) as an experimental paradigm of anxiety and depression, and Novel Object Recognition Test (NORT) and the Morris Water Maze Test (MWMT) as memory tests on Swiss albino mice. The tests were carried out on the 1st, 7th, 14th, and the 21st days of the study, and the extract groups were compared with normal controls and positive controls (receiving bromazepam and paroxetine at the doses of 1 mg/kg and 11.5 mg/kg for anxiety and depression, respectively). The daily oral gavage of the mice by the PATE induced a significant anxiolytic and antidepressant-like effect by shortening immobility time and decreasing downtime in the different tests. PATE at both doses was shown to have no impact on memory following the NORT and MWM tests. Different compounds, such as gallic acid, catechin, chlorogenic acid, caffeic acid, oleuropein, p-coumaric acid, trans-4-hydroxy-3-methoxycinnamic acid, myricetin, and quercetin, were identified during the phytochemical analysis carried out using HPLC analysis. This research supports and promotes the extract’s traditional use, suggesting its use as a phytomedicine against depression and anxiety, and calls for further research to clarify its mode of action.

Reserpine-induced altered neuro-behavioral, biochemical and histopathological assessments prevent by enhanced antioxidant defence system of thymoquinone in mice.

Thymoquinone (Tq), an active compound of Nigella sativa, has been known for its anti-inflammatory, antioxidant, and neuroprotective characteristics. The present study is aimed to evaluate the effect of Tq on reserpine (Rsp)-induced behavioral (anxiety and/or depression) and, memory deficit; hippocampal inflammatory markers, oxidative markers, antioxidant enzymes, acetylcholinesterase (AChE) activity and histopathology in male mice. Animals were injected with Rsp at a dose of 2mg/ml/kg and doses of Tq (10 and 20mg/ml/kg) for 28days. After the treatment period, behavioral tests [Elevated plus maze (Epm); Light dark box test (Lda); Morris water maze (Mwm); Forced swim test (Fst); Tail suspension test (Tst)] were conducted. After analysis of behaviors, mice were decapitated and brain samples were collected, the hippocampus was removed from the whole-brain sample for biochemical analysis and histology. Administration of Tq at both doses prevent adverse effects of Rsp and increased time spent in open arm and lightbox in Lda and Epm respectively, decreased immobility period in Fst and Tst, decreased latency escape in Mwm, reduced lipid peroxidation (lpo) and inflammatory cytokines, increased defensive enzymes, reduced acetylcholinesterase (AChE) activity and corrected histological lines. It is concluded that Rsp-instigated behavioral and memory deficits were prevented by Tq possibly via its strong antioxidant and anti-inflammatory effects.

Anxiolytic Effect of Two Tobacco Essential Oils (Nicotiana tabacum Linn.) on Mice

Tobacco (Nicotiana tabacum Linn.) is a famous traditional herb used in folk medicine. The essential oils of tobacco have been demonstrated in modern studies to possess antioxidant, anti-inflammatory, and neuroprotective properties, while its anxiolytic effect has not been reported. The purpose of this study was to evaluate the anxiolytic effect of Yunnan tobacco essential oil (YTO) and Zimbabwe tobacco essential oil (ZTO) on mice. The constituents of YTO and ZTO were analyzed by GC/MS. The anxiolytic effect of YTO and ZTO (0.1%, 1%, and 10%, v/v) on male ICR mice was evaluated in the light–dark box test (LDB) and the elevated plus maze test (EPM) test via inhalation and transdermal administration. After the behavioral tests, salivary corticosterone levels in mice were measured. The behavioral analysis showed that the administration of both YTO and ZTO elevated the time that the mice spent in the light chamber in the LDB test compared to the untreated control. In the EPM test, YTO and ZTO increased the time spent in open arms and the number of entries into the open arms. In addition, both YTO and ZTO significantly decreased salivary corticosterone levels in mice (p ≤ 0.001). In summary, our results demonstrated that inhalation and transdermal administration of both YTO and ZTO showed anxiolytic effect on male ICR mice.

BOTOX® counteracts the innate anxiety-related behaviours in correlation with increased activities of key antioxidant enzymes in the hippocampus of ageing experimental mice

Cholinergic crisis and oxidative stress in the hippocampus of the brain have been known to induce anxiety disorders upon ageing. BOTOX® is a widely used therapeutic form of botulinum neurotoxin that acts by inhibiting the release of acetylcholine (ACh) from the nerve terminals at the neuromuscular junction. BOTOX® can migrate from the muscle to the brain through retrograde axonal transport and modulate neuroplasticity. While a mild dose of BOTOX® has been used to manage various neurological deficits and psychiatric complications including depression, the efficacy and experimental evidence for its anxiolytic effects and antioxidant properties remain limited. In this study, we have investigated the effect of BOTOX® on the innate anxiety-like behaviours in ageing mice upon exposure to different behavioural paradigms like open field test, elevated plus maze and light-dark box test, and estimated the enzymatic activities of key antioxidants in the hippocampus. Results revealed that animals injected with a mild intramuscular dosage of BOTOX® showed reduced level of innate anxiety-related symptoms and increased activities of hippocampal antioxidant enzymes compared to the control group. This study strongly supports that BOTOX® could be implemented to prevent or treat anxiety and hippocampal oxidative stress resulting from ageing, emotional and mood disorders.

Early-life experiences altered the maturation of the lateral habenula in mouse models, resulting in behavioural disorders in adulthood.

Background:Abnormally high activity in the lateral habenula causes anxiety- or depression-like behaviours in animal experimental models. It has also been reported in humans that excessive stress in early life is correlated with the onset of psychiatric disorders in adults. These findings raise the question of whether maturation of the lateral habenula is affected under the influence of early-life experiences, which could govern behaviours throughout life.Methods:We examined the maturation of the lateral habenula in mice based on neuronal activity markers and plastic components: Zif268/Egr1, parvalbumin and perineuronal nets. We examined the effect of early-life stress using repeated maternal deprivation.Results:First, we found a transient highly sensitive period of the lateral habenula under stress. The lateral habenula matured through 4 stages: postnatal days 1–9 (P1–9), P10–20, around P35 and after P35. At P10–20, the lateral habenula was highly sensitive to stress. We also observed experience-dependent maturation of the lateral habenula. Only mice exposed to chronic stress from P10–20 exhibited changes specific to the lateral habenula at P60: abnormally high stress reactivity shown by Zif268/Egr1 and fewer parvalbumin neurons. These mice showed anxiety- or depression-like behaviours in the light–dark box test and forced swim test.Limitations:The effect of parvalbumin neurons in the lateral habenula on behavioural alterations remains unknown. It will be important to understand the “sensitive period” of the neuronal circuits in the lateral habenula and how the period P10–20 is different from P9 or earlier, or P35 or later.Conclusion:In mice, early-life stress in the period P10–20 led to late effects in adulthood: hyperactivity in the lateral habenula and anxiety or depression, indicating differences in neuronal plasticity between stages of lateral habenula maturation.

Stigmasterol can be new steroidal drug for neurological disorders: Evidence of the GABAergic mechanism via receptor modulation

BackgroundGamma-aminobutyric acid A (GABAA) receptors have been implicated in anxiety and epileptic disorders. Hypothesis/PurposeThis study aimed to investigate the effects of stigmasterol, a plant sterol (phytosterol) isolated from Artemisia indica Linn on neurological disorders. MethodsStigmasterol was evaluated on various recombinant GABAA receptor subtypes expressed in Xenopus laevis oocytes and its anxiolytic and anticonvulsant potential was assessed using the elevated plus maze (EPM), light-dark box (LDB) test, and pentylenetetrazole- (PTZ-) induced seizure paradigms. Furthermore, computational modeling of α2β2γ2L, α4β3δ, and α4β3 subtypes was performed to gain insights into the GABAergic mechanism of stigmasterol. For the first time, a model of GABAδ subtype was generated. Stigmasterol was targeted to all the binding sites (neurotransmitters, positive and negative modulator binding sites) of GABAA α2β2γ2L, α4β3, and α4β3δ complexes by in silico docking. ResultsStigmasterol enhanced GABA-induced currents at ternary α2β2γ2L, α4β3δ, and binary α4β3 GABAAR subtypes. The potentiation of GABA-induced currents at extrasynaptic α4β3δ was significantly higher compared to the binary α4β3 subtype, indicating that the δ subunit is important for efficacy. Stigmasterol was found to be a potent positive modulator of the extrasynaptic α4β3δ subtype, which was also confirmed by computational analysis. The computational analysis reveals that stigmasterol preferentially binds at the transmembrane region shared by positive modulators or a binding site constituted by the M2-M3 region of α4 and M1-M2 of β3 at α4β3δ complex. In in vivo studies, Stigmasterol (0.5–3.0 mg/kg, i.p.) exerted significant anxiolytic and anticonvulsant effects in an identical manner of allopregnanolone, indicating the involvement of a GABAergic mechanism. ConclusionTo our knowledge, this is the first study reporting the positive modulation of GABAA receptors, anxiolytic and anticonvulsant potential of stigmasterol. Thus, stigmasterol is considered to be a candidate steroidal drug for the treatment of neurological disorders due to its positive modulation of GABA receptors.

Bioactive metabolites of Blumea lacera attenuate anxiety and depression in rodents and computer-aided model.

Blumea lacera is an edible plant with imperative medicinal values. However, the anxiolytic and antidepressant roles of B. lacera have not been well‐explained. Therefore, the current study aims to explore the impending bioactive metabolites and roles of B. lacera methanol leaf extract (Me‐BLL) in attenuating anxiety and depression through several experimental and computer‐aided approaches. The chemical characterization of Me‐BLL was performed through standard phytochemical and GC‐MS analyses. To explore the neuropharmacological insights, Swiss albino mice were treated with Me‐BLL at doses of 200–400 mg/kg, p.o. The anxiolytic effects were observed employing elevated plus maze (EPM), light–dark box (LDB), and hole‐board (HBT) tests, while antidepressant effects were evaluated using forced swimming (FST) and tail suspension tests (TST). Diazepam (1 mg/kg, i.p.) and fluoxetine HCl (20 mg/kg, p.o.) were used as the reference standard. The phytochemical analyses revealed several bioactive metabolites, including higher contents of total phenolics and flavonoids. The EPM and LDB tests demonstrated an increased time spent in open arms and light box, and the HBT showed an increased number of head dipping, indicating the anxiolytic effects of Me‐BLL. The TST and FST revealed a decrease in immobility time, meaning the persuasive antidepressant effects. The antioxidative effects of Me‐BLL have also been observed prominently. Correspondingly, the computer‐aided investigation confirmed several bioactive lead molecules. Specifically, thymol and cuminol revealed potential anxiolytic and antioxidant effects, while stigmast‐5‐en‐3.beta.‐ol and gamma‐sitosterol possessed promising antidepressant effects. Taken these results as a base, the plant has imperative potentials in managing anxiety and depression‐like disorders.

Pharmacological Blockade of PPARα Exacerbates Inflammatory Pain-Related Impairment of Spatial Memory in Rats

Peroxisome proliferator-activated receptors (PPARs) are ligand-dependent transcription factors that exist in three isoforms: PPARα, PPARβ/δ and PPARγ. Studies suggest that the PPAR signalling system may modulate pain, anxiety and cognition. The aim of the present study was to investigate whether endogenous signalling via PPARs differentially modulates innate anxiety responses and mnemonic function in the presence and absence of inflammatory pain. We examined the effects of intraperitoneal administration of GW6471 (PPARα antagonist), GSK0660 (PPARβ/δ antagonist), GW9662 (PPARγ antagonist), and N-palmitoylethanolamide (PEA) on rat behaviour in the elevated plus maze (EPM), open field (OF), light-dark box (LDB), and novel object recognition (NOR) tests in the presence or absence of chronic inflammatory pain. Complete Freund’s Adjuvant (CFA)-injected rats exhibited impaired recognition and spatial mnemonic performance in the NOR test and pharmacological blockade of PPARα further impaired spatial memory in CFA-treated rats. N-oleoylethanolamide (OEA) levels were higher in the dorsal hippocampus in CFA-injected animals compared to their counterparts. The results suggest a modulatory effect of CFA-induced chronic inflammatory pain on cognitive processing, but not on innate anxiety-related responses. Increased OEA-PPARα signalling may act as a compensatory mechanism to preserve spatial memory function following CFA injection.

CB1 receptor neutral antagonist treatment epigenetically increases neuropeptide Y expression and decreases alcohol drinking

Alcohol consumption is mediated by several important neuromodulatory systems, including the endocannabinoid and neuropeptide Y (NPY) systems in the limbic brain circuitry. However, molecular mechanisms through which cannabinoid-1 (CB1) receptors regulate alcohol consumption are still unclear. Here, we investigated the role of the CB1 receptor-mediated downstream regulation of NPY via epigenetic mechanisms in the amygdala. Alcohol drinking behavior was measured in adult male C57BL/6J mice treated with a CB1 receptor neutral antagonist AM4113 using a two-bottle choice paradigm while anxiety-like behavior was assessed in the light-dark box (LDB) test. The CB1 receptor-mediated changes in the protein levels of phosphorylated cAMP-responsive element binding protein (pCREB), CREB binding protein (CBP), H3K9ac, H3K14ac and NPY, and the mRNA levels of Creb1, Cbp, and Npy were measured in amygdaloid brain structures. Npy-specific changes in the levels of acetylated histone (H3K9/14ac) and CBP in the amygdala were also measured. We found that the pharmacological blockade of CB1 receptors with AM4113 reduced alcohol consumption and, in an ethanol-naïve cohort, reduced anxiety-like behavior in the LDB test. Treatment with AM4113 also increased the mRNA levels of Creb1 and Cbp in the amygdala as well as the protein levels of pCREB, CBP, H3K9ac and H3K14ac in the central and medial nucleus of amygdala, but not in the basolateral amygdala. Additionally, AM4113 treatment increased occupancy of CBP and H3K9/14ac at the Npy gene promoter, leading to an increase in both mRNA and protein levels of NPY in the amygdala. These novel findings suggest that CB1 receptor-mediated CREB signaling plays an important role in the modulation of NPY function through an epigenetic mechanism and further support the potential use of CB1 receptor neutral antagonists for the treatment of alcohol use disorder.

Anxiety-related defensive behavioral responses in mice selectively bred for High and Low Activity.

High and Low Activity strains of mice (displaying low and high anxiety-like behavior, respectively) with 7.8-20 fold differences in open-field activity were selected and subsequently inbred to use as a genetic model for studying anxiety-like behavior in mice (DeFries et al., 1978, Behavior Genetics, 8:3-13). These strains exhibited differences in other anxiety-related behaviors as assessed using the light-dark box, elevated plus-maze, mirror chamber, and elevated square-maze tests (Henderson et al., 2004, Behavior Genetics, 34: 267-293). The purpose of these experiments was three-fold. First, we repeated a 6-day behavioral battery using updated equipment and software to confirm the extreme differences in anxiety-like behaviors. Second, we tested novel object exploration, a measure of anxiety-like behavior that does not rely heavily on locomotion. Third, we conducted a home cage wheel running experiment to determine whether these strains differ in locomotor activity in a familiar, home cage environment. Our behavioral test battery confirmed extreme differences in multiple measures of anxiety-like behaviors. Furthermore, the novel object test demonstrated that the High Activity mice exhibited decreased anxiety-like behaviors (increased nose pokes) compared to Low Activity mice. Finally, male Low Activity mice ran nearly twice as far each day on running wheels compared to High Activity mice, while female High and Low Activity mice did not differ in wheel running. These results support the idea that the behavioral differences between High and Low Activity mice are likely to be due to anxiety-related factors and not simply generalized differences in locomotor activity.

ACE2 Knock‐out Mice Show Decreased Blood Pressure Response and Increased Anxiety‐like Behavior to Acute Stress

Stress increases Ang-II production and elevates sympathetic outflow which results in anxiety-related behavior and hypertension. Here, we investigated a potential contribution of Angiotensin Converting Enzyme-2 (ACE2) in the regulation of stress and anxiety-related behavior, in conscious freely moving mice. Previous studies reported that overexpression of ACE2 attenuates HPA axis and decreases anxiety-related behavior (Wang et al., 2018); however, deletion of ACE2 and its implication for such responses are largely unknow. Male mice (30-33 g), 6 ACE2 knock-outs (KO) and 6 wild type (WT) controls were chronically implanted with blood pressure (BP) transducers for continuous recording of BP, heart rate (HR) and locomotor activity. Following a 1-week recovery, mice were subjected to resident-intruder test for 10 min, for the measurement of stress-induced cardiovascular changes. During the dark/active period, a naïve intruder-mouse was suddenly introduced in the experimental mice's cages and their cardiovascular responses were analyzed using the Ponemah software (DSI). In response to intruder-intrusion for 10 min, ACE2 KO mice showed significant (p<0.05) attenuation in BP increases (+15 ±7 mmHg) compared to their WT controls (+39 ±7 mmHg). However, no significant difference was observed in HR increase in ACE2 KO versus WT mice (+166 ±40 and +173±38 bpm, respectively, p=0.45). In contrast, ACE2 KO mice exhibited a significant increase in locomotor activity compared to controls (179 ±19 and 111 ±14 arbitrary units, respectively, p<0.05). These mice were later subjected to the elevated plus maze (EPM) and light-dark box (LDB) tests for 5 min to evaluate anxiety-related behavior. Interestingly ACE2 KO mice were observed to spend more time in closed arms (244 ±19 s) in EPM compared to WT controls (218 ±22 s, p<0.05). However, in the LDB test, ACE2 KO mice showed no difference (286 ±18 s) compared to WT (279 ±19 s, ns). All mice were then chronically implanted subcutaneously with osmotic minipumps filled with an AT1 receptor antagonist (losartan, 10 mg/kg). A week later, mice were again subjected to the intruder test. ACE2 KO mice showed substantial attenuation in BP increase to intruder-intrusion compared to WT mice (+6±3 and +19±6 mmHg respectively, p<0.05); with no significant difference in HR increase in both the groups. Interestingly, pre-treatment with losartan attenuated the intruder-induced locomotor activity in ACE2 KO mice (149±29, p=0.11). In addition, losartan treatment did not attenuate the time ACE2 KO mice spent in closed arms in EPM; but exhibited a decreased time spent in the dark compartment in the LDB test. Surprisingly, our results did not show exacerbated BP responses to acute stress in the absence of ACE2 but instead produced decreased BP responses suggesting other compensatory mechanisms involved. Losartan-mediated attenuation of the increased locomotor activity and anxiety-related behaviors in ACE2 KO mice strongly suggests an Ang-II mediated anxiety-related behaviors. Our experimental findings further extend the current notion that ACE2 potentially contributes to the regulation of stress and anxiety.

Postnatal Oxytocin Treatment Improves Survival and Improves Behavioral Outcomes in an Animal Model of Neonatal Abstinence Syndrome

Objective To investigate the therapeutic effect of the neuropeptide oxytocin in an animal model of neonatal abstinence syndrome. Hypothesis Prenatal exposure to drugs of abuse (eg. opioids and benzodiazepines) results in a severe withdrawal syndrome known as neonatal abstinence syndrome (NAS). NAS is a serious health problem with increasing prevalence. Standard of care pharmacological intervention consists of morphine, methadone, buprenorphine, clonidine, and phenobarbital. Safer and more effective treatments are urgently needed. The neuropeptide oxytocin has been shown to reverse drug and alcohol withdrawal syndromes in adult animals and humans. Here, we examined the effect of postnatal oxytocin treatment on survival and behavioral outcomes in neonatal rats prenatally exposed to opioids or benzodiazepines. Methods Pregnant Sprague-Dawley rats were injected subcutaneously with escalating doses of morphine (10-50 mg/kg/day) or diazepam (2-15 mg/kg/day) starting at gestational day seven through parturition. Upon delivery, rat pups received daily subcutaneous injections of 2 mg/kg oxytocin or saline for the first 10 postnatal days and survival was measured. A second cohort of morphine and diazepam exposed rat pups received injections of 0.3, 1, or 2 mg/kg oxytocin or saline for the first 10 postnatal days and survival was assessed for 30 days. Surviving animals were subjected to a battery of behavioral assessments between postnatal day 30 and 45 to determine how early life oxytocin treatment impacts neurocognitive outcomes. These assessments included a Locomotor Assay, Light-Dark Box Test, Passive Avoidance Task, and Social Interaction Test. Animals were then sacrificed, blood was collected and processed, and glucose oxidase, coritcosterone, and aldosterone was measured using Enzyme Immunoassay (EIA). Results In the first cohort of animals exposed to morphine prenatally, survival was significantly improved with 2 mg/kg oxytocin treatment compared to saline (100% vs 66.67%; P=0.008). The same pattern was observed with animals exposed to diazepam prenatally (100% vs 66.5%; P=0.0149). In the second cohort of animals exposed to morphine prenatally, all doses of oxytocin (0.3, 1, and 2 mg/kg) improved survival compared to saline (88.89%, 100%, 100% vs 50%, respectively; P<0.0001). A similar pattern of improved survival following the two highest doses of oxytocin, but not 0.3 mg/kg, was observed with animals exposed to diazepam prenatally (68.75%, 100%, 100% vs 62.5%, respectively; P=0.0176). Preliminary findings for improvements in learning and memory and social behavior were also observed. No differences in the measured biological outcomes was observed. Conclusions These findings provide insights in to the potential for oxytocin as a novel treatment option for NAS. Given the high unmet need in NAS and the established safety profile of oxytocin, clinical trials appear warranted.

Anxiolytic-like and antidepressant-like effects of ethanol extract of Terminalia chebula in mice

Terminalia chebula (T.chebula) fruit is referred as “King of Medicines” in Tibet and is listed as a key plant in “Ayurvedic Materia Medica” due to its diverse pharmacological activity. The present study was aimed to investigate the comorbid antidepressant-like and anxiolytic-like effects of ethanol extract from T.chebula fruit using experimental behavioral tests in mice. In addition, the study explored the effects of extract on monoamine oxidase –A (MAO-A) levels in mouse brain. Two doses of the T.chebula extract (100 or 200 mg/kg, p.o.) were treated continuously for fifteen days to mice. Regarding antidepressant-like effects, the treatment of T.chebula extract at both dose (100 or 200 mg/kg, p.o.) levels resulted with significant (p < 0.001) reduction in duration of immobility time and increase in swimming time as compared to control group in forced swimming test. Moreover, both doses declined the duration of immobility time in the tail suspension test and increased the number of crossing in the center area using open-field test. Additionally, the dose 200 mg/kg treatment showed a significant reduction (p < 0.05) in MAO-A activity in mouse brain. For anxiolytic activity, both doses significantly (p < 0.001) improved the time spent in open arm and the number of head dips in elevated plus maze test. The higher duration of time spent in light chamber and higher number of crossing between the light and dark chambers by extract treatment in light-dark box test also supported the anxiolytic behavior. The obtained results supported the antidepressant-like and anxiolytic-like effects of ethanol extract of T.chebula in mice.

Swimming exercise attenuates anxiety-like behavior by reducing brain oxidative stress in type 2 diabetic mice

Anxiety-related behaviors are among the most prevalent psychiatric disorders in patients with type 2 diabetes (T2D). The protective effect of exercise on neuropsychiatric disorders has been documented. However, there are no studies that examined whether swimming exercise can decrease anxiety-like symptoms in type 2 diabetes. We investigated the effects of swimming exercise on body weight, anxiety-like behavior, glucose and insulin levels, and brain oxidative stress in male C57BL/6 mice. T2D-induced mice were subjected to swimming exercise, then anxiety-like behaviors were measured by the open field, light-dark box, and elevated plus-maze tests. Glucose and insulin levels were measure in serum, and antioxidant/oxidative markers including glutathione (GSH), malondialdehyde (MDA), and glutathione disulfide (GSSG) were measured in the brain. Our findings showed that T2D increased body weight, anxiety-like symptoms, glucose and insulin resistance, and oxidative stress by increasing MDA and GSSG levels in the brain of mice. Interestingly, swimming exercise reversed these parameters in diabetic mice. Our findings clearly indicate that there is a protective impact of swimming exercise on anxiety-like behavior by reducing insulin resistance and brain oxidative stress in mice with type 2 diabetes. Further studies are needed to validate these findings in humans.

Imipramine attenuates anxiety- and depressive-like effects of acute and prolonged ethanol-abstinence in male rats by modulating SERT and GR expression in the dorsal hippocampus

AimsConsidering that serotoninergic agents attenuate symptoms of anxiety and are used to treat depression, we investigated whether subchronic treatment with imipramine, a serotonin/noradrenaline reuptake inhibitor, would prevent the anxiogenic-like behaviour induced by acute and/or chronic ethanol withdrawal. We also investigated whether those changes were related to the disfunctioning of hypothalamic–pituitary–adrenal (HPA) axis and serotonergic neurotransmission. Main methods264 Male Wistar rats were treated with ethanol 6% (vol./vol.) for 21 days. Acute ethanol withdrawal was induced by abrupt discontinuation of treatment and sustained for 48 h. Protracted abstinence was sustained for an additional period of 21 days. Behavioural tests included the Elevated Plus Maze (EPM) or Light/Dark Box (LDB) after acute abstinence, and the Forced Swim Test (FST) after protracted abstinence. Imipramine (15 mg/kg, i.p.) was administered 24, 19 and 1 h before EPM or LDB tests. Key findingsAcute abstinence decreased exploration of the open arms of the EPM, without changing exploration of LDB. Additionally, chronic abstinent rats displayed more time immobile in the FST, when compared to control animals. These effects were attenuated by imipramine treatment, without changing basal response. Imipramine prevented protracted abstinence -induced decrease in glucocorticoid receptor (GR) and serotonin transporter (SERT) expression in the dorsal hippocampus. SignificanceOur findings indicate that chronic ethanol withdrawal affects the hippocampal serotonergic system by decreasing serotonin transporter expression. It also disturbs the HPA axis functioning through an imbalance on GR and mineralocorticoid (MR) expression.

Observational Fear Learning in Rats: Role of Trait Anxiety and Ultrasonic Vocalization.

Rats can acquire fear by observing conspecifics that express fear in the presence of conditioned fear stimuli. This process is called observational fear learning and is based on the social transmission of the demonstrator rat’s emotion and the induction of an empathy-like or anxiety state in the observer. The aim of the present study was to investigate the role of trait anxiety and ultrasonic vocalization in observational fear learning. Two experiments with male Wistar rats were performed. In the first experiment, trait anxiety was assessed in a light–dark box test before the rats were submitted to the observational fear learning procedure. In the second experiment, ultrasonic vocalization was recorded throughout the whole observational fear learning procedure, and 22 kHz and 50 kHz calls were analyzed. The results of our study show that trait anxiety differently affects direct fear learning and observational fear learning. Direct fear learning was more pronounced with higher trait anxiety, while observational fear learning was the best with a medium-level of trait anxiety. There were no indications in the present study that ultrasonic vocalization, especially emission of 22 kHz calls, but also 50 kHz calls, are critical for observational fear learning.

Antihypernociceptive and Neuroprotective Effects of the Aqueous and Methanol Stem-Bark Extracts of Nauclea pobeguinii (Rubiaceae) on STZ-Induced Diabetic Neuropathic Pain.

The greatest common and devastating complication of diabetes is painful neuropathy that can cause hyperalgesia and allodynia. It can disturb psychosocial functioning by increasing levels of anxiety and depression. This work was designed to evaluate the antihyperalgesic, antidepressant, and anxiolytic-like effects of the aqueous and methanol extracts of Nauclea pobeguinii stem-bark in diabetic neuropathy induced by streptozotocin in mice. Diabetic neuropathy was induced in mice by the intraperitoneal administration of 200 mg/kg streptozotocin (STZ) to provoke hyperglycemia. Nauclea pobeguinii aqueous and methanol extracts at the doses of 150 and 300 mg/kg were administered by oral route, and their effects were evaluated on antihyperalgesic activity (Von Frey filaments, hot plate, acetone, and formalin tests), blood glucose levels, body weight, serum, sciatic nerve proinflammatory cytokines (TNF-α, IL-1β, and IL-6) and sciatic nerve growth factor (IGF and NGF) rates, depression (open field test, forced swimming test, tail suspension test), and anxiety (elevated plus maze, light-dark box test, social interaction). Oral administration of Nauclea pobeguinii stem-bark aqueous and methanol extracts (150 and 300 mg/kg) produced antihyperalgesic, antidepressant, and anxiolytic-like effects in STZ-induced diabetic neuropathic mice. Extracts also triggered a decrease in glycaemia and increased body weight in treated animals. They also significantly (p <0.001) reduced tumour necrosis factor alpha (TNF-α), interleukin-1 beta (IL-1β), and IL-6 and significantly (p <0.001) increased nerve growth factor (NGF) and insulin-like growth factor (IGF) in sciatic nerves. The results of this study confirmed that Nauclea pobeguinii aqueous and methanol extracts possess antihyperalgesic, antidepressant, and anxiolytic activities and could be beneficial therapeutic agents.

A modified four vessel occlusion model of global cerebral ischemia in rats

BackgroundTo develop and evaluate a modified four vessel occlusion (4VO) model of global cerebral ischemia-reperfusion (GCI/R) in rats based on the Pulsinelli and Brierley's method. New methodsVertebral arteries (VAs) were isolated and then permanently ligated with 5-0 nylon surgical sutures under visual conditions. A total of 24 h later, GCI was induced by transient clipping of the bilateral common carotid artery for 20 min. Cognitive function and visual perception were then evaluated by behavioral and histopathological approaches. ResultsThere was no significant difference in the survival rates between the groups. The modified 4VO group had a significantly lower body weight at each time point assessed. In the Y-maze test, the percentage of time spent and distance traveled in the III arm was significantly decreased on day 28, suggesting that cognitive function may have been impaired by the modified 4VO model. The modified 4VO procedure induced severe hippocampal damage but did not result in noticeable changes in visual perception, as indicated by the light-dark box test, and analysis of the optic tract and retinal structures. The modified 4VO procedure-induced cognitive deficits were thus likely the result of hippocampal damage, not visual perception. Comparison with existing methodsThe advantage of this model is the permanent ligation of the bilateral VAs under visual conditions rather than electrocoagulation, which is performed blind. ConclusionsThis modified 4VO model can mimic the GCI/R method of the Pulsinelli and Brierley and may serve as a valuable tool for studies on GCI/R.

Phenotypes of reinforcement sensitivity as predictors of the response to acute antidepressant treatment in rats

One of the biggest threats to modern societies is the increasing prevalence of mood disorders. Cognitive deficits associated with depressive and bipolar disorders are a major driver of functional impairment and the ensuing disability of the suffering individuals. Growing evidence has indicated strong inter-individual differences in the vulnerability to development and effectivity of treatment of these psychiatric conditions, linking various levels of reinforcement sensitivity with specific mood conditions. In this study, we took a unique opportunity to investigate how trait sensitivity to reinforcement determines the reactivity of rats to acute antidepressant treatment.For this, using a preclinical version of the probabilistic reversal-learning (PRL) paradigm, we identified 4 phenotypes of sensitivity to negative and positive feedback in rats, which could represent various types of potential vulnerability to affective disorders. Subsequently, using the light/dark box (LDB) and progressive ratio schedule of reinforcement (PRSR) tests, we evaluated inter-phenotypic differences in the effects of acute treatment with 3 different antidepressant drugs (escitalopram, mirtazapine and clomipramine, each in 3 doses) on anxiety and appetitive motivation of experimental animals.We report statistically significant differences between the investigated phenotypes of reinforcement sensitivity in the effects of acute escitalopram treatment on anxiety in the LDB test. We also report phenotype-independent effects of mirtazapine on motivation and anxiety and a lack of effect of clomipramine.These results demonstrate for the first time that trait sensitivity to reinforcement could have important implications for the effectiveness of treatment in affective disorders.