Tail Suspension Test Research Articles

µ-Opioid receptor antagonism facilitates the anxiolytic-like effect of oxytocin in mice

Mood and anxiety disorders are leading causes of disability worldwide and are major contributors to the global burden of diseases. Neuropeptides, such as oxytocin and opioid peptides, are important for emotion regulation. Previous studies have demonstrated that oxytocin reduced depression- and anxiety-like behavior in male and female mice, and opioid receptor activation reduced depression-like behavior. However, it remains unclear whether the endogenous opioid system interacts with the oxytocin system to facilitate emotion regulation in male and female mice. We hypothesized that opioid receptor blockade would inhibit the anxiolytic- and antidepressant-like effects of oxytocin. In this study, we systemically administered naloxone, a preferential μ−opioid receptor antagonist, and then intracerebroventricularly administered oxytocin. We then tested mice on the elevated zero maze and the tail suspension tests, respective tests of anxiety- and depression-like behavior. Contrary to our initial hypothesis, naloxone potentiated the anxiolytic-like, but not the antidepressant-like, effect of oxytocin. Using a selective μ−opioid receptor antagonist, D-Phe-Cys-Tyr-D-Trp-Arg-Thr-Pen-Thr-NH2, and a selective κ−opioid receptor antagonist, norbinaltorphimine, we demonstrate that μ−opioid receptor blockade potentiated the anxiolytic-like effect of oxytocin, whereas κ−opioid receptor blockade inhibited the oxytocin-induced anxiolytic-like effects. The present results suggest that endogenous opioids can regulate the oxytocin system to modulate anxiety-like behavior. Potential clinical implications of these findings are discussed.

Bambusa vulgaris attenuates Haloperidol-induced motor deficit and non-Motor co-morbidity in rats through up-regulation of Dopamine transmission and mitigation of pro-inflammatory cytokines activities

BackgroundBamboo is a plant widely distributed in many parts of the world and grows in about 18 provinces in China. One of the species of the plant is Bambusa vulgaris. An ethnobotanical survey of the plant revealed its values in managing neurodegenerative diseases, including Parkinson's disease. ObjectiveThis study examined the effect of hydroethanolic leaf extract of Bambusa vulgaris (BVE) on motor functions and non-motor co-morbidity, dopamine content, pro-inflammatory cytokines and oxidative species in haloperidol-treated rats. MethodsRats were pretreated with distilled water (10 mL/kg), B. vulgaris extract (100, 200 and 400 mg/kg) and levodopa-carbidopa (LD-CD; 25/100 mg/kg, orally). Precisely one hour post every treatment, haloperidol (2 mg/kg, i.p) was administered to the rats across all groups every 48 h for 21 days. Motor and non-motor functions were assessed on day 22. After that, brains were removed and processed for dopamine content evaluation, pro-inflammatory cytokines determination, oxidative damage assessment and histopathological examinations of the striatum and substantia nigra. ResultsB. vulgaris increased (P < 0.01; 400 mg/kg) the distance covered and decreased the frequency foot slips (P < 0.01, 0.001; 200–400 mg/kg) in the beam work test; decreased (P < 0.05–0.0001; 100–400 mg/kg) the catalepsy behavior in the catalepsy bar test; reversed hypo-locomotor activity (P < 0.0001; 400 mg/kg) in open field test; and decreased (P < 0.05–0.001; 100–400 mg/kg) the non-motor behavioural deficit in tail suspension test. BVE increased (P < 0.01; 200 mg/kg) dopamine concentration in the brain and decreased TNF-α (P < 0.05; 200 mg/kg) and IL-6 (P < 0.01, 0.001; 100–400 mg/kg) concentrations in the brain. BVE significantly increased the GSH (P < 0.05, 0.001; 100–200 mg/kg) and Catalase (P < 0.05, 0.01; 100–400 mg/kg) levels and decreased the MDA level (P < 0.05, 0.01; 200–400 mg/kg) in the brain tissue. ConclusionOur findings suggest that the hydroethanol leaf extract of Bambusa vulgaris reverses the haloperidol-induced motor deficits and non-motor co-morbidity by mitigating the pathophysiological abnormalities associated with the progression of the disease. Based on these outcomes, the peak effect was observed at 200 mg/kg.

Prebiotics modulate the microbiota–gut–brain axis and ameliorate anxiety and depression-like behavior in HFD-fed mice

Previous research has demonstrated that Prebiotics can influence the composition of the gut microbiota, consequently impacting mood regulation. This study aimed to assess the effects of Prebiotics, specifically Fructooligosaccharides (FOS) and Galactooligosaccharides (GOS) on neuroinflammation, depression, and anxiety-like behavior in a mouse model fed a high-fat diet (HFD). Initially, mice were divided into two groups: a control group on a standard diet (n = 15) and a group on an HFD for 18 weeks (n = 45). By the 13th week, the HFD group was further divided into experimental groups: Control (n = 15), HFD (n = 15), HFD receiving Prebiotics (n = 15), and HFD receiving Fluoxetine (n = 15). From the 13th week onward, the HFD + Prebiotics group received both the high-fat diet and a combination of FOS and GOS, while the HFD + Fluoxetine group received Fluoxetine in their drinking water. In the 18th week, all mice underwent tests to evaluate behavior, including the Tail Suspension Test (TST), Forced Swimming Test (FST), Sucrose Preference Test (SPT), and the Plus Maze Test (PMT), after which they were euthanized. Mice on the HFD exhibited increased body weight, abdominal size, blood glucose, triglyceride levels, cholesterol, insulin, HOMA index, and higher serum IL-1β. These obese mice also displayed an increased number of microglia and astrocytes, activation of the TLR4 pathway, and elevated levels of neuroinflammatory markers like TNF-α, IL-1β, and COX-2. Moreover, obese mice showed increased activation of the IDO pathway and decreased levels of NMDA receptors. Additionally, markers of neurogenesis and synaptic plasticity, such as PSD, SAP 102, CREB-p, and BDNF, were lower. Treatment with FOS and GOS reversed symptoms of depression and anxiety in mice subjected to HD. This improvement in behavior resulted from a reduction in dysbiosis with an increase in acetate-producing bacteria (B. acidifaciens and B. dorei) and intestinal permeability, leading to a decrease in chronic peripheral and central inflammation. Furthermore, the modulation of the gut-brain axis by FOS and GOS promoted elevated acetate and GPR43 levels in the brain and a reduction in the levels of pro-inflammatory cytokines, positively impacting signaling pathways of neuronal proliferation and survival in the hippocampus and prefrontal cortex.

Synergistic antidepressant-like effect of citicoline and CB 1 agonist in male mice.

The endocannabinoid system plays a key role in the control of many emotional-correlated reactions such as stress, depressed mood, and anxiety. Moreover, citicoline has neuroprotective properties and indicates beneficial effects in the treatment of depressive problems. Acute restraint stress (ARS) is an experimental model used for the induction of rodent models of depression. This research was designed to assess the effects of intracerebroventricular (i.c.v.) injection of cannabinoid CB1 receptor agents on citicoline-induced response to depression-like behaviors in the non-acute restraint stress (NARS) and ARS mice. For i.c.v. microinjection, a guide cannula was implanted in the left lateral ventricle of male mice. The ARS model was carried out by movement restraint for 4 h. Depression-related behaviors were assessed by forced swimming test (FST), tail suspension test (TST), and splash test. The results exhibited that the ARS mice showed depressive-like responses. I.c.v. infusion of ACPA (1 μg/mouse) induced an antidepressant-like effect in the NARS and ARS mice by reduction of immobility time in the FST and TST as well as enhancement of grooming activity time in the splash test. On the other hand, i.c.v. microinjection of AM251 dose-dependently (0.5 and 1 μg/mouse) induced a depressant-like effect in the NARS mice. I.p. injection of citicoline (80 mg/kg) induced an antidepressant-like response in the NARS and ARS mice. Furthermore, ACPA (0.25 μg/mouse, i.c.v.) potentiated the antidepressant-like response induced by citicoline (20 mg/kg, i.p.) in the NARS and ARS mice. However, AM251 (0.25 μg/mouse, i.c.v.) reversed the antidepressant-like effect produced by the citicoline (80 mg/kg, i.p.) in the NARS and ARS mice. Interestingly, our results indicated a synergistic effect between citicoline and ACPA based on the induction of an antidepressant-like effect in the NARS and ARS mice. These results suggested an interaction between citicoline and cannabinoid CB1 receptors on the modulation of depression-like behaviors in the NARS and ARS mice.

Depression-like Behavior Induced by Repeated Administration of Dexamethasone to Lipopolysaccharide-inflamed Mice.

Over the years, animal models of depression have been developed by loading chronic stress, inducing neuroinflammation, or administering drugs that induce depression; however, these results have poor reproducibility. Therefore, it is necessary to develop animal models that exhibit definitive symptoms of depression for studies on potential therapeutics. This study was aimed at investigating depression-like symptoms and their pathogenesis in lipopolysaccharide (LPS)-inflamed mice treated with dexamethasone (DEX). Male ICR mice were injected with LPS, followed by injection with DEX a day later and each day for 6 consecutive days. Depression-like behavior, expression of the glial markers glial fibrillary acidic protein (GFAP) and ionized calcium-binding adapter molecule 1 (Iba1), and the number of the immature neuronal marker doublecortin (DCX)-positive cells were assessed using tail-suspension test (TST), forced swim test (FST), western blot analysis, and immunohistochemical analysis. Mice in the LPS+DEX group had significantly longer immobility time in the TST and FST than did those in the LPS- or DEX-only and control groups on day 7 post-LPS administration. GFAP and Iba1 expression was significantly elevated in the hippocampus of mice in the LPS group than in those of mice in the control group. Moreover, a significantly lower number of DCX-positive cells was observed in the hippocampal dentate gyrus of mice in the LPS+DEX group compared with that in mice in the LPS- or DEX-only and control groups on day 7 after LPS administration. Repeated DEX administration to LPS-inflamed mice may induce definitive depression-like symptoms by decreasing the number of immature neurons in the hippocampal dentate gyrus. This novel mouse model of depression was produced by repeated administration of steroids to inflamed mice.

Targeting Large-Conductance Calcium-Activated Potassium Channels to Ameliorate Lipopolysaccharide-Induced Depressive-Like Behavior in Mice.

Neuroinflammation plays crucial role in the development and progression of depression. Large conductance calcium- and voltage-dependent potassium (BK) channels mediate the activation of microglia. Herein, we investigated whether BK channels could serve as a target for the treatment of inflammation-associated depression. Lipopolysaccharide (LPS, 0.83mg/kg) was injected intraperitoneally (i.p.) to induce neuroinflammation and depressive-like behavior in 6-8week ICR mice. Adeno-associated virus (AAV) constructs (AAV9-Iba1p-BK shRNA-EGFP (BK shRNA-AAV) or AAV9-Iba1p-NC shRNA-EGFP (NC shRNA-AAV)) were unilaterally injected intracerebroventricularly to selectively knock down BK channels in microglia. The tail suspension test (TST) and forced-swim test (FST) were used to evaluate depressive-like behavior in mice 24h after LPS challenge. The morphology of microglia, expression of BK channels, levels of cytokines, and expression and activity of indoleamine 2,3-dioxygenase (IDO) were measured by immunohistochemistry, western blot, quantitative real time PCR, and enzyme-linked immunosorbent assay (ELISA), respectively. Either paxilline (i.p.), a specific BK channel blocker, or BK shRNA-AAV effectively inhibited the activation of microglia, reduced the production of IL-1β in the hippocampus and suppressed the expression and activity of IDO in the hippocampus and prefrontal cortex, resulting in the amelioration of depressive-like behavior in mice. These data suggest for the first time that BK channels are involved in LPS-induced depressive-like behaviors. Thus, microglia BK channels may be a potential drug target for the depression treatment.

Neuronal and Molecular Mechanisms Underlying Chronic Pain and Depression Comorbidity in the Paraventricular Thalamus.

Patients with chronic pain often develop comorbid depressive symptoms, which makes the pain symptoms more complicated and refractory. However, the underlying mechanisms are poorly known. Here, in a repeated complete Freund's adjuvant (CFA) male mouse model, we reported a specific regulatory role of the paraventricular thalamic nucleus (PVT) glutamatergic neurons, particularly the anterior PVT (PVA) neurons, in mediating chronic pain and depression comorbidity (CDC). Our c-Fos protein staining observed increased PVA neuronal activity in CFA-CDC mice. In wild-type mice, chemogenetic activation of PVA glutamatergic neurons was sufficient to decrease the 50% paw withdrawal thresholds (50% PWTs), while depressive-like behaviors evaluated with immobile time in tail suspension test (TST) and forced swim test (FST) could only be achieved by repeated chemogenetic activation. Chemogenetic inhibition of PVA glutamatergic neurons reversed the decreased 50% PWTs in CFA mice without depressive-like symptoms and the increased TST and FST immobility in CFA-CDC mice. Surprisingly, in CFA-CDC mice, chemogenetically inhibiting PVA glutamatergic neurons failed to reverse the decrease of 50% PWTs, which could be restored by rapid-onset antidepressant S-ketamine. Further behavioral tests in chronic restraint stress mice and CFA pain mice indicated that PVA glutamatergic neuron inhibition and S-ketamine independently alleviate sensory and affective pain. Molecular profiling and pharmacological studies revealed the 5-hydroxytryptamine receptor 1D (Htr1d) in CFA pain-related PVT engram neurons as a potential target for treating CDC. These findings identified novel CDC neuronal and molecular mechanisms in the PVT and provided insight into the complicated pain neuropathology under a comorbid state with depression and related drug development.

Pharmacological Investigation of Pithecellobium dulce Stem Bark extract for Anti-Depressant Activity on Mice and Rats

Pithecellobium dulce (PD), commonly known as Jangli-jilebi, is a Manila tamarind belonging to the family Leguminosae. P. dulce (PD) is used to treat various diseases like diarrhea, asthma, leprosy, paralysis, inflammatory, anti-bacterial, spermicidal, anti-convulsant, etc. In this paper, we studied the activity of P. Dulce for depression, which is a debilitating, life-threatening, and common disease affecting different sections of the community. Chemical and synthetic medications used to treat this disease have significant negative side effects, and only 50–60% of patients fully recover. At the same time, the available scientific information about this species is scarce, and there are no reports related to its possible effects on the central nervous system. In this work, the effects of acetone and methanolic extracts of the stem bark of P. dulce (PD) were evaluated in mice and rats utilizing behavioral assays sensitive to clinically effective anti-depressant compounds. In both the forced swim test and the tail suspension test, the extracts (100 and 200 mg/kg) administered orally were able to shorten the immobility duration of mice and rats in a dose-dependent manner. According to the current study's findings, PD extract may have antidepressant potential and be useful in treating those who suffer from depressive disorders. These findings proved that PD has specifically anti-depressive in vivo effects.

Natural product Kaji-ichigoside F1 exhibits rapid antidepression via activating the AMPA–BDNF–mTOR pathway and inhibiting the NMDAR–CaMKIIα pathway

BackgroundDepression is a common and recurrent neuropsychiatric disorder. Recent studies have shown that the N-methyl-d-aspartate (NMDA) receptor (NMDAR) is involved in the pathophysiology of depression. Previous studies have found that Kaji-ichigoside F1 (KF1) has a protective effect against NMDA-induced neurotoxicity. However, the antidepressant mechanism of KF1 has not been confirmed yet. PurposeIn the present study, we aimed to evaluate the rapid antidepressant activity of KF1 and explore the underlying mechanism. Study designFirst, we explored the effect of KF1 on NMDA-induced hippocampal neurons and the underlying mechanism. Second, depression was induced in C57BL/6 mice via chronic unpredictable mild stress (CUMS), and the immediate and persistent depression-like behavior was evaluated using the forced swimming test (FST) after a single administration of KF1. Third, the contributions of NMDA signaling to the antidepressant effect of KF1 were investigated using pharmacological interventions. Fourth, CUMS mice were treated with KF1 for 21 days, and then their depression-like behaviors and the underlying mechanism were further explored. MethodsThe FST was used to evaluate immediate and persistent depression-like behavior after a single administration of KF1 with or without NMDA pretreatment. The effect of KF1 on depressive-like behavior was investigated in CUMS mice by treating them with KF1 once daily for 21 days through the sucrose preference test, FST, open field test, and tail suspension test. Then, the effects of KF1 on the morphology and molecular and functional phenotypes of primary neuronal cells and hippocampus of mice were investigated by hematoxylin–eosin staining, Nissl staining, propidium iodide staining, TUNEL staining, Ca2+ imaging, JC-1 staining, ELISA, immunofluorescence analysis, RT-PCR, and Western blot. ResultsKF1 could effectively improve cellular viability, reduce apoptosis, inhibit the release of LDH and Ca2+, and increase the mitochondrial membrane potential and the number of dendritic spines numbers in hippocampal neurons. Moreover, behavioral tests showed that KF1 exerted acute and sustained antidepressant-like effects by reducing Glu-levels and ameliorating neuronal damage in the hippocampus. Additionally, in vivo and in vitro experiments revealed that PSD95, Syn1, α-amino-3‑hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), and brain-derived neurotrophic factor (BDNF) were upregulated at the protein level, and BDNF and AMPA were upregulated at the mRNA level. NR1 and NR2A showed the opposite trend. ConclusionThese results confirm that KF1 exerts rapid antidepressant effects mainly by activating the AMPA–BDNF–mTOR pathway and inhibiting the NMDAR–CaMKIIα pathway. This study serves as a new reference for discovering rapid antidepressants.

Effects of cannabidiol in post-stroke mood disorders in neonatal rats.

Neonatal rats can manifest post-stroke mood disorders (PSMD) following middle cerebral artery occlusion (MCAO). We investigated whether cannabidiol (CBD) neuroprotection, previously demonstrated in neonatal rats after MCAO, includes prevention of PSMD development. Seven-day-old Wistar rats (P7) underwent MCAO and received either vehicle or 5 mg/kg CBD treatment. Brain damage was quantified by MRI, and neurobehavioral and histological (TUNEL) studies were performed at P14 and P37. PSMD were assessed using the tail suspension test, forced swimming test, and open field tests. The dopaminergic system was evaluated by quantifying dopaminergic neurons (TH+) in the Ventral Tegmental Area (VTA), measuring brain dopamine (DA) concentration and DA transporter expression, and assessing the expression and function D2 receptors (D2R) through [35S]GTPγS binding. Animals without MCAO served as controls. CBD reduced MCAO-induced brain damage and improved motor performance. At P14, MCAO induced depressive-like behavior, characterized by reduced TH+ cell population and DA levels, which CBD did not prevent. However, CBD ameliorated hyperactivity observed at P37, preventing increased DA concentration by restoring D2R function. These findings confirm the development of PSMD following MCAO in neonatal rats and highlight CBD as a neuroprotective agent capable of long-term functional normalization of the dopaminergic system post-MCAO. MCAO in neonatal rats led to post-stroke mood disorders consisting in a depression-like picture in the medium term evolving towards long-term hyperactivity, associated with an alteration of the dopaminergic system. The administration of CBD after MCAO did not prevent the development of depressive-like behavior, but reduced long-term hyperactivity, normalizing dopamine receptor function. These data point to the importance of considering the development of depression-like symptoms after neonatal stroke, a well-known complication after stroke in adults. Our work confirms the interest of CBD as a possible treatment for neonatal stroke.

Design, Synthesis, and Activity Evaluation of Fluorine-Containing Scopolamine Analogues as Potential Antidepressants.

This study aimed to develop novel rapid-acting antidepressants with sustained efficacy and favorable safety profiles. We designed and synthesized a series of fluorine-containing scopolamine analogues and evaluated their antidepressant potential. In vitro cytotoxicity assays showed that most of these compounds exhibited minimal toxicity against neuronal and non-neuronal mammalian cell lines (IC50 > 100 μM). The antidepressant activities of the compounds were evaluated using the tail suspension test, and S-3a was identified as a lead compound with potent and sustained antidepressant effects. Behaviorally, S-3a alleviated depressive symptoms in mice and displayed a higher cognitive safety margin than scopolamine. Toxicological assessments confirmed S-3a's safety, while pharmacokinetics showed a rapid clearance (half-life: 16.6 min). Mechanistically, S-3a antagonized M1 receptors and elevated BDNF levels, suggesting its potential as an antidepressant for further exploration.

New curcumin-loaded nanocapsules as a therapeutic alternative in an amnesia model.

This study aimed to investigate the action of two different formulations of curcumin (Cur)-loaded nanocapsules (Nc) (Eudragit [EUD] and poly (ɛ-caprolactone) [PCL]) in an amnesia mice model. We also investigated the formulations' effects on scopolamine-induced (SCO) depressive- and anxiety-like comorbidities, the cholinergic system, oxidative parameters, and inflammatory markers. Male Swiss mice were randomly divided into five groups (n = 8): group I (control), group II (Cur PCL Nc 10mg/kg), group III (Cur EUD Nc 10mg/kg), group IV (free Cur 10mg/kg), and group V (SCO). Treatments with Nc or Cur (free) were performed daily or on alternate days. After 30min of treatment, the animals received the SCO and were subjected to behavioral tests 30min later (Barnes maze, open-field, object recognition, elevated plus maze, tail suspension tests, and step-down inhibitory avoidance tasks). The animals were then euthanized and tissue was removed for biochemical assays. Our results demonstrated that Cur treatment (Nc or free) protected against SCO-induced amnesia and depressive-like behavior. The ex vivo assays revealed lower acetylcholinesterase (AChE) and catalase (CAT) activity, reduced thiobarbituric species (TBARS), reactive species (RS), and non-protein thiols (NSPH) levels, and reduced interleukin-6 (IL-6) and tumor necrosis factor (TNF) expression. The treatments did not change hepatic markers in the plasma of mice. After treatments on alternate days, Cur Nc had a more significant effect than the free Cur protocol, implying that Cur may have prolonged action in Nc. This finding supports the concept that it is possible to achieve beneficial effects in nanoformulations, and treatment on alternate days differs from the free Cur protocol regarding anti-amnesic effects in mice.

A63 RESTRAINED STRESS IN MICE INDUCES TRANSLOCATION OF GUT COMMENSAL BACTERIAL INTO DISTAL ORGANS

Abstract Background Bacterial translocation is defined as the migration of bacteria from the intestinal lumen into extraintestinal tissues; this process has been implicated in the pathophysiology of gastrointestinal disorders including irritable bowel syndrome (IBS) and central nervous system disorders. In our recent study, we found that gut bacteria from patients with IBS can disrupt the mucus layer and penetrate into the lamina propria in our microbiota-humanized mouse model. It is well known that psychological stress triggers or exacerbates IBS symptoms. Furthermore, experimental stress models have been able to reproduce some features of IBS and demonstrate that gut bacteria can translocate into the mesenteric lymph node (MLN), liver, and spleen. These studies suggested that bacterial translocation might induce changes in behavior and brain function. However, the direct causal relationship between bacterial translocation and behavioral changes, and the mechanism of bacterial translocation remains unclear. Aims To investigate translocation of commensal bacteria within the gut wall and their migration into distant organs using a mouse stress model. Methods SPF C57BL/6 mice were split into 2 groups: restraint stress group (3 hrs x 7 days, n=9) and non-stress control group (n=8). After the last session of stress, we conducted light/dark preference and tail suspension tests. We collected jejunum, ileum, and colon samples for histology. We also sampled blood, MLN, liver, spleen, and brain for histology and bacterial cultures. The tissues were collected under aseptic conditions. The blood or organ homogenates were plated and incubated in aerobic and anaerobic conditions. Intestinal tissues were submitted to fluorescence in situ hybridization staining with a bacterial universal probe in combination with immunofluorescence to co-stain with e-cadherin and CD103. The images were taken by confocal microscopy. Results The chronic restrain stress-induced anxiety-like, but not depressive behavior, as assessed by the light/dark test. Compared to the controls, bacterial culture was more frequently positive in the stress group: blood (0% vs 25%), MLN (0% vs 50%), spleen (0% vs 25%), liver (0% vs 25%), and brain (25% vs 74%). The histology showed that intestinal bacteria were present within the gut wall and brain in the stress group. Interestingly, these bacteria co-localized with the goblet cells in the jejunum, ileum and colon, and CD103+ dendritic cells in the colon (Fig. 1). Conclusions We found that mice subjected to the restraint stress exhibit abnormal behavior, accompanied by bacterial infiltration into the gut wall, as well as bacterial translocation into distal organs, including brain. Our histology data suggest a potential contribution of goblet cells-dendritic cells pathway in commensal gut bacteria translocation in the restrained stress model. Intestinal bacteria were present within the gut wall in the stress group. Funding Agencies CIHR Farncombe Innovation Fund

A13 MICROBIOTA FROM PATIENTS WITH INFLAMMATORY BOWEL DISEASE (IBD) INDUCE ALTERED BEHAVIOUR AND VISCERAL HYPERSENSITIVITY IN MICROBIOTA-HUMANIZED MICE

Abstract Background IBD is characterized by relapsing episodes of tissue-damaging inflammation in the gastrointestinal tract. Abdominal pain is common in IBD and often persists in the absence of overt inflammation. The treatment has limited efficacy, in part due to our partial understanding of its pathophysiology, and thus commonly leads to dependency on opioids. Moreover, patients with IBD are more likely to develop psychiatric comorbidities (anxiety and depression), further impairing the disease course and quality of life. The gut microbiota has been shown to modulate pain, mood, and anxiety. Gut bacterial composition and function are altered in patients with IBD. However, whether IBD microbiota affects pain perception and emotional behaviour is unknown. Aims To determine whether microbiota from patients with IBD contributes to visceral hypersensitivity and behavioural abnormalities in a microbiota-humanized mouse model. Methods Adult germ-free C57BL/6 mice (n=65) of both sexes were colonized with fecal microbiota from 7 patients with IBD (Crohn’s Disease n=5, Ulcerative Colitis n=2) and 3 healthy controls (HC). Mice were fed with a human-like (Western) diet. Behavioural tests (light preference, open field, and tail suspension tests) were employed to assess anxiety- and depression-like behaviour. Visceral sensitivity was assessed by measuring visceromotor responses to colorectal distension. Results Compared to mice with HC microbiota, mice with IBD microbiota had reduced body weight gain. However, no differences in colon length were found, suggesting that IBD microbiota did not induce overt colonic inflammation. Mice with IBD microbiota displayed a reduced preference for the light chamber and increased immobility in the tail suspension test compared to HC mice, suggestive of anxiety- and depression-like behaviour, respectively. Importantly, no differences in overall locomotion were observed, thus ruling out sickness-like behaviour. When subjected to colorectal distension, mice with IBD microbiota had an overall higher visceromotor response (area under the curve) compared to HC mice. Furthermore, they displayed increased responses to non-noxious stimuli (100 μL distension), suggestive of visceral allodynia. Conclusions Our data demonstrate that microbiota from patients with IBD negatively affects the gut-brain axis, by inducing changes in emotionality-related behaviour and triggering visceral hypersensitivity. Uncovering the microbial products and molecular mechanisms underlying these abnormalities will guide the development of novel microbiota-based therapies for patients with IBD. Funding Agencies CCC, CIHRCrohn's and Colitis Foundation (USA)

Antidepressant, Antidiarrheal, Thrombolytic and Phytochemical Profiling of Ethanol Extract of Amomum aromaticum Leaves: In vivo and In vitro Approaches

The study evaluated several pharmacological effects including antidepressant, antidiarrheal and thrombolytic activities of ethanol extract of Amomum aromaticum leaves (EEAA). Upon the assessment for qualitative phytochemical groups in the extract, several doses of EEAA (1000 - 4000 mg/kg) were studied to find acute oral toxicity in mouse for safe dose selection. Then EEAA was tested whether it demonstrates antidepressant activity in tail suspension test (TST) and forced swim test (FST). Antidiarrheal and clot lysis activities of EEAA were evaluated in castor oil-induced diarrhoea in mouse and In vitro clot lysis method, respectively. Oral administration of EEAA (1000 - 4000 mg/kg) showed no morality after 10 days, and no sign of acute toxicity observed within 24 hrs post-treatment. The qualitative phytochemical screening showed the presence of carbohydrate, alkaloid, flavonoid, tannin, saponin, and polyphenol groups in EEAA. The TST and FST resulted with significant improvement in mobility in mice treated with EEAA (400 mg/kg), where fluoxetine (20 mg/kg) was used as standard in both tests. EEAA treatment also showed a moderate dose-dependent anti-diarrheal effect. The 400 mg/kg oral dosing for 14 days decreased the rate of defecation by 52.8% compared to the control group. This study also demonstrated that EEAA possesses clot lysis activity. Hence, further intense investigations are suggested to identify specific potential active phytochemicals. Bangladesh Pharmaceutical Journal 27(1): 51-58, 2024 (January)

Anti-oxidant and neuro-modulatory effects of bioactive Byttneria pilosa leaf extract in swiss albino mice using behavioral models.

Byttneria pilosa, a flowering plant from the Malvaceae family traditionally used to treat ailments such as boils and scabies, is here investigated for its potential health benefits. The study focused on evaluating its antioxidant and antidiabetic properties in vitro, as well as the in vivo anxiolytic and antidepressant activities of the methanol extract of B. pilosa leaf (MEBP). The study employed various assays to evaluate antioxidant activity, including 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging, reducing power capacity, and quantification of the total phenolic and flavonoid contents of MEBP. Additionally, anxiolytic and antidepressant activities were evaluated through four tests: elevated plus-maze test (EPMT), light-dark box test (LDBT), forced swimming test (FST), and tail suspension test (TST). Antidiabetic effect was determined using α-amylase inhibition assay. Docking analysis was performed using BIOVIA and Schrödinger Maestro (v11.1), and the absorption, distribution, metabolism, and excretion/toxicity (ADME/T) properties of bioactive substances were investigated using a web-based technique. MEBP exhibited moderate antioxidant activity in DPPH radical scavenging and reducing power capacity assays, with a dose-dependent response. The total phenolic and flavonoid contents measured were 70 ± 1.53mg and 22.33 ± 1.20mg, respectively. MEBP demonstrated significant effects in α-amylase inhibition comparable to acarbose. In behavioral tests, MEBP dose-dependently altered time spent in open arms/light box and closed arms/dark box, indicating anxiolytic effects. Moreover, MEBP significantly reduced immobility duration in FST and TST, suggesting antidepressant properties. Molecular docking analysis revealed favorable interactions between beta-sitosterol and specific targets, suggesting the potential mediation of anxiolytic and antidiabetic effects. Overall, MEBP exhibits notable anxiolytic and antidepressant properties, along with moderate antioxidant and antidiabetic activities.

Two polygenic mouse models of major depressive disorders identify TMEM161B as a potential biomarker of disease in humans.

Treatments are only partially effective in major depressive disorders (MDD) but no biomarker exists to predict symptom improvement in patients. Animal models are essential tools in the development of antidepressant medications, but while recent genetic studies have demonstrated the polygenic contribution to MDD, current models are limited to either mimic the effect of a single gene or environmental factor. We developed in the past a model of depressive-like behaviors in mice (H/Rouen), using selective breeding based on behavioral reaction after an acute mild stress in the tail suspension test. Here, we propose a new mouse model of depression (H-TST) generated from a more complex genetic background and based on the same selection process. We first demonstrated that H/Rouen and H-TST mice had similar phenotypes and were more sensitive to glutamate-related antidepressant medications than selective serotonin reuptake inhibitors. We then conducted an exome sequencing on the two mouse models and showed that they had damaging variants in 174 identical genes, which have also been associated with MDD in humans. Among these genes, we showed a higher expression level of Tmem161b in brain and blood of our two mouse models. Changes in TMEM161B expression level was also observed in blood of MDD patients when compared with controls, and after 8-week treatment with duloxetine, mainly in good responders to treatment. Altogether, our results introduce H/Rouen and H-TST as the two first polygenic animal models of MDD and demonstrate their ability to identify biomarkers of the disease and to develop rapid and effective antidepressant medications.

Antidepressant-Like Activity and Molecular Docking Analysis of a Sesquiterpene Lactone Isolated from the Root Bark of Ximenia americana (L.).

Depression, a global cause of disability and premature death, is often treated by traditional healers in Africa using medicinal herbs such as Ximenia americana (L.). With recent pharmacological studies showing the potential antidepressant properties of X. americana extract, this study aimed to evaluate the antidepressant-like effects of the compound(s) isolated from X. americana extract using the forced swim test (FST) and tail suspension test (TST) models predictive of depression. The extracts, administered orally within a dose range of 100-400 mg/kg, notably decreased the immobility time in both the FST and the TST. The most significant reduction occurred at the highest dose of 400 mg/kg, with a decrease of 117.66 s in FST and 53.5 s in TST. However, this reduction in immobility was not linked to changes in movements, as observed in an open-field test (OFT), suggesting that the effect of the extracts was not due to activation of locomotion. Subsequently, a sesquiterpene lactone, dehydrocostus lactone (1) was isolated through solubility-based fractionation and column chromatography of the active root bark extract of X. americana. Dehydrocostus lactone (400 mg/kg) demonstrated a 46.50 s reduction in immobility time in the FST, which was comparable to the positive control, imipramine (30 mg/kg). With a highly favorable docking score of -8.365 kcal/mol on an antidepressant target, monoamine oxidase A (MAO-A; pdb ID: 2BXS), dehydrocostus lactone (1) potentially outperforms the standard MAO-A inhibitor drug, isocarboxazid (-5.847 kcal/mol). Dehydrocostus lactone (1) displayed strong interactions involving hydrogen bond and hydrophobic and electrostatic interactions with specific MAO-A binding site residues. These findings highlight that the antidepressant-like activity of X. americana is partly attributed to the presence of dehydrocostus lactone. Additionally, it also supports the traditional medicinal use of the plant for treating depression.

Bark extract of Chaetocarpus castanocarpus (Roxb.) exhibits potent sedative, anxiolytic, and antidepressant effects through an in vivo approach in Swiss albino mice.

Standard phytochemical investigations were performed to identify the secondary metabolites in the methanol extract of Chaetocarpus castanocarpus bark (MECC) and investigate the neuropharmacological potential of MECC in Swiss albino mice. Swiss albino mice were used in the forced swimming test (FST) and tail suspension test (TST) to evaluate the antidepressant effect of MECC. Also, the hole board test (HBT) and elevated plus maze (EPM) were conducted to examine anxiolytic activities. In contrast, the open field test (OFT) and hole cross test (HCT) were employed to evaluate sleeping disorders. Alkaloids, glycosides, flavonoids, terpenoids, coumarins, and tannins are only a few secondary metabolites identified in MECC by qualitative and quantitative phytochemical investigations. The oral administration of MECC considerably shortened the immobility duration during FST and TST. Encouraging dose-dependent anxiolytic effects were also observed in all relevant experiments compared to the control. Additionally, during the OFT and HCT assessment, a noteworthy decline in the locomotor activities of the experimental animals was observed. The results of this investigation suggest that the Chaetocarpus castanocarpus bark is a possible source of therapeutic candidates for treating neurological disorders.

Abstract TP28: The Effects of Social Isolation on Cerebral Amyloid Angiopathy

Introduction: Cerebral amyloid angiopathy (CAA) is characterized by amyloid β (Aβ) deposition in the cortical and leptomeningeal vessels, and it is a largely untreatable cause of intracerebral hemorrhage and dementia. Studies estimate a 10-50% prevalence of CAA in the general elderly population, positioning it as one of the strongest vascular contributors to age-related cognitive impairment. With aging, the prevalence of social isolation (SI) also increases. Isolated individuals have an increased risk of Aβ-related cognitive decline and heightened inflammatory response to stress. Yet, whether and how SI exacerbates CAA-induced cognitive decline is unknown. Methods: TgSwDI mice harboring Swedish, Dutch, and Iowa mutations of human amyloid precursor protein were used as a mouse model of CAA. Male and female C57BL6 wildtype (WT) and CAA mice were randomly assigned to paired housing (PH) or SI at 3 months. Neurobehaviors were measured at baseline and every 3 months using the novel object recognition test (NORT), tail suspension test (TST), and fear conditioning (FC). At 12 months, microglia phenotype, vascular structure, and Aβ burden were assessed using flow cytometry and immunostaining. Results: Both WT and CAA isolated animals displayed significantly greater immobility in TST at 9 months post-SI, suggesting a depression-like behavior (n=10-15/grp, p&lt;0.0001). Isolated CAA mice displayed exacerbated cognitive deficits in NORT and FC while WT mice showed intact cognition (n=10-15/grp, p&lt;0.05). Specifically, SI-induced cognitive deficits were more prominent in the female CAA mice compared to males (n=5-8/grp, p&lt;0.01). Sex differences were also observed in CAA mice in frequencies of Aβ-containing endothelial cells (CD31 + ) and vessel-associated microglia (VAM, CD45 int CD11b + CD31 + ) as well as in microglial phagocytosis of Aβ (n=3/grp, p&lt;0.05). SI increased the frequency of Aβ-containing microglia in isolated CAA mice compared to their PH littermates. Conclusion: SI induced behavioral deficits in both WT and CAA mice but exacerbated cognitive decline only in the CAA SI mice. SI also influences microglial phagocytosis of Aβ. Further research is needed to determine the cellular and molecular mechanism underlying SI-induced changes in CAA.