NMDA receptors are involved in the antidepressant-like effects of capsaicin following amphetamine withdrawal in male mice

Anethole as a promising antidepressant for maternal separation stress in mice by modulating oxidative stress and nitrite imbalance

The occurrence of major depressive disorder is widespread and can be observed in individuals belonging to all societies. It has been suggested that changes in the NO pathway and heightened oxidative stress may play a role in developing this condition. Anethole is a diterpene aromatic compound found in the Umbelliferae, Apiaceae, and Schisandraceae families. It has potential pharmacological effects like antioxidant, anxiolytic, analgesic, anti-inflammatory, antidiabetic, gastroprotective, anticancer, estrogenic, and antimicrobial activities. This study aimed to investigate the potential antidepressant properties of Anethole in a mouse model experiencing maternal separation stress while also examining its impact on oxidative stress and nitrite levels. The research involved the participation of 40 male NMRI mice, separated into five distinct groups to conduct the study. The control group was administered 1 ml/kg of normal saline, while the MS groups were given normal saline and Anethole at 10, 50, and 100 mg/kg doses. The study comprised various behavioural tests, including the open field test (OFT), forced swimming test (FST), and splash test, to assess the effects of Anethole on the mice. In addition to the behavioural tests, measurements were taken to evaluate the total antioxidant capacity (TAC), malondialdehyde (MDA), and nitrite levels in the hippocampus of the mice. According to the findings, maternal separation stress (MS) led to depressive-like conduct in mice, including a rise in immobility duration during the FST and a reduction in the duration of grooming behaviour in the splash test. Additionally, the results indicated that MS correlated with an increase in the levels of MDA and nitrite and a reduction in the TAC in the hippocampus. However, the administration of Anethole resulted in an increase in grooming activity time during the splash test and a decrease in immobility time during the FST. Anethole also exhibited antioxidant characteristics, as demonstrated by its ability to lower MDA and nitrite levels while increasing the TAC in the hippocampus. The results suggest that Anethole may have an antidepressant-like impact on mice separated from their mothers, likely partly due to its antioxidant properties in the hippocampus.

Withdrawal from 3-Fluoroethamphetamine induces hyperactivity and depression-like behaviors in male mice

3-Fluoroethamphetamine (3-FEA) belongs to the amphetamine class of stimulant drugs and functions as a releasing agent for the monoamine neurotransmitters norepinephrine, dopamine, and serotonin. 3-FEA acts on the central nervous system and elicits physical and mental side effects, such as euphoria, increased heart rate, and excitement. However, little is known about the withdrawal symptoms and behavioral changes induced by 3-FEA administration. This study aimed to evaluate the short-term consequences of 3-FEA administration (twice a day, 7 days, i.p.; 1 and 10 mg/kg) in C57BL/6J mice (male, 7 weeks old) at three behavioral levels following 1-4 days of withdrawal. The evaluation included (1) withdrawal score, (2) hyperactivity (open field [OF], elevated plus maze [EPM], and cliff avoidance [CA] test), and (3) depression-like behavior (forced-swim test). In the withdrawal score test, withdrawal behavior increased in all 3-FEA groups at 16 and 40 h after withdrawal. In the OF, EPM, and CA tests, the 3-FEA administration group showed significant changes in terms of hyperactivity. In addition, in the forced-swim test, both the 1 mg/kg and 10 mg/kg 3-FEA groups showed increased immobility time. These findings indicate that 3-FEA administration may lead to physical dependence, demonstrated by the withdrawal score increase and significant changes in hyperactivity and depression-like behavior following repeated administration and drug cessation. In conclusion, this study reveals the adverse consequences of 3-FEA administration and highlights the need for awareness raising and regulatory action to control the use of this new psychoactive substance.

Possible role of NO/NMDA pathway in the autistic-like behaviors induced by maternal separation stress in mice

Autism spectrum disorder (ASD) is a complex neurodevelopmental disorder. Maternal separation (MS) stress is an established model of early-life stress associated with autistic-like behaviors. Altered glutamatergic and nitrergic neurotransmissions may contribute to the pathophysiology of ASD. However, the specific mechanisms underlying these alterations and their relationship to MS-induced autistic-like behaviors remain unclear. Addressing this knowledge gap, this study aims to elucidate the involvement of the nitric oxide (NO)/ N-methyl-D-aspartate (NMDA) pathway in MS-induced autistic-like behaviors in mice. This knowledge has the potential to guide future research, potentially leading to the development of targeted interventions or treatments aimed at modulating the NO/NMDA pathway to ameliorate ASD symptoms. Ninety male Naval Medical Research Institute (NMRI) mice were assigned to six groups (n = 15) comprising a control group (treated with saline) and five groups subjected to MS and treated with saline, ketamine, NMDA, L-NAME, and L-arginine. Behavioral tests were conducted, including the three-chamber test, shuttle box, elevated plus-maze, and marble burying test. Gene expression of iNOS, nNOS, and NMDA-R subunits (NR2A and NR2B), along with nitrite levels, was evaluated in the hippocampus. The findings demonstrated that MS induced autistic-like behaviors, accompanied by increased gene expression of iNOS, nNOS, NR2B, NR2A, and elevated nitrite levels in the hippocampus. Modulation of the NO/NMDA pathway with activators and inhibitors altered the effects of MS. These results suggest that the NO/NMDA pathway plays a role in mediating the negative effects of MS and potentially contributes to the development of autistic-like behaviors in maternally separated mice.

Inhibition of xCT by sulfasalazine alleviates the depression-like behavior of adult male mice subjected to maternal separation stress

Maternal separation (MS) can induce emotional disorders. Our previous study reported that MS resulted in depression-like behavior. In this study, we aimed to explore the role of xCT in depression-like behavior in adult mice subjected to MS stress. Pups were divided into the control group, the control + sulfasalazine (SSZ, 75 mg/kg/day, i.p.) group, the MS group, and the MS+SSZ group. After MS, all pups were raised until PD60. Then, the depression-like behavior was detected by the novelty suppressed feeding (NSF) test, the forced swimming test (FST), and the tail suspension test (TST). The synaptic plasticity was examined by electrophysiological recordings and molecular biotechnology. The data showed that, compared with the control group, the mice in the MS group presented depression-like behavior, impairment of long-term potentiation (LTP), a reduction in the number of astrocytes, and activation of the microglia. Moreover, the expression of xCT was increased in the prefrontal cortex of MS mice, the EAAT2 and the Group Ⅱ metabotropic glutamate receptors (mGluR2/3) were decreased, and the level of pro-inflammatory factors was increased in the prefrontal cortex. After the administration with SSZ, the depression-like behavior and the impairment of LTP were alleviated, the number of astrocytes was increased, and the microglial activation was inhibited. Moreover, the levels of EAAT2 and mGluR2/3 were ameliorated, the over-activation of the microglia was mitigated, and the levels of glutamate and pro-inflammatory factors were decreased. In conclusion, the inhibition of xCT by SSZ could alleviate depression-like behavior partly via modulating the homeostasis of the glutamate system and dampening neuroinflammation.

Amphetamine exposure alters behaviors, and neuronal and neurochemical activation in the brain of female prairie voles

Previous studies have shown that 3-day d-amphetamine (AMPH) treatment effectively induced conditioned place preferences (CPP) and impaired pair bonding behaviors in prairie voles (Microtus ochrogaster). Using this established animal model and treatment regimen, we examined the effects of the demonstrated threshold rewarding dose of AMPH on various behaviors and their potential underlying neurochemical systems in the brain of female prairie voles. Our data show that 3-day AMPH injections (0.2 mg/kg/day) impaired social recognition and decreased depressive-like behavior in females without affecting their locomotion and anxiety-like behaviors. AMPH treatment also decreased neuronal activation indicated by the labeling of the early growth response protein 1 (Egr-1) as well as the number of neurons double-labeled for Egr-1 and corticotrophin-releasing hormone (CRH) in the dentate gyrus (DG) of the hippocampus and paraventricular nucleus of the hypothalamus (PVN) in the brain. Further, AMPH treatment decreased the number of neurons double-labeled for Egr-1 and tyrosine hydroxylase (TH) but did not affect oxytocinergic neurons in the PVN or cell proliferation and neurogenesis markers in the DG. These data not only demonstrate potential roles of the brain CRH and dopamine systems in mediating disrupted social recognition and depressive-like behaviors by AMPH in female prairie voles, but also further confirm the utility of the prairie vole model for studying interactions between psychostimulants and social behaviors.

Targeting autophagy and neuroinflammation pathways with plant-derived natural compounds as potential antidepressant agents

Major depressive disorder (MDD) is a life-threatening disease that presents several characteristics. The pathogenesis of depression still remains poorly understood. Moreover, the mechanistic interactions of natural components in treating depression to target autophagy and neuroinflammation are yet to be evaluated. This study overviewed the effects of plant-derived natural components in regulating critical pathways, particularly neuroinflammation and autophagy, associated with depression. A list of natural components, including luteolin, apigenin, hyperforin, resveratrol, salvianolic acid b, isoliquiritin, nobiletin, andrographolide, and oridonin, have been investigated. All peer-reviewed journal articles were searched by Scopus, MEDLINE, PubMed, Web of Science, and Google Scholar using the appropriated keywords, including depression, neuroinflammation, autophagy, plant, natural components, etc. The neuroinflammation and autophagy dysfunction are critically associated with the pathophysiology of depression. Natural components with higher efficiency and lower complications can be used for targeting neuroinflammation and autophagy. These components with different doses showed the beneficial antidepressant properties in rodents. These can modulate autophagy markers, mainly AMPK, LC3II/LC3I ratio, Beclin-1. Moreover, they can regulate the NLRP3 inflammasome, resulting in the suppression of proinflammatory cytokines (e.g., IL-1β and IL-18). Future in vitro and in vivo studies are required to develop novel therapeutic approaches based on plant-derived active components to treat MDD.

Capsaicin Reduces Ethanol Consumption in C57BL/6 but not DBA/2 Mice

Objective

Capsaicin, the pungent analgesic substance of hot peppers which produces a burning sensation and pain is known to affect Substance P and central opioid activities. This experiment was designed to test the effect of capsaicin on alcohol consumption in C57BL/6 and DBA/2 mice. These two strains are known to differ in both their alcohol consumption and their endogenous opioid distribution and response to alcohol. It is hypothesized that this effect may be mediated by both increases Substance P and decreases beta-endorphin.

Methods

After i.p. administration of 0.01 and 0.001 mg/kg of capsaicin with a vehicle or the vehicle alone as the control for eight days in C57BL/6 and DBA/2 mice on limited access alcohol model, Capsaicin’s effects on 2-hour alcohol, 22-hours water, 24-hours food intake and body weight were studied.

Results

In this study, as expected, C57BL/6 mice drank significantly more alcohol than DBA/2 mice under baseline conditions. Capsaicin at both doses tested significantly reduced baseline alcohol consumption in C57BL/6 but not DBA/2 mice. These effects were selective for alcohol as capsaicin did not disrupt food or water consumption.

Conclusion

These results demonstrate that capsaicin differentially affects those mechanisms underlying alcohol consumption in two strains of mice known to differ in their preference for and consumption of alcohol. This effect is hypothesized to be related to differences in the response of the endogenous opioid system.

Beneficial Effects of Capsaicin in Disorders of the Central Nervous System

Capsaicin is a natural compound found in chili peppers and is used in the diet of many countries. The important mechanism of action of capsaicin is its influence on TRPV1 channels in nociceptive sensory neurons. Furthermore, the beneficial effects of capsaicin in cardiovascular and oncological disorders have been described. Many recent publications show the positive effects of capsaicin in animal models of brain disorders. In Alzheimer’s disease, capsaicin reduces neurodegeneration and memory impairment. The beneficial effects of capsaicin in Parkinson’s disease and depression have also been described. It has been found that capsaicin reduces the area of infarction and improves neurological outcomes in animal models of stroke. However, both proepileptic and antiepileptic effects of capsaicin in animal models of epilepsy have been proposed. These contradictory results may be caused by the fact that capsaicin influences not only TRPV1 channels but also different molecular targets such as voltage-gated sodium channels. Human studies show that capsaicin may be helpful in treating stroke complications such as dysphagia. Additionally, this compound exerts pain-relieving effects in migraine and cluster headaches. The purpose of this review is to discuss the mechanisms of the beneficial effects of capsaicin in disorders of the central nervous system.

Ameliorative effect of Allium atroviolaceum on sperm quality in cyclophosphamide-treated mice

Background

Cyclophosphamide (CP) is an anti-neoplastic alkylating agent that is extensively used in different chemotherapy regimens. Adverse effects on the reproductive system, especially spermatogenesis, are one of the most important side effects of this drug. It is medically essential to use complementary and alternative drugs. Herbal drugs have long been used as a complementary treatment. Our purpose was to study the effect of hydroalcoholic Allium atroviolaceum L. extract on spermatogenesis in CP-treated mice.

Results

CP affected a significant decrease in sperm count, motility, viability, and morphology. Sperm count was significantly higher in the all extract groups than in the group of control (p<0.001) and CP group (p<0.001, p<0.01). Sperm motility was significantly greater in the extract (100 and 200mg/kg) groups than in the group of control (p<0.05 and <0.001). Sperm immotility and rotational movement were significantly higher in the CP group than in the CP+extract groups (p<0.001). The sperm viability was significantly greater in the CP+extract (200mg/kg) group than in the CP group (p<0.001). The number of headless sperm, sperm with initial tail, with coiled tail, and sperm with curved body, was significantly lower in the CP+extract (200mg/kg) group than in the CP group (p<0.001).

Conclusion

A. atroviolaceum extract treatment significantly improved CP-induced reproductive toxicity.

The effects of minocycline in improving of methamphetamine withdrawal syndrome in male mice

Methamphetamine (METH) is a potent psychostimulant drug with an increasing rate of abuse over recent years. Depressive-like behaviors are one of the major symptoms patients in the METH withdrawal period experience. There is limited evidence regarding the METH withdrawal treatment, and conventional managements are not completely effective. Furthermore, extensive promising literature supports minocycline, a well-known antibiotic with anti-oxidant, anti-inflammatory properties, to treat depressive-like behaviors. Therefore, we hypothesized that administration of minocycline might mitigate the methamphetamine (METH) induced depression in male mice. Administration of METH (2 mg/kg) to mice two times a day for 14 constitutive days was done to induce the METH-induced withdrawal syndrome model. Animals were divided into 10 groups (n = 10 in each group), and three doses of minocycline (2.5, 5 and 10 mg/kg) were daily administered to male albino mice for 10 days. Following the behavioral test, the animals were scarified, their hippocampus were dissected to measure oxidative stress parameters. Our data revealed that chronic administration of minocycline provoked antidepressant effects in behavioral tests, such as forced swim test (FST), tail suspension test (TST) and splash test. Additionally, minocycline was able to improve oxidative stresses and neuronal damage in the hippocampus and restore the body's antioxidant system by increasing glutathione (GSH) and the cellular energy (ATP) and reducing the malondialdehyde (MDA) level. According to our promising results of minocycline on targeting mitochondria and its performance, we suggest minocycline as a new therapeutic option in clinical trials of depression treatment.

Diosgenin via NMDA Receptor Exerted Anxiolytic-like Effect on Maternally Separated Mice

BACKGROUND AND AIM

Anxiety is one of the most common psychiatric disorders that lead to the disruption of daily life and also the quality of life. Routine medications have many side effects and cause physical dependence and psychosocial addiction. Diosgenin is a phytosteroid found in a number of herbs. The present study aimed to investigate the anxiolytic-like effect of diosgenin in the maternal separation model in male mice focusing on the role of NMDA receptors.

MATERIALS AND METHODS

Maternal separation (MS) paradigm was performed daily (3 h) from postnatal day (PND) 2-14. Male mice were treated with different doses of diosgenin to find effective and sub-effective doses. In the next step, mice were treated with an effective dose of diosgenin plus NMDA and or a sub-effective dose of diosgenin plus ketamine (NMDA antagonist). Valid behavioral tests for the evaluation of anxiety-like behavior were performed. Then, mice were euthanized, the hippocampus was dissected out and gene expression of NMDA receptors (NR2a and NR2b subunits) was assessed.

RESULTS

MS provokes anxiety-like behaviors in the open field test (OFT) and elevated plus maze (EPM) test. Diosgenin significantly mitigated the negative effects of MS. Co-administration of NMDA attenuated anxiolyticlike effect of the effective dose of diosgenin, while ketamine potentiated the anxiolytic effect of sub-effective dose of diosgenin. Furthermore, MS increased the expression of the NMDA receptor in the hippocampus which to some extent modulated with diosgenin.

CONCLUSION

Diosignin has an anxiolytic-like effect on MS mice which at least, in part, mediated through NMDA receptors.

Clozapine attenuates mitochondrial dysfunction, inflammatory gene expression, and behavioral abnormalities in an animal model of schizophrenia

Beyond abnormalities in the neurotransmitter hypothesis, recent evidence suggests that mitochondrial dysfunction and immune-inflammatory responses contribute to the pathophysiology of schizophrenia. The prefrontal cortex (PFC) undergoes maturation and development during adolescence, which is a critical time window in life that is vulnerable to environmental adversities and the development of psychiatric disorders such as schizophrenia. Applying eight weeks of post-weaning social isolation stress (PWSI) to rats, as an animal model of schizophrenia, we decided to investigate the effects of PWSI on the mitochondrial function and expression of immune-inflammatory genes in the PFC of normal and stressed rats. To do this, control and PWSI rats were divided into treatment (clozapine; CLZ, 2.5 mg/kg/day for 28 days) and non-treatment sub-groups. Our results showed PWSI caused schizophrenic-like behaviors in rats and induced mitochondrial dysfunction as well as upregulation of genes associated with innate immunity in the PFC. Chronic treatment with CLZ attenuated the effects of PWSI on behavioral abnormalities, mitochondrial dysfunction, and immune-inflammatory responses in the PFC of rats. These results may advance our understanding about the mechanism of action of CLZ that targets mitochondrial dysfunction and immune-inflammatory responses as factors involved in the pathophysiology of schizophrenia.

Possible Involvement of N-methyl-D-aspartate Receptor (NMDA-R) in the Antidepressant- like Effect of Trigonelline in Male Mice

Background and Aim:

Depression is a mood disorder with high global prevalence. Depression is associated with a reduction in the hippocampal volume and change in its neurotransmitters function. Trigonelline is an alkaloid with neuroprotective activity. The aim of this study was to investigate the possible role of N-methyl-Daspartate (NMDA) receptor in the antidepressant-like effect of trigonelline, considering histopathological modifications of the hippocampus.

Methods:

60 Naval Medical Research Institute (NMRI) male mice were divided into 6 groups including group 1 (normal saline), groups 2, 3 and 4 (trigonelline at doses of 10, 50 and 100 mg/kg), group 5 (effective dose of trigonelline plus NMDA agonist) and group 6 (sub-effective dose of trigonelline plus NMDA antagonist). Forced swimming test (FST) was used to assess depressive-like behavior. Hippocampi were separated under deep anesthesia and used for histopathological evaluation as well as NMDA receptor gene expression assessment.

Results:

Trigonelline at doses of 10, 50 and 100 significantly reduced the immobility time in the FST in comparison to the control group. The administration of the sub-effective dose of trigonelline plus ketamine (an NMDA receptor antagonist) potentiated the effect of the sub-effective dose of trigonelline. In addition, co-treatment of an effective dose of trigonelline with NMDA mitigated the antidepressant-like effect of trigonelline. Trigonelline at doses of 50 and 100 mg/kg significantly increased the diameter of the CA1 area of the hippocampus.

Conclusion:

Trigonelline showed an antidepressant-like effect in mice, probably via attenuation of NMDA receptor activity and an increase in the CA1 region of the hippocampus.

Possible involvement of NMDA receptor in the anxiolytic-like effect of caffeic acid in mice model of maternal separation stress

Background and aim

Anxiety disorders are one of the most common psychiatric disorders worldwide. Common anti-anxiety medications are associated with several side effects. Caffeic acid (CA) is a phenolic compound with several pharmacological effects. The aim of this study was to investigate the anxiolytic-like effect of CA in maternally separated (MS) mice focusing on the possible involvement of the NMDA receptor.

Materials and methods

In this study, we used the MS paradigm (as a valid animal model of anxiety) in male mice and examined their anxiety-like behavior in postnatal day (PND) 45. The animals were divided into 12 experimental groups. Mice treated with CA alone and in combination with the NMDA receptor agonist/antagonist and then using open field (OFT) and elevated plus maze (EPM) anxiety-like behavior was assessed. Finally, the expression of NMDA receptor subtypes was assessed in the hippocampus using RT- PCR.

Results

Finding showed that CA exerted anxiolytic –like effects in the OFT and EPM tests. We showed that administration of effective dose of NMDA significantly reversed the anxiolytic-like effect of effective dose of CA and co-administration of ketamine (a NMDA receptor antagonist) significantly potentiated the effect of sub-effective dose of CA. Furthermore, ketamine enhanced the CA-reducing effect on NMDA receptors in the MS mice.

Conclusion

Our finding demonstrated that, probably at least, NMDA receptors are involved in the anxiety-like properties of CA in MS mice.

Effect of hydroalcoholic Allium atroviolaceum L. on the pathology of testicular tissue in cyclophosphamide-treated mice

Background

The most important side effects of Cyclophosphamide, as an anticancer broad-spectrum drug, are the negative effects on the reproduction and fertility because of oxidative stress. Considering the antioxidant properties of medicinal plants, especially those of the Allium genus, this paper studied the effect of hydroalcoholic extract of Allium atroviolaceum L. on the pathology of testicular tissue in CP-treated mice.

Methods

Groups of this experimental study consisted of normal saline recipients; three groups receiving A. atroviolaceum extract at 50, 100, 200 mg/kg; three groups receiving A. atroviolaceum extract at 50, 100, and 200 mg/g and 6.6 mg/kg of Cyclophosphamide; and a group given Cyclophosphamide at 1.6 mg/kg. All injections were performed intra-peritoneally. After 30 days, the testicular histological profile as well as the number of spermatozoa, the number of primary and round spermatocytes, and the number of spermatogonia were investigated.

Results

Cyclophosphamide treatment significantly reduced the lumen diameter, the seminiferous tubule diameter, the epithelial thickness, as well as decreased the quantity of spermatozoa and round and primary spermatocytes compared to the control group. Cyclophosphamide groups treated with A. atroviolaceum extract at 50, 100 and 200 mg/kg in a significant manner improved these variables (P < 0.001).

Conclusion

A. atroviolaceum extract can significantly improve Cyclophosphamide-induced toxicity and pathological process on testicular tissue. It seems that this plant, with high antioxidant capacity, can be considered a complementary therapy for Cyclophosphamide to prevent undesirable effects on the reproductive system.

Angiotensin (1-7) through modulation of the NMDAR-nNOS-NO pathway and serotonergic metabolism exerts an anxiolytic-like effect in rats

Although recent studies have shown that angiotensin (1-7) (Ang [1-7]) exerts anti-stress and anxiolytic-like effects, the underlying mechanisms remain elusive. The ventral hippocampus (VH) is proposed to be a critical brain region for mood and stress management through the N-methyl-d-aspartate receptor (NMDAR) signaling pathway. However, the role of VH NMDAR signaling in the effects of Ang (1-7) remains unclear. In the present study, Ang (1-7) was injected into the bilateral VH of stressed rats, or in combination with a Fyn kinase inhibitor, NMDAR antagonist, neuronal nitric oxide synthase (nNOS) inhibitor, or nitric oxide (NO) scavenger. Anxiety-like behaviors were assessed using the open field test and elevated plus maze test, while alterations in NMDAR-nNOS-NO signaling and serotonergic metabolism were examined in the VH. After 21 days of chronic restraint stress, anxiety-like behaviors were evident. Levels of phosphorylated NR2B (a key NMDAR subunit), its upstream kinase Fyn, as well as activity of nNOS and monoamine oxidase (MAO) were markedly reduced. In contrast, levels of serotonin were increased. Bilateral VH infusion of Ang (1-7) recovered NMDAR-nNOS-NO signaling and MAO-mediated serotonin metabolism, as well as reducing anxiety-like behaviors in stressed rats. These effects were diminished by blockade of MasR (Ang [1-7]-specific receptor), Fyn kinase, NMDAR, nNOS, or NO production. Altogether, these findings indicate that Ang (1-7) exerts anxiolytic effects through modulation of the NMDAR-nNOS-NO pathway and serotonergic metabolism. Future translational research should focus on the relationship between Ang (1-7), glutamatergic neurotransmission, and serotonergic neurotransmission in the VH.

Synergistic antidepressant-like effect of capsaicin and citalopram reduces the side effects of citalopram on anxiety and working memory in rats

RATIONALE

We have previously shown that in rats, capsaicin (Cap) has antidepressant-like properties when assessed using the forced swimming test (FST) and that a sub-threshold dose of amitriptyline potentiates the effects of Cap. However, synergistic antidepressant-like effects of the joint administration of Cap and the selective serotonin reuptake inhibitor citalopram (Cit) have not been reported.

OBJECTIVES

To assess whether combined administration of Cap and Cit has synergistic effects in the FST and to determine whether this combination prevents the side effects of Cit.

METHODS

Cap, Cit, and the co-administration of both substances were evaluated in a modified version of the FST (30-cm water depth) conducted in rats, as well as in the open field test (OFT), elevated plus maze (EPM), and Morris water maze (MWM).

RESULTS

In line with previous studies, independent administration of Cap and Cit displayed antidepressant-like properties in the FST, while the combined injection had synergistic effects. In the OFT, neither treatment caused significant increments in locomotion. In the EPM, the time spent in the closed arms was lower in groups administered either only Cap or a combination of Cap and Cit than in groups treated with Cit alone. In the MWM, both Cap and the joint treatment (Cap and Cit) improved the working memory of rats in comparison with animals treated only with Cit.

CONCLUSION

Combined administration of Cap and Cit produces a synergistic antidepressant-like effect in the FST and reduces the detrimental effects of Cit on anxiety and working memory.

Rutin via Increase in the CA3 Diameter of the Hippocampus Exerted Antidepressant-Like Effect in Mouse Model of Maternal Separation Stress: Possible Involvement of NMDA Receptors

Methods

Mouse neonates were exposed to MS paradigm 3 hours daily from postnatal days (PND) 2 to 14. The control and MS mice were divided separately into 16 groups (n = 8) (8 groups for each set) including mice that received normal saline, mice that received rutin at doses of 10, 50, and 100 mg/kg, mice that received NMDA at a dose of 150 mg/kg, mice that received ketamine (NMDA antagonist) at a dose of 0.25 mg/kg, mice that received NMDA antagonist plus a subeffective dose of rutin, and mice that received NMDA plus an effective dose of rutin. Forced swimming test (FST) was performed. Afterwards, the hippocampus was evaluated in cases of histopathological changes as well as expression of NR2A and NR2B genes.

Results

Rutin significantly reduced immobility time in the FST. The expression of NR2A and NR2B subunits of NMDA receptor in MS mice was significantly higher than that in the control group. Rutin significantly decreased the expression of NR2B and NR2A subunits in the hippocampus. The CA3 diameter and percentage of dark neurons in the hippocampus of MS mice significantly decreased and increased, respectively, which partially reversed following rutin administration.

Conclusion

Rutin, partially, through a neuroprotective effect on the hippocampus exerted antidepressant-like effect. We concluded that NMDA receptors, at least in part, mediated the beneficial effect of rutin.

Attenuation of oxidative stress and neurotoxicity involved in the antidepressant-like effect of the MK-801(dizocilpine) in Bacillus Calmette-Guerin-induced depression in mice

Background The emerging line of research suggests that neuro-inflammation and oxidative stress are linked to the development of depression-like behavior. The tryptophan metabolizing enzyme, indolamine 2,3-dioxygenase (IDO), serves as an important interface between chronic inflammation and depression. IDO is induced by pro-inflammatory cytokines and diverts tryptophan towards the kynurenine pathway, decreasing serotonin synthesis. Further, the metabolites of kynurenine pathway increase brain oxidative stress and also cause N-methyl-D-aspartate (NMDA) receptor-mediated exitotoxicity. The resulting oxidative damage and dysfunction in glutamatergic neurotransmission alters the network connectivity of the brain, which may be the further mechanism for emergence of depression-like symptoms. Methods A depression-like illness was induced in mice by injecting Bacillus Calmette-Guerin (BCG) suspended in isotonic saline at a dose of 107 CFU I.P. The mice were then divided into different groups and were administered MK-801 or normal saline for the next 21 days, after which a battery of behavior and biochemical tests were conducted to assess them. Results The BCG group had significantly reduced sucrose preference index and an increase in immobility time in forced swim test (FST) and Tail Suspension Test (TST) as compared to the saline group. There was also a significant increase in the brain MDA levels and a decline in the brain GSH levels. The hippocampal tissue from the BCG group had significantly more comet cells than the saline group. The NMDA receptor antagonist, MK-801, was able to reverse the BCG-induced depression-like behaviour. MK-801 also showed significant decrease in brain oxidative stress but failed to show significant protection against BCG-induced neurotoxicity observed in comet assay. Conclusions The NMDA receptor antagonist, MK-801, mitigated BCG-induced, depressive-like behavior in mice by improving the sucrose preference and decreasing the duration of immobility time in TST and FST. The overall improvement in depression-like behavior was accompanied by a reduction in brain oxidative stress and comet cells, thus suggesting the antioxidant and neuroprotective action of MK-801.

Yueju-Ganmaidazao Decoction confers rapid antidepressant-like effects and the involvement of suppression of NMDA/NO/cGMP signaling

ETHNOPHARMACOLOGICAL RELEVANCE

Yueju-Ganmaidazao Decoction (YG) is a multiherbal medicine prescribed for treatment of mood disorder, consisting of two classical traditional Chinese herbal medicine Yueju and Ganmaidazao. Yueju and Ganmaidazao both are used for depression treatment. The combined decoction of Yueju and Ganmaidazao is prescribed to achieve optimal clinical outcomes by dealing with different symptoms of depression. Recent studies indicated ethanol extract of Yueju was capable to confer rapid antidepressant-like response. The antidepressant activity of YG decoction with fast-onset feature remains to be investigated.

AIM OF THE STUDY

Rapid and safe antidepressant treatment is urgently needed. This study aimed to assess the rapid antidepressant-like activity of YG and the underlying mechanism, focusing on NMDA/NO/cGMP signaling.

MATERIALS AND METHODS

The optimal doses for immediate and persistent antidepressant-like response were first screened using tail suspension test (TST) and forced swimming test (FST) post a single administration of YG. The rapid action was further confirmed by using the chronic mild stress (CMS) and learned helplessness (LH) paradigms. The expressions of NMDA receptor subunits were evaluated post stress and YG. The contributions of NMDA, NO, and cGMP signaling to the antidepressant effect of YG were investigated systematically using pharmacological interventions.

RESULTS

The optimal dose for immediate and persistent antidepressant potential, evidenced with reduced immobility times in TST or FST from 30 min to 7 days, was determined. The rapid antidepressant-like effect was confirmed in CMS and LH paradigms, including instant normalization of sucrose preference behavior. The expression of NMDA subunit NR1 in the hippocampus was reduced from 30 min to 5 days post YG. In animals subjected to CMS and LH, hippocampal NR1 expression increased, reversed by YG. YG's antidepressant-like effect was blunted by pretreatment with the agonists along the signalings including NMDA (75 mg/kg), L-arginine (750 mg/kg) and sildenafil (5 mg/kg) in TST or FST. Conversely, administration of subeffective dose of individual antagonists, including MK-801 (0.05 mg/kg), 7-nitroindazole (30 mg/kg), methylene blue (10 mg/kg), in combination with a subeffective dose of YG, elicited antidepressant effects.

CONCLUSION

YG conferred rapid antidepressant-like effects, and the antidepressant response was essentially dependent on suppression of NMDA/NO/cGMP signaling.

Progesterone exerts antidepressant-like effect in a mouse model of maternal separation stress through mitigation of neuroinflammatory response and oxidative stress

Context: Experiencing early-life adversity plays a key role in the development of mood disorders in adulthood. Experiencing adversities during early life period negatively affects brain development. Sex steroids such as progesterone affect the brain structure and functions and subsequently affects behaviour.Objective: We assess the antidepressant-like effect of progesterone in a mouse model of maternal separation (MS) stress, focussing on its anti-neuroinflammatory and antioxidative effects.Materials and methods: NMRI mice were treated with progesterone (10, 50, and 100 mg/kg, i.p., respectively) for 14 days. Valid behavioural tests including forced swimming test (FST), splash test and open field test (OFT) were used. Quantitative reverse transcription-PCR (qRT-PCR) was used for evaluation of genetic expression in the hippocampus. Antioxidant capacity was assessed by the FRAP method and the level of malondialdehide by TBA.Results: MS provoked depressive-like behaviour in mice. Treatment of MS mice with progesterone increased the grooming activity time in the splash test and decreased the immobility time in the FST. In addition, progesterone decreased the expression of inflammatory genes related to neuroinflammation (IL-1β, TNF-α, TLR4 and NLRP3) as well as increased the antioxidant capacity and decreased the lipid peroxidation (MDA) in the hippocampus.Discussion and Conclusion: Administration of progesterone significantly mitigated the negative effects of MS on behaviours relevant to depressive-like behaviour as well as attenuated neuro-immune response and oxidative stress in the hippocampus of MS mice. In this context, we conclude that progesterone, at least partially, via attenuation of oxidative stress and neuroinflammation, exerts antidepressant-like effects.

Implication of NMDA-NO pathway in the antidepressant-like effect of ellagic acid in male mice

Depression is one the common psychiatric disorders through the world. Nitric oxide (NO) and N-methyl-d-aspartate receptor (NMDA-R) are involved in the pathophysiology of depression. Previous studies have been reported various pharmacological properties for ellagic acid (EA). We aimed to evaluate possible involvement of NMDA-NO pathway in the antidepressant-like effect of EA. To do this, we used relevant behavioral tests to evaluate depressive-like behavior. In order to find effective and sub-effective doses of agents, mice treated with EA (6.25, 12.5, 25, 50 and 100 mg/kg), L-NAME (5 and 10 mg/kg), L-arg (25 and 50 mg/kg), NMDA (75 and 150 mg/kg) and ketamine (0.25 and 0.5 mg/kg). Furthermore, mice were treated with combination of sub-effective dose of EA plus sub-effective doses of L-NAME and/or ketamine as well as treated with effective dose of EA in combination of effective doses of L-arg and/or NMDA. Level of NO and gene expression of NR2A and NR2B subunits of NMDA-R were assessed in the hippocampus. Results showed that EA dose dependently provoked antidepressant-like effects and also decreased the hippocampal NO level as well as expression of NMDA-Rs. Co-administration of sub-effective doses of L-NAME or ketamine with sub-effective dose of EA potentiated the effect of EA on behaviors, NO level as well as NMDA-Rs gene expression in the hippocampus. However, co-treatment of effective dose of EA with effective doses of L-arg or NMDA mitigated effects of EA. In conclusion, our data suggested that NMDA-NO, partially at least, are involved in the antidepressant-like effect of EA.

On the role of corticosterone in behavioral disorders, microbiota composition alteration and neuroimmune response in adult male mice subjected to maternal separation stress

Experiencing psychosocial adversities in early life such as maternal separation (MS) increases the risk of psychiatric disorders. Immune-inflammatory responses have imperative roles in the pathophysiology of psychiatric disorders. MS relatively changes the composition of intestinal microbiota leading to an overactivation of the hypothalamic-pituitary-adrenal (HPA) axis, and subsequently increases the corticosterone level. In this study, we aimed to evaluate the role of corticosterone in behavioral changes and microbiota modifications in a mouse model of MS afflicted neuroinflammatory response in the hippocampus. For this purpose, 180 min of MS stress was applied to mice at postnatal day (PND) 2-14 followed by behavioral tests including forced swimming test (FST), splash test, open field test (OFT) and elevated plus maze (EPM) at PND 50-52. For evaluating the role of corticosterone, mice were subjected to adrenalectomy. Using real-time RT-PCR, the expression of inflammatory genes was determined in the hippocampus and colon tissues. We found that MS provoked depressive- and anxiety-like behaviors in adult male mice. In addition, MS was able to active a neuroimmune response in the hippocampus, motivate inflammation and histopathologic changes in the colon tissue and modify the composition of gut microbiota as well. Interestingly, our findings showed that adrenalectomy (decline in the corticosterone level), could modulate the above-mentioned negative effects of MS. In conclusion, our results demonstrated that overactivation of HPA axis and the subsequent increased level of corticosterone could act, possibly, as the deleterious effects of MS on behavior, microbiota composition changes and activation of neuroimmune response.

Involvement of NO/NMDA-R pathway in the behavioral despair induced by amphetamine withdrawal

Abrupt discontinuation of chronic amphetamine consumption leads to withdrawal symptoms including depression, anhedonia, dysphoria, fatigue, and anxiety. These irritating symptoms may result in continuing to take the drug or can lead to suicidal behavior. Past studies have shown the involvement of various biologic systems in depression induced following amphetamine withdrawal (AW). However, there is no evidence about the relation between nitric oxide (NO) with NMDA receptors on depression following AW. In this study, we examined the involvement of the NO/NMDA pathways on depressive-like behaviors after 24 h withdrawal following 5 continuous days of amphetamine administration in male NMRI mice. Behavioral tasks used for depression assessment included the forced swimming test (FST), the Splash test and the open field test (OFT). In order to evaluate the role of NO/NMDA pathways animals treated with MK-801 (NMDA-R antagonist), Aminoguanidine (AG), a selective iNOS inhibitor, Nω-Nitro-l-arginine (L-NNA), a non-selective NOS inhibitor and 7-Nitro indazole (7-NI), a selective nNOS inhibitor. We also measured the level of nitrite in the hippocampus. Our data showed that AW induced the depressive-like effect in the FST and the Splash test. We showed that administration of AG, L-NNA, and MK-801 mitigated AW induced depression, however, 7-NI was failed to decrease depressive-like behaviors. Also, the antidepressant-like effect of co-injection of sub-effective doses of MK-801 with AG suggested that inducible nitric oxide synthase (iNOS) is associated with NMDA-R in AW induced depression. In conclusion, both NO and NMDA-R pathways are involved and related to each other in depression induced following AW.

Capsaicin protects cortical neurons against ischemia/reperfusion injury via down-regulating NMDA receptors

Capsaicin, the ingredient responsible for the pungent taste of hot chili peppers, is widely used in the study and management of pain. Recently, its neuroprotective effect has been described in multiple studies. Herein, we investigated the underlying mechanisms for the neuroprotective effect of capsaicin. Direct injection of capsaicin (1 or 3nmol) into the peri-infarct area reduced the infarct volume and improved neurological behavioral scoring and motor coordination function in the middle cerebral artery occlusion (MCAO)/reperfusion model in rats. The time window of the protective effect of capsaicin was within 1h after reperfusion, when excitotoxicity is the main reason of cell death. In cultured cortical neurons, administration of capsaicin attenuated glutamate-induced excitotoxic injury. With respect to the mechanisms of the neuroprotective effect of capsaicin, reduced calcium influx after glutamate stimulation was observed following capsaicin pretreatment in cortical neurons. Trpv1 knock-out abolished the inhibitory effect of capsaicin on glutamate-induced calcium influx and subsequent neuronal death. Reduced expression of GluN1 and GluN2B, subunits of NMDA receptor, was examined after capsaicin treatment in cortical neurons. In summary, our studies reveal that the neuroprotective effect of capsaicin in cortical neurons is TRPV1-dependent and down-regulation of the expression and function of NMDA receptors contributes to the protection afforded by capsaicin.