1-(Phenylselanyl)-2-(p-tolyl)indolizine: A selenoindolizine with potential antidepressant-like activity in mice mediated by the modulation of dopaminergic and noradrenergic systems

1-(Phenylselanyl)-2-(p-tolyl)indolizine (MeSeI) is a selenoindolizine with an antidepressant-like effect in mice by regulation of the serotonergic system. This study investigated the involvement of dopaminergic and noradrenergic systems in the antidepressant-like action of MeSeI. For this purpose, Swiss male mice were pretreated with different antagonists, after 15 min, the MeSeI was administrated by intragastric (i.g.) via; after 30 min, the mouse behavior was assessed in the forced swimming test (FST). The action of MeSeI on the activity of monoamine oxidase (MAO) was determined. The pretreatment of mice with haloperidol (0.05 mg/kg, intraperitoneally, i.p.; non-selective dopamine receptor antagonist), sulpiride (50 mg/kg, i.p.; D2 receptor antagonist), yohimbine (1 mg/kg, i.p.; α2 receptor antagonist), and propranolol (2 mg/kg, i.p.; non-selective β receptor antagonist), inhibited the anti-immobility action of MeSeI (50 mg/kg, i.g.) in the FST. This blocking effect was not observed when SCH23390 (0.01 mg/kg, i.p.; D1 receptor antagonist), and prazosin (1 mg/kg, i.p.; α1 receptor antagonist) were administered. The coadministration of subeffective doses of bupropion (3 mg/kg. i.g.; dopamine and noradrenaline reuptake inhibitor) and MeSeI (0.5 mg/kg. i.g.) reduced the immobility time in the FST. Furthermore, MeSeI inhibited MAO-A and B activities in vitro and ex vivo tests. These results suggest that MeSeI exerts its antidepressant-like effect via regulation of the D2, α2, and β1 receptors and the inhibition of MAO-A and B activities. Molecular docking investigations corroborated these results. This study provides comprehensive insights into the antidepressant-like mechanism of MeSeI in mice, suggesting its potential as a novel antidepressant candidate.

The antidepressant-like and glioprotective effects of the Y2 receptor antagonist SF-11 in the astroglial degeneration model of depression in rats: Involvement of glutamatergic inhibition

In this study, we explored the potential antidepressant-like properties of the brain-penetrant Y2 receptor (Y2R) antagonist SF-11 [N-(4-ethoxyphenyl)- 4-(hydroxydiphenylmethyl)- 1-piperidinecarbothioamide] in the astroglial degeneration model of depression with an emphasis on checking the possible mechanisms implicated in this antidepressant-like effect. The model of depression relies on the loss of astrocytes in the medial prefrontal cortex (mPFC) in Sprague-Dawley rats after administering the gliotoxin L-alpha-aminoadipic acid (L-AAA). SF-11 was administered intraperitoneally (i.p.) once (10 mg/kg) or for three consecutive days (10 mg/kg/day), and the effects of L-AAA and SF-11 injected alone or in combination were investigated using the forced swim test (FST), sucrose intake test (SIT), Western blotting, immunohistochemical staining, and microdialysis. SF-11 produced an antidepressant-like effect after single or three-day administration in rats subjected to astrocyte impairment, as demonstrated by the FST and SIT, respectively. Immunoblotting and immunohistochemical analyses showed that SF-11 reversed the L-AAA-induced astrocyte cell death in the mPFC, suggesting it is glioprotective. Microdialysis studies showed that SF-11 decreased extracellular glutamate (Glu) levels compared to basal value when administered alone and compared to the basal value and control group in LAAA-treated rats. The results from immunoblotting analysis indicated the involvement of Y2Rs in the astrocyte ablation model of depression and the antidepressant-like effect of SF-11. In addition, we observed the participation of the caspase-3 apoptotic pathway in the mechanism of gliotoxin action induced by L-AAA. These findings demonstrate that SF-11, a Y2R antagonist, elicited a rapid antidepressant-like response, possibly linked to its ability to inhibit glutamatergic neurotransmission.

Effect of citicoline and transcranial direct current stimulation on depressive-like behaviors in mice & quot

Recent investigations revealed the positive role of transcranial direct current stimulation (tDCS) in the treatment of depressive-like behavior & quot. Citicoline is a dietary supplement. It acts as a neuroprotective factor for the treatment of neurological disorders. The aim of this research was to evaluate a possible interaction between tDCS and citicoline on the modulation of depressive-like behavior s & quot in male mice. For tDCS, an electrode was surgically implanted in the left prefrontal of the brain of male mice & quot. Acute restraint stress was induced by movement restraint for 4h. Locomotor activity and depressive-like behaviors & quot were examined by open field test (OFT), forced swimming test (FST), and tail suspension test (TST). The results indicated that the intraperitoneal (i.p.) administration of citicoline, left prefrontal anodal tDCS, and co-treatment of citicoline and tDCS had no significant effect on locomotor activity. I.p. injection of citicoline (30mg/kg) decreased immobility time in the FST and TST, showing an antidepressant-like effect & quot. Moreover, the application of left prefrontal anodal tDCS (0.2mA) for 20min induced antidepressant-like effect & quot by reducing immobility time in the FST and TST. Co-administration of citicoline (7 and 15mg/kg) along with tDCS (0.1mA) decreased immobility time in the FST and TST, indicating an antidepressant-like effect & quot. Therefore, it can be concluded that administration of citicoline in combination with tDCS enhanced the efficacy of tDCS for remedy of depressive-like behaviors & quot.

Role of the AMPA receptor in antidepressant effects of ketamine and potential of AMPA receptor potentiators as a novel antidepressant

Ketamine exerts rapid and long-lasting antidepressant effects in patients with treatment-resistant depression. However, its clinical use is limited by its undesirable psychotomimetic side effects. Accumulating evidence from preclinical studies has shown that the antidepressant effects of ketamine are dependent on α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPA-R) activation, which triggers activation of the mechanistic target of rapamycin pathway and brain-derived neurotrophic factor release. Thus, AMPA-R has emerged as a promising new target for novel antidepressants with a rapid onset of action. However, almost all known AMPA-R potentiators carry the risk of a narrow bell-shaped dose-response curve and a poor safety margin against seizures. Our data suggest that agonistic activity is not only related to the risks of bell-shaped dose-response curves and seizures but also to the reduced synaptic transmission and procognitive effects of AMPA-R potentiators. In this review, we describe our original screening approach that led to the discovery of an investigational AMPA-R potentiator with low agonistic activity, TAK-653. We further review the in vitro and in vivo profiles of TAK-653, including its procognitive and antidepressant-like effects, as well as its safety profile, in comparison with known AMPA-R potentiators with agonistic activity and AMPA, an AMPA-R agonist. The low agnostic activity of TAK-653 may overcome limitations of known AMPA-R potentiators. This article is part of the Special Issue on 'Ketamine and its Metabolites'.

Kamikihito rescued depressive-like behaviors and hippocampus neurogenesis in chronic restraint stress rats

Background and aim

Substantial evidence suggests the effectiveness of plant-based medicine in stress-related diseases. Kamikihito (KKT), a Japanese traditional herbal medicine (Kampo), has been used for anemia, insomnia, and anxiety. Recent studies revealed its ameliorating effect on cognitive and memory dysfunction in several animal models. We, therefore, determined whether daily supplementation of KKT has an antidepressant-like effect on the stress-induced behavioral and neurological changes in rats.

Experimental procedure

The effect of KKT against the stress-induced changes in anxiety- and depressive-like behaviors and hippocampal neurogenesis were determined using a rat model of chronic restraint stress (CRS). KKT was orally administered daily at 300 or 1000 mg/kg during 21 consecutive days of CRS (6 h/day). The effect of CRS and KKT on physiological parameters, including body weight gain, food/water consumptions, plasma corticosterone (CORT) levels, and percentage of adrenal gland weight to body weight, were firstly measured. Anxiety- and depressive-like behaviors in rats were assessed in the open field test (OFT), sucrose preference test (SPT), and forced swimming test (FST). Hippocampal neurogenesis was determined by immunohistochemistry.

Results and conclusion

CRS for 21 days caused a significant decrease in body weight gain and increase in plasma CORT levels and percentage of adrenal gland weight to body weight, which were rescued by KKT treatment. KKT also suppressed the CRS-induced anxiety- and depressive-like behaviors and impairment of hippocampal neurogenesis. These results suggest that daily treatment of KKT has a protective effect against physiological, neurological, and behavioral changes in a rat model of depression.

Neuropeptide Y Y2 and Y5 receptors as potential targets for neuroprotective and antidepressant therapies: Evidence from preclinical studies

There is currently no effective treatment either for neurological illnesses (ischemia and neurodegenerative diseases) or psychiatric disorders (depression), in which the Glu/GABA balance is disturbed and accompanied by significant excitotoxicity. Therefore, the search for new and effective therapeutic strategies is imperative for these disorders. Studies conducted over the last several years indicate that the neuropeptide Y (NPY)-ergic system may be a potential therapeutic target for neuroprotective or antidepressant compounds. This review focuses on the neuroprotective roles of Y2 and Y5 receptors (YRs) in neurological disorders such as ischemia, Alzheimer's disease, Parkinson's disease, Huntington's disease, and in psychiatric disorders such as depression. It summarizes current knowledge on the possible mechanisms underlying the neuroprotective or antidepressant-like actions of Y2R and Y5R ligands. The review also discusses ligands acting at Y2R and Y5R and their limitations as in vivo pharmacological tools. The results from the preclinical studies discussed here may be useful in developing effective therapeutic strategies to treat neurological diseases on the one hand and psychiatric disorders on the other, and may pave the way for the development of novel Y2R and Y5R ligands as candidate drugs for the treatment of these diseases.

TAK-653, an AMPA receptor potentiator with minimal agonistic activity, produces an antidepressant-like effect with a favorable safety profile in rats

The N-methyl-d-aspartate receptor antagonist, ketamine, exhibits rapid and sustained antidepressant activity in patients with treatment-resistant depression (TRD), but its use is associated with psychotomimetic side effects. Evidence has suggested that the activation of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors followed by activation of the mechanistic target of rapamycin (mTOR) signaling pathway and production of brain derived neurotrophic factor (BDNF) protein may underlie the antidepressant efficacy of ketamine. In this study, we characterized the antidepressant-like effects of TAK-653, a novel AMPA receptor potentiator with virtually no agonistic activity. In rat primary cortical neurons, TAK-653 significantly increased phosphorylated and activated forms of mTOR and p70S6 kinase and their upstream regulators Akt and extracellular signal-regulated kinase (ERK). TAK-653 also significantly increased BDNF protein levels in rat primary cortical neurons. Ketamine at 30 mg/kg, i.p. produced antidepressant-like effects in the reduction of submissive behavior model (RSBM) in rats. Ketamine's antidepressant-like effect was blocked by pretreatment with the AMPA receptor antagonist NBQX at 10 mg/kg, i.p., indicating the essential role of AMPA receptor activation in the antidepressant-like effect of ketamine. Consistent with this finding, a sub-chronic administration of TAK-653 for 6 days produced significant antidepressant-like effect in the rat RSBM. Unlike ketamine, however, TAK-653 did not induce a hyperlocomotor response in rats, which is a behavioral index associated with psychotomimetic side effects in humans. TAK-653 may be a promising drug for the treatment of major depressive disorders including TRD with the potential for an improved safety profile compared with ketamine.

Usefulness of cell-penetrating peptides and penetration accelerating sequence for nose-to-brain delivery of glucagon-like peptide-2

Neuropeptides are expected as therapeutic drug candidates for central nervous system (CNS) disorders. Intracerebroventricular (i.c.v.) administration of glucagon-like peptide-2 (GLP-2) has an antidepressant-like effect not only in depression model mice but also in treatment-resistant depression model mice. However, because i.c.v. administration is very invasive, research is progressing on brain delivery using intranasal administration as a non-invasive method. After intranasal administration of the drug, there are two routes to the brain. That of direct delivery from the paracellular route of olfactory epithelium to the brain via the olfactory bulb has been studied, and that of systemic absorption via the paracellular route of respiratory epithelium has been put to practical use. The high degree of vascularization and permeability of the nasal mucosa enables drug delivery via the paracellular route that leads to systemic delivery. Therefore, suppressing systemic absorption may increase drug delivery to brain, so we focused on the transcellular route. We created a GLP-2 derivative by adding cell-penetrating peptides (CPP) and penetration accelerating sequences (PAS), which are reported to provide efficient intracellular uptake, to GLP-2. However, to deliver GLP-2 by the transcellular route, GLP-2 must not only be taken up into cells but also move out of the cells. We investigated in vitro and in vivo function of PAS-CPP-GLP-2 to enable the translocation of GLP-2 directly from the nose to the brain. Derivatization of PAS-CPP-GLP-2 prevented its degradation. In the evaluation of intracellular dynamics, PAS-CPP-GLP-2 enhanced cellular uptake by macropinocytosis with CPP and promoted escape from endosomal vesicles by PAS. This study also showed that PAS-CPP-GLP-2 can move out of cells. Furthermore, only this PAS-CPP-GLP-2 showed an antidepression-like effect within 20 min of intranasal administration. Intranasal administered PAS-CPP-GLP-2 surprisingly showed the effect at the same dose with i.c.v. administration, but intravenous administered PAS-CPP-GLP-2 did not show the effect. These results suggested that PAS-CPP-GLP-2 can be efficiently delivered from the nose to the CNS and show a pharmacological effect, demonstrating the usefulness of PAS and CPP for nose-to-brain delivery of GLP-2.

Discovery of δ opioid receptor full agonists lacking a basic nitrogen atom and their antidepressant-like effects

We have recently reported that the elaboration of the N-substituent in the δ opioid receptor (DOR) antagonist naltrindole (NTI) enabled the regulation of the DOR activities from full inverse agonists to weak partial agonists. The investigations of amide-type NTI derivatives revealed that N-phenylacetyl and N-dihydrocinnamoyl derivatives 3a and 3b were DOR full agonists. The same transformations were applied to a DOR agonist KNT-127 to provide the more potent DOR agonists 6a and 6b. Among the tested compounds, the most efficacious compound 6a showed dose-dependent antidepressant-like effects in the mouse forced swim test. The antidepressant-like effects by 6a seemed to be more potent than those of KNT-127, which is a more potent DOR agonist in in vitro assays. The amide-type compound like 6a may more fully penetrate into the central nervous system.

Patchouli alcohol protects against chronic unpredictable mild stress-induced depressant-like behavior through inhibiting excessive autophagy via activation of mTOR signaling pathway

Patchouli alcohol (PA), a tricyclic sesquiterpene, is the major chemical component of patchouli oil. This study investigated the antidepressant-like effect and mechanism of PA in chronic unpredictable mild stress (CUMS). Our results showed that PA markedly attenuated CUMS-induced depressant-like behaviors, including an effective increase of sucrose preference and spontaneous exploratory capacity, as well as reduction of immobility time. In addition, PA markedly attenuated CUMS-induced mTOR, p70S6K, and 4E-BP-1 phosphorylation reduction in the hippocampus. Furthermore, PA reversed CUMS-induced increases in LC3-II and p62 levels and CUMS-induced decrease in PSD-95 and SYN-I levels. These results indicated that the antidepressant-like effect of PA was correlated with the activation of the mTOR signaling pathway. Moreover, behavioral experimental results showed that the antidepressant-like effect of PA was blocked by rapamycin (autophagy inducer and mTOR inhibitor) and chloroquine (autophagic flux inhibitor). These results suggest that PA exerted antidepressant-like effect in CUMS rats through inhibiting autophagy, repairing synapse, and restoring autophagic flux in the hippocampus by activating the mTOR signaling pathway. The results render PA a promising antidepressant agent worthy of further development into a pharmaceutical drug for the treatment of depression.

Purpurin exerted antidepressant-like effects on behavior and stress axis reactivity: evidence of serotonergic engagement

RATIONALE AND OBJECTIVES

Major depression represents a significant public health problem worldwide, and effective regimen is lacking. The present study investigated the antidepressant-like effects of purpurin, a natural anthraquinone compound from Rubia tinctorum L., and explored the underlying mechanism(s).

METHODS

Forced swim test (FST) and tail suspension test (TST) were used to assess antidepressant-like effects of purpurin in mice. Effects of purpurin on neuroendocrine responsivity were evaluated at the level of corticosterone and ACTH following acute restraint stress and intracerebroventricular injection of corticotrophin-releasing-factor (CRF). Serotonergic mechanisms underlying purpurin antidepressant effect were explored using biochemical, neurochemical, and pharmacological paradigms.

RESULTS

Chronic purpurin treatment exerted in mice dose-dependently antidepressant-like effects on behavior and stress axis reactivity (n = 9-11 per group). The purpurin-triggered antidepressant-like effects are serotonergically dependent, since purpurin-treated mice showed escalated levels of brain serotonin and suppressed monoamine oxidase (MAO) activity (n = 8-11 per group). Consistently, chemical depletion of brain serotonin by p-chlorophenylalanine (PCPA) abolished the antidepressant-like effects of purpurin on behavior and stress axis responsivity (n = 9-10 per group). Moreover, the antidepressant effect by purpurin was preferentially counteracted by 1A-selective 5-HT receptor antagonist WAY-100635, but potentiated by 1A-selective agonist 8-OH-DPAT and sub-effective dose of serotonergic antidepressant fluoxetine (n = 9-11 per group), suggesting a crucial role for 5-HT1A related serotonergic system in mediating such purpurin antidepressant effect.

CONCLUSION

We have revealed the antidepressant-like effects of purpurin on both behavior and stress axis reactivity in mice, with serotonergic system that preferentially couples with 5-HT1A receptors being critically engaged.

Neurobehavioral effects of selected tobacco constituents in rodents following subchronic administration

Bidirectional correlations between cigarette smoking and affective disorders, such as depression, anxiety, and schizophrenia, are well documented. These findings have led to substantial investigations into the effects of the major tobacco alkaloid, nicotine, and to a lesser extent, of other tobacco constituents, on the central nervous system (CNS). However, systematic profiling of the neuropharmacological effects of tobacco constituents is limited. To elucidate the effects of selected tobacco constituents on the CNS, we used the SmartCube® system, which captures and classifies behavioral features of compound-treated mice, to profile the psychiatric drugs-like properties of previously reported neuroactive tobacco compounds in mice. Daily intraperitoneal injection of nicotine (0.5 and 1 mg/kg/day) and anatabine (5 mg/kg/day) for 7 days produced antidepressant-like behavioral SmartCube® signatures in mice, and these results were supported by the improved active coping responses in the forced swim tests. Conversely, ferulic acid did not show any identifiable class signatures in the SmartCube® tests, but rather displayed subclass signatures associated with acetylcholinesterase inhibitors. In novel object recognition memory test in rats, ferulic acid improved memory after 7 days of subcutaneous injection at 0.3 or 3 mg/kg/day. These results support previous findings showing the antidepressant drug-like effects of nicotine and the nootropic effects of ferulic acid. This is also the first report on the antidepressant drug-like effects of anatabine in rodents. This study provides a systemic behavioral evaluation of tobacco alkaloids and further insights into the association between affective disorders and smoking incidence.

Monoamine Involvement in the Antidepressant-Like Effect of β-Caryophyllene

BACKGROUND

Major depressive disorder is a psychiatric disorder that affects 4.4% of the population worldwide. Although the majority of antidepressant drugs ameliorate depressive symptoms, there is still a need for safer and more effective antidepressant.

OBJECTIVE

Evaluate the antidepressant-like activity of sesquiterpene compound β-caryophyllene (BCP) for the possible contribution of the monoamine and hippocampal levels of brain-derived neurotrophic factor (BDNF).

METHODS

Male albino Swiss mice were subjected to the forced swimming test after acute treatment and to the tail suspension test after repeated treatment. Hippocampal levels of BDNF were assayed by enzyme-linked immunosorbent assay.

RESULTS

The anti-immobility effect of BCP was reverted by pretreatment with an inhibitor of catecholamine synthesis α-methyl-p-tyrosine (100 mg/kg, i.p.), α2-adrenergic antagonist yohimbine (1 mg/kg, i.p.), and β-adrenergic antagonist propranolol (2 mg/kg, i.p.), but not by pretreatment with either α1-adrenergic antagonist prazosin (1 mg/kg, i.p.) or 5-HT1A antagonist NAN-190 (0.5 mg/kg, i.p.), thereby suggesting the involvement of α2 and β-adrenergic receptors, but not of the α1-adrenergic and 5-HT1A serotonergic receptors, in BCP's antidepressive-like activity. Furthermore, BCP increased BDNF levels in the hippocampus after 14 days of treatment. No treatments in this study altered locomotor activity in the open field test.

CONCLUSION

This study provides a new mechanism of BCP-induced antidepressant-like effect mediated by some sub-types of catecholaminergic neurotransmitter system that could be a candidate for clinical tests of new treatments for depressive disorders.

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.

Mitochondrial transplantation attenuates lipopolysaccharide- induced depression-like behaviors

The dysfunction of mitochondria plays important roles in the development of depression. Interestingly, increasing numbers of evidence show the therapeutic benefits of mitochondria transfer. Therefore, we hypothesized that injection of exogenous mitochondria would contribute to ameliorate depressive-like symptoms. In this study, the antidepressant-like effect of intravenous isolated mitochondria was evaluated on a lipopolysaccharide (LPS)- induced model of depression. The depressive-like behaviors were assessed using forced swim test (FST), tail suspension test (TST) and sucrose preference test. Besides, the neurogenesis, expression of brain-derived neurotrophic factor (BDNF), glial activation, neuroinflammation, oxidative stress and ATP production were determined in the hippocampus. The results showed that treatment of isolated mitochondria decreased the immobility time of mice in the FST and TST, and attenuated the decrease in sucrose preference test. Moreover, isolated mitochondria significantly reduced the activation of astrocyte and microglia as well as neuroinflammation (i.e. 1 L-1β, TNF-α and COX-2), increased BDNF expression and neurogenesis, restored the dysfunction of ATP production and oxidative stress in inflammation- induced depression. Taken together, the data suggested for the first time that injection of isolated mitochondria ameliorated LPS- induced depressive-like behaviors. The new discovery for the present study provides that mitochondrial transplantation might act as a new therapeutic strategy for MDD.

Antinociceptive and antidepressive efficacies of the combined ineffective doses of S-ketamine and URB597

Clinical studies have demonstrated that the NMDA receptor antagonist ketamine produces rapid antidepressant responses. There are safety concerns and adverse effects that limit the utilization of ketamine in psychiatry. Some studies have suggested combination therapy for optimal ketamine use. In this study, we evaluated the potential for combination therapy of ineffective doses of ketamine and fatty acid amide hydrolase inhibitor URB597 for the treatment of depression and pain in male NMRI mice. Intraperitoneal administration of ketamine (10 mg/kg) at the time intervals of 115, 145, and 160 min and ketamine (5 mg/kg) at the time interval of 160 min after administration increased the tail-flick latency, indicating an antinociceptive effect. The same doses of ketamine decreased immobility time in the forced swim test (FST), showing an antidepressant-like effect. Moreover, URB597 at the doses of 0.5 and 1 mg/kg induced an antinociceptive effect, while it at the dose of 1 mg/kg produced an antidepressant-like response. Furthermore, co-administration of the ineffective doses of ketamine (2.5 mg/kg) and URB597 (0.1 mg/kg) caused antinociceptive and antidepressant-like effects, while each one of them alone did not alter the performance of mice in the FST and tail-flick tests. It should be noted that none of the treatments alter animal locomotor activity compared to the control group. Therefore, the combined administration of ineffective doses of ketamine and URB597 might be an effective strategy in the therapy of depression and pain.

TAK-137, an AMPA receptor potentiator with little agonistic effect, produces antidepressant-like effect without causing psychotomimetic effects in rats

Ketamine produces a rapid-onset antidepressant effect in patients with treatment-resistant depression (TRD), although it concurrently causes undesirable psychotomimetic side effects. Accumulating evidence suggests that ketamine produces antidepressant effects via activation of the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPA-R), with consequent activation of the mammalian target of rapamycin (mTOR) pathway and up-regulation of brain-derived neurotrophic factor (BDNF). We previously reported that TAK-137, an AMPA-R potentiator with little agonistic effect, had potent procognitive effects with lower risks of bell-shaped dose-response and seizure induction. In this study, we characterized the potential of TAK-137 as a novel antidepressant in rats. In rat primary cortical neurons, TAK-137 increased the phosphorylated form of Akt, extracellular signal-regulated kinase, mTOR, and p70S6 kinase, and dose-dependently increased the expression level of BDNF protein. The antidepressant-like effects of ketamine and TAK-137 were assessed on the day after final administration using the novelty-suppressed feeding test in rats. A single intraperitoneal administration of ketamine shortened the latency to feed. Under these conditions, oral administration of TAK-137 for 3 days shortened the feeding latency. Ketamine induced hyperlocomotion and reduced prepulse inhibition, which may be associated with psychotomimetic effects, while TAK-137 did not. TAK-137 may be a safer and rapid-onset therapeutic drug for the treatment of major depressive disorder, including TRD.

Monoaminergic and aminoacidergic receptors are involved in the antidepressant-like effect of ginsenoside Rb1 in mouse hippocampus (CA3) and prefrontal cortex

Ginsenoside Rb1 (Rb1), as the major bioactive ingredient of Panax ginseng C.A. Meyer, elicited a novel antidepressant-like effect in the forced swim test (FST) in chronic unpredictable mild stress (CUMS) rats in our previous study. To further explore the molecular mechanism of Rb1 on the neurotransmitters such as 5-hydroxytryptamine (5-HT), 5-hydroxyindole-3-acetic acid (5-HIAA), norepinephrine (NE), dopamine (DA), homovanillic acid (HVA), dihydroxyphenylacetic acid (DOPAC), glutamate (Glu) and gamma-aminobutyric acid (GABA) in this antidepressant-like effect, the neurochemical changes in the monoaminergic and aminoacidergic receptors were investigated in the present pharmacological study by using reuptake inhibitors, receptors agonists and antagonists. The results showed that a sub-effective dose of Rb1 (5 mg/kg, p.o.) co-administered with fluoxetine (1 mg/kg, i.p., a selective serotonin reuptake inhibitor), reboxetine (2.5 mg/kg, i.p., a noradrenalin reuptake inhibitor), bupropion (10 mg/kg, i.p., a dopaminergic reuptake inhibitor), Mk-801 (0.05 mg/kg, i.p., an N-methyl-d-aspartic acid (NMDA) receptor antagonist) or baclofen (0.1 mg/kg, i.p., a selective GABA agonist) significantly decreased the immobility time in the FST. In addition, pretreating mice with NAN190 (0.5 mg/kg, i.p., a 5-HT_1A receptor antagonist), ketanserin (5 mg/kg, i.p., a 5-HT_2A/2C receptor antagonist), ondansetron (1 mg/kg, i.p., a 5-HT_3A receptor antagonist), prazosin (1 mg/kg, i.p., an α₁-adrenoceptor antagonist), yohimbine (1 mg/kg, i.p., an α₂-adrenoceptor antagonist), SCH23390 (0.05 mg/kg, i.p., a selective D₁ receptor antagonist), haloperidol (0.2 mg/kg, i.p., a non-selective D₂ receptor antagonist), NMDA (75 mg/kg, i.p., an agonist at the glutamate site) or bicuculline (4 mg/kg, i.p., a competitive GABA antagonist) reversed the antidepressant-like effect of Rb1 (10 mg/kg, p.o.) in the FST. The results obtained for the neurotransmitters in the mouse hippocampus (CA3) and prefrontal cortex showed that Rb1 up-regulated the levels of 5-HT, 5-HIAA, NE, DA, and GABA and decreased the level of Glu. However, there were no significant differences in HVA or DOPAC. Furthermore, there were no significant alterations in the total path of spontaneous locomotor activity in all treatments. These results suggest that both monoaminergic (serotonergic, noradrenergic and dopaminergic) and aminoacidergic (glutamatergic and GABAergic) receptors may be involved in the antidepressant-like effect of Rb1.

Antidepressant-like Effect of Bacopaside I in Mice Exposed to Chronic Unpredictable Mild Stress by Modulating the Hypothalamic-Pituitary-Adrenal Axis Function and Activating BDNF Signaling Pathway

Preliminary studies conducted in our laboratory have confirmed that Bacopaside I (BS-I), a saponin compound isolated from Bacopa monnieri, displayed antidepressant-like activity in the mouse behavioral despair model. The present investigation aimed to verify the antidepressant-like action of BS-I using a mouse model of behavioral deficits induced by chronic unpredictable mild stress (CUMS) and further probe its underlying mechanism of action. Mice were exposed to CUMS for a period of 5 consecutive weeks to induce depression-like behavior. Then, oral gavage administrations with vehicle (model group), fluoxetine (12 mg/kg, positive group) or BS-I (5, 15, 45 mg/kg, treated group) once daily were started during the last two weeks of CUMS procedure. The results showed that BS-I significantly ameliorated CUMS-induced depression-like behaviors in mice, as characterized by an elevated sucrose consumption in the sucrose preference test and reduced immobility time without affecting spontaneous locomotor activity in the forced swimming test, tail suspension test and open field test. It was also found that BS-I treatment reversed the increased level of plasma corticosterone and decreased mRNA and protein expressions of glucocorticoid receptor induced by CUMS exposure, indicating that hypothalamic-pituitary-adrenal (HPA) axis hyperactivity of CUMS-exposed mice was restored by BS-I treatment. Furthermore, chronic administration of BS-I elevated expression levels of brain-derived neurotrophic factor (BDNF) (mRNA and protein) and activated the phosphorylation of extracellular signal-regulated kinase and cAMP response element-binding protein in the hippocampus and prefrontal cortex in mice subjected to CUMS procedure. Taken together, these results indicated that BS-I exhibited an obvious antidepressant-like effect in mouse model of CUMS-induced depression that was mediated, at least in part, by modulating HPA hyperactivity and activating BDNF signaling pathway.

Genistein, a dietary soy isoflavone, exerts antidepressant-like effects in mice: Involvement of serotonergic system

Genistein, a principal isoflavone property of soybeans, possesses multiple pharmacological activities such as neuroprotection. Recently, it was reported that genistein exerted antidepressant-like effects in animal models, but the mechanism of action remains ambiguous. The purpose of this study was to investigate the antidepressant-like effect of genistein in mice and explore the underlying mechanism(s), using two mouse models of depression, i.e. forced swim test (FST) and tail suspension test (TST). Chronic, but not acute (single dose), genistein treatment (5, 15 or 45 mg/kg, p.o., once per day for three weeks) exerted dose-dependently antidepressant-like effect in mice, concomitant with escalated levels of brain monoamines and suppressed monoamine oxidase (MAO) activity. Chemical depletion of brain serotonin by PCPA abrogated the antidepressant-like action of genistein, but it was not the case for ablation of NA by DSP-4. Moreover, the anti-depression by genistein was preferentially counteracted by co-administration of 5-HT_1A receptor antagonist WAY-100635, suggesting a pivotal role for 5-HT system coupled with 5-HT_1A receptors in mediating such genistein anti-depression. This point was further validated by the fact that genistein action was potentiated by co-treatment with 8-OH-DPAT, a selective 5-HT_1A receptor agonist. Collectively, these findings confirm that chronic genistein administration to mice engenders antidepressant-like efficacy evidenced by lessened behavioral despair. Serotonergic system that preferentially couples with 5-HT_1A receptors may be critically responsible for the present genistein anti-depression.

Single and chronic L-serine treatments exert antidepressant-like effects in rats possibly by different means

In the present study, the effects of both single (6 mmol L-serine/10 ml/kg orally administrated) and chronic (2% L-serine solution freely given for 28 days) treatments on depression-like behavior were evaluated in Wistar rats, representing the control, and Wistar Kyoto rats, representing an animal model of depression. Both single and chronic L-serine treatments decreased the duration of immobility, which is an index of a depressive-like state, in the forced swimming test in both strains. However, the decreases in the duration of immobility appear to be regulated differently by the different mechanisms involved in single and chronic L-serine treatments. In the prefrontal cortex and hippocampus, single L-serine treatment increased the concentrations of L-serine, but not D-serine, while chronic L-serine treatment increased those of D-serine, but not L-serine. These data suggest that the antidepressant-like effects of single and chronic L-serine treatments may have been induced by the increased L-serine and D-serine concentrations, respectively, in the brain. In addition, chronic L-serine treatment increased cystathionine concentrations in the hippocampus and prefrontal cortex in Wistar rats, but not in Wistar Kyoto rats, suggesting that Wistar Kyoto rats have an abnormality in the serine-cystathionine metabolic pathway. In conclusion, single and chronic L-serine treatments may induce antidepressant-like effects via the different mechanisms related to serine metabolism in the brain.

Meyer

ETHNOPHARMACOLOGY RELEVANCE

Ginsenoside Rb1, a 20 (S)-protopanaxadiol, is a major active ingredient of Panax ginseng C.A. Meyer, which as the King of Chinese herbs, has been wildly used for the treatment of central nervous system diseases. Previous studies have shown that 20 (S)-protopanaxadiol possesses a novel antidepressant-like effect in the treatment of depression, whereas ginsenoside Rb1 in depression has been rarely reported.

AIM OF THE REVIEW

The present study was to investigate the antidepressant-like effect of ginsenoside Rb1 and its relevant mechanisms.

MATERIALS AND METHODS

The whole experiment was divided into two parts: one part we examined the antidepressant-like effect of ginsenoside Rb1 with open-field test (OFT), tail suspension test (TST), forced swim test (FST), 5-HTP induced head-twitch and reserpine response in mice, another part we used chronic unpredicted mild stress (CUMS) model to further explore the antidepressant-like effect of ginsenoside Rb1 with caffeine, fluoxetine and p-Chlorophenylalanine (PCPA) in rats. Furthermore, the levels of monoamine neurotransmitters of NE, 5-HT, DA and their metabolites 5-HIAA, DOPAC, HVA were all measured by ELISA kits after the CUMS protocol.

RESULTS

Our data indicated that 7 days treatment with ginsenoside Rb1 (4, 8, 10mg/kg, p.o.) significantly decreased immobility time in the FST and TST in mice, and played important roles in mice which were induced by 5-HTP (200mg/kg, i.p.) and reserpine (4mg/kg, i.p.). On the basis of CUMS model, 21 days treatment with ginsenoside Rb1 not only had effective interactions with caffeine (5mg/kg, i.p.), fluoxetine (1mg/kg, i.p.) and PCPA (100mg/kg, i.p.), but also significantly up-regulated the 5-HT, 5-HIAA, NE and DA levels in CUMS rats' brain, whereas HVA and DOPAC had no significant difference. Moreover, there was no alteration in spontaneous locomotion in any experimental group.

CONCLUSIONS

These results suggest that ginsenoside Rb1 exhibits significant antidepressant-like effect in behavioral tests, chronic animal model and drug interactions, its mechanisms mainly mediated by central neurotransmitters of serotonergic, noradrenergic and dopaminergic systems.

Kososan, a Kampo medicine, prevents a social avoidance behavior and attenuates neuroinflammation in socially defeated mice

Background

Kososan, a Kampo (traditional Japanese herbal) medicine, has been used for the therapy of depressive mood in humans. However, evidence for the antidepressant efficacy of kososan and potential mechanisms are lacking. Recently, it has been recognized that stress triggers neuroinflammation and suppresses adult neurogenesis, leading to depression and anxiety. Here, we examined whether kososan extract affected social behavior in mice exposed to chronic social defeat stress (CSDS), an animal model of prolonged psychosocial stress, and neuroinflammation induced by CSDS.

Methods

In the CSDS paradigm, C57BL/6J mice were exposed to 10 min of social defeat stress from an aggressive CD-1 mouse for 10 consecutive days (days 1–10). Kososan extract (1.0 g/kg) was administered orally once daily for 12 days (days 1–12). On day 11, the social avoidance test was performed to examine depressive- and anxious-like behaviors. To characterize the impacts of kososan on neuroinflammation and adult neurogenesis, immunochemical analyses and ex vivo microglial stimulation assay with lipopolysaccharide (LPS) were performed on days 13–15.

Results

Oral administration of kososan extract alleviated social avoidance, depression- and anxiety-like behaviors, caused by CSDS exposure. CSDS exposure resulted in neuroinflammation, as indicated by the increased accumulation of microglia, the resident immune cells of the brain, and their activation in the hippocampus, which was reversed to normal levels by treatment with kososan extract. Additionally, in ex vivo studies, CSDS exposure potentiated the microglial pro-inflammatory response to a subsequent LPS challenge, an effect that was also blunted by kososan extract treatment. Indeed, the modulatory effect of kososan extract on neuroinflammation appears to be due to a hippocampal increase in an anti-inflammatory phenotype of microglia while sparing an increased pro-inflammatory phenotype of microglia caused by CSDS. Moreover, reduced adult hippocampal neurogenesis in defeated mice was recovered by kososan extract treatment.

Conclusions

Our findings suggest that kososan extract prevents a social avoidant behavior in socially defeated mice that is partially mediated by the downregulation of hippocampal neuroinflammation, presumably by the relative increased anti-inflammatory microglia and regulation of adult hippocampal neurogenesis. Our present study also provides novel evidence for the beneficial effects of kososan on depression/anxiety and the possible underlying mechanisms.

Electronic supplementary material

The online version of this article (doi:10.1186/s12974-017-0876-8) contains supplementary material, which is available to authorized users.

Ethanol induced antidepressant-like effect in the mouse forced swimming test: modulation by serotonergic system

AIM

The present investigation explored the modulatory role of serotonergic transmission in the acute ethanol-induced effects on immobility time in the mouse forced swim test (FST).

METHODS AND RESULTS

Acute i.p. administration of ethanol (20% w/v, 2 or 2.5 g/kg, i.p.) decreased the immobility time in FST of mice, indicating its antidepressant-like effect while lower doses of ethanol (1, 1.5 g/kg, i.p.) were devoid of any effect in the FST. The mice pre-treated with a sub-effective dose of 5-HT_2A agonist, DOI (10 μg/mouse, i.c.v.) or 5-HT_1A receptor antagonist, WAY 100635 (0.1 μg/mouse, i.c.v.) but not with the 5-HT_2A/2C antagonist, ketanserin (1.5 μg/mouse, i.c.v.) exhibited a synergistic reduction in the immobility time induced by sub-effective dose of ethanol (1.5 g/kg, i.p.). On the other hand, ethanol (2.5 g/kg, i.p.) failed to decrease the immobility time in mice, pre-treated with 5-HT_1A agonist, 8-OH-DPAT (0.1 μg/mouse, i.c.v.) or ketanserin (1.5 μg/mouse, i.c.v.). In addition, pre-treatment with a 5-HT neuronal synthesis inhibitor, p-CPA (300 mg/kg, i.p. × 3 days) attenuated the anti-immobility effect ethanol (2.5 g/kg, i.p.) in mouse FST.

CONCLUSIONS

Thus, the results of the present study points towards the essentiality of the central 5-HT transmission at the synapse for the ethanol-induced antidepressant-like effect in the FST wherein the regulatory role of the 5-HT_1A receptor or contributory role of the 5-HT_2A/2C receptor-mediated mechanism is proposed in the anti-immobility effect of acute ethanol in mouse FST.

Antidepressant-Like Effect of Isorhynchophylline in Mice

Isorhynchophylline (IRN), an oxindole alkaloid, has been identified as the main active ingredient responsible for the biological activities of Uncaria rhynchophylla (Miq) Miq ex Havil. (Rubiaceae). Previous studies in our laboratory have revealed that IRN possesses potent neuroprotective effects in different models of Alzheimer's disease. However, the antidepressant-like effects of IRN are remained unclear. The present study aims to evaluate the antidepressant-like effects of IRN. The antidepressant-like effects of IRN was determined by using animal models of depression including forced swimming and tail suspension tests. The acting mechanism was explored by determining the effect of IRN on the levels of monoamine neurotransmitters and the activities of monoamine oxidases. Intragastric administration of IRN at 10, 20 and 40 mg/kg for 7 days caused a significant reduction of immobility time in both forced swimming and tail suspension tests, while IRN did not stimulate locomotor activity in the open-field test. In addition, IRN treatment antagonized reserpine-induced ptosis and significantly enhanced the levels of monoamine neurotransmitters including norepinephrine (NE) and 5-hydroxytryptamine (5-HT), and the activity of monoamine oxidase A (MAO-A) in the hippocampus and frontal cortex of mice. These results suggest that the antidepressant-like effects of IRN are mediated, at least in part, by the inhibition of monoamine oxidases.

Schisandra chinensis produces the antidepressant-like effects in repeated corticosterone-induced mice via the BDNF/TrkB/CREB signaling pathway

The present study aimed to examine the antidepressant-like effects and the possible mechanisms of Schisandra chinensis on depressive-like behavior induced by repeated corticosterone injections in mice. Here we evaluated the effect of an ethanol extract of the dried fruit of S. chinensis (EESC) on BDNF/TrkB/CREB signaling in the hippocampus and the prefrontal cortex. Three weeks of corticosterone injections in mice resulted in depressive-like behavior, as indicated by the significant decrease in sucrose consumption and increase the immobility time in the forced swim test, but without any influence on the locomotor activity. Further, there was a significant increase in serum corticosterone level and a significant downregulation of BDNF/TrkB/CREB signaling pathway in the hippocampus and prefrontal cortex in CORT-treated mice. Treatment of mice with EESC (600mg/kg) significantly ameliorated all the behavioral and biochemical changes induced by corticosterone. Moreover, pharmacological inhibition of BDNF signaling by K252a abolished entirely the antidepressant-like effect triggered by chronic EESC treatment. These results suggest that EESC produces an antidepressant-like effect in CORT-induced depression in mice, which is possibly mediated, at least in part, by rectifying the stress-based hypothalamic-pituitary-adrenal (HPA) axis dysfunction paradigm and upregulation of BDNF/TrkB/CREB signaling pathway.

Ferulic acid chronic treatment exerts antidepressant-like effect: role of antioxidant defense system

Oxidative stress has been claimed a place in pathophysiology of depression; however, the details of the neurobiology of this condition remains incompletely understood. Recently, treatments employing antioxidants have been thoroughly researched. Ferulic acid (FA) is a phenolic compound with antioxidant and antidepressant-like effects. Herein, we investigated the involvement of the antioxidant activity of chronic oral FA treatment in its antidepressant-like effect using the tail suspension test (TST) and the forced swimming test (FST) in mice. The modulation of antioxidant system in blood, hippocampus and cerebral cortex was assessed after stress induction through TST and FST. Our results show that FA at the dose of 1 mg/kg has antidepressant-like effect without affecting locomotor activity. The stress induced by despair tests was able to decrease significantly the activities of superoxide dismutase (SOD) in the blood, catalase (CAT) in the blood and cerebral cortex and glutathione peroxidase (GSH-Px) in the cerebral cortex. Thiobarbituric acid-reactive substances (TBA-RS) levels were increased significantly in the cerebral cortex. Furthermore, the results show that FA was capable to increase SOD, CAT and GSH-Px activities and decrease TBA-RS levels in the blood, hippocampus and cerebral cortex. These findings demonstrated that FA treatment in low doses is capable to exert antidepressant-like effect with the involvement of the antioxidant defense system modulation.

The role of glutamatergic, GABA-ergic, and cholinergic receptors in depression and antidepressant-like effect

Depression is one of the most common mental disorders and social issue worldwide. Although there are many antidepressants available, the effectiveness of the therapy is still a serious issue. Moreover, there are many limitations of currently used antidepressants, including slow onset of action, numerous side effects, or the fact that many patients do not respond adequately to the treatment. Therefore, scientists are searching for new compounds with different mechanisms of action. Numerous data indicate the important role of glutamatergic, GABA-ergic, and cholinergic receptors in the pathomechanism of major depressive disorder. This review presents the role of glutamatergic, GABA-ergic, and cholinergic receptors in depression and antidepressant-like effect.

The role of serotonergic, adrenergic and dopaminergic receptors in antidepressant-like effect

Depression is a serious global illness, becoming more and more common in developed countries. Because of specific symptoms it is considered as a leading cause of disability all over the world with a high death factor due to suicides. There are many antidepressants used in the therapy, but still more than 30% of patients do not respond to the treatment. The heterogeneous nature of the illness and its complex, unclear aetiology may be responsible for these difficulties. Next to the main monoaminergic hypothesis of depression there are also many other approaches connected with the pathophysiology of the disease, including hypothalamic-pituitary-adrenal axis dysregulation, dopaminergic, cholinergic, glutamatergic or GABA-ergic neurotransmission. Nevertheless, it can be unambiguously stated that serotonergic, noradrenergic and dopaminergic systems are precisely connected with pathogenesis of depression, and should be therefore considered as valuable targets in patients' treatment. Bearing that in mind, this review presents the role of serotonergic, adrenergic and dopaminergic receptors in antidepressant-like effect.

Antidepressant-like effect of food-derived pyroglutamyl peptides in mice

The N-terminal glutamine residue, exposed by enzymatic cleavage of precursor proteins, is known to be modified to a pyroglutamyl residue with a cyclic structure in not only endogenous but also food-derived peptides. We investigated the effects of wheat-derived pyroglutamyl peptides on emotional behaviors. Pyroglutamyl leucine (pyroGlu-Leu, pEL) and pyroglutamyl glutaminyl leucine (pyroGlu-Gln-Leu, pEQL) exhibited antidepressant-like activity in the tail suspension and forced swim tests in mice. pEQL exhibited more potent antidepressant-like activity than pEL after i.p. and i.c.v. administration. pEQL exhibited antidepressant-like activity at a lower dose than Gln-Gln-Leu, suggesting that pyroglutamyl peptide had more potent activity. To examine whether pyroglutamyl peptides increased hippocampus neurogenesis, associated with the effects of antidepressants, we measured 5-bromo-2'-deoxyuridine (BrdU) incorporation. pEL and pEQL increased BrdU-positive cells in the dentate gyrus of the hippocampus. Intriguingly, pEL did not increase hippocampal mRNA and protein expression of brain-derived neurotrophic factor (BDNF), which is a factor associated with both neuropoietic and antidepressive effects. Thus, pyroglutamyl peptides may enhance hippocampal neurogenesis via a pathway independent of BDNF. We also confirmed that pEL and pEQL were produced in the subtilisin digest of major wheat proteins, glutenin and gliadin, after heat treatment. pEL and pEQL are the first peptides derived from wheat proteins to be shown to exhibit an antidepressant-like activity.

Cycloartane triterpenoid saponins from water soluble of Passiflora edulis Sims and their antidepressant-like effects

ETHNOPHARMACOLOGICAL RELEVANCE

Various species of genus Passiflora have been used as traditional folk medicines owing to their sedative and anti-hypertensive properties. Passiflora edulis Sims most widely grown in the warm temperate for their fragrant fruits and their twigs and leaves are used as a folk medicine for treating both anxiety and nervousness in American countries. The present study was to evaluate the antidepressant-like effect and the active components of this plant.

MATERIALS AND METHODS

The alcohol extracts of the stems (PES, 10 and 2 g/kg of the plant materials) and leaves (PEL, 10 and 2 g/kg of the plant materials) of Passiflora edulis Sims were orally administered to mice for 7 day. The animals were tested in the forced swim test (FST) and tail suspension test (TST). After behavioral assay of ethanol extract, phytochemical research of the stems and leaves (5.7 kg) of Passiflora edulis Sims were developed and further bioactive verification of monomeric compounds were conducted.

RESULTS

There are mainly cycloartane triterpenoids and their saponins isolated from this plant, including two new cycloartane triterpenoid saponins named cyclopassifloside ХII (1) and ХIII (2), together with six known cycloartane triterpenoids, cyclopassifloic acids B and E, cyclopassiflosides II, VI, IX and XI. The ethanol extract of Passiflora edulis Sims together with isolated compounds cyclopassiflosides IX and XI may possess antidepressant-like effect.

CONCLUSIONS

Cycloartane triterpenoid was one of the main compositions of Passiflora edulis Sims and possess antidepressant-like activity.

Evidence of the involvement of the monoaminergic systems in the antidepressant-like effect of Aloysia gratissima

ETHNOPHARMACOLOGICAL RELEVANCE

Aloysia gratissima (Verbenaceae) is an aromatic plant distributed in South America and, employed in folk medicine for the treatment of nervous systems illness, including depression. The neuroprotective and antidepressant-like activities of the aqueous extract of Aloysia gratissima (AE) administered orally has already been demonstrated.In this study the involvement of monoaminergic systems in the antidepressant-like effect of the AE was investigated.

MATERIALS AND METHODS

The implication of the monoaminergic systems in the antidepressant-like activity of Aloysia gratissima was evaluated using different pharmacological antagonists that were administered previously to the acute oral administration of AE (10 mg/kg). The antidepressant-like effect was assessed in the TST and locomotor activity was evaluated in the open-field test in mice.

RESULTS

The anti-immobility effect elicited by AE in the TST was prevented by the pre-treatment of mice with the antagonists, NAN-190 (5-HT(1A) receptor), ketanserin (5-HT(2A/2C) receptor), prazosin (α1-adrenoceptor), yohimbine (α2-adrenoceptor), SCH23390 (dopamine D1 receptor), or sulpiride (dopamine D2 receptor).

CONCLUSIONS

These results indicate that the antidepressant-like effect of AE in the TST is dependent on its interaction with the serotonergic (5-HT(1A) and 5-HT(2A/2C)), noradrenergic (α1 and α2-adrenoceptors) and dopaminergic (D1 and D2 receptors) systems, suggesting that this specie might act as a new potential resource for developing antidepressants to treat depressive disorders.

The antidepressant-like effect of bacopaside I: possible involvement of the oxidative stress system and the noradrenergic system

In the present study, the antidepressant-like effect of bacopaside I, a saponin compound present in the Bacopa monniera plant, was evaluated by behavioral and neurochemical methods. Bacopaside I (50, 15 and 5 mg/kg) was given to mice via oral gavage for 7 successive days. The treatment significantly decreased the immobility time in mouse models of despair tests, but it did not influence locomotor activity. Neurochemical assays suggested that treatment by bacopaside I (50, 15 and 5 mg/kg) improved brain antioxidant activity to varying degrees after the behavioral despair test. Bacopaside I (15 and 5 mg/kg) significantly reversed reserpine-induced depressive-like behaviors, including low temperature and ptosis. Conversely, bacopaside I did not affect either brain MAO-A or MAO-B activity after the behavioral despair test in mice. Additionally, 5-hydroxytryptophan (a precursor of 5-serotonin) was not involved in the antidepressant-like effect of bacopaside I. These findings indicated that the antidepressant-like effect of bacopaside I might be related to both antioxidant activation and noradrenergic activation, although the exact mechanism remains to be further elucidated.

Antidepressant-like effects of young green barley leaf (Hordeum vulgare L.) in the mouse forced swimming test

BACKGROUND

Young green barley leaf is one of the richest sources of antioxidants and has been widely consumed for health management in Japan. In this study, we examined whether oral administration of young green barley leaf has an antidepressant effect on the forced swimming test in mice.

MATERIALS AND METHODS

Mice were individually forced to swim in an open cylindrical container, one hour after oral administration of young green barley leaf (400 or 1000 mg / kg) or imipramine (100 mg / kg). Expression of mRNA for nerve growth factor (NGF), brain-derived neurotrophic factor, and glucocorticoid receptor in the brain was analyzed using real-time quantitative polymerase chain reaction (PCR).

RESULTS

There was a significant antidepressant-like effect in the forced swimming test; both 400 and 1000 mg / kg young green barley leaves, as well as the positive control imipramine (100 mg / kg), reduced the immobility duration compared to the vehicle group. The expression of mRNA for NGF detected in the hippocampus immediately after the last swimming test was higher than that in the non-swimming group (Nil). Oral administration of imipramine suppressed this increase to the level of the Nil group. Young green barley leaf (400 and 1000 mg / kg) also showed a moderate decrease in the expression of mRNA for NGF, in a dose-dependent manner.

CONCLUSION

Oral administration of young green barley leaf is able to produce an antidepressant-like effect in the forced swimming test. Consequently it is possible that the antidepressant-like effects of the young green barley leaf are, at least in part, mediated by an inhibition of the increase in the hippocampus levels of NGF.

Evaluation of Antidepressant-like Effect of Citrus Maxima Leaves in Animal Models of Depression

OBJECTIVES

This study planned to assess antidepressant like activity of aqueous extract from leaves of Citrus maxima Merr. (Rutaceae).

MATERIALS AND METHODS

Boiling was used for aqueous extraction. Acute toxicity study was performed in mice. Antidepressant activity was studied using locomotor activity test, modified forced swimming test (FST) and tail suspension test (TST). Three doses 100, 200 and 300 mg/kg of aqueous extract of leaves were selected for testing. Fluoxetine (20 mg/kg, i.p.) and imipramine (30 mg/kg, i.p.) were used as the standard drugs.

RESULTS

Aqueous extract of Citrus maxima leaves significantly reduced immobility time in both TST and FST. In locomotor activity testing it showed psychostimulant effect. Extract increased the climbing behavior in FST, which is similar to effect observed with imipramine.

CONCLUSION

The results of this study suggest that antidepressant like effect of Citrus maxima seems to be mediated by an increase in norepinephrine level in synapses.