Echinacoside ameliorates post-stroke depression by activating BDNF signaling through modulation of Nrf2 acetylation

BACKGROUND

Post-stroke depression (PSD) affects approximately one-third of stroke survivors, leading to adverse outcomes in rehabilitation, reduced quality of life, and increased mortality rates. Despite these implications, the underlying causes of PSD remain unclear, posing challenges for prevention and treatment. Echinacoside (ECH), a natural compound with known neuroprotective and antidepressant properties, holds significant therapeutic potential for PSD. However, the precise mechanism of its action remains unknown.

PURPOSE

To unravel the specific mechanism through which ECH alleviates PSD by exploring the intricate interplay between ECH and Nrf2, as well as its impact on the BDNF/TrkB signaling axis.

STUDY DESIGN AND METHODS

A rat PSD model was established though middle cerebral artery occlusion coupled with chronic unpredictable mild stress, followed by ECH treatment. The rats' depressive state was evaluated using the sucrose preference test and force swimming test. Brain damage was assessed through TTC staining, Nissl staining, and TUNEL assay. The multifaceted mechanism of ECH in PSD was investigated using immunofluorescence, immunohistochemistry, RT-qPCR, dual-luciferase assay, and western blotting. Additionally, the interaction between ECH and Nrf2 was explored through molecular docking and microscale thermophoresis.

RESULTS

Our findings unveiled a novel facet of ECH action, demonstrating its unique ability to upregulate Nrf2 through acetylation within the hippocampus of PSD-affected rats (p < 0.05). Moreover, ECH showcased its distinctive potential by enhancing BDNF transcriptional activity, activating the BDNF/TrkB signaling axis, and orchestrating a comprehensive response against oxidative stress and apoptosis, thereby alleviating PSD symptoms in rats (p < 0.05).

CONCLUSIONS

This study not only provides insights into the pivotal role of Nrf2 in mediating the BDNF/TrkB axis activation by ECH but also highlights the novelty of ECH's mechanism in addressing PSD. The elucidation of these unique aspects positions ECH as a groundbreaking candidate for further exploration and development in the realm of PSD intervention.

IV low dose ketamine infusions for treatment resistant depression: Results from a five-year study at a free public clinic in an academic hospital

Individuals with major depressive disorder and treatment resistant depression (MDD-TRD) have limited and sometimes poorly tolerated therapeutic options. Low dose ketamine has presented promising and potent antidepressant effects in this population. To support the existent literature, we conducted a longitudinal study examining five years of real-world clinical data on the use of IV low-dose ketamine alongside standard care for MDD-TRD outpatients. For this study we collected demographic information, clinical scale scores, side effects and dropout data. The data was analyzed using descriptive statistics, effect size using Cohen's D analysis, and multivariate ANOVA (MANOVA) to determine the impact of sociodemographic variables. 71 outpatients (50.28 years old, SD: 14.26; female 74.65%) were included in the analysis. The results showed a significant reduction in depressive symptoms and suicide ideation (SI) by treatment endpoint. 54.93% of patients responded to the treatment, 78.26% experienced transient and mild side effects, and 11.27% of dropped out of the treatment. Multivariate analysis showed that the demographic variables did not impact treatment effect or tolerability. The results of this study suggest that IV low dose ketamine treatment is effective, fast-acting, and well tolerated for the management of depressive symptoms and SI in patients with MDD-TRD in naturalistic clinical practice.

Ketamine can produce oscillatory dynamics by engaging mechanisms dependent on the kinetics of NMDA receptors

Ketamine is an NMDA-receptor antagonist that produces sedation, analgesia and dissociation at low doses and profound unconsciousness with antinociception at high doses. At high and low doses, ketamine can generate gamma oscillations (>25 Hz) in the electroencephalogram (EEG). The gamma oscillations are interrupted by slow-delta oscillations (0.1-4 Hz) at high doses. Ketamine's primary molecular targets and its oscillatory dynamics have been characterized. However, how the actions of ketamine at the subcellular level give rise to the oscillatory dynamics observed at the network level remains unknown. By developing a biophysical model of cortical circuits, we demonstrate how NMDA-receptor antagonism by ketamine can produce the oscillatory dynamics observed in human EEG recordings and non-human primate local field potential recordings. We have discovered how impaired NMDA-receptor kinetics can cause disinhibition in neuronal circuits and how a disinhibited interaction between NMDA-receptor-mediated excitation and GABA-receptor-mediated inhibition can produce gamma oscillations at high and low doses, and slow-delta oscillations at high doses. Our work uncovers general mechanisms for generating oscillatory brain dynamics that differs from ones previously reported, and provides important insights into ketamine's mechanisms of action as an anesthetic and as a therapy for treatment-resistant depression.

Antidepressant effect of Perilla frutescens essential oil through monoamine neurotransmitters and BDNF/TrkB signal pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Traditional Chinese medicine posits that affect-mind ill-being is the primary cause of depression, with Qi movement stagnation as its pathogenesis. As such, clinical treatment for depression should prioritize regulating Qi and relieving depressive symptoms. The pharmacological properties of traditional Chinese medicine indicate that Perilla frutescens may have potential therapeutic effects on depression and other neuropsychiatric diseases due to its ability to regulate Qi and alleviate depressive symptoms. Although previous studies have reported the antidepressant effects of Perilla frutescens, the mechanism underlying PFEO inhalation-mediated antidepressant effect remains unclear.

AIM OF THE STUDY

The aim of this investigation is to elucidate the antidepressant mechanisms of PFEO by examining its effects on monoamine neurotransmitters and the BDNF/TrkB signaling pathway.

MATERIALS AND METHODS

The CUMS rat model of depression was established, and the depressive state of the animals was assessed through sucrose preference and forced swim tests. ELISA assays were conducted to determine monoamine neurotransmitter levels in the hippocampus and cerebral cortex of rats. Immunohistochemistry, western blotting, and RT-PCR experiments were employed to investigate the BDNF/TrkB signaling pathway's regulation of depression via PFEO inhalation.

RESULTS

It has been observed that inhalation administration of PFEO can significantly enhance the preference for sugar water in CUMS rats and reduce their immobility time during forced swimming. Additionally, there was an increase in the levels of monoamine transmitters in both the hippocampus and cerebral cortex of these rats. Furthermore, there was an upregulation in the expression levels of BDNF and TrkB positive cells as well as BDNF and TrkB proteins within both regions, along with increased BDNF mRNA and TrkB mRNA expression levels.

CONCLUSION

The antidepressant effect of PFEO via inhalation administration is speculated to be mediated through the monoamine neurotransmitters and BDNF/TrkB signaling pathway.

Gut microbiota-based metabolites of Xiaoyao Pills (a typical Traditional Chinese medicine) ameliorate depression by inhibiting fatty acid amide hydrolase levels in brain

ETHNOPHARMACOLOGICAL RELEVANCE

Traditional Chinese medicines (TCMs) are often prepared in oral dosage forms, making TCMs interact with gut microbiota after oral administration, which could affect the therapeutic effect of TCM. Xiaoyao Pills (XYPs) are a commonly used TCM in China to treat depression. The biological underpinnings, however, are still in its infancy due to its complex chemical composition.

AIM OF THE STUDY

The study aims to explore XYPs' underlying antidepressant mechanism from both in vivo and in vitro.

MATERIALS AND METHODS

XYPs were composed of 8 herbs, including the root of Bupleurum chinense DC., the root of Angelica sinensis (Oliv.) Diels, the root of Paeonia lactiflora Pall., the sclerotia of Poria cocos (Schw.) Wolf, the rhizome of Glycyrrhiza uralensis Fisch., the leaves of Mentha haplocalyx Briq., the rhizome of Atractylis lancea var. chinensis (Bunge) Kitam., and the rhizome of Zingiber officinale Roscoe, in a ratio of 5:5:5:5:4:1:5:5. The chronic unpredictable mild stress (CUMS) rat models were established. After that, the sucrose preference test (SPT) was carried out to evaluate if the rats were depressed. After 28 days of treatment, the forced swimming test and SPT were carried out to evaluate the antidepressant efficacy of XYPs. The feces, brain and plasma were taken out for 16SrRNA gene sequencing analysis, untargeted metabolomics and gut microbiota transformation analysis.

RESULTS

The results revealed multiple pathways affected by XYPs. Among them, the hydrolysis of fatty acids amide in brain decreased most significant via XYPs treatment. Moreover, the XYPs' metabolites which mainly derived from gut microbiota (benzoic acid, liquiritigenin, glycyrrhetinic acid and saikogenin D) were found in plasma and brain of CUMS rats and could inhibit the levels of FAAH in brain, which contributed to XYPs' antidepressant effect.

CONCLUSIONS

The potential antidepressant mechanism of XYPs by untargeted metabolomics combined with gut microbiota-transformation analysis was revealed, which further support the theory of gut-brain axis and provide valuable evidence of the drug discovery.

Effects of liraglutide on depressive behavior in a mouse depression model and cognition in the probe trial of Morris water maze test

BACKGROUND

We investigated the effects of liraglutide, a glucagon-like peptide-1 (GLP-1) agonist, on a depression-like phenotype in mice exposed to chronic unpredictable stress (CUS). Learning and memory were also assessed using the Morris water maze (MWM) test.

METHODS

Liraglutide (0.3 mg/kg/day for 21 days) was administered to mice with or without exposure to CUS. After 21 days of CUS, the forced swim test (FST) was performed to assess its antidepressant effect. To evaluate cognitive function, liraglutide was administered to mice under stress-free conditions for 21 days, and then the MWM test was performed on 6 consecutive days.

RESULTS

Chronic liraglutide treatment reduced FST immobility in mice with and without CUS. In the probe trial of the Morris water maze test, the search error rate was reduced and the time spent and path length in the target quadrant and the number of platform crossings were increased.

LIMITATION

Additional animal model experiments and molecular level studies are needed to support the results obtained in this study.

CONCLUSIONS

Liraglutide appears to exert antidepressant effects and could improve cognitive function. Based on these results, GLP-1 agonists could have potential as novel antidepressants.

Natural products for the treatment of stress-induced depression: Pharmacology, mechanism and traditional use

ETHNOPHARMACOLOGICAL RELEVANCE

Depression, one of the most common psychiatric disorders, is the fourth leading cause of long-term disability worldwide. A series of causes triggered depression, including psychological stress and conflict, as well as biological derangement, among which stress has a pivotal role in the development of depression. Traditional herbal medicine has been used for the treatment of various disorders including depression for a long history with multi-targets, multi-levels and multi-ways, attracting great attention from scholars. Recently, natural products have been commercialized as antidepressants which have become increasingly popular in the world health drug markets. Major research contributions in ethnopharmacology have generated and updated vast amount of data associated with natural products in antidepressant-like activity.

AIMS OF THE REVIEW

This review aims to briefly discuss the pathological mechanism, animal models of stress-induced depression, traditional use of herbal medicines and especially recapitulate the natural products with antidepressant activity and their pharmacological functions and mechanism of action, which may contribute to a better understanding of potential therapeutic effects of natural products and the development of promising drugs with high efficacy and low toxicity for the treatment of stress-induced depression.

MATERIALS AND METHODS

The contents of this review were sourced from electronic databases including PubMed, Sci Finder, Web of Science, Science Direct, Elsevier, Google Scholar, Chinese Knowledge On frastructure (CNKI), Wan Fang, Chinese Scientific and Technological Periodical Database (VIP) and Chinese Biomedical Database (CBM). Additional information was collected from Yao Zhi website (https://db.yaozh.com/). Data were obtained from April 1992 to June 2021. Only English language was applied to the search. The search terms were 'stress-induced depression', 'pathological mechanism' in the title and 'stress', 'depression', 'animal model' and 'natural products' in the whole text.

RESULTS

Stress-induced depression is related to the monoaminergic system, hypothalamic-pituitary-adrenal (HPA) axis, neuronal plasticity and a series of inflammatory factors. Four main types of animal models of stress-induced depression were represented. Fifty-eight bioactive phytochemical compounds, fifty-six herb medicines and five formulas from traditional Chinese medicine were highlighted, which exert antidepressant effects by inhibiting monoamine oxidase (MAO) reaction, alleviating dysfunction of the HPA axis and nerve injury, and possessing anti-inflammatory activities.

CONCLUSIONS

Natural products provide a large number of compounds with antidepressant-like effects, and their therapeutic impacts has been highlighted for a long time. This review summarized the pathological mechanism and animal models of stress-induced depression, and the natural products with antidepressant activity in particular, which will shed light on the action mechanism and clinical potential of these compounds. Natural products also have been a vital and promising source for future antidepressant drug discovery.

Bilateral sequential theta burst stimulation for multiple-therapy-resistant depression: A naturalistic observation study

Depression is a significant health issue with treatment resistance reported in about one third of patients. Treatment resistance results in significant disability, impaired quality of life, and increased healthcare costs. Repetitive transcranial magnetic stimulation (rTMS) is a treatment option for treatment resistant depression (TRD) with response and remission rates in open-label studies being as high as 58% and 37% respectively. Theta-burst is a faster and novel rTMS paradigm that has shown promise as a treatment for TRD in some preliminary studies. In a naturalistic design, we evaluated the response, remission and tolerability of bilateral sequential (right then left) prefrontal theta-burst rTMS (bsTBS) in 50 patients with TRD (600 pulses/session, 20 sessions, 100% of resting motor threshold (80% if intolerant to 100%, n = 2), F4/F3 of 10-20-20 EEG localization). Data was collected over 36 months from a specialized academic TMS clinic. Patients had multiple-treatment resistance with at least two failed trials of different antidepressants with 20% also having failed electroconvulsive therapy and 66% having received professional therapy. We found a 28% remission rate (HAMD-17 score of ≤7) and a 52% response rate (≥50% reduction in HAMD-17) with a 42% reduction in average HAMD-17 score. The treatment was well tolerated, with muscle contractions, mild pain or discomfort, headache, scalp irritation, and changes to vitals being captured as occasional adverse events with two instances of syncope (0.22% of treatments). This naturalistic study shows that bsTBS is a promising paradigm for a multiple-TRD patient population with approximately one-third of treatments achieving remission and over half achieving significant response.

Ginsenoside Rk1 alleviates LPS-induced depression-like behavior in mice by promoting BDNF and suppressing the neuroinflammatory response

Ginsenoside Rk1, a saponin component produced by heat-processed ginseng, possesses anti-inflammatory and antitumor activities. The aim of our study was to explore the effects of Rk1 on Lipopolysaccharide (LPS)-induced depression-like behavior in mice and to observe its effects on oxidative stress, the inflammatory response and brain-derived neurotrophic factor (BDNF) - tropomyosin-related kinase B (TrkB) signaling. After mice were pretreated with Rk1 (5, 10, and 20 mg/kg), the immobility time in both the forced swimming test (FST) and the tail suspension test (TST) was reduced, suggesting that Rk1 effectively improved depression-like symptoms. Rk1 (10 and 20 mg/kg) and Fluoxetine (Flu, 20 mg/kg) increased the activity of the antioxidant enzyme SOD in the brain and protected against lipid peroxidation. Different concentrations of Rk1 (10 and 20 mg/kg) and Flu significantly decreased the levels of tumor necrosis factor (TNF)-α and interleukin (IL)-1 in serum, while Rk1 (5, 10, and 20 mg/kg) and Flu reduced the concentrations of IL-6 in a dose-dependent manner. Western blot analysis showed that the administration of Rk1 (20 mg/kg) and Flu significantly downregulated the level of Sirt1 and that Rk1 (5, 10, and 20 mg/kg) and Flu inhibited the p-NF-κb/NF-κb and p-IκB-α/IκB-α ratios, which indicated that the neuroprotective effect of Rk1 may be related to the suppression of inflammation. In addition 5, 10 and 20 mg/kg Rk1 significantly attenuated the LPS-induced decreases in BDNF and TrkB. These results indicated that Rk1 acts as an antidepressant through its antioxidant activity, the inhibition of neuroinflammation, and the positive regulation of the BDNF-TrkB pathway. This study may help develop active ginsenoside-based compounds for neurodegenerative diseases.

Subanesthetic ketamine exerts antidepressant-like effects in adult rats exposed to juvenile stress

Juvenile stress, like that caused by childhood maltreatment, is a significant risk factor for psychiatric disorders such as depression later in life. Recently, the antidepressant effect of ketamine, a noncompetitive N-methyl-d-aspartate receptor antagonist, has been widely investigated. However, little is known regarding its efficacy against depressive-like alterations caused by juvenile stress, which is clinically relevant in human depression. In the present study, we evaluated the antidepressant-like effect of ketamine in adult rats that had been subjected to juvenile stress. Depressive-like behavior was assessed using the forced swim test (FST), and electrophysiological and morphological alterations in the layer V pyramidal cells of the prelimbic cortex were examined using whole-cell patch-clamp recordings and subsequent recording-cell specific fluorescence imaging. We demonstrated that ketamine (10 mg/kg) attenuated the increased immobility time caused by juvenile stress in the FST, restored the diminished excitatory postsynaptic currents, and caused atrophic changes in the apical dendritic spines. Ketamine's effects reversing impaired excitatory/inhibitory ratio of postsynaptic currents were also revealed. These results indicated that ketamine could be effective in reversing the depression-like alterations caused by juvenile stress.

Oxytocin Exerts Antidepressant-like effect by potentiating dopaminergic synaptic transmission in the mPFC

Oxytocin (OT) and dopamine (DA) are two important elements that are closely related to mental and reward processes in the brain. OT controlled DA functional regulation contributes to various behaviours such as social reward, social cognition and emotion-related behaviours. Previous studies indicated that diminished dopaminergic transmission in the medial prefrontal cortex (mPFC) is correlated with the pathophysiology of depression. However, the interaction of OT and DA and their roles in antidepressant effects still require further exploration. Here, we investigated the antidepressant effect of OT through local mPFC administration, and further explored the underlying mechanisms that indicated that OT could strengthen dopaminergic synaptic transmission with OT receptor (OTR) activation dependent in the mPFC. Our results showed that local administration of OT in the mPFC exerts antidepressant (-like) effects in both naïve and social defeat stress (SDS) depressive animal model. Mechanism study suggested that OT enhances DA level with OTR activation dependent, and elevated mPFC DA levels might further enhance excitatory synaptic transmission by activating the D1/PKA/DARPP32 intracellular signalling pathway in the mPFC. Hence, our study revealed that the activation of OTR strengthens excitatory synaptic transmission via the potentiation of dopaminergic synaptic transmission, especially via D1R activation dependent, in the mPFC, which may be the underlying mechanism of antidepressant (-like) effects mediated by OT. With specifically activation of the D1/PKA/DAPRR32 signalling pathway, our results may augment the important role of OT in reward circuits in the central nervous system.

A systematic review and meta-analysis of deep brain stimulation in treatment-resistant depression

BACKGROUND

Deep brain stimulation (DBS) has been applied in treatment-resistant depression (TRD) as a putative intervention targeting different brain regions. However, the antidepressant effects of DBS for TRD in recent clinical trials remain controversial.

METHODS

We searched Scopus, EMBASE, the Cochrane Library, PubMed, and PsycINFO for all published studies investigating the efficacy of DBS in TRD up to Feb 2017. Hamilton depression rating scale (HDRS) scores and Montgomery-Asberg depression rating scale (MARDS) scores were compared between baseline levels and those after DBS using the standardized mean difference (SMD) with 95% confidence intervals (CIs). The pooled response and remission rates were described using Risk Difference with 95% CIs.

RESULTS

We identified 14 studies of DBS in TRD targeting the subcallosal cingulate gyrus (SCG), ventral capsule/ventral striatum (VC/VS), medial forebrain bundle (MFB), and nucleus accumbens (NAcc). The overall effect sizes showed a significant reduction in HDRS after DBS stimulation in these four regions, with a standardized mean difference of -3.02 (95% CI=-4.28 to -1.77, p<0.00001) for SCG, -1.64 (95% CI=-2.80 to -0.49, p=0.005) for VC/VS, -2.43 (95% CI=-3.66 to -1.19, p=0.0001) for MFB, and -1.30 (95% CI=-2.16 to -0.44, p=0.003) for NAcc. DBS was effective, with high response rates at 1, 3, 6, and 12months. Some adverse events (AEs), especially some specific AEs related to targeting regions, occurred during the DBS treatment.

CONCLUSIONS

DBS significantly alleviates depressive symptoms in TRD patients by targeting the SCG, VC/VS, MFB, and NAcc. Several adverse events might occur during DBS therapy, although it is uncertain whether some AEs can be linked to DBS treatment. Further confirmatory trials are required involving larger sample sizes.

Evidence for the involvement of opioid system in the antidepressant-like effect of ascorbic acid

Considering the involvement of the opioid system in major depressive disorder (MDD), mainly concerning refractory MDD, and the evidence that ascorbic acid may exert a beneficial effect for the treatment of this disorder, this study investigated the involvement of the opioid system in the antidepressant-like effect of ascorbic acid in the tail suspension test (TST). Treatment of Swiss mice with the non-selective opioid receptor antagonist naloxone (1 mg/kg, i.p.) prevented the reduced immobility time caused by ascorbic acid (1 mg/kg, p.o.) in the TST. Additionally, administration of the selective μ1-opioid receptor antagonist, naloxonazine (10 mg/kg, i.p.), also abolished the antidepressant-like action of the same dose of ascorbic acid in the TST. We also investigated the possible relationship between the opioid system and NMDA receptors in the mechanism of action of ascorbic acid or ketamine (0.1 mg/kg, i.p.) in the TST. Treatment of mice with naloxone (1 mg/kg, i.p.) blocked the synergistic antidepressant-like effect of ascorbic acid (0.1 mg/kg. p.o.) and MK-801 (0.001 mg/kg, p.o., a non-competitive NMDA receptor antagonist) in the TST. Combined administration of ketamine and MK-801 induced a synergistic antidepressant-like action, and naloxone partially abolished this effect. Our results indicate that the antidepressant-like effect of ascorbic acid in the TST appears to be dependent on the activation of the opioid system, especially μ1-opioid receptors, which might be an indirect consequence of NMDA receptor inhibition elicited by ascorbic acid administration.

Comparative efficacy and tolerability of pharmacological and somatic interventions in adult patients with treatment-resistant depression: a systematic review and network meta-analysis

OBJECTIVE

Major depressive disorder (MDD) affects about 10-15% of the general population in a lifetime. A considerable number of patients fail to achieve full symptom remission despite adequate treatment and are considered treatment resistant (TRD). The current study compared the relative efficacy and tolerability of pharmacological and somatic TRD interventions by means of a Bayesian network meta-analysis.

RESEARCH DESIGN AND METHODS

An electronic literature search of MEDLINE, MEDLINE In-Process, EMBASE, PsycInfo, EconLit and Cochrane Library databases for trials published between September 2003 and September 2014 was conducted. Key outcomes extracted were disease severity change from baseline, response and remission rates at various timepoints and discontinuation due to adverse events.

RESULTS

Of the 3876 abstracts identified, 31 publications/randomised controlled trials (RCTs) were included in the analysis; 19 RCTs investigating 13 pharmacological interventions and 12 RCTs investigating electroconvulsive therapy (ECT) and repetitive transcranial magnetic stimulation (rTMS). The evidence synthesis investigating efficacy outcomes of TRD treatments demonstrated superior efficacy for ketamine compared to pharmacological and somatic interventions at 2 weeks after treatment initiation. At 4, 6 and 8 weeks, quetiapine augmentation (800 mg/day) and risperidone augmentation were found to be the first and second best treatments, respectively. Networks were small for response rate and remission rate outcomes at most timepoints. The most tolerable treatment was lamotrigine augmentation showing a comparable profile to placebo/sham.

CONCLUSIONS

This analysis revealed scarcity of long-term data on sustained remission that would allow a comparative long-term efficacy assessment. Key limitations of the analysis can be considered the search timeframe and the use of mapping formula for the depression scores.

Effects of a single bilateral infusion of R-ketamine in the rat brain regions of a learned helplessness model of depression

Effects of a single bilateral infusion of R-enantiomer of ketamine in rat brain regions of learned helplessness model of depression were examined. A single bilateral infusion of R-ketamine into infralimbic (IL) portion of medial prefrontal cortex (mPFC), CA3 and dentate gyrus (DG) of the hippocampus showed antidepressant effects. By contrast, a single bilateral infusion of R-ketamine into prelimbic (PL) portion of mPFC, shell and core of nucleus accumbens, basolateral amygdala and central nucleus of the amygdala had no effect. This study suggests that IL of mPFC, CA3 and DG of hippocampus might be involved in the antidepressant actions of R-ketamine.

Food-derived hydrophilic antioxidant ergothioneine is distributed to the brain and exerts antidepressant effect in mice

BACKGROUND

Clinically used antidepressants suffer from various side effects. Therefore, we searched for a safe antidepressant with minimal side effects among food ingredients that are distributed to the brain. Here, we focused on ERGO (ergothioneine), which is a hydrophilic antioxidant and contained at high levels in edible golden oyster mushrooms. ERGO is a typical substrate of carnitine/organic cation transporter OCTN1/SLC22A4, which is expressed in the brain and neuronal stem cells, although little is known about its permeation through the BBB (blood-brain barrier) or its neurological activity.

METHODS

To clarify the exposure of ERGO to brain and the possible antidepressant-like effect after oral ingestion, ERGO or GOME (golden oyster mushroom extract) which contains 1.2% (w/w) ERGO was mixed with feed and provided to mice for 2 weeks, and then ERGO concentration and antidepressant-like effect were evaluated by LC-MS/MS and FST (forced swimming test) or TST (tail suspension test), respectively.

RESULTS

Diet containing ERGO or GOME greatly increased the ERGO concentrations in plasma and brain, and significantly decreased the immobility time in both FST and TST. The required amount of GOME (~37 mg/day) to show the antidepressant-like effect corresponds to at most 8 g/day in humans. In mice receiving GOME-containing diet, doublecortin-positive cells showed a significant increase from the basal level, suggesting promotion of neuronal differentiation.

CONCLUSION

Thus, orally ingested ERGO is transported across the BBB into the brain, where it may promote neuronal differentiation and alleviate symptoms of depression at plausibly achieved level of daily ingestion.

Biological activities of Zn(II)-S-methyl-cysteine complex as antiradical, inhibitor of acid phosphatase enzyme and in vivo antidepressant effects

The antidepressant effect of simple Zn(II) salts has been proved in several animal models of depression. In this study, a coordination metal complex of Zn(II) having a sulfur containing ligand is tested as antidepressant for the first time. Forced swimming test method on male Wistar rats shows a decrease in the immobility and an increase in the swimming behavior after treatment with [Zn(S-Met)2] (S-Met=S-methyl-l-cysteine) being more effective and remarkable than ZnCl2. The thiobarbituric acid and the pyranine consumption (hydroxyl and peroxyl radicals, respectively) methods were applied to evaluate the antioxidant activity of S-Met and [Zn(S-Met)2] showing evidence of attenuation of hydroxyl but not peroxyl radicals activities. UV-vis studies on the inhibition of acid phosphatase enzyme (AcP) demonstrated that S-methyl-l-cysteine did not produce any effect but, in contrast, [Zn(S-Met)2] complex behaved as a moderate inhibitor. Finally, bioavailability studies were performed by fluorescence spectroscopy denoting the ability of the albumin to transport the complex.

The role of ketamine in treatment-resistant depression: a systematic review

Background:

At least 10-20% of the patients suffering from depression meet criteria for treatment-resistant depression (TRD). In the last decades, an important role of glutamate in mood modulation has been hypothesized and ketamine, a non noncompetitive antagonist of the N-methyl-D-aspartate (NMDA) receptors, has been demonstrated to be effective in both MDD and TRD. However, concerns emerged about the optimal dosage, and frequency of administration of this treatment.

Methods:

aiming to systematically review the current literature focusing on the main pharmacological properties and impact of ketamine in TRD, a detailed literature search in PubMed/Medline and ScienceDirect databases was conducted. Twenty-four manuscripts including a total of 416 patients fulfilled inclusion criteria.

Results:

Most studies demonstrated that the NMDA antagonist ketamine has rapid antidepressant effects in TRD patients, confirming the active role of glutamate in the pathophysiology of this complex condition. Ketamine has been demonstrated to be rapidly effective and was associated with a significant clinical improvement in depressive symptoms within hours after administration. Also, ketamine was also found to be effective in reducing suicidality in TRD samples.

Limitations:

The long-term efficacy of ketamine has not been investigated by most studies. The psychotomimetic properties may complicate the application of this pharmacological agent.

Conclusions:

Ketamine may be considered a valid and intriguing antidepressant option for the treatment of TRD. Further studies are needed to evaluate its long-term antidepressant efficacy in patients with TRD.