Antidepressant effect of helicid in chronic unpredictable mild stress model in rats

Comparing the effect of fluoxetine, escitalopram, and sertraline, on the level of BDNF and depression in preclinical and clinical studies: a systematic review

Brain-derived neurotrophic factor (BDNF) dysfunction is one of the most important mechanisms underlying depression. It seems that selective serotonin reuptake inhibitors (SSRIs) improve depression via affecting BDNF level. In this systematic review, for the first time, we aimed to review the effect of three SSRIs including fluoxetine, escitalopram, and sertraline, on both depression and BDNF level in preclinical and clinical studies. PubMed electronic database was searched, and 193 articles were included in this study. After reviewing all manuscripts, only one important difference was found: subjects. We found that SSRIs induce different effects in animals vs. humans. Preclinical studies showed many controversial effects, while human studies showed only two effects: improvement of depression, with or without the improvement of BDNF. However, most studies used chronic SSRIs treatment, while acute SSRIs were not effectively used and evaluated. In conclusion, it seems that SSRIs are reliable antidepressants, and the improvement effect of SSRIs on depression is not dependent to BDNF level (at least in human studies).

Effect of a multi-strain probiotic mixture consumption on anxiety and depression symptoms induced in adult mice by postnatal maternal separation

BACKGROUND

Intestinal microbial composition not only affects the health of the gut but also influences centrally mediated systems involved in mood, through the "gut-brain" axis, a bidirectional communication between gut microbiota and the brain. In this context, the modulation of intestinal microbiota and its metabolites through the administration of probiotics seems to represent a very promising approach in the treatment of the central nervous system alterations. Early postnatal life is a critical period during which the brain undergoes profound and essential modulations in terms of maturation and plasticity. Maternal separation (MS), i.e., the disruption of the mother-pup interaction, represents a pivotal paradigm in the study of stress-related mood disorders, by inducing persistent changes in the immune system, inflammatory processes, and emotional behavior in adult mammals.

RESULTS

We conducted experiments to investigate whether sustained consumption of a multi-strain probiotic formulation by adult male mice could mitigate the effects of maternal separation. Our data demonstrated that the treatment with probiotics was able to totally reverse the anxiety- and depressive-like behavior; normalize the neuro-inflammatory state, by restoring the resting state of microglia; and finally induce a proneurogenic effect. Mice subjected to maternal separation showed changes in microbiota composition compared to the control group that resulted in permissive colonization by the administered multi-strain probiotic product. As a consequence, the probiotic treatment also significantly affected the production of SCFA and in particular the level of butyrate.

CONCLUSION

Gut microbiota and its metabolites mediate the therapeutic action of the probiotic mix on MS-induced brain dysfunctions. Our findings extend the knowledge on the use of probiotics as a therapeutic tool in the presence of alterations of the emotional sphere that significantly impact on gut microbiota composition. Video Abstract.

Canagliflozin attenuates chronic unpredictable mild stress induced neuroinflammation via modulating AMPK/mTOR autophagic signaling

Although vast progress has been made to understand the pathogenesis of depression, existing antidepressant remedies, with several adverse effects, are not fully adequate. Interestingly, new emerging theories implicating an altered HPA-axis, tryptophan metabolism, neuroinflammation and altered gut integrity were proposed to further identify novel therapeutic targets. Along these lines, canagliflozin (CAN), a novel antidiabetic medication with anti-inflammatory and neuroprotective activity may present an effective treatment for depression; nevertheless, no studies have explored its effect on depressive disorder yet. To this end, this study aimed to investigate the possible antidepressant activity of CAN in CUMS and the mechanisms underlying its action on the gut-brain inflammation axis as well as the alteration in the TRY/KYN pathway in addition to its role in modulating the autophagic signaling cascade. Interestingly, CAN successfully attenuated the CUMS-induced elevations in despair and anhedonic behaviors as well as the elevated serum CORT. Furthermore, it enhanced gut integrity via hampering the CUMS-induced colonic inflammation and amending colonic tight junction proteins. The enhanced gut integrity was further corroborated by a notable anti-inflammatory and neuroprotective activity manifested via the observed mitigation of immune cell activation in addition to IDO hippocampal protein content and promotion of the autophagy cascade. Our findings postulate the possible anti-inflammatory and neuroprotective effects of CAN and the implication of TRY/KYN and AMPK/mTOR signaling pathways in the CUMS-induced MDD. Hence, this study shed light to the promising role of CAN in the augmentation of the current antidepressant treatments.

Anti-depressant-like effect of fermented Gastrodia elata Bl. by regulating monoamine levels and BDNF/NMDAR pathways in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Gastrodia elata Blume (GE) is a Chinese medicinal herb commonly used to treat central nervous system-related diseases, including headaches, dizziness, epilepsy, numbness of the limbs and depression.

AIM OF THE STUDY

Microbial-based fermentation has been successfully used to increase the extract efficiency of medicinal herbs in recent years. However, no study has hitherto explored the anti-depressant-like effect of GE processed by microorganisms. Herein, this subject aimed to clarify the anti-depressant-like effect of fermented Gastrodia elata Bl. (FGE) and its active chemical constituents.

MATERIALS AND METHODS

The chronic unpredictable mild stress (CUMS) model, a well-established animal model of depression, was induced in Kunming (KM) mice. The mice were administrated with FGE for 3 weeks. The sucrose preference test (SPT), open field test (OFT) and tail suspension test (TST) were conducted. Moreover, the levels of serotonin (5-HT) and dopamine (DA) in brain tissue homogenates, the concentration of Ca²⁺ and the activity of MAO in serum, H&E and Nissl staining in the hippocampus, and the hippocampus protein expressions of BDNF, NMDAR1, NMDAR2A and NMDAR2B relevant to depression were detected. Furthermore, chemical constituents of FGE were further isolated, and the protective activity of the obtained compounds against NMDA-induced PC-12 cell damage was assessed.

RESULTS

FGE could alleviate the depression state in CUMS-induced mice and reduce apoptosis of neuronal cells in the hippocampus. Furthermore, FGE could improve the contents of 5-HT, DA and decrease the concentration of Ca²⁺ and MAO activity in brain tissue and serum compared with the control group. It could reverse the decreased expression of BDNF, NMDAR2A and NMDAR2B and increase NMDAR1 protein expression. Investigation of the active constituents from FGE yielded two new compounds, (4-(((4-ethoxybenzyl) oxy)methyl)-phenol 1 and 3-((4-hydroxy benzyl)oxy)propane-1,2-diol) 2, with twelve known compounds (3-14). The compounds (3-((4-hydroxybenzyl)oxy)propane-1,2-diol 2, 4, 4'-dihydroxyd iphenyl methane 3, and bungein A 4) protected against NMDA-induced PC-12 cells damage.

CONCLUSION

This study demonstrated that FGE could improve the depressive behavior of CUMS-induced mice and exert a protective effect on nerve cells in the brain. Importantly, compounds 2-4 are the active components of FGE. Overall, the above findings suggest that FGE has huge prospects for application in treating depression-related diseases.

Momordica charantia fruit extract with antioxidant capacity improves the expression of tyrosine-phosphorylated proteins in epididymal fluid of chronic stress rats

OBJECTIVE

Although the protective effects of Momordica charantia L. (MC) extract on chemical-induced testicular damage have been studied, the preventive effects of MC extract on functional proteins in the epididymis under chronic stress have never been reported. This study investigated the protective effects of MC fruit extract on protein secretion, especially tyrosine-phosphorylated proteins, in the epididymis of rats exposed to chronic unpredictable stress (CUS).

METHODS

Total phenolic compounds (TPC), total flavonoid compounds (TFC) and antioxidant capacities of MC extract were measured. Adult male rats were divided into 4 groups: control group, CUS group, and 2 groups of CUS that received different doses of MC extract (40 or 80 mg/kg). In treated groups, rats were given MC daily, followed by induction of CUS (1 stressor was randomly applied from a battery of 9 potential stressors) for 60 consecutive days. Plasma corticosterone and testosterone levels were analyzed after the end of experiment. Expressions of heat-shock protein 70 (HSP-70) and tyrosine-phosphorylated proteins present in the fluid of the head and tail of the epididymis were quantified using Western blot.

RESULTS

MC extract contained TPC of (19.005 ± 0.270) mg gallic acid equivalents and TFC of (0.306 ± 0.012) mg catechin equivalents per gram, and had 2,2-diphenyl-1-picrylhydrazyl antioxidant capacity of (4.985 ± 0.086) mg trolox equivalents per gram, radical 50% inhibitory concentration of (2.011 ± 0.008) mg/mL and ferric reducing antioxidant power of (23.697 ± 0.819) µmol Fe(II) per gram. Testosterone level in the epididymis was significantly increased, while the corticosterone level was significantly improved in groups treated with MC extract, compared to the CUS animals. Particularly, an 80 mg/kg dose of MC extract prevented the impairments of HSP-70 and tyrosine-phosphorylated protein expressions in the luminal fluid of the epididymis of CUS rats.

CONCLUSION

MC fruit extract had antioxidant activities and improved the functional proteins secreted from the head and tail of the epididymis. It is possible to develop the MC fruit extract as a male fertility supplement for enhancing functional sperm maturation in stressed men.

GC/MS Profiling, Anti-Collagenase, Anti-Elastase, Anti-Tyrosinase and Anti-Hyaluronidase Activities of a Stenocarpus sinuatus Leaves Extract

Today, skin care products and cosmetic preparations containing natural ingredients are widely preferred by consumers. Therefore, many cosmetic brands are encouraged to offer more natural products to the market, such as plant extracts that can be used for their antiaging, antiwrinkle, and depigmentation properties and other cosmetic purposes. In the current study, the volatile constituents of the hexane-soluble fraction of a Stenocarpus sinuatus (family Proteaceae) leaf methanol extract (SSHF) were analyzed using GC/MS analysis. Moreover, the antiaging activity of SSHF was evaluated through in vitro studies of anti-collagenase, anti-elastase, anti-tyrosinase, and anti-hyaluronidase activities. In addition, an in silico docking study was carried out to identify the interaction mechanisms of the major compounds in SSHF with the active sites of the target enzymes. Furthermore, an in silico toxicity study of the identified compounds in SSHF was performed. It was revealed that vitamin E (α-tocopherol) was the major constituent of SSHF, representing 52.59% of the extract, followed by γ-sitosterol (8.65%), neophytadiene (8.19%), β-tocopherol (6.07%), and others. The in vitro studies showed a significant inhibition by SSHF of collagenase, elastase, tyrosinase, and hyaluronidase, with IC₅₀ values of 60.03, 177.5, 67.5, and 38.8 µg/mL, respectively, comparable to those of the positive controls epigallocatechin gallate (ECGC, for collagenase, elastase, hyaluronidase) and kojic acid (for tyrosinase). Additionally, the molecular docking study revealed good acceptable binding scores of the four major compounds, comparable to those of ECGC and kojic acid. Besides, the SSHF identified phytoconstituents showed no predicted potential toxicity nor skin toxicity, as determined in silico. In conclusion, the antiaging potential of SSHF may be attributed to its high content of vitamin E in addition to the synergetic effect of other volatile constituents. Thus, SSHF could be incorporated in pharmaceutical skin care products and cosmetics after further studies.

Helicid Improves Lipopolysaccharide-Induced Apoptosis of C6 Cells by Regulating SH2D5 DNA Methylation via the CytC/Caspase9/Caspase3 Signaling Pathway

DNA methylation is reportedly associated with stress responses and depression. Treatment with antidepressants can regulate DNA methylation and, subsequently, gene expression in the hippocampus. Hence, DNA methylation is a potential target for treatment of depression. Screening of high-throughput data of a rat model of chronic unpredictable mild stress revealed relatively low expression of SH2 domain-containing 5 (SH2D5). SH2D5 can be overexpressed by treatment with helicid. Therefore, in order to further explore the role of SH2D5 in depression and whether helicid mediates the DNA methylation of SH2D5 as a potential antidepressant role, SH2D5 was overexpressed in C6 cells as a lipopolysaccharides (LPS)-induced model of depression. The expression levels of Bax, Bcl-2, Bad, and Daxx, and changes to the CytC/caspase9/caspase3 signal pathway were detected by qRT-PCR and Western blot analyses. After treatment with helicid or silencing of SH2D5, the above indices were detected. The results showed that helicid regulated the CytC/caspase9/caspase3 signaling pathway and improved the apoptosis indices of C6 cells through the overexpression of SH2D5. Interestingly, silencing of SH2D5 reversed the effects of helicid on the above indices. Then, in order to study the underlying mechanism, the cells were administered to helicid or 5-aza-2'-deoxycytidine (5-AzaD) and expression of SH2D5 was detected by qRT-PCR and Western blot analyses, while to assess the DNA methylation level of SH2D5 using bisulfite sequencing/PCR. The results showed that SH2D5 was hypermethylated with low expression in LPS-induced C6 cells, which was reversed by helicid and 5-AzaD. These results suggest that helicid may affect the CytC/caspase9/caspase3 apoptosis signaling pathway and improve the apoptosis indices by mediating DNA methylation of SH2D5.

Helicid Reverses the Effect of Overexpressing NCALD, Which Blocks the sGC/cGMP/PKG Signaling Pathway in the CUMS-Induced Rat Model

Background

Increasing evidence has shown that apoptosis in the hippocampus is closely related to depressive-like behavior. We previously reported that helicid had good antidepressant activities, which manifested as the alleviation of depression-like behaviors and the reversal of the high expression of neurocalcin delta (NCALD) in chronic unpredictable mild stress (CUMS) rats. The aim of this study was, therefore, to characterize the antidepressant-like effects and underlying mechanism of helicid on CUMS rats by silencing NCALD and using rescue experiments.

Methods

We developed the CUMS rat model using CUMS stimulation from week 0 to week 6. The rats were treated with helicid, or NCALD silenced, then we overexpressed NCALD using adeno-associated virus. We also measured the protein levels of sGCα1, sGCβ1, PKG1/2, and cleaved caspase-3 in hippocampal tissues using western blotting and measured cGMP using an ELISA.

Results

Treating CUMS rats by silencing NCALD or by the administration of helicid improved the depressive-like behavior. The levels of proteins, including sGC, PKG, cleaved caspase-3, and cGMP, in hippocampus all decreased. NCALD overexpression reversed these decreases and reversed the alleviation of depression-like behaviors in CUMS rats. Limitation. We only detected the antidepressant effects of helicid in the hippocampus; therefore, other parts of brain should also be studied.

Conclusions

Inhibition of NCALD, as well as helicid administration, alleviated antidepressant-like behavior by regulating the expressions of apoptotic cytokines and the sGC/cGMP/PKG signaling pathway. Overexpressing NCALD reversed the amelioration effects of silenced NCALD and helicid administration.

Antidepressant-like effect of Ganoderma lucidum spore polysaccharide-peptide mediated by upregulation of prefrontal cortex brain-derived neurotrophic factor

A 28-kDa polysaccharide-peptide (PGL) with antidepressant-like activities was isolated from spores of the mushroom Ganoderma lucidum. It was unadsorbed on DEAE-cellulose. Its internal amino acid sequences manifested pronounced similarity with proteins from the mushrooms Lentinula edodes and Agaricus bisporus. The monosaccharides present in 28-kDa PGL comprised predominantly of glucose (over 90%) and much fewer galactose, mannose residues, and other residues. PGL manifested antidepressant-like activities as follows. It enhanced viability and DNA content in corticosterone-injured PC12 cells(a cell line derived from a pheochromocytoma of the rat adrenal medulla with an embryonic origin from the neural crest containing a mixture of neuroblastic cells and eosinophilic cells) and reduced LDH release. A single acute PGL treatment shortened the duration of immobility of mice in both tail suspension and forced swimming tests. PGL treatment enhanced sucrose preference and shortened the duration of immobility in mice exposed to chronic unpredictable mild stress (CUMS). Chronic PGL treatment reversed the decline in mouse brain serotonin and norepinephrine levels but did not affect dopamine levels. PGL decreased serum corticosterone levels and increased BDNF mRNA and protein levels and increased synapsin I and PSD95 levels in the prefrontal cortex. This effect was completely blocked by pretreatment with the BDNF antagonist K252a, indicating that PGL increased synaptic proteins in a BDNF-dependent manner.Key points• An antidepressive polysaccharide-peptide PGL was isolated from G. lucidum spores.• PGL protected PC12 nerve cells from the toxicity of corticosterone.• PGL upregulated BDNF expression and influenced key factors in the prefrontal cortex.

Musk (Moschus moschiferus) Attenuates Changes in Main Olfactory Bulb of Depressed Mice: Behavioral, Biochemical, and Histopathological Evidence

BACKGROUND

Musk (Moschus moschiferus) has been described to have a significant impact on the central nervous system, as well as anticonvulsion and antidepressant effects. This study was designed to evaluate the efficacy of musk in alleviating alterations induced in olfactory bulb of depressed mice exposed to chronic stress and identify the mechanism behind it.

METHODS

Fifty male albino mice were divided into five groups (n = 10 each): control, musk, chronic unpredictable mild stress (CUMS), fluoxetine-treated, and musk-treated groups were included in this study. Behavioral changes and serum levels of corticosterone and proinflammatory cytokines included tumor necrosis factor α, interleukin 6, and oxidant/antioxidant profile were assessed at the end of the experiment. Main olfactory bulb (MOB) has been processed for histopathological examination. Gene expression of caspase-3, glial fibrillary acidic protein, and Ki67 were assessed in the MOB using quantitative real-time polymerase chain reaction.

RESULTS

The study showed that musk inhalation significantly reduced (p < 0.001) corticosterone level, immobility time, inflammatory cytokines, and oxidative stress markers in CUMS-exposed mice compared to the untreated CUMS group. Musk lessened CUMS-associated neuronal alterations in the MOB and significantly reduced apoptosis and enhanced neural cell proliferation (p < 0.001) comparable to fluoxetine. Musk significantly enhanced the level of antioxidants in the serum and significantly reduced inflammatory cytokines. The anti-inflammatory and antioxidant activity of musk and its constituents seemed to be behind its neuroprotective effect observed in this study.

CONCLUSION

Musk effectively ameliorated the chronic stress-induced behavioral, biochemical, and neuronal structural changes in MOB mostly through its antioxidant and anti-inflammatory effect.

Antidepressant-like effects of helicid on a chronic unpredictable mild stress-induced depression rat model: Inhibiting the IKK/IκBα/NF-κB pathway through NCALD to reduce inflammation

We previously reported that helicid, an active plant monomer of Helicid nilgirica Bedd, had good antidepressant pharmacological activities. However, the potential mechanism of action remains unknown. Current investigation showed the antidepressant-like effects of helicid and its effects on the neurocalcin delta (NCALD) gene, and its mechanism of action through a depression model in rats exposed to chronic unpredictable mild stress (CUMS). We evaluated depression symptoms using the sucrose preference test (SPT), open field test (OFT), and forced swimming test (FST). By silencing NCALD and using rescue experiments, the IL-6, iNOS, IL-1β, COX-2, and TNF-α levels in the hippocampus or peripheral blood were determined using western blotting and ELISAs. The expression of IKKβ, p-IкBα, p-IKKβ, NF-кB p65, and IкBα were tested using western blots of the cytoplasmic or nuclear samples. Helicid and silencing NCALD relieved the CUMS-irritated depressive-like actions of rats, which were shown by increased consumption of sucrose, numbers of rearings, total running distance, zone crossings, and reduced immobility times. Helicid or silencing NCALD reversed the CUMS-induced high levels of IL-1β, COX-2, IL-6, TNF-α, and iNOS in the hippocampus or peripheral blood. Helicid or silencing NCALD also reduced the expressions of p-IκBα and p-IKKβ in the cytoplasm and the expression of nuclear NF-κB p 65 in hippocampus, and simultaneously elevated cytoplasmic expressions of IκBα, IKKβ, and NF-κB p65 in the hippocampus. Notably, after NCALD overexpression, the biochemical indices of rat helicid administration were reversed. In conclusion, the antidepressant action of helicid was mediated through NCALD in rats of CUMS by repressing hippocampal neuro-inflammation and abating the activation of the IKK/IκBα/NF-κB pathway.

Chronic Inhibition of FAAH Reduces Depressive-Like Behavior and Improves Dentate Gyrus Proliferation after Chronic Unpredictable Stress Exposure

Symptoms of depressive disorders such as anhedonia and despair can be a product of an aberrant adaptation to stress conditions. Chronic unpredictable stress model (CUS) can generate an increase in the activity of the hypothalamic-pituitary-adrenal axis (HPA) and induce a reduction of neurotrophin signaling and the proliferation of neural progenitors in the adult dentate gyrus, together with increased oxidative stress. Levels of the endocannabinoid anandamide (AEA) seem to affect these depression-by-stress-related features and could be modulated by fatty acid amide hydrolase (FAAH). We aimed to evaluate the effects of FAAH inhibitor, URB597, on depressive-like behavior and neural proliferation of mice subjected to a model of CUS. URB597 was administered intraperitoneally at a dose of 0.2 mg/kg for 14 days after CUS. Depressive-like behaviors, anhedonia, and despair were evaluated in the splash and forced swimming tests, respectively. Alterations at the HPA axis level were analyzed using the relative weight of adrenal glands and serum corticosterone levels. Oxidative stress and brain-derived neurotrophic factor (BDNF) were also evaluated. Fluorescence immunohistochemistry tests were performed for the immunoreactivity of BrdU and Sox2 colabeling for comparison of neural precursors. The administration of URB597 was able to reverse the depressive-like behavior generated in mice after the model. Likewise, other physiological responses associated with CUS were reduced in the treated group, among them, increase in the relative weight of the adrenal glands, increased oxidative stress, and decreased BDNF and number of neural precursors. Most of these auspicious responses to enzyme inhibitor administration were blocked by employing a cannabinoid receptor antagonist. In conclusion, the chronic inhibition of FAAH generated an antidepressant effect, promoting neural progenitor proliferation and BDNF expression, while reducing adrenal gland weight and oxidative stress in mice under the CUS model.

Gastrodiae Rhizoma Water Extract Ameliorates Hypothalamic-Pituitary-Adrenal Axis Hyperactivity and Inflammation Induced by Chronic Unpredictable Mild Stress in Rats

Gastrodiae Rhizoma is a highly valuable traditional herbal medicine commonly used to treat neurological disorders. The present study is designed to determine the antidepressant-like effect of the Gastrodiae Rhizoma water extract (GRWE) on a depression model and the potential mechanisms. The chronic unpredictable mild stress (CUMS) rat model was used to induce depression. The sucrose preference test, open field test, forced swimming test, and tail suspension test were performed to assess the depressive-like behaviors, respectively. Hypothalamic-pituitary-adrenal (HPA) function was measured via plasma corticosterone (CORT), adrenocorticotrophic hormone (ACTH), hypothalamic corticotropin-releasing factor (CRF), and glucocorticoid receptor (GR) concentrations. Plasma concentrations of proinflammatory cytokines including interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) were also evaluated. The results showed that GRWE significantly attenuates the behavioral abnormalities in CUMS rats, as shown by elevated sucrose consumption, raised locomotor activity, and reduced immobility duration. Moreover, GRWE treatment reduced CORT, ACTH, CRF, and GR levels and decreased the plasma IL-1β, IL-6, and TNF-α concentrations. These findings indicate that GRWE improves depressive behaviors in a chronic stress model of rats; its effect may be ascribed to the modulation of the HPA axis activity and inflammatory response.

Effect of chronic unpredictable mild stress on the expression profile of serotonin receptors in rats and mice: a meta-analysis

Chronic-stress-induced depression is recognized as a widespread public health concern. Selective serotonin reuptake inhibitors (SSRIs) have been the most common treatment for this illness. However, the role of 5-hydroxytryptamine (5-HT) receptor subtypes in stress-induced depression remains unclear. Evidence from Animal studies has reported a variety of results regarding the effects of chronic unpredictable mild stress (CUMS) on serotonin signaling pathways and 5-HT receptor subtypes. This divergence may rely on differences in protocols, methods, and studied pathways. Thus, the aim of this systematic review was to weigh the currently available findings regarding serotonin receptor changes in animal models of CUMS. Overall, our meta-analysis results showed the association of altered expression of 5-HT_1A receptors in the frontal cortex and 5-HT_2A receptors both in the whole cortex and the hypothalamus of rats following CUMS. Moreover, by using a qualitative-structured analysis and the application of risk-of-bias tools, we identified possible sources of data variation between the studied literature, which should be taken into account in future animal studies of chronic-stress induced depression.

Glucocorticoids in the Physiological and Transcriptional Regulation of 5-HT1A Receptor and the Pathogenesis of Depression

There is growing increase in the global prevalence of depression, but treatment outcome of this highly disabling disease is not satisfactory. Many patients are not benefitted by the currently prescribed antidepressants-together with this partial remission is very common. Improving treatment strategies and developing better therapeutic agents for treating depression is therefore highly needed. Stress-related epigenetic changes play a critical role in the pathogenesis as well as treatment of depression. Stressful events activate hypothalamic-pituitary-adrenal axis to increase circulating levels of glucocorticoids (GCs), and a greater sensitivity to this fright and flight response increases risk of depression. A role of serotonin (5-hydroxytryptamine; 5-HT) in responses to stress and in the pathogenesis and treatment of depression is well established. Substantial evidence supports a critical role of 5-HT1A receptors in these effects of 5-HT. The present article targets stress-induced higher and sustained increases of GCs and mediated influences on the physiological as well transcriptional regulation of 5-HT1A receptors to evaluate their causal role in the pathogenesis of depression. It is suggested that synthetic compounds with antagonist activity for GC receptors and agonist activity for 5-HT1A receptors may prove better therapeutic agents for treating depression.

Helicid Reverses Lipopolysaccharide-Induced Inflammation and Promotes GDNF Levels in C6 Glioma Cells through Modulation of Prepronociceptin

Helicid suppresses inflammatory factors and protects nerve cells in the hippocampus of rats with depression, but the mechanisms underlying its protective effects are unclear at present. In this investigation, we conducted gene silencing, Helicid intervention and rescue experiments to explore the protective actions of PNOC, the prepronociceptin gene known to regulate inflammatory processes, and Helicid on a C6 cell model of inflammation induced by LPS. Collective data from Western blots, ELISA, immunofluorescence and flow cytometry experiments showed that PNOC silencing or administration of Helicid led to reduced inflammatory factor levels, oxidative stress and expression of glial fibrillary acidic protein (GFAP), along with increased glial cell lines-derived neurotrophic factor (GDNF) expression. Furthermore, expression of p-Akt in the Akt signaling pathway was increased. Interestingly, overexpression of PNOC in the Helicid treatment group partially reversed the Helicid-induced changes in the above biochemical indexes. Our collective results provide strong evidence of Helicid-mediated regulation of the Akt signaling pathway through PNOC to improve cell inflammation and oxidative stress.

Optimization of food deprivation and sucrose preference test in SD rat model undergoing chronic unpredictable mild stress

BACKGROUND

The chronic unpredictable mild stress (CUMS) model has long been considered the best model for exploring the pathophysiological mechanisms underlying depression. However, there are no widely recognised standards for strategies for modeling and for behavioral testing. The present study aimed to optimize the protocols for food deprivation and the sucrose preference test (SPT) for the CUMS model.

METHODS

We first evaluated the effects of different long periods of food deprivation on the body weight of Sprague Dawley (SD) rats by testing food deprivation for 24 hours (8:00-8:00+), food deprivation for 12 hours during the daytime (8:00-20:00) and food deprivation for 12 hours at night (20:00-8:00+). Next, we established a SD rat CUMS model with 15 different stimulations, and used body weight measurement, SPT, forced swim test (FST), open field test (OFT) and Morris water maze (MWM) test to verify the success of the modeling. In the SPT, consumption of sucrose and pure water within 1 and 12 hours was measured.

RESULTS

Twelve hours of food deprivation during the daytime (8:00-20:00) had no effect on body weight, while 12 hours of food deprivation at night (20:00-8:00+) and 24 hours of food deprivation (8:00-8:00+) significantly reduced the mean body weight of the SD rats. When SPT was used to verify the successful establishment of the CUMS rat model, sucrose consumption measured within 12 hours was less variable than that measured within 1 hour.

CONCLUSIONS

Twelve hours of food deprivation in the daytime (8:00-20:00) may be considered a mild stimulus for the establishment of a CUMS rat model. Measuring sucrose consumption over 12 hours is recommended for SPT.

Anti-inflammatory and antioxidative properties of helicid protect against CCl4 induced acute liver injury in mice

Acute liver injury can be caused by chemicals and can lead to liver failure. We investigated the protective effect of helicid (HEL) on acute liver injury caused by CCl₄ in mice. We found that ALT and AST levels as well as hepatic pathological damage in mice treated with CCl₄ was increased significantly, while the effects were decreased by HEL treatment. HEL treatment increased the activity of T-SOD, GSH and CAT and reduced the level of MDA in CCl₄ treated mice. HEL improved the histopathology of liver caused by CCl₄. HEL also reduced TNF-α, IL-1β and IL- 6 activity caused by CCl₄. We investigated the phosphorylation of p65 and IκB protein and found that HEL can alleviate liver damage via the NF-κB signaling pathway. Our findings indicate that HEL protects against acute liver injury induced by CCl₄. The protective effect of HEL appears to be due to its antioxidative and anti-inflammatory properties through the NF-κB signaling pathway.

Susceptibility to Hyperglycemia in Rats With Stress-Induced Depressive-Like Behavior: Involvement of IL-6 Mediated Glucose Homeostasis Signaling

Depression is a common psychiatric disorder comorbid with diabetes and may lead to high morbidity, disability, and mortality. However, the underlying mechanism behind their association remains unknown. Cytokine-mediated inflammation in brain may play important roles in the pathogenesis of depression and insulin resistance. In the present study, we subjected the rats to chronic unpredictable mild stress (CUMS) for 3 to 8 weeks. The tests to ascertain depression-like behaviors including open field test (OFT) and forced swimming test (FST) were performed, and levels of morning fasting blood glucose, triglyceride (TG), total cholesterol (CHOL), high density lipoprotein cholesterol (HDL-C), and low density lipoprotein cholesterol (LDL-C), body weight, food intake, histopathological examinations of liver, adipose tissues and hypothalamus, hypothalamic GLUT4 as well as the IL-6-mediated glucose homeostasis signaling pathway were measured. The results showed that CUMS exposure resulted in the depression-like behavior at various time points in rats. Moreover, the rats exhibited increased peripheral glucose levels, impaired hepatocytes and hippocampal neurons, and decreased hypothalamic GLUT4 levels after 6 weeks of CUMS exposure. Meanwhile, activated IL-6 but suppressed IL-6-mediated glucose homeostasis signaling was observed in the hypothalamus. Markers of lipid metabolism including TG, CHOL, HDL-C and LDL-C were dysregulated, and body weight and food intake were decreased in the CUMS-exposed rats. Our results show that depressed rats induced by 6-week CUMS stimulation display susceptibility to hyperglycemia, which is associated with IL-6-mediated inhibition of glucose homeostasis signaling in the hypothalamus.

Ocimum basilicum (Basil) Modulates Apoptosis and Neurogenesis in Olfactory Pulp of Mice Exposed to Chronic Unpredictable Mild Stress

BACKGROUND

Ocimum basilicum (O. basilicum) was described to have antidepressant and anxiolytic activities. Although the relationship between the main olfactory bulb (MOB) and depression was recently reported, the chronic stress-induced dysfunction of the MOB is not clearly described.

OBJECTIVES

This study aimed to assess the efficacy of inhalation of O. basilicum essential oils in improving chronic unpredictable mild stress (CUMS)-induced changes in MOB of mice and understand the mechanism underlying such effect.

MATERIALS AND METHODS

Adult male mice (n=40) were assigned into four groups included the control, CUMS-exposed, CUMS + fluoxetine (FLU), CUMS + O. basilicum. Behavioral changes, serum corticosterone level, and gene expression of GFAP, Ki 67, and caspase-3 were assessed using real-time PCR (RT-PCR). Histopathological and immunochemical examination of the MOB was performed.

RESULTS

FLU and O. basilicum significantly down-regulated (p = 0.002, p<0.001) caspase-3 gene expression indicating reduced apoptosis and up-regulated (p = 0.002, p < 0.001) Ki67 gene expression indicating enhanced neurogenesis in MOB, respectively. FLU and O. basilicum-treated mice markedly improved MOB mitral cell layer distortion and shrinkage induced by CUMS.

CONCLUSION

O. basilicum relieved both biochemically and histopathological chronic stress-induced changes in the main olfactory bulb possibly through up-regulation of gene expression of GFAP and Ki67 and down-regulation of caspase-3 in the MOB.

Effect of Electroacupuncture on Reuptake of Serotonin via miRNA-16 Expression in a Rat Model of Depression

The current study aimed to investigate the effects and mechanisms of electroacupuncture (EA) treatment applied to Bai hui (GV20) and Yin tang (GV29) acupoints (1 mA, 2 Hz, continuous wave, 20 minutes) for 28 days in a rat model of chronic unpredictable mild stress (CUMS) on reuptake of serotonin (5-hydroxytryptamine (5-HT)) and miRNA-16 levels in the hippocampus and serum. Rats were housed in individual cages, and CUMS was used to establish a rat model of depression. After EA treatment for 4 weeks, behavioral changes and indices including 5-HT transporter (SERT), 5-HT, and miRNA-16 levels in the hippocampus and serum were examined. The EA treatment significantly improved base levels of sucrose preference and exploratory behavior and significantly decreased SERT protein and mRNA expression in the hippocampus of depressed rats. Significantly increased 5-HT levels were observed, and miRNA-16 levels were significantly decreased in the hippocampus and serum of depressed rats. In conclusion, the antidepressant effects of EA treatment may be affected via inhibition of 5-HT reuptake, upregulation of 5-HT levels, and inhibition of miRNA-16 expression in the hippocampus and serum.

Excretion, Metabolism and Cytochrome P450 Inhibition of Methyl 3,4-Dihydroxybenzoate (MDHB): A Potential Candidate to Treat Neurodegenerative Diseases

BACKGROUND AND OBJECTIVES

Methyl 3,4-dihydroxybenzoate (MDHB) has the potential to prevent neurodegenerative diseases (NDDs). The present work investigated its excretion, metabolism, and cytochrome P450-based drug-drug interactions (DDIs).

METHODS

After intragastric administration of MDHB, the parent drug was assayed in the urine and faeces of mice. Metabolites of MDHB in the urine, faeces, brain, plasma and liver were detected by liquid chromatography-hybrid quadrupole time-of-flight mass spectrometry (LC-QTOF/MS). A cocktail approach was used to evaluate the inhibition of cytochrome P450 isoforms by MDHB.

RESULTS

The cumulative excretion permille of MDHB in the urine and faeces were found to be 0.67 ± 0.31 and 0.49 ± 0.44‰, respectively. A total of 96 metabolites of MDHB were identified, and all IC₅₀ (half-maximal inhibitory concentration) values of MDHB towards cytochrome P450 isoforms were > 100 μM.

CONCLUSIONS

The results suggest that MDHB has a low parent drug cumulative excretion percentage and that MDHB has multiple metabolites and is mainly metabolized through the loss of -CH₂ and -CO₂, the loss of -CH₂O, ester bond hydrolysis, the loss of -O and -CO₂, isomerization, methylation, sulfate conjugation, the loss of -CH₂O and -O and glycine conjugation, glycine conjugation, the loss of two -O groups and alanine conjugation, the loss of -CH₂O and -O and glucose conjugation, glucuronidation, glucose conjugation, etc., in vivo. Finally, MDHB has a low probability of cytochrome P450-based DDIs.

Antidepressant-like effects of the Guanxin Danshen formula via mediation of the CaMK II-CREB-BDNF signalling pathway in chronic unpredictable mild stress-induced depressive rats

Background

Depression is a chronic and recurrent syndrome of mood disorder causing immense social and economic burden; thus, treatment should be improved. Guanxin Danshen formula (GXDSF), a natural botanical drug composition prescription, has significant cardiovascular protective effects and is widely used in the clinical treatment of myocardial ischaemic diseases. However, it is still unclear and seldom studied whether GXDSF has neuroprotective effects against depressive disorders. This study explored whether GXDSF has antidepressant-like effects in rats exposed to chronic unpredictable mild stress (CUMS) and analysed the possible underlying neurotrophic expression and psychotropic mechanisms.

Methods

The present study was designed to investigate the antidepressant effects of GXDSF treatment in a CUMS-induced rat model. Based on the clinical doses, the drug-treated group was intragastrically administered GXDSF for 30 days, and rats were simultaneously exposed to CUMS stimulation for 30 days. After induction and drug administration, the depression-like behaviours were determined via the sucrose preference test (SPT), the open field test (OFT), the tail suspension test (TST), and the forced swim test (FST). ELISA kits were used to examine the monoaminergic neurotransmitters, monoamine oxidase (MAO) and Ca²⁺ levels in the hippocampus. Moreover, we measured and analysed the brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) levels and the upstream regulation and signal pathways of BDNF and NGF to explore their related mechanisms in this animal model of depression, including calcium-calmodulin dependent protein kinase-II (CaMKII) and cAMP response element-binding (CREB).

Results

The results revealed that GXDSF may possess significant antidepressant-like effects via improving body weight, raising the sucrose preference in the SPT, increasing the total distance, the number of upright stands, and the residence time of the central zone in the open field test (OPF) and reducing the immobility time in the TST and FST. In addition, GXDSF significantly upregulated the relative levels of neurotransmitters, including dopamine (DA), norepinephrine (NE), and serotonin (5-HT), in a dose-dependent manner and inhibited MAO activities in the hippocampus. Moreover, GXDSF reversed the decline in intracellular CREB and p-CREB expression induced by CUMS, downregulated the phosphorylation levels of intracellular CaMKII and its two subunits CaMKIIα and CaMKIIβ in the hippocampus, and thus, clearly upregulated the downstream effector protein expression levels of BDNF, NGF, and synitaxine-1 in the hippocampus. These data suggest that the antidepressant effects of GXDSF have a potential relationship with regulating changes in the CaMKII-CREB-BDNF pathway.

Conclusions

Despite several limitations of this study, the results have suggested that GXDSF administration possesses antidepressant-like effects in CUMS-treated rats and provide the first in vivo demonstration of a possible mechanism of GXDSF via regulating changes in the CaMKII-CREB-BDNF signalling pathway. These findings provide a novel potential substrate by which herbal antidepressants may exert therapeutic effects in the treatment of depression.

Evaluation of biomarkers of stress in chronic stress-exposed comorbid depression model Wistar rats

Background In recent years, increased stress in human life has a dual effect on brain and body physiology. Chronic stress takes a toll on physiology as well as on quality of life, ultimately leading to affective disorders. Rodent models are indispensable tools for studying the etiology and progress of depression. C-reactive protein has been proposed as a novel inflammatory marker. Methods Rats were divided into control and experimental stress groups (n = 6 each). The experimental group consisted of rats that were exposed to a set of chronic unpredictable stressors for 15 days. At the end of the 15th day, the animals were anesthetized, and blood samples were collected through cardiac puncture. Then the blood samples were analyzed for selected biochemical and oxidative stress parameters. Results Serum glutamic oxaloacetic transaminase (p < 0.0001), serum glutamic pyruvic transaminase (p < 0.001), serum malondialdehyde (p < 0.0001), total antioxidant level (p < 0.0001), and serum cortisol (p < 0.0001) were significantly increased in the stressed group when compared with the control group. C-reactive protein significantly (p < 0.0001) increased in the stressed group when compared with the control group. Conclusion Our results demonstrate that chronic unpredictable stress ameliorated depression-like behavior, which might have caused the dysregulation of the hypothalamic-pituitary-adrenal axis, causing the imbalance in the biochemical and oxidative parameters increasing the inflammatory markers. The inflammation-induced model of the chronic unpredictable stress model of comorbid depression might provide a variety of new targets for antidepressant therapies.

Helicid Ameliorates Learning and Cognitive Ability and Activities cAMP/PKA/CREB Signaling in Chronic Unpredictable Mild Stress Rats

Helicid (4-formylphenyl-O-β-D-allopyranoside), an active component found in seeds from the Chinese herb Helicia nilagirica, has been reported to exert sedative, analgesic, hypnotic and antidepressant effects. The present study was designed to evaluate the antidepressant, learning and cognitive improvement effects of helicid in a chronic unpredictable mild stress (CUMS) model of depression in rats and to explore cAMP/protein kinase A (PKA)/cAMP response element-binding (CREB) signaling pathway. Sprague-Dawley rats were randomly assigned to six groups (n = 10): control; CUMS; CUMS + fluoxetine (5 mg/kg) and CUMS + helicid at 8, 16 and 32 mg/kg. All rats were subjected to 12 weeks of CUMS protocols and drug administration during the last 6 weeks of CUMS. Our results showed that helicid, at a dose of 32 mg/kg, significantly reversed decreases in body weight and sucrose consumption, increased the distance and number of crossings in the open-field test (OFT), reduced immobility times in the forced swimming test (FST) and improved spatial memory in the Morris water maze (MWM); all of these effects had been induced by CUMS paradigm. Immunohistochemistry showed that administration of helicid could promoted the proliferation of neurons in the hippocampal CA1 and dentate gyrus (DG) regions. CUMS rats treated with helicid had dramatically decreased protein levels of serotonin transporters (SERTs). In addition, CUMS resulted in a significant reduction in the expression of cAMP, PKA C-α and p-CREB, each of which were partially attenuated by helicid administration. These results indicated that helicid could improve depressive behaviors, learning and cognitive deficits and increase hippocampal neurogenesis, which may be mediated by the regulation of SERTs, activation of the cAMP/PKA/CREB signaling pathway and upregulation of p-CREB levels in hippocampal.