Seahorse treatment improves depression-like behavior in mice exposed to CUMS through reducing inflammation/oxidants and restoring neurotransmitter and neurotrophin function

The chronic unpredictable mild stress (CUMS) Paradigm: Bridging the gap in depression research from bench to bedside

Depression is a complicated neuropsychiatric condition with an incompletely understoodetiology, making the discovery of effective therapies challenging. Animal models have been crucial in improving our understanding of depression and enabling antidepressant medication development. The CUMS model has significant face validity since it induces fundamental depression symptoms in humans, such as anhedonia, behavioral despair, anxiety, cognitive impairments, and changes in sleep, food, and social behavior. Its construct validity is demonstrated by the dysregulation of neurobiological systems involved in depression, including monoaminergic neurotransmission, the hypothalamic-pituitary-adrenal axis, neuroinflammatory processes, and structural brain alterations. Critically, the model's predictive validity is demonstrated by the reversal of CUMS-induced deficits following treatment with clinically effective antidepressants such as selective serotonin reuptake inhibitors, serotonin-norepinephrine reuptake inhibitors, tricyclic antidepressants, and monoamine oxidase inhibitors. This review comprehensivelyassesses the multifarious depressive-like phenotypes in the CUMS model using behavioral paradigms like sucrose preference, forced swim, tail suspension, elevated plus maze, and novel object recognition tests. It investigates the neurobiological mechanisms that underlie CUMS-induced behaviors, including signaling pathways involving tumor necrosis factor-alpha, brain-derived neurotrophic factor and its receptor TrkB, cyclooxygenase-2, glycogen synthase kinase-3 beta, and the kynurenine pathway. This review emphasizes the CUMS model's importance as a translationally relevant tool for unraveling the complex mechanisms underlying depression and facilitating the development of improved and targeted interventions for this debilitating neuropsychiatric disorder by providing a comprehensive overview of its validity, behavioral assessments, and neurobiological underpinnings.

Understanding the Antidepressant Mechanisms of Acupuncture: Targeting Hippocampal Neuroinflammation, Oxidative Stress, Neuroplasticity, and Apoptosis in CUMS Rats

Depression is recognized globally as one of the most intractable diseases, and its complexity and diversity make treatment extremely challenging. Acupuncture has demonstrated beneficial effects in various psychiatric disorders. However, the underlying mechanisms of acupuncture's antidepressant action, particularly in depression, remain elusive. Therefore, this study aimed to investigate the effects of acupuncture on chronic unpredictability stress (CUMS)-induced depressive symptoms in rats and to further elucidate its underlying molecular mechanisms. All rats were exposed to CUMS of two stressors every day for 28 days, except for the control group. One hour before CUMS, rats were given a treatment with acupuncture, electroacupuncture, sham-acupuncture, or fluoxetine (2.1 mg/kg). Behavioral tests and biological detection methods were conducted in sequence to evaluate depression-like phenotype in rats. The findings of this study demonstrate that acupuncture therapy effectively ameliorated depression-like behavior induced by CUMS in rats. Additionally, acupuncture exerted a restorative effect on the alterations induced by CUMS in the levels of malondialdehyde (MDA), catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), interleukin-1β (IL-1β), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), brain-derived neurotrophic factor (BDNF), cyclic AMP response element-binding protein (CREB), postsynaptic density95 (PSD95), gamma-aminobutyric acid (GABA), and acetylcholine (ACh). Additionally, our findings indicate that acupuncture also modulates the ERK and Caspase-3 apoptotic pathways in the hippocampus of CUMS rats. This study suggests that acupuncture may play a potential preventive role by regulating hippocampal neuroinflammatory response, levels of oxidative stress, apoptotic processes, and enhancing synaptic plasticity.

Anti-Photoaging Effects of Antioxidant Peptide from Seahorse (Hippocampus abdominalis) in In Vivo and In Vitro Models

Overexposure to ultraviolet (UV) radiation can lead to photoaging, which contributes to skin damage. The objective of this study was to evaluate the effects of an antioxidant peptide (SHP2) purified from seahorse (Hippocampus abdominalis) alcalase hydrolysate on UVB-irradiated skin damage in human keratinocyte (HaCaT) and human dermal fibroblast (HDF) cells and a zebrafish model. The data revealed that SHP2 significantly enhanced cell viability by attenuating apoptosis through the reduction of intracellular reactive oxygen species (ROS) levels in UVB-stimulated HaCaT cells. Moreover, SHP2 effectively inhibited ROS, improved collagen synthesis, and suppressed the secretion of matrix metalloproteinases (MMPs) in UVB-irradiated HDF cells. SHP2 restored the protein levels of HO-1, Nrf2, and SOD, while decreasing Keap1 expression in UVB-treated HDF, indicating stimulation of the Keap1/Nrf2/HO-1 signaling pathway. Furthermore, an in vivo study conducted in zebrafish confirmed that SHP2 inhibited photoaging by reducing cell death through the suppression of ROS generation and lipid peroxidation. Particularly, 200 µg/mL of SHP2 exerted a remarkable anti-photoaging effect on both in vitro and in vivo models. These results demonstrate that SHP2 possesses antioxidant properties and regulates skin photoaging activities, suggesting that SHP2 may have the potential for use in the development of cosmetic products.

Effects of adjunctive esketamine on depression in elderly patients undergoing hip fracture surgery: a randomized controlled trial

BACKGROUND

Depression is a prevalent perioperative psychiatric complication among elderly hip fracture patients. Esketamine has rapid and robust antidepressant effects. However, it is unknown whether it can alleviate depressive symptoms in elderly patients who undergo hip fracture surgery. This study aimed to explore whether the adjunctive esketamine in patient-controlled intravenous analgesia (PCIA) could improve depressive symptoms in elderly patients undergoing hip fracture surgery.

METHODS

A single-center, prospective, double-blind and randomized controlled clinical trial was carried out from July 2022 to August 2023 at the Wenzhou People's Hospital among 90 patients, aged ≥ 65 years with hip fracture undergoing elective surgery. Participants were randomly allocated to either the esketamine group (group S) or the control group (group C). In Group S, patients were administered 0.5 mg/kg of esketamine as a PCIA adjuvant for 48 h, while the control group received saline. The primary outcome was the assessment of depressive symptoms using the Geriatric Depression Scale-15 (GDS-15) on postoperative day 2. The secondary outcomes were assessments of depressive symptoms on postoperative day 7 and postoperative day 30, serum levels of brain-derived neurotrophic factor (BDNF) and 5-hydroxytryptamine (5-HT), postoperative pain intensity, the number of effective PCIA presses, sufentanil consumption, and adverse events.

RESULTS

The prevalence and GDS-15 scores of depression were significantly lower in group S on postoperative day 2 (28.6% vs. 53.5%; 3.5 ± 1.8 vs. 4.3 ± 1.7, P < 0.05). In group S, the number of effective PCIA presses was significantly lower on postoperative day 2 than that in group C [2(1-4) vs. 1(0-2), P<0.05]. Higher levels of BDNF (23.8 ± 1.7 ng/mL vs. 25.3 ± 2.0 ng/mL, P < 0.05) and 5-HT (219.5 ± 19.5 ng/mL vs. 217.0 ± 22.2 ng/mL, P < 0.05) in the blood were observed on postoperative day 2 in group S.

CONCLUSION

In elderly patients aged ≥ 65 years undergoing hip fracture surgery, the administration of adjunctive esketamine in PCIA could improve depressive symptoms and increase levels of BDNF and 5-HT in the blood.

TRIAL REGISTRATION

Chinese Clinical Trial Registry, ChiCTR2200061956 (Date: 13/07/2022).

Electroconvulsive therapy combined with esketamine improved depression through PI3K/AKT/GLT-1 pathway

Neuron excitotoxic damage induced by extracellular glutamate accumulation pathologically is one of the main mechanisms of depression. Glutamate transporter-1 (GLT-1) expressed in astrocyte is responsible for glutamate clearance to maintain glutamate balance. Electroconvulsive therapy (ECT) is prevalently recommended for severe depression due to its significant anti-depressant effect. Esketamine could offer advantages of rapid anti-depressant effect and neuron protection. The aim of this study is to investigate the anti-depressant efficacy of esketamine plus ECT, and further to explore the mechanism. Firstly, total 12 patients were randomized into anesthesia with propofol (P) or propofol+esketamine (PK) before ECT. 24-Hamilton Depression Scale (HAMD) was used to evaluate the severity of depression after each ECT. Then, depressive rat model was built using chronic unpredictable mild stress method, and subsequently received infusion of esketamine (5 mg/kg) or saline before ECT treatment (0.5 mA; 100 V) for consecutive 10 days. Tests including sucrose preference test, open field test and forced swimming test were used to evaluate depression-like behaviors. In next experiments, rats were injected with RIL, DHK or LY294002 intracerebroventricularly for continuous 10 days before individual treatment. After the fifth and sixth ECT, PK group displayed lower HAMD score compared to P group. In rat model, we found that esketamine plus ECT could significantly improve depression-like behaviors and decrease glutamate level. Esketamine and ECT could both activate PI3K/Akt/GLT-1 pathway. The GLT-1 agonist RIL made equivalent effect as esketamine plus ECT. Furthermore, after using PI3K/Akt inhibitor LY294002 and GLT-1 inhibitor DHK, esketamine plus ECT could neither improve depression-like symptoms, nor upregulate GLT-1 level. Our present study suggested that esketamine plus ECT could dramatically improve depression symptom. The activation of PI3K/Akt/GLT-1 pathway may be the potential mechanism.

Antidepressant-like effect of riparin I and riparin II against CUMS-induced neuroinflammation via astrocytes and microglia modulation in mice

Depression is a common mood disorder and many patients do not respond to conventional pharmacotherapy or experience a variety of adverse effects. This work proposed that riparin I (RIP I) and riparin II (RIP II) present neuroprotective effects through modulation of astrocytes and microglia, resulting in the reversal of depressive-like behaviors. To verify our hypothesis and clarify the pathways underlying the effect of RIP I and RIP II on neuroinflammation, we used the chronic unpredictable mild stress (CUMS) depression model in mice. Male Swiss mice were exposed to stressors for 28 days. From 15 th to the 22 nd day, the animals received RIP I or RIP II (50 mg/kg) or fluoxetine (FLU, 10 mg/kg) or vehicle, by gavage. On the 29 th day, behavioral tests were performed. Expressions of microglia (ionized calcium-binding adaptor molecule-1 - Iba-1) and astrocyte (glial fibrillary acidic protein - GFAP) markers and levels of cytokines tumor necrosis factor alfa (TNF-α) and interleukin 1 beta (IL-1β) were measured in the hippocampus. CUMS induced depressive-like behaviors and cognitive impairment, high TNF-α and IL-1β levels, decreased GFAP, and increased Iba-1 expressions. RIP I and RIP II reversed these alterations. These results contribute to the understanding the mechanisms underlying the antidepressant effect of RIP I and RIP II, which may be related to neuroinflammatory suppression.

Histone 3 Trimethylation Patterns are Associated with Resilience or Stress Susceptibility in a Rat Model of Major Depression Disorder

Major Depressive Disorder (MDD) is a severe and multifactorial psychiatric condition. Evidence has shown that environmental factors, such as stress, significantly explain MDD pathophysiology. Studies have hypothesized that changes in histone methylation patterns are involved in impaired glutamatergic signaling. Based on this scenario, this study aims to investigate histone 3 involvement in depression susceptibility or resilience in MDD pathophysiology by investigating cellular and molecular parameters related to i) glutamatergic neurotransmission, ii) astrocytic functioning, and iii) neurogenesis. For this, we subjected male Wistar rats to the Chronic Unpredictable Mild Stress (CUMS) model of depression. We propose that by evaluating the sucrose consumption, open field, and object recognition test performance from animals submitted to CUMS, it is possible to predict with high specificity rats with susceptibility to depressive-like phenotype and resilient to the depressive-like phenotype. We also demonstrated, for the first time, that patterns of H3K4me3, H3K9me3, H3K27me3, and H3K36me3 trimethylation are strictly associated with the resilient or susceptible to depressive-like phenotype in a brain-region-specific manner. Additionally, susceptible animals have reduced DCx and GFAP and resilient animals present increase of AQP-4 immunoreactivity. Together, these results provide evidence that H3 trimethylations are related to the development of the resilient or susceptible to depressive-like phenotype, contributing to further advances in the pathophysiology of MDD and the discovery of mechanisms behind resilience.

Knocking out Selenium Binding Protein 1 Induces Depressive-Like Behavior in Mice

Selenium binding protein 1 (SELENBP1) is involved in neurologic disorders, such as multiple sclerosis, spinal cord injury, Parkinson's disease, epilepsy, and schizophrenia. However, the role of SELENBP1 in the neurogenesis of depression, which is a neurologic disorder, and the underlying mechanisms of oxidative stress and inflammation in depression remain unknown. In this study, we evaluated the changes in the expression levels of SELENBP1 in the hippocampus of a mouse model of depression and in the serum of human patients with depression using the Gene Expression Omnibus database. These changes were validated using blood samples from human patients with depression and mouse models with chronic unpredictable mild stress (CUMS)-induced depressive-like behavior. We also investigated the effects of SELENBP1 knockout (KO) on inflammation, oxidative stress, and hippocampal neurogenesis in mice with CUMS-induced depression. Our results revealed that SELENBP1 levels was decreased in the blood of human patients with depression and in the hippocampus of mice with CUMS-induced depression. SELENBP1 KO increased CUMS-induced depressive behavior in mice and caused dysregulation of inflammatory cytokines and oxidative stress. This led to a decrease in the numbers of doublecortin- and Ki67-positive cells, which might aggravate CUMS-induced depressive symptoms. These findings suggest that SELENBP1 might be involved in the regulation of neurogenesis in mice with depression and could be served as a potential target for diagnosing and treating depression.

Involvement of PI3K/AKT Pathway in the Rapid Antidepressant Effects of Crocetin in Mice with Depression-Like Phenotypes

The current first-line antidepressants have the drawback of slow onset, which greatly affects the treatment of depression. Crocetin, one of the main active ingredients in saffron (Crocus sativus L.), has been demonstrated to have antidepressant activities, but whether it has a rapid antidepressant effect remains unclear. This study aimed to investigate the onset, duration, and mechanisms of the rapid antidepressant activity of crocetin (20, 40 and 80 mg/kg, intraperitoneal injection) in male mice subjected to chronic restraint stress (CRS). The results of behavioral tests showed that crocetin exerted rapid antidepressant-like effect in mice with depression-like phenotypes, including rapid normalization of depressive-like behaviors within 3 h, and the effects could be maintained for 2 days. Hematoxylin-eosin (HE) and Nissl staining showed that crocetin ameliorated hippocampal neuroinflammation and nerve injuries in mice with depression-like phenotypes. The levels of inflammatory factors, corticosterone and pro brain-derived neurotrophic factor in crocetin-administrated mice serum were significantly reduced compared with those in the CRS group, as well as the levels of inflammatory factors in hippocampus. What's more, Western blot analyses showed that, compared to CRS-induced mice, the relative levels of mitogen-activated kinase phosphatase 1 and toll-like receptor 4 were significantly reduced after the administration of crocetin, and the relative expressions of extracellular signal-regulated kinase 1/2 (ERK1/2), cAMP-response element binding protein, phosphorylated phosphoinositide 3 kinase (p-PI3K)/PI3K, phosphorylated protein kinase B (p-AKT)/AKT, phosphorylated glycogen synthase kinase 3β (p-GSK3β)/GSK3β, phosphorylated mammalian target of rapamycin (p-mTOR)/mTOR were markedly upregulated. In conclusion, crocetin exerted rapid antidepressant effects via suppressing the expression of inflammatory cytokines and the apoptosis of neuronal cells through PI3K/AKT signaling pathways. The rapid antidepressant effect of crocetin (40 mg/kg) could be maintained for at least 2 days after single treatment.

Repetitive transcranial magnetic stimulation and fluoxetine attenuate astroglial activation and benefit behaviours in a chronic unpredictable mild stress mouse model of depression

Objectives: Repetitive transcranial magnetic stimulation (rTMS) has been considered as an effective antidepressant treatment; however, the mechanism of its antidepressant effect is still unclear. Fluoxetine, a selective serotonin reuptake inhibitor antidepressant, may be neuroprotective. The objective of the present study was to evaluate the effect and underlying possible neuroprotective mechanism of rTMS and fluoxetine on abnormal behaviours in a depressive mouse model induced by chronic unpredictable mild stress (CUMS).Methods: After 28 days of CUMS exposure, mice were chronically treated with rTMS (10 Hz for 5 s per train, total 20 trains per day) and (or) fluoxetine (5 mg/kg/day, intraperitoneally) for 28 days targeting on the frontal cortex. After the behavioural tests, the protein expressions of glial fibrillary acidic protein (GFAP), brain-derived neurotrophic factor (BDNF) and tyrosine kinase B (TrkB) were measured by immunohistochemistry and (or) Western Blot.Results: The results showed rTMS and (or) fluoxetine attenuated the locomotion decrease, anxiety and depressive like behaviours in the CUMS-exposed mice.Conclusion: Our results suggest that both rTMS and fluoxetine could benefit the CUMS-induced abnormal behaviours including depressive-like behaviours, and the beneficial effects of rTMS as well as fluoxetine on depression might be partly related to their neuroprotective effect on attenuating astroglial activation and BDNF decrease.

Role of BDNF-TrkB signaling in the antidepressant-like actions of loganin, the main active compound of Corni Fructus

AIMS

Corni Fructus (CF) and some CF-contained prescriptions are commonly used in clinical treatment of depression. This investigation aims to evaluate the main active compound of CF in antidepressant properties and its key target.

METHODS

Firstly, this study established a behavioral despair model and used high-performance liquid chromatography method to evaluate the antidepressant-like effects of water extract, 20%, 50%, and 80% ethanol extracts of CF, and its main active compound. Then, this study created chronic unpredictable mild stress (CUMS) model to assess loganin's antidepressant-like properties, and its target was evaluated by quantitative real-time polymerase chain reaction, Western blot, Immunofluorescence, enzyme-linked immunosorbent assay, and tyrosine receptor kinase B (TrkB) inhibitor.

RESULTS

Results showed that the different extracts of CF significantly shortened the immobility time in forced swimming and tail suspension tests. Moreover, loganin alleviated CUMS-induced depression-like behavior, promoted neurotrophy and neurogenesis, and inhibited neuroinflammation. Furthermore, K252a blocked the improvement of loganin on depression-like behavior, and eliminated the enhancement of neurotrophy and neurogenesis and the inhibition of neuroinflammation.

CONCLUSION

Overall, these results indicated that loganin could be used as a major active compound of CF for the antidepressant-like properties and exerted antidepressant-like actions by regulating brain derived neurotrophic factor (BDNF)-TrkB signaling, and TrkB could be used as key target for itsantidepressant-like actions.

Effects of aerobic exercise on depression-like behavior and TLR4/NLRP3 pathway in hippocampus CA1 region of CUMS-depressed mice

BACKGROUND AND PURPOSE

The paper observes regulation of the expression levels of NLRP3 and TLR4 in hippocampal CA1 neurons in CUMS mice by aerobic exercise with constructing CUMS depression mouse model, in order to explore the neuroprotective mechanism of aerobic exercise on the hippocampus of depressed mice.

STUDY DESIGN AND METHOD

24 healthy male 8-week-old C57BL/6 mice were randomly divided into CG, MG and ME. Thirteen stress-stimulating factors were randomly formulated into a CUMS stress-stimulating program. The mice were underwent 28 days of CUMS depression model, referenced clinical means for experimental research. The study was approved by the Ethics Committee of Yichun University (YCUEC IRB number LSK NO.2022.18). After model preparation, ME mice were subjected to moderate-intensity treadmill exercise training for 8 weeks. TST, FST and SPT were used to detect the depression-like behaviors of the mice in each group. Nissl staining was used to compare the cell morphology in the CA1 region of the mouse hippocampus. Immunohistochemical staining and western blot were used to detect the changes in the expression levels of NLRP3, TLR4 and other proteins in the CA1 region of the mouse hippocampus.

RESULTS

The results of neurobehavioral assessment showed that, the immobility time of TST and FST were significantly increased, and SPT index was significantly decreased of MG mice. Compared with MG, ME mice significantly improved depression-like behaviors such as TST, FST and SPT index. Nissl staining showed that the morphology of neurons in CA1 region of hippocampus of MG mice were mostly vacuolar-like, with severe nuclear pyknosis. Abnormal morphological changes such as vacuolar-like and pyknotic pyknosis of neurons in the hippocampal CA1 region of ME mice were significantly reduced. Protein expression test showed that the number of NLRP3, TLR4, IL-1β and IL-10 positive neurons in hippocampal CA1 region of MG mice increased significantly compared with CG, and the proportion of positive cells increased significantly, while NLRP3 and TLR4 positive neurons in the hippocampal CA1 region of ME mice were significantly reduced, the proportion of TLR4 positive cells was significantly reduced.

CONCLUSION

Systematic moderate-intensity exercise can effectively improve the depression-like behavior of CUMS depressed mice through the expression of TLR4/NLRP3 inflammatory signaling pathway, and provide an effective experimental basis for the clinical rehabilitation treatment of depression.

Integrating Metabolomics and Network Pharmacology to Explore the Mechanism of Xiao-Yao-San in the Treatment of Inflammatory Response in CUMS Mice

Depression can trigger an inflammatory response that affects the immune system, leading to the development of other diseases related to inflammation. Xiao-Yao-San (XYS) is a commonly used formula in clinical practice for treating depression. However, it remains unclear whether XYS has a modulating effect on the inflammatory response associated with depression. The objective of this study was to examine the role and mechanism of XYS in regulating the anti-inflammatory response in depression. A chronic unpredictable mild stress (CUMS) mouse model was established to evaluate the antidepressant inflammatory effects of XYS. Metabolomic assays and network pharmacology were utilized to analyze the pathways and targets associated with XYS in its antidepressant inflammatory effects. In addition, molecular docking, immunohistochemistry, Real-Time Quantitative Polymerase Chain Reaction (RT-qPCR), and Western Blot were performed to verify the expression of relevant core targets. The results showed that XYS significantly improved depressive behavior and attenuated the inflammatory response in CUMS mice. Metabolomic analysis revealed the reversible modulation of 21 differential metabolites by XYS in treating depression-related inflammation. Through the combination of liquid chromatography and network pharmacology, we identified seven active ingredients and seven key genes. Furthermore, integrating the predictions from network pharmacology and the findings from metabolomic analysis, Vascular Endothelial Growth Factor A (VEGFA) and Peroxisome Proliferator-Activated Receptor-γ (PPARG) were identified as the core targets. Molecular docking and related molecular experiments confirmed these results. The present study employed metabolomics and network pharmacology analyses to provide evidence that XYS has the ability to alleviate the inflammatory response in depression through the modulation of multiple metabolic pathways and targets.

Antidepressant effects of 70% ethanolic extract of Lonicerae japonicae flos and it contained chlorogenic acid via upregulation of BDNF-TrkB pathway in the hippocampus of mice

Lonicera japonica flos (LJF) is a common clinical herb with outstanding medicinal and nutritional value. This study aimed to evaluate the antidepressant effects of LJF's active extract and compound chlorogenic acid (CGA) around brain-derived neurotrophic factor(BDNF)-tropomyosin receptor kinase B (TrkB) pathway. The results showed that LJF's extracts and CGA had significant antidepressant effects, and the antidepressant effects of different extracts of LJF were highly positively correlated with the content of CGA (forced swimming test, r = 0.998; tail suspension test, r = 0.934). Moreover, LJF-70% ethanolic extract and CGA improved chronic unpredictable mild stress-induced depressive behavior, upregulated protein expression levels of BDNF and p-TrkB in the hippocampus, restored the damage of hippocampal neurons, and protected liver from damage. In summary, this study demonstrated for the first time that LJF-70% ethanolic extract was the active extract of LJF in antidepressant and CGA was its active compound, and the antidepressant mechanisms mainly involved the upregulation of BDNF-TrkB signaling pathway in the hippocampus of mice.

Environmental enrichment initiated in adolescence restores the reduced expression of synaptophysin and GFAP in the hippocampus of chronically stressed rats in a sex-specific manner

This study aims at investigating whether environmental enrichment (EE) initiated in adolescence can alter chronic unpredictable stress (CUS)-associated changes in astroglial and synaptic plasticity markers in male and female rats. To this end, we studied possible alterations in hippocampal glial fibrillary acidic protein (GFAP) and synaptophysin (SYN) in CUS rats previously housed in EE. Wistar rats on postnatal day (PND) 23 were housed for 10 weeks in standard housing (SH) or enriched conditions. On PND 66, animals were exposed to CUS for 4 weeks. SYN and GFAP expressions were evaluated in CA1 and CA3 subfields and dentate gyrus (DG). CUS reduced the expression of SYN in all hippocampal areas, whereas lower GFAP expression was evident only in CA1 and CA3. The reduced expression of SYN in DG and CA3 was evident to male SH/CUS rats, whereas the reduced GFAP expression in CA1 and CA3 was limited to SH/CUS females. EE housing increased the hippocampal expression of both markers and protected against CUS-associated decreases. Our findings indicate that the decreases in the expression of SYN and GFAP following CUS are region and sex-specific and underline the neuroprotective role of EE against these CUS-associated changes.

Melatonin alleviates depression-like behaviors and cognitive dysfunction in mice by regulating the circadian rhythm of AQP4 polarization

Depression is a common chronic psychiatric illness, which is resistant to medical treatments. While melatonin may alleviate certain depression symptoms, evidence for its efficacy against core symptoms is lacking. Here, we tested a mechanism whereby melatonin rescues the behavioral outcomes of the chronic unpredictable mild stress (CUMS) mouse model of depression. CUMS mice showed depressive behaviors to tail suspension, open field behavior, and sucrose preference test, and cognitive dysfunction in the Morris water maze. Impairments in these measures were relieved by melatonin treatment. Moreover, CUMS mice had impaired glymphatic function across the sleep-wake cycle due to the astrocytic loss and disturbance of circadian regulation of the polarized expression of aquaporin-4 (AQP4) water channels in perivascular astrocytes. EEG results in CUMS mice showed a reduced total sleep time and non-rapid eye movement (NREM) sleep, due to sleep fragmentation in the light phase. CUMS mice lost the normal rhythmic expressions of circadian proteins Per2, Cry2, Bmal1, Clock, and Per1. However, the melatonin treatment restored glymphatic system function and the polarization of AQP4, while improving sleep structure, and rectifying the abnormal expression of Per2, Bmal1, Clock, and Per1 in CUMS mice. Interestingly, Per2 expression correlated negatively with the polarization of AQP4. Further studies demonstrated that Per2 directed the location of AQP4 expression via interactions with the α-dystrobrevin (Dtna) subunit of AQP4 in primary cultured astrocytes. In conclusion, we report a new mechanism whereby melatonin improves depression outcomes by regulating the expression of the circadian protein Per2, maintaining the circadian rhythm of astrocytic AQP4 polarization, and restoring glymphatic function.

Targeting mitophagy for depression amelioration: a novel therapeutic strategy

Major depressive disorder is a global psychiatric condition characterized by persistent low mood and anhedonia, which seriously jeopardizes the physical and mental well-being of affected individuals. While various hypotheses have been proposed to explicate the etiology of depression, the precise pathogenesis and effective treatment of this disorder remain elusive. Mitochondria, as the primary organelles responsible for cellular energy production, possess the ability to meet the essential energy demands of the brain. Research indicated that the accumulation of damaged mitochondria is associated with the onset of depression. Mitophagy, a type of cellular autophagy, specifically targets and removes excess or damaged mitochondria. Emerging evidence demonstrated that mitophagy dysfunction was involved in the progression of depression, and several pharmacological interventions that stimulating mitophagy exerted excellent antidepressant actions. We provided an overview of updated advancements on the regulatory mechanism of mitophagy and the mitophagy abnormality in depressed patients and animals, as well as in cell models of depression. Meanwhile, various therapeutic strategies to restore mitophagy for depression alleviation were also discussed in this review.

Fluoxetine Ameliorates the Aggravation of UC Symptoms in C57BL/6 Mice Induced by CUMS

OBJECTIVE

Patients with chronic ulcerative colitis (UC) often have mental symptoms such as depression and anxiety, and stress can lead to gastrointestinal diseases. However, the correlation between mental stress and UC is unclear. In this paper, chronic unpredictable mild stress (CUMS) was utilized to evaluate the involvement of mental factors in the pathogenesis of UC.

METHODS

The CUMS model was used to evaluate the direct/indirect involvement of mental factors in the pathogenesis of UC. The behavior was evaluated by the open field, forced swimming, and tail suspension tests. Body weight, the disease activity index (DAI) score, colon length, and HE staining of colon tissue were used to evaluate the action of CUMS and fluoxetine.

RESULTS

The results showed that weight loss and the DAI score increased in CUMS mice, but they had no meaningful effect on colon length and morphological structure of colon tissue. However, CUMS aggravated dextran sulfate sodium (DSS)-induced colon length shortening and colon morphological structure damage. Fluoxetine significantly improved the DAI score, shortened colon length, and damaged morphology and structure of the colons induced by CUMS combined with DSS in mice. Fluoxetine also decreased the level of IL-6 in the serum and the TNF-α and IFN-γ levels of colon tissue. Fluoxetine simultaneously improved behavioral abnormalities induced by CUMS combined with DSS in mice.

CONCLUSION

CUMS aggravated the UC symptoms induced by DSS, and fluoxetine could improve the UC symptoms due to its improvement in the inflammatory level and behavioral abnormalities.

Suppressive effects of bilobalide on depression-like behaviors induced by chronic unpredictable mild stress in mice

Background: Depression is a psychiatric disorder with depressed mood and even suicide attempts as the main clinical symptoms, and its pathogenesis has not yet been fully elucidated. Brain derived neurotrophic factor (BDNF) plays an important role in the pathogenesis of depression. Purpose: The main aim of the present study was to evaluate the effectiveness and reveal the potential mechanisms of bilobalide (BB) intervention in alleviating depression-like behaviors by using chronic unpredictable mild stress (CUMS) mice via mediating the BDNF pathway. Methods: Behavioral assessments were carried out by using the sucrose preference test (SPT), tail suspension test (TST), and forced swimming test (FST). CUMS mice were randomly divided into 5 groups: CUMS + solvent, CUMS + BB low, CUMS + BB medium, CUMS + BB high and CUMS + fluoxetine. Total serum levels of tumor necrosis factor (TNF-α) and interleukin-6 (IL-6) were measured by ELISA. Expression of TNF-α, IL-6, AKT, GSK3β, β-catenin, Trk-B and BDNF in the mouse hippocampus was assessed by western blotting. Results: BB treatment reduced the levels of pro-inflammatory cytokines (IL-6 and TNF-α) and increased the protein expression of BDNF in the hippocampus region of the CUMS mice. Moreover, BB treatment enhanced the AKT/GSK3β/β-catenin signaling pathway which is downstream of the BDNF receptor Trk-B in the hippocampus of these mice. Conclusions: Overall, the experimental results indicated that BB reverses CUMS-induced depression-like behavior. BB exerts antidepressant-like effects by inhibiting neuroinflammation and enhancing the function of neurotrophic factors.

The role of ROS/p38 MAPK/NLRP3 inflammasome cascade in arsenic-induced depression-/anxiety-like behaviors of mice

Arsenic pollution in groundwater remains a serious public health concern around the world. Recent years, arsenic-related neurological and psychiatric disorders have been reported increasingly. However, the exact mechanisms of it remains elusive. In this study, arsenic exposure through drinking water resulted in depression-/anxiety-like behaviors in mice accompanied by oxidative stress and NOD-like receptor thermal protein domain associated protein 3 (NLRP3) inflammasome activation in prefrontal cortex (PFC) and hippocampus, two main affected areas found in neurobehavioral disorders. Intervention by NAC, a ROS scavenger, diminished the social behavior impairments in mice as well as ROS generation and NLRP3 inflammasome activation. Further study revealed that it was p38 MAPK signaling pathway that mediated ROS-induced NLRP3 inflammasome activation. Overall, our findings suggested that ROS/p38 MAPK/NLRP3 inflammasome cascade was involved in arsenic-induced depression-/anxiety-disorders. Furthermore, NAC might be a potential therapeutic agent for arsenic-induced depression-/anxiety-disorders by inhibiting both ROS generation and ROS-induced NLRP3 inflammasome activation.

Comorbidity of Anxiety and Hypertension: Common Risk Factors and Potential Mechanisms

Anxiety is more common in patients with hypertension, and these two conditions frequently coexist. Recently, more emphasis has been placed on determining etiology in patients with comorbid hypertension and anxiety. This review focuses on the common risk factors and potential mechanisms of comorbid hypertension and anxiety. Firstly, we analyze the common risk factors of comorbid hypertension and anxiety including age, smoking, alcohol abuse, obesity, lead, and traffic noise. The specific mechanisms underlying hypertension and anxiety were subsequently discussed, including interleukin (IL)-6 (IL-6), IL-17, reactive oxygen species (ROS), and gut dysbiosis. Increased IL-6, IL-17, and ROS accelerate the development of hypertension and anxiety. Gut dysbiosis leads to hypertension and anxiety by reducing short-chain fatty acids, vitamin D, and 5-hydroxytryptamine (5-HT), and increasing trimethylamine N-oxide (TAMO) and MYC. These shared risk factors and potential mechanisms may provide an effective strategy for treating and preventing hypertension and comorbid anxiety.

Irisin attenuates ethanol-induced behavioral deficits in mice through activation of Nrf2 and inhibition of NF-κB pathways

This study aims to investigate the effect of irisin on ethanol-induced behavioral deficits and explore the underlying mechanisms. A mouse model of ethanol addiction/withdrawal was constructed through chronic ethanol administration. Depressive-like behaviors were evaluated by the tail suspension test and forced swimming test, and anxiety-like behaviors were evaluated by the marble-burying test and elevated plus maze test. The expression of Nrf2 was measured by western blotting. Levels of inflammatory mediators (NF-κB, TNF-α, IL-1β and IL-6) and oxidative stress factors (ROS, MDA, GSH and SOD) were detected by ELISA. The ethanol-induced PC12/BV2 cell injury model was used to elucidate whether the effect of irisin on ethanol-induced neurological injury was related to anti-inflammatory and antioxidant mechanisms. Ethanol-induced ethanol preference and emotional deficits were improved by chronic irisin treatment; however, these improvements were partly reversed by cotreatment with the Nrf2 inhibitor ML385. Further results implied that the improvement effect of irisin on behavioral abnormalities may be related to its anti-inflammatory and antioxidant effects. In detail, irisin inhibited ethanol-induced abnormal expression of ROS and MDA and upregulated the expression of GSH and SOD. Meanwhile, irisin treatment inhibited ethanol-induced overexpression of NF-κB, TNF-α, IL-1β and IL-6 in the hippocampus and cerebral cortex. The regulation of oxidative stress factors by irisin was reversed after ML385 treatment. In the in vitro study, overexpression of oxidative stress factors in ethanol-treated PC12 cells was inhibited by irisin treatment; however, the prevention was reversed after the knockdown of Nrf2 siRNA. Moreover, ethanol-induced overexpression of inflammatory mediators in BV2 cells was also inhibited by irisin treatment. Irisin improved depressive and anxiety-like behaviors induced by ethanol addiction/withdrawal in mice, and this protection was greatly associated with the NF-κB-mediated anti-inflammatory signaling pathway and Nrf2-mediated antioxidative stress signaling pathway.

Integrated LC-MS and network pharmacology methods to screen quantitative indicators in the Hippocampus histrix Kaup and method transfer

Hippocampus histrix Kaup is a popular marine medicine with high medicinal and healthcare values. In this study, liquid chromatography-mass spectrometry (LC-MS) analysis combined with network pharmacological method was used to screen for suitable quantitative indicators for the quality control of H. histrix Kaup. Firstly, an LC-MS analytical method for the simultaneous determination of 12 nucleosides in extracts of H. histrix Kaup was established. And then, a network pharmacological method incorporated target prediction, protein-protein interaction network, components-targets network, and targets-pathways network was performed to screen for quantitative indicators. Finally, the developed LC-MS method was transferred to liquid chromatographs to improve the generalizability of the method. All 12 nucleotides were authenticated in extracts of H. histrix Kaup by comparing with the standards. The optimal chromatographic separation conditions are as follows: the chromatographic separation was achieved on an Acquire BEH-C18 column (2.1 mm * 100 mm, 1.7 µm) and gradient elution was performed using methanol solution and buffer (0.30% formic acid and 10 mmol/L ammonium acetate) as mobile phase at a flow rate of 0.15 mL/min and an acquisition wavelength of 260 nm. Network pharmacology results showed that adenosine, and uridine show excellent pharmacological activity. Integration the content, correlation, chromatographic separation, and pharmacological activity of each compound in H. histrix Kaup, uridine and adenosine were tentatively determined as quantitative indicators for quality control in H. histrix Kaup. The established LC-MS method was successfully transferred to liquid chromatographs, and the method is stable and reliable for the quality control of H. histrix Kaup. This developed integrated strategy was successfully used to screen quantitative indicators in the H. histrix Kaup.

The protective effect of luteolin on the depression-related dry eye disorder through Sirt1/NF-κB/NLRP3 pathway

Luteolin has been reported to exhibit therapeutic effect on depressive-like behaviors in mice. Nevertheless, the therapeutic effect of luteolin on the depression-related dry eye disorder remains inconclusive. In this study, C57 mice were subjected to chronic unpredictable mild stress in a dry environment (relative humidity in the cage <40%). The behavioral test and phenol red cotton thread test were employed to select the mice with both dry eye and depression-like behavior. The mechanism of luteolin on depression-related dry eye disorder was assessed by the Sirt1 selective inhibitor EX-527. Luteolin alleviated depressive-like behaviors induced by CUMS, increased tear secretion and restored corneal defects in mice. The secretions of pro-inflammatory factors IL-1β, IL-6, IL-18 and TNF-α were decreased in hippocampi and corneal tissues by Luteolin treatment. Luteolin treatment up-regulated Sirt1 expression and down-regulated Ac-NF-κB, NLRP3, Ac-Caspase-1, GSDMD-N, Cleaved IL-1β, and Cleaved IL-18 expressions. In addition, the selective inhibition of Sirt1 could weaken the therapeutic effect of luteolin on depression-related dry eye disorder. The beneficial effect of luteolin through Sirt1/NF-κB/NLRP3 signaling pathway might be a therapeutic strategy for the depression-related dry eye disorder.

Sperm transport and male pregnancy in seahorses: An unusual model for reproductive science

The Syngnathidae (seahorses and pipefishes) are a group of teleost fishes in which, uniquely, developing embryos are hosted throughout pregnancy by males, using a specialized brood pouch situated on the abdomen or tail. Seahorses have evolved the most advanced form of brood pouch, whereby zygotes and embryos are intimately connected to the host's circulatory system and also bathed in pouch fluid. The pouch is closed to the external environment and has to perform functions such as gaseous exchange, removal of waste and maintenance of appropriate osmotic conditions, much like the mammalian placenta. Fertilization of the oocytes occurs within the brood pouch, but unlike the mammalian situation the sperm transport mechanism from the ejaculatory duct towards the pouch is unclear, and the sperm: egg ratio (about 5:1) is possibly the least of any vertebrate. In this review, there is highlighting of the difficulty of elucidating the sperm transport mechanism, based on studies of Hippocampus kuda. The similarities between seahorse pouch function and the mammalian placenta have led to suggestions that the pouch provides important nutritional support for the developing embryos, supplementing the nutritional functions of the yolk sac provided by the oocytes. In this review, there is a description of the recent evidence in support of this hypothesis, and also emphasis, as in mammals, that embryonic development depends on nutritional support from the placenta-like pouch at important stages of the gestational period ("critical windows").

Platycladus orientalis seed extract as a potential triple reuptake MAO inhibitor rescue depression phenotype through restoring monoamine neurotransmitters

ETHNOPHARMACOLOGY RELEVANCE

Platycladus orientalis seeds are recorded in traditional Chinese medicine (TCM) formulations for modulation of mood and physical activity in "Shen Nong Ben Cao Jing" and "Compendium of Materia Medica" and so on. Recently, we identified its extracting components and looked for the potentials in treatment for depression by improving the function of monoamine neurotransmitters.

AIM OF THE STUDY

We investigated the mechanism of action of the seed extracts of P. orientalis (S4) to rescue depressive behavior in a chronic, unpredicted, mild stress (CUMS)-induced model in rats.

MATERIALS AND METHODS

We used ultra-fast liquid chromatography coupled with triple quadrupole-time of flight tandem mass spectrometry to analyze the chemical constituents in S4. An assay platform in zebrafish and molecular docking were used to analyze if S4 regulated rest/wake behavior and predict the biological targets which correlated with monoamine neurotransmitters. Depressive-behavior tests (body weight, sucrose preference test, tail-suspension test, forced-swimming test) were carried in the CUMS model. After behavior tests and killing, rat brains were separated into the hippocampus, frontier cortex and dorsal raphe nucleus. The main monoamine neurotransmitters and their metabolite concentrations in these three brain regions were measured by rapid resolution liquid chromatography coupled with triple quadrupole tandem mass spectrometry.

RESULTS

Forty-one compounds were identified in S4, including fatty acids, terpenoids, amino acids, plant sterols and flavonoids. S4 could increase the total rest time and decrease the waking activity of zebrafish. S4 showed high correlation with adrenaline agonists, 5-hydroxytryptamine (5-HT) reuptake inhibitors and dopamine agonists. CUMS-group rats, compared with controls, had significantly decreased body weight and preference for sucrose water, whereas the immobility time in the tail-suspension test and forced-swimming test was increased. S4 could significantly rescue the increased levels of 5-HT, noradrenaline and dopamine in the prefrontal cortex and dorsal raphe nucleus.

CONCLUSIONS

We demonstrated that S4 was a potential inhibitor of MAO reuptake that could rescue depression in a CUMS-model rats by restoring monoamine neurotransmitters in different encephalic regions.

Anxiolytic and antidepressive potentials of rosmarinic acid: A review with a focus on antioxidant and anti-inflammatory effects

Depression and anxiety are the most prevalent neuropsychiatric disorders that have emerged as global health concerns. Anxiolytic and antidepressant drugs, such as benzodiazepines, selective serotonin reuptake inhibitors, monoamine oxidase inhibitors, and tricyclics, are the first line used in treating anxiety and depression. Although these drugs lack efficacy and have a delayed response time and numerous side effects, their widespread abuse and market continue to grow. Over time, traditional practices using natural and phytochemicals as alternative therapies to chemical drugs have emerged to treat many pathological conditions, including anxiety and depression. Recent preclinical studies have demonstrated that the phenolic compound, rosmarinic acid, is effective against several neuropsychiatric disorders, including anxiety and depression. In addition, rosmarinic acid showed various pharmacological effects, such as cardioprotective, hepatoprotective, lung protective, antioxidant, anti-inflammatory, and neuroprotective effects. However, the potentialities of the use of rosmarinic acid in the treatment of nervous system-related disorders, such as anxiety and depression, are less or not yet reviewed. Therefore, the purpose of this review was to present several preclinical and clinical studies, when available, from different databases investigating the effects of rosmarinic acid on anxiety and depression. These studies showed that rosmarinic acid produces advantageous effects on anxiety and depression through its powerful antioxidant and anti-inflammatory properties. This review will examine and discuss the possibility that the anxiolytic and anti-depressive effects of rosmarinic acid could be associated with its potent antioxidant and anti-inflammatory activities.

Selection of the Male or Female Sex in Chronic Unpredictable Mild Stress-Induced Animal Models of Depression

Depression is a serious public health problem and an important factor leading to disease-related disability. Influenced by many factors, such as psychological, hormonal, and genetic factors, the incidence rate of depression in females is approximately two times that in males. However, in preclinical neuroscience research, the selection of the animals' sex for use in depression models has been controversial. At present, in most preclinical studies, the animals generally chosen in depression models have been male rodents rather than female rodents. It remains doubtful whether the data obtained from male animals can be generalized to female animals. The performance of female animals in preclinical studies of depression has been inconclusive. Based on a review of a large number of original studies in the PubMed database, it was found that although male rodents are more commonly used in the study of depression, the use of female animals also shows good modeling of depression and has its advantages. The influence of the animals' sex in the chronic unpredictable mild stress (CUMS) model needs further research.

Contribution of hippocampal BDNF/CREB signaling pathway and gut microbiota to emotional behavior impairment induced by chronic unpredictable mild stress during pregnancy in rats offspring

Background

Numerous studies have shown that exposure to prenatal maternal stress (PMS) is associated with various psychopathological outcomes of offspring. The accumulating evidence linking bacteria in the gut and neurons in the brain (the microbiota-gut-brain axis) has been aconsensus; however, there is a lack of research on the involvement mechanism of gut microbiota in the regulation of the BDNF/CREB signaling pathway in the hippocampus of prenatally stressed offspring.

Methods

Pregnant rats were subjected to chronic unpredictable mild stress (CUMS) to establish the prenatal maternal stress model. The body weight was measured and the behavioral changes were recorded. Offspring were tested to determine emotional state using sucrose preference test (SPT), open-field test (OFT) and suspended tail test (STT). Gut microbiota was evaluated by sequencing the microbial 16S rRNA V3-V4 region, and the interactive analysis of bacterial community structure and diversity was carried out. The expression of hippocampal BDNF, TrkB and CREB mRNA and proteins were respectively measured using RT-PCR and Western blotting.

Results

Prenatal maternal stress increased maternal plasma corticosterone levels, slowed maternal weight gain and caused depression-like behaviors (all P < 0.05). In offspring, prenatal maternal stress increased plasma corticosterone levels (P < 0.05) and emotional behavior changes (depression-like state) were observed (P < 0.05). The species abundance, diversity and composition of the offspring's gut microbiota changed after the maternal stress during pregnancy (P < 0.05). Compared with the control group's offspring, the species abundance of Lactobacillaceae was dropped, while the abundance of the Muribaculaceae species abundance was risen. Concurrent, changes in the hippocampal structure of the offspring and decreases in expression of BDNF/CREB signaling were noted (P < 0.05).

Conclusions

Prenatal maternal stress leads to high corticosterone status and abnormal emotion behavior of offspring, which may be associated with the abnormal BDNF/CREB signaling in hippocampus of offspring caused by the change of gut microbiota composition.

Polysaccharides from Polygonatum cyrtonema Hua Reduce Depression-Like Behavior in Mice by Inhibiting Oxidative Stress-Calpain-1-NLRP3 Signaling Axis

Polysaccharides from Polygonatum cyrtonema Hua (PSP) exert antioxidant, anti-inflammatory, and antidepressant effects. Production of reactive oxygen species (ROS) and activation of the calpain system and the NOD-like receptor protein 3 (NLRP3) inflammasome are closely related to the pathogenesis of depression. However, the relationships among those pathways and the protective effects of PSP have not been characterized. In this study, lipopolysaccharide (LPS) and chronic unpredictable mild stress- (CUMS-) induced depression models were used to evaluate the protective mechanisms of PSP against depression. ROS levels were measured in HT-22 cells using flow cytometry. Brain tissues were collected to determine the levels of oxidation-related indicators and inflammatory cytokines. The protein levels of calpain-1, calpain-2, calpastatin, phosphatase and Tensin Homolog deleted on Chromosome 10 (PTEN), suprachiasmatic nucleus circadian oscillatory protein (SCOP), nuclear factor-erythroid factor 2-related factor 2 (Nrf2), heme oxygenase-1 (HO-1), NLRP3, apoptosis-associated speck-like protein (ASC), caspase-1, cleaved-caspase-1, ionized calcium binding adapter molecule 1 (Iba1), phosphorylation of extracellular signal-regulated kinase (p-ERK), nuclear factor-kappa B (NF-κB), interleukin-1β (IL-1β), and glial fibrillary acidic protein (GFAP) were measured using western blotting or immunofluorescence. In cellular experiments, we showed that PSP attenuated LPS-induced production of ROS in HT-22 cells. In animal experiments, we found that LPS increased the expression of calpain-1, NLRP3, ASC, caspase-1, cleaved-caspase-1, Iba1, p-ERK, NF-κB, and GFAP and reduced the expression of calpastatin, PTEN, SCOP, and Nrf2. Administration of PSP reversed these changes. N-Acetyl-L-cysteine (NAC) administration also inhibited oxidative stress and activation of the calpain system and the NLRP3 inflammasome. Furthermore, PSP, calpeptin, MCC950 (a selective NLRP3 inflammasome inhibitor), and NAC reduced LPS-induced proinflammatory cytokine release. We also showed that PSP prevented CUMS-induced changes in the calpain system and the Nrf2 and NLRP3 signaling pathways and reduced depression-like behavior. These results indicate that PSP exerts antidepressant effects through regulation of the oxidative stress-calpain-1-NLRP3 signaling axis.

Indole-3-Carbinol Selectively Prevents Chronic Stress-Induced Depression-but not Anxiety-Like Behaviors via Suppressing Pro-Inflammatory Cytokine Production and Oxido-Nitrosative Stress in the Brain

Indole-3-carbinol (I3C), a phytochemical enriched in most cruciferous vegetables, has been shown to display various biological activities such as anti-oxidative stress, anti-inflammation, and anti-carcinogenesis. In this study, we investigated the regulatory effect of I3C on chronic stress-induced behavioral abnormalities in mice. Results showed that repeated I3C treatment at the dose of 10, 30, and 60 mg/kg prevented chronic social defeat stress (CSDS)-induced behavioral abnormalities in the tail suspension test, forced swimming test, sucrose preference test, and social interaction test in mice, and did not affect CSDS-induced behavioral abnormalities in the elevated plus maze, light-dark test, and open-field test, suggesting that the I3C treatment selectively prevents the onset of depression- but not anxiety-like behaviors in chronically stressed mice. Further analysis demonstrated that repeated I3C treatment (60 mg/kg, 10 days) prevented CSDS-induced increases in levels of interleukin-1β (IL-1β), IL-6, and tumor necrosis factor-α (TNF-α) mRNA and protein, but did not affect CSDS-induced decreases in levels of IL-4, IL-10, and Ym-1 mRNA and/or protein in the hippocampus and prefrontal cortex, suggesting that I3C can selectively prevent chronic stress-induced pro-inflammatory but not anti-inflammatory responses in the brain. Further analysis showed that repeated I3C treatment (60 mg/kg, 10 days) prevented CSDS-induced increases in levels of nitrite and malondialdehyde (MDA), decreases in contents of glutathione (GSH), and decreases in levels of brain derived neurotrophic factor (BDNF) protein in the hippocampus and prefrontal cortex. These results demonstrated that I3C selectively prevents chronic stress-induced depression-like behaviors in mice likely through suppressing neuroinflammation and oxido-nitrosative stress in the brain.

Total Triterpenes of Wolfiporia cocos (Schwein.) Ryvarden & Gilb Exerts Antidepressant-Like Effects in a Chronic Unpredictable Mild Stress Rat Model and Regulates the Levels of Neurotransmitters, HPA Axis and NLRP3 Pathway

Purpose:Wolfiporia cocos is frequently used in traditional Chinese medicine to treat depression. However, antidepressant-like effects of the main active ingredients of Wolfiporia cocos, total triterpenes of Wolfiporia cocos (TTWC), are not well studied. This study aimed to investigate those effects and explore their specific mechanisms of action in depth.

Methods: Chemical components of TTWC were analyzed using LC-MS. Depression-like behavior in rats were induced by chronic unpredictable mild stress (CUMS). The suppressive effects of TTWC (60, 120, 240 mg/kg) against CUMS-induced depression-like behavior were evaluated using the forced swimming test (FST), open field test (OFT) and sucrose preference test (SPT). Levels of 5-hydroxytryptamine (5-HT), glutamate (GLU), corticotropin-releasing hormone (CRH), interleukin-1 beta (IL-1beta), interleukin-18 (IL-18), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-alpha) in different groups were determined by ELISA. Western blotting (WB) was used to detect the expression of NLRP3, ASC, pro-caspase-1, caspase-1, pro-IL-1beta, IL-1beta, pro-IL-18, and IL-18 in the prefrontal cortex. Additionally, the mRNA levels of NLRP3, ASC, caspase-1, IL-1beta and IL-18 were detected by RT-PCR.

Results: A total of 69 lanostane-type triterpene acids of TTWC were identified. The results showed that TTWC exhibited an antidepressant-like effect in CUMS rats, reversed the decreased sugar preference in the SPT, reduction of immobility time in the FST, reduced the rest time, increased the total moving distance in the OFT. TTWC increased 5-HT levels and decreased GLU levels in the hippocampus. Moreover, TTWC decreased CRH levels in serum, indicating the regulation of over-activation of the hypothalamic-pituitary-adrenal (HPA) axis. In addition, reduced serum levels of IL-1beta, IL-18, IL-6, and TNF-alpha. The WB results implied that TTWC inhibited the expression of NLRP3, ASC, caspase-1, IL-1beta, and IL-18 in the prefrontal cortex and enhanced the expression of pro-caspase-1, pro-IL-1beta, and pro-IL-18. Although most of the results were not significant, PCR results showed that TTWC inhibited the expression of NLRP3, ASC, caspase-1, IL-1beta, and IL-18 in the prefrontal cortex.

Conclusion: TTWC treatment exerted an antidepressant-like effect and regulates neurotransmitters, HPA axis and NLRP3 signaling pathway. These results indicated the potential of TTWC in preventing the development of depression.

High-frequency repetitive transcranial magnetic stimulation mitigates depression-like behaviors in CUMS-induced rats via FGF2/FGFR1/p-ERK signaling pathway

High-frequency repetitive transcranial magnetic stimulation (rTMS) is a widely used and effective biological treatment for depression. Although previous studies have shown that astrocyte function may be modified by rTMS, the specific neurobiological mechanisms underlying its antidepressant action are not clear. Substantial evidence has accumulated indicating that neurotrophin dysfunction and neuronal apoptosis play a role in the development of depression. To evaluate this hypothesis, we applied a chronical unpredictable mild stress (CUMS) protocol to induce depression-like behaviors in rats, followed by the delivery of 10-Hz rTMS for 3 weeks. Behavioral outcome measures consisted of a sucrose preference test, forced swimming test, and open field test. Histological analysis focused on apoptosis, expression of GFAP and FGF2, and FGF2 pathway-related proteins. The results showed that after rTMS treatment, the rats' sucrose preference increased, open field performance improved while the immobility time of forced swimming decreased. The behavioral changes seen in rTMS treated rats were accompanied by marked reductions in the number of TUNEL-positive neural cells and the level of expression of BAX and by an increase in Bcl2. Furthermore, the expression of GFAP and FGF2 was increased, along with activation of FGF2 downstream pathway. These results suggest that rTMS treatment can improve depression-like behavior, attenuate neural apoptosis, and reverse reduction of astrocytes in a rat model of depression. We hypothesize that the therapeutic action of rTMS in CUMS-induced rats is linked to the activation of the FGF2/FGFR1/p-ERK signaling pathway.

Tenuifolin ameliorates chronic restraint stress-induced cognitive impairment in C57BL/6J mice

The general consensus is that stress affects the central nervous system and can lead to cognitive problems. The root of Polygala tenuifolia (P. tenuifolia) is a well-known traditional Chinese medicine used for improving brain function. Tenuifolin (TEN) is the major constituent of P. tenuifolia and has a promising neuroprotective property. The purpose of this study was to investigate the alleviating effect of TEN on cognitive impairment induced by chronic restraint stress (CRS) and its mechanism. Our results showed that CRS exposure resulted in impaired cognitive performance in C57BL/6J mice, as indicated by decreased responses in Y-maze, novel objects recognition, and step-through passive avoidance tests. TEN treated daily orally (10 and 20 mg/kg) for 30 days reversed these behavior changes. Meanwhile, TEN could significantly regulate interleukin (IL)-6 and IL-10 levels in the hippocampus. TEN inhibited the toll-like receptor 4/nuclear factor-kappa B-mediated inflammation, as well as adrenocorticotropic hormone and corticosterone levels in serum. Most importantly, we found that TEN also upregulated the expressions of brain-derived neurotrophic factor, tropomyosin kinase B, glucocorticoid receptor, glutamate receptor 1, and synapse-associated proteins. Collectively, these data suggest that TEN has a potential improvement effect on memory loss caused by CRS.

Acupuncture Relieves Stress-Induced Depressive Behavior by Reducing Oxidative Stress and Neuroapoptosis in Rats

Oxidative stress is closely related to the occurrence of depression. Acupuncture has been proved to be an effective method for treating depression. In order to explore the mechanism of the antidepressant effect of acupuncture, this study performed acupuncture prevention on chronic unpredictable mild stress (CUMS) depression model rats, and observed the effect of acupuncture on hippocampal oxidative stress and Nrf2 signaling pathway. Male SD rats were randomly divided into control group, CUMS group, acupuncture group, and fluoxetine group (n = 10/group). Fluoxetine, a common antidepressant, was used as a positive control drug in this study. In the fluoxetine group, rats were given fluoxetine (2.1 mg/kg) intragastrically once a day for 28 days. The acupoints of Shangxing (GV23) and Fengfu (GV16) were applied in acupuncture group, once every other day for 14 times in total. Behavioral tests and biological detections were used to evaluate the effects of the interventions and the changes of factors related to oxidative stress, Nrf2 pathway, and neuronal apoptosis. The results showed that both acupuncture and fluoxetine could increase sugar preference rate in SPT and decrease immobility time in FST in depression model rats. It also significantly decreased oxidative stress products such as ROS and H2O2, and elevated the protein and mRNA expressions of Nrf2 and HO-1. From Nissl’s staining, there were more abundant nerve cells in two intervention groups compared with CUMS group. Plus, acupuncture down-regulated the expression levels of Bax and caspase-3 and up-regulated the expression of Bcl-2. Our findings indicate that acupuncture improved depression-like behaviors of CUMS rats. And CUMS-induced depression-like behaviors in rats were related to oxidative stress and neuronal apoptosis in hippocampus. Acupuncture showed antidepressant effects in reducing oxidative stress products via regulating the Nrf2/HO-1 signaling pathway so that prevented neuronal apoptosis.

Neuroprotective Efficiency of Prodigiosins Conjugated with Selenium Nanoparticles in Rats Exposed to Chronic Unpredictable Mild Stress is Mediated Through Antioxidative, Anti-Inflammatory, Anti-Apoptotic, and Neuromodulatory Activities

PURPOSE

Depression is a mood disorder accompanied by intensive molecular and neurochemical alterations. Currently, available antidepressant therapies are not fully effective and are often accompanied by several adverse impacts. Accordingly, the ultimate goal of this investigation was to clarify the possible antidepressant effects of prodigiosins (PDGs) loaded with selenium nanoparticles (PDGs-SeNPs) in chronic unpredictable mild stress (CUMS)-induced depression-like behavior in rats.

METHODS

Sixty Sprague Dawley rats were randomly allocated into six groups: control, CUMS group (depression model), fluoxetine (Flu, 10 mg/kg)+CUMS, PDGs+CUMS (300 mg/kg), sodium selenite (Na2SeO3, 400 mg/kg)+CUMS, and PDGs-SeNPs+CUMS (200 mg/kg). All treatments were applied orally for 28 consecutive days.

RESULTS

PDGs-SeNPs administration prevented oxidative insults in hippocampal tissue, as demonstrated by decreased oxidant levels (nitric oxide and malondialdehyde) and elevated innate antioxidants (glutathione, glutathione peroxidase, glutathione reductase, superoxide dismutase, and catalase), in addition to the upregulated expression of nuclear factor erythroid 2-related factor 2 and heme oxygenase-1 in rats exposed to CUMS. Additionally, PDGs-SeNPs administration suppressed neuroinflammation in hippocampal tissue, as determined by the decreased production of pro-inflammatory cytokines (tumor necrosis factor-alpha, interleukin-1β, and interleukin-6), increased anti-inflammatory cytokine interleukin-10, and decreased inflammatory mediators (prostaglandin E2, cyclooxygenase-2, and nuclear factor kappa B). Moreover, PDGs-SeNPs administration in stressed rats inhibited neuronal loss and the development of hippocampal apoptosis through enhanced levels of B cell lymphoma 2 and decreased levels of caspase 3 and Bcl-2-associated X protein. Interestingly, PDGs-SeNPs administration improved hormonal levels typically disrupted by CUMS exposure and significantly modulated hippocampal levels of monoamines, brain-derived neurotrophic factor, monoamine oxidase, and acetylcholinesterase activities, in addition to upregulating the immunoreactivity of glial fibrillary acidic protein in CUMS model rats.

CONCLUSION

PDGs-SeNPs may serve as a prospective antidepressant candidate due to their potent antioxidant, anti-inflammatory, and neuroprotective potential.

Quercetin reverses chronic unpredictable mild stress-induced depression-like behavior in vivo by involving nuclear factor-E2-related factor 2

Quercetin is a flavonoid compound rich in many natural plants with a wide range of pharmacological effects and nutritional value. Although previous studies have initially shown the antidepressant effect of quercetin in some models. However, the exact mechanism of the antidepressant effect of quercetin on the depression model induced by chronic unpredictable mild stress (CUMS) is still unclear or has not been clearly elucidated. The present study aimed to investigate the antidepressant effect of quercetin in vivo on a CUMS-induced depression model that is closest to human depression, and to explore its mechanism of action around nuclear factor-E2-related factor 2 (Nrf2) related signaling pathways, for the first time. Our results demonstrated that CUMS for 21 consecutive days caused significant decreases in the sucrose preference, and the horizontal score and vertical score in the open field test of mice respectively by 22.6%, 34.4%, and 66.6% (all P < 0.01), and a significant increase in the immobility time during the forced swimming test by 110.5% (P < 0.01), but fortunately, after chronic oral administration of high dose quercetin at 40 mg/kg, the abnormalities of the above indicators were significantly reversed by 26.2%, 40.1%, 152.7%, 43.5% (all P < 0.01). Further western blot analysis showed that CUMS caused the phosphorylation or expression levels of phosphoinositide 3-kinase (PI3K), protein kinase B (Akt), Nrf2 and heme oxygenase-1 (HO-1) proteins in the hippocampus of mice to significantly down-regulate by 60.0%, 72.1%, 90.0% and 50.1% (all P < 0.01), while after chronic oral administration of high dose quercetin at 40 mg/kg, the abnormalities of these proteins were significantly up-regulated by 85.8%, 182.0%, 325.1% and 60.3% (all P < 0.01). In addition, CUMS also caused significant reduction in the levels of antioxidants including superoxide dismutase (SOD) and glutathione-s transferase (GST) in the mice hippocampus by 51.3%, 40.3% (both P < 0.01), while after chronic oral administration of high dose quercetin at 40 mg/kg, the abnormalities of the above indicators were significantly reversed by 69.2% and 49.5% (both P < 0.01), as well as significant elevation in the levels of lipid peroxide malondialdehyde (MDA), inflammation medium nitric oxide (NO) and inducible nitric oxide synthase (iNOS) by 156.4%, 255.4% and 72.7% (all P < 0.01), while after chronic oral administration of high dose quercetin at 40 mg/kg, the abnormalities of the above indicators were significantly reversed by 45.9%, 26.8% and 55.2% (all P < 0.01). The medium dose of quercetin (20 mg/kg) only reversed some of the above indicators, while the low dose of quercetin (10 mg/kg) had no reversal effect on the above indicators. Collectively, the present study confirmed for the first time that quercetin weakened CUMS-induced depression in vivo, and its mechanism was at least partially attributable to the upregulation of hippocampal Nrf2 and the inhibition of iNOS, thereby correcting the central inflammatory response, and the imbalance between oxidation and antioxidant.

3-O-Acetyl-11-keto-β-boswellic acid ameliorates chronic unpredictable mild stress induced HPA axis dysregulation in relation with glutamate/GABA aberration in depressive rats

Overt expression of brain glucocorticoid receptor (GR) leads to elevation of glutamate release causes cerebral excitotoxicity which in turn produce neuropsychological disorders. The aim of our work is to study the consequence of 3-O-Acetyl-11-keto-β-boswellic acid (AKBA) on chronic unpredictable mild stress (CUMS) induced HPA axis dysregulation in relative to glutamate and GABA irregularity in depressive rats. AKBA (5, 10 &15mg/kg) was administered for 28 days parallel with CUMS induction in rats. Behavioural studies, tail suspension test (TST), open field exploratory (OFT) and forced swim test (FST) were performed. Biochemical studies including plasma corticosterone, glutamate GABA and glutamic acid decarboxylase (GAD) enzyme activity were studied. Glucocorticoid receptor expression and brain histology were studied to observe the effect of AKBA. CUMS induction results in depressive state of the animals were confirmed by the sucrose preference test. The administration of AKBA significantly reduced the immobility time and improved the exploratory behaviour. Plasma corticosterone and brain glutamate level was decreased and GABA level were increased significantly evident with GAD activation in AKBA-treated animals, further confirmed with decreased GR expression improves architecture of prefrontal cortex region. Correlation study illustrates behavioural improvements undeviating the biochemical alteration and GR expression after AKBA treatment during depression. AKBA significantly reversed the CUMS-induced glutamate/GABA abnormalities through the adaptation of central HPA axis regulation. Hence this study concludes that AKBA can be a better alternative to treat depressive disorders.

A Reliable High-Throughput Screening Model for Antidepressant

Depression is the most frequent affective disorder and is the leading cause of disability worldwide. In order to screen antidepressants and explore molecular mechanisms, a variety of animal models were used in experiments, but there is no reliable high-throughput screening method. Zebrafish is a common model organism for mental illness such as depression. In our research, we established chronic unpredictable mild stress (CUMS) models in C57BL/6 mice and zebrafish; the similarities in behavior and pathology suggest that zebrafish can replace rodents as high-throughput screening organisms. Stress mice (ip., 1 mg/kg/d, 3 days) and zebrafish (10 mg/L, 20 min) were treated with reserpine. As a result, reserpine caused depression-like behavior in mice, which was consistent with the results of the CUMS mice model. Additionally, reserpine reduced the locomotor ability and exploratory behavior of zebrafish, which was consistent with the results of the CUMS zebrafish model. Further analysis of the metabolic differences showed that the reserpine-induced zebrafish depression model was similar to the reserpine mice model and the CUMS mice model in the tyrosine metabolism pathway. The above results showed that the reserpine-induced depression zebrafish model was similar to the CUMS model from phenotype to internal metabolic changes and can replace the CUMS model for antidepressants screening. Moreover, the results from this model were obtained in a short time, which can shorten the cycle of drug screening and achieve high-throughput screening. Therefore, we believe it is a reliable high-throughput screening model.

The Combination of Aquilaria sinensis (Lour.) Gilg and Aucklandia costus Falc. Volatile Oils Exerts Antidepressant Effects in a CUMS-Induced Rat Model by Regulating the HPA Axis and Levels of Neurotransmitters

The Aquilaria sinensis (Lour.) Gilg (CX)-Aucklandia costus Falc. (MX) herbal pair is frequently used in traditional Chinese medicine prescriptions for treating depression. The volatile oil from CX and MX has been shown to have good pharmacological activities on the central nervous system, but its curative effect and mechanism in the treatment of depression are unclear. Therefore, the antidepressant effect of the volatile oil from CX-MX (CMVO) was studied in chronic unpredictable mild stress (CUMS) rats. The suppressive effects of CMVO (25, 50, 100 μL/kg) against CUMS-induced depression-like behavior were evaluated using the forced swimming test (FST), open field test (OFT) and sucrose preference test (SPT). The results showed that CMVO exhibited an antidepressant effect, reversed the decreased sugar preference in the SPT and prolongation of immobility time in the FST induced by CUMS, increased the average speed, time to enter the central area, total moving distance, and enhanced the willingness of rats to explore the environment in the OFT. Inhalational administration of CMVO decreased levels of adrenocorticotropic hormone and corticosterone in serum and the expression of corticotropin-releasing hormone mRNA in the hypothalamus, which indicated regulation of over-activation of the hypothalamic-pituitary-adrenal (HPA) axis. In addition, CMVO restored levels of 5-hydroxytryptamine (5-HT), dopamine, norepinephrine and acetylcholine in the hippocampus. The RT-PCR and immunohistochemistry results showed that CMVO up-regulated the expression of 5-HT_1A mRNA. This study demonstrated the antidepressant effect of CMVO in CUMS rats, which was possibly mediated via modulation of monoamine and cholinergic neurotransmitters and regulation of the HPA axis.

Anti-Inflammatory Effects of Asian Fawn Lily (Erythronium japonicum) Extract on Lipopolysaccharide-Induced Depressive-Like Behavior in Mice

Neuroinflammation is associated with an increased risk of depression. Lipopolysaccharide (LPS) treatment is known to induce pro-inflammatory cytokine secretion and a depressive-like phenotype in mice. Although Erythronium japonicum exhibits various health benefits, the role of E. japonicum extract (EJE) in inflammation-associated depression is unknown. This study aimed to explore the anti-inflammatory effect of EJE on LPS-induced depressive symptoms in mice using the open field test (OFT), passive avoidance test (PAT), tail suspension test (TST), and forced swim test (FST). LPS-treated mice had significantly increased immobility time in the TST and FST, decreased step-through latency time in the PAT, and decreased locomotor activity in the OFT. However, administration of 100 and 300 mg/kg of EJE significantly improved these depressive-like behaviors. EJE also prevented the increase in mRNA levels of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), IL-6, and monocyte chemoattractant protein-1 (MCP-1), and the decrease in IL-10 levels by inhibiting nuclear factor-κB (NF-κB) subunit p65 phosphorylation. Additionally, LPS-treated mice showed markedly decreased brain-derived neurotrophic factor (BDNF) levels and phosphorylation of phosphoinositide 3-kinase (PI3K) and Akt, while EJE treatment significantly increased these levels in the hippocampus. These results suggest that EJE ameliorated LPS-induced depressive-like behavior by reducing LPS-induced neuroinflammation and activating the BDNF-PI3K/Akt pathway.

Long-Term Exposure to Ceftriaxone Sodium Induces Alteration of Gut Microbiota Accompanied by Abnormal Behaviors in Mice

Background: Growing evidence points out that a disturbance of gut microbiota may also disturb the gut–brain communication. However, it is not clear to what extent the alteration of microbiota composition can modulate brain function, affecting host behaviors. Here, we investigated the effects of gut microbiota depletion on emotional behaviors.

Methods: Mice in the experimental group were orally administered ceftriaxone sodium solution (250 mg/ml, 0.2 ml/d) for 11 weeks. The open-field test and tail-suspension test were employed for the neurobehavioral assessment of the mice. Fecal samples were collected for 16s rDNA sequencing. The serum levels of cytokines and corticosterone were quantified using enzyme-linked immunosorbent assays. The immunohistochemistry method was used for the detection of brain-derived neurotrophic factor (BDNF) and c-Fos protein.

Results: The gut microbiota for antibiotic-treated mice showed lower richness and diversity compared with normal controls. This effect was accompanied by increased anxiety-like, depression-like, and aggressive behaviors. We found these changes to be possibly associated with a dysregulation of the immune system, abnormal activity of the hypothalamic-pituitary-adrenal axis, and an alteration of neurochemistry.

Conclusions: The findings demonstrate the indispensable role of microbiota in the gut–brain communication and suggest that the absence of conventional gut microbiota could affect the nervous system, influencing brain function.

Hippocampal mRNA expression profiling in mice exposed to chronic unpredictable mild stress

Depression is a state of low mood and aversion to activity, affecting a person's thoughts, behavior, motivation, feelings and sense of well-being, which is associated with dramatical gene expression changes in hippocampus. Rodents induced by chronic unpredictable mild stress (CUMS) demonstrate typical depression-like behaviors similar to clinical patients, therefore, are commonly used as a model for depression and antidepressant study. In order to enhance our understanding of the molecular mechanisms of the pathogenesis of depression, in the present study, the hippocampal mRNA expression profile of mice exposed to CUMS for 5 weeks was sequenced using Illumina HiSeq 4000 platform followed by enrichment analysis, including Hierarchical Cluster, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway, and protein-protein interaction (PPI) network. Totally, 346 differently expressed mRNAs, including 208 downregulated and 138 upregulated, were identified in the hippocampus of the CUMS mice. KEGG biological pathway analysis showed that the upregulated and downregulated mRNAs were mostly enriched in 29 pathways and 8 pathways, respectively. PPI network analysis exposed that glyceraldehyde 3-phosphate dehydrogenase was the crucial node with high connectivity degree. Additionally, most of these genes in PPI network analysis have previously been linked to energy metabolism and corticosterone responses. Overall, our results indicate the possible novel molecular targets for the therapy of depression.