Animal models for the study of depressive disorder

Astrocytic P2X7 receptor regulates depressive-like behavioral reactions of mice in response to acute stressful stimulation

Acute stress causes depressive-like reactions in the tail suspension (TST) and forced swim tests (FST) of mice. Similarly, inescapable foot shock is able to promote the development of anhedonia as indicated by decreased sucrose consumption of treated mice in the sucrose preference test (SPT). The astrocyte-specific deletion of the P2X7R by a conditional knockout strategy or its knockdown by the intracerebroventricular (i.c.v.) delivery of an adeno-associated virus (AAV) expressing P2X7R-specific shRNA in astrocytes significantly prolonged the immobility time in TST and FST. In contrast, the shRNA-induced downregulation of the P2X7R in neurons, oligodendrocytes, or microglia had no detectable effect on the behavior of treated mice in these tests. Moreover, sucrose consumption in the SPT was not altered following inescapable foot shock treatment in any of these cell type-specific approaches. Immunohistochemistry indicated that the administered astrocyte-specific AAV efficiently conveyed expression of shRNA by hippocampal CA1 astrocytes, but not by neurons. In conclusion, P2X7R in astrocytes of this area of the brain appears to be involved in depressive-like reactions to acute stressors.

Comparison of CUMS at different pregnancy stages, maternal separation, and their effects on offspring in postpartum depression mouse models

Due to the diversity of postpartum depression (PPD) patients and the complexity of associated pathophysiological changes, most current animal models cannot accurately simulate PPD-like symptoms. In this study, we established a reliable animal model for PPD by inducing chronic unpredictable mild stress (CUMS) at different stages (pre-pregnancy, pregnancy, or postnatal) in female mice, followed by maternal separation (MS) from day 2-21 after delivery. The results for female mice subjected to pre-pregnancy stress were not statistically significant due to a lower conception rate. However, female mice exposed to CUMS during either the gestational or postnatal stage, followed by MS, successfully exhibited PPD-like symptoms. The models were deemed effective based on observed behavioral abnormalities, impaired hippocampal neuron functioning, and reduced serum concentrations of neurotransmitters (5-HT, GABA, and NE). Additionally, mice that underwent gestational CUMS followed by MS displayed a more dysfunctional hypothalamic-pituitary-adrenal (HPA) axis and more severe uterine inflammation. The study also investigated the impact of PPD on the behavior and neurodevelopment of adolescent offspring through behavioral tests, enzyme-linked immunosorbent assay (ELISA), hematoxylin-eosin (HE) staining, and western blotting (WB). The results indicated that adolescent offspring of mothers with PPD exhibited behavioral and neurodevelopmental disorders, with male offspring being more susceptible than females. Female mice exposed to both CUMS and MS during the postnatal period had more severe adverse effects on their offspring compared to the other model groups.

Behavioral Animal Models and Neural-Circuit Framework of Depressive Disorder

Depressive disorder is a chronic, recurring, and potentially life-endangering neuropsychiatric disease. According to a report by the World Health Organization, the global population suffering from depression is experiencing a significant annual increase. Despite its prevalence and considerable impact on people, little is known about its pathogenesis. One major reason is the scarcity of reliable animal models due to the absence of consensus on the pathology and etiology of depression. Furthermore, the neural circuit mechanism of depression induced by various factors is particularly complex. Considering the variability in depressive behavior patterns and neurobiological mechanisms among different animal models of depression, a comparison between the neural circuits of depression induced by various factors is essential for its treatment. In this review, we mainly summarize the most widely used behavioral animal models and neural circuits under different triggers of depression, aiming to provide a theoretical basis for depression prevention.

Bibliometric analysis of research in epilepsy and comorbid depression from 2014 to 2023

BACKGROUND

Epilepsy and depression have complicated bidirectional relationships. Our study aimed to explore the field of epilepsy comorbid with depression in a bibliometric perspective from 2014-2023.

AIM

To improve our understanding of epilepsy and depression by evaluating the relationship between epilepsy and depression, bibliometric analyses were performed.

METHODS

Epilepsy and depression-related publications from the last decade were retrieved from the Web of Science Core Collection. We conducted bibliometric and visual analysis using VOSviewer and CiteSpace, examining authorships, countries, institutions, journals of publication, co-citations of references, connections between keywords, clusters of keywords, and keywords with citation bursts.

RESULTS

Over the past ten years, we collected 1045 research papers focusing on the field of epilepsy and comorbid depression. Publications on epilepsy and depression have shown a general upward trend over time, though with some fluctuations. The United States, with 287 articles, and the University of Melbourne, contributing 34 articles, were the top countries and institutions, respectively. In addition, in the field of epilepsy and depression, Professor Lee, who has published 30 articles, was the most contributing author. The hot topics pay attention to the quality of life in patients with epilepsy and depression.

CONCLUSION

We reported that quality of life and stigma in patients with epilepsy comorbid with depression are possible future hot topics and directions in the field of epilepsy and depression research.

Nanomaterial-Based Strategies for Attenuating T-Cell-Mediated Immunodepression in Stroke Patients: Advancing Research Perspectives

This review article discusses the potential of nanomaterials in targeted therapy and immunomodulation for stroke-induced immunosuppression. Although nanomaterials have been extensively studied in various biomedical applications, their specific use in studying and addressing immunosuppression after stroke remains limited. Stroke-induced neuroinflammation is characterized by T-cell-mediated immunodepression, which leads to increased morbidity and mortality. Key observations related to immunodepression after stroke, including lymphopenia, T-cell dysfunction, regulatory T-cell imbalance, and cytokine dysregulation, are discussed. Nanomaterials, such as liposomes, micelles, polymeric nanoparticles, and dendrimers, offer advantages in the precise delivery of drugs to T cells, enabling enhanced targeting and controlled release of immunomodulatory agents. These nanomaterials have the potential to modulate T-cell function, promote neuroregeneration, and restore immune responses, providing new avenues for stroke treatment. However, challenges related to biocompatibility, stability, scalability, and clinical translation need to be addressed. Future research efforts should focus on comprehensive studies to validate the efficacy and safety of nanomaterial-based interventions targeting T cells in stroke-induced immunosuppression. Collaborative interdisciplinary approaches are necessary to advance the field and translate these innovative strategies into clinical practice, ultimately improving stroke outcomes and patient care.

Functional Connectivity Differences in the Resting-state of the Amygdala in Alcohol-dependent Patients with Depression

RATIONALE AND OBJECTIVES

The mechanism of comorbidity between alcohol dependence and depressive disorders are not well understood. This study investigated differences in the brain function of alcohol-dependent patients with and without depression by performing functional connectivity analysis using resting-state functional magnetic resonance imaging.

MATERIALS AND METHODS

A total of 29 alcohol-dependent patients with depression, 31 alcohol-dependent patients without depression and 31 healthy control subjects were included in this study. The resting-state functional connectivity between the amygdala and the whole brain was compared among the three groups. Additionally, we examined the correlation between functional connectivity values in significantly different brain regions and levels of alcohol dependence and depression.

RESULTS

The resting-state functional connectivity between the left amygdala and the right caudate nucleus was decreased in alcohol-dependent patients. Additionally, the resting-state functional connectivity of the right amygdala with the right caudate nucleus, right transverse temporal gyrus, right temporal pole: superior temporal gyrus were also decreased. In alcohol-dependent patients with depression, not only was functional connectivity between the above brain regions significantly decreased, but so was functional connectivity between the right amygdala and the left middle temporal gyrus. Also, there was no significant correlation between the resting-state functional connectivity values in statistically significant brain regions and the levels of alcohol dependence and depression.

CONCLUSION

The impairment of the functional connectivity of the amygdala with caudate nucleus and partial temporal lobe may be involved in the neural mechanism of alcohol dependence comorbidity depressive disorders.

Conjugation of sulpiride with a cell penetrating peptide to augment the antidepressant efficacy and reduce serum prolactin levels

Depression ranks as the fourth most prevalent global disease, with suicide incidents occurring at a younger age. Sulpiride (SUL), an atypical antidepressant drug acting as a dopamine D2 receptor antagonist and possessing anti-inflammatory properties, exhibits limited ability to penetrate the blood brain barrier (BBB). This weak penetration hampers its inhibitory effect on prolactin release in the pituitary gland, consequently leading to hyperprolactinemia. In order to enhance the central nervous system efficacy of sulpiride and reduce serum prolactin levels, we covalently linked sulpiride to VPALR derived from the nuclear DNA repair protein ku70. In vivo study on depressive mice using intraperitoneal injection of VPALR-SUL demonstrated a significant increase in struggle time and total distance compared to those treated with only sulpiride while also reducing serum prolactin concentration. The pharmacokinetic study results showed that VPALR-SUL prolonged half-life and increased bioavailability. In conclusion, VPALR-SUL exhibited potential for enhancing sulpiride transport across the BBB, augmenting its antidepressant effects, and reducing serum prolactin levels. This study laid a foundation for improving sulpiride delivery and developing novel antidepressants.

Immunotherapy for depression: Recent insights and future targets

Depression stands as a prominent contributor to global disability, entailing an elevated risk of suicide. Substantial evidence supports the notion that immune dysregulation may play a role in the development of depression and impede responses to antidepressant treatments. Immune dysregulation may cause depression in susceptible individuals through raising inflammatory responses. Differences in immune cell types and the release of pro-inflammatory mediators are observed in the blood and cerebrospinal fluid of patients with major depressive disorder, which is associated with neuroimmune dysfunction. Therefore, the interaction of peripheral and central immune targets in depression needs to be understood. Urgent attention is required for the development of innovative therapeutics directed at modulating immune responses for the treatment of depression. This review delineates the immune mechanisms involved in the pathogenesis of depression, assesses the therapeutic potential of immune system targeting for depression treatment, and deliberates on the merits and constraints of employing immunotherapy in the management of depression.

NADPH-oxidases as potential pharmacological targets for thrombosis and depression comorbidity

There is a complex interrelationship between the nervous system and the cardiovascular system. Comorbidities of cardiovascular diseases (CVD) with mental disorders, and vice versa, are prevalent. Adults with mental disorders such as anxiety and depression have a higher risk of developing CVD, and people with CVD have an increased risk of being diagnosed with mental disorders. Oxidative stress is one of the many pathways associated with the pathophysiology of brain and cardiovascular disease. Nicotinamide adenine dinucleotide phosphate oxidase (NOX) is one of the major generators of reactive oxygen species (ROS) in mammalian cells, as it is the enzyme that specifically produces superoxide. This review summarizes recent findings on the consequences of NOX activation in thrombosis and depression. It also discusses the therapeutic effects and pharmacological strategies of NOX inhibitors in CVD and brain disorders. A better comprehension of these processes could facilitate the development of new therapeutic approaches for the prevention and treatment of the comorbidity of thrombosis and depression.

Potential Role of Bmal1 in Lipopolysaccharide-Induced Depression-Like Behavior and its Associated "Inflammatory Storm"

Inflammation plays an important role in the pathogenesis of depression; however, the underlying mechanisms remain unclear. Apart from the disordered circadian rhythm in animal models and patients with depression, dysfunction of clock genes has been reported to be involved with the progress of inflammation. This study aimed to investigate the role of circadian clock genes, especially brain and muscle ARNT-like 1 (Bmal1), in the linkage between inflammation and depression. Lipopolysaccharide (LPS)-challenged rats and BV2 cells were used in the present study. Four intraperitoneal LPS injections of 0.5 mg/kg were administered once every other day to the rats, and BV2 cells were challenged with LPS for 24 h at the working concentration of 1 mg/L, with or without the suppression of Bmal1 via small interfering RNA. The results showed that LPS could successfully induce depression-like behaviors and an "inflammatory storm" in rats, as indicated by the increased immobility time in the forced swimming test and the decreased saccharin preference index in the saccharin preference test, together with hyperactivity of the hypothalamic-pituitary-adrenal axis, hyperactivation of astrocyte and microglia, and increased peripheral and central abundance of tumor necrosis factor-α, interleukin 6, and C-reactive protein. Moreover, the protein expression levels of brain-derived neurotrophic factor, triggering receptor expressed on myeloid cells 1, Copine6, and Synaptotagmin1 (Syt-1) decreased in the hippocampus and hypothalamus, whereas the expression of triggering receptor expressed on myeloid cells 2 increased. Interestingly, the fluctuation of temperature and serum concentration of melatonin and corticosterone was significantly different between the groups. Furthermore, protein expression levels of the circadian locomotor output cycles kaput, cryptochrome 2, and period 2 was significantly reduced in the hippocampus of LPS-challenged rats, whereas Bmal1 expression was significantly increased in the hippocampus but decreased in the hypothalamus, where it was co-located with neurons, microglia, and astrocytes. Consistently, apart from the reduced cell viability and increased phagocytic ability, LPS-challenged BV2 cells presented a similar trend with the changed protein expression in the hippocampus of the LPS model rats. However, the pathological changes in BV2 cells induced by LPS were reversed after the suppression of Bmal1. These results indicated that LPS could induce depression-like pathological changes, and the underlying mechanism might be partly associated with the imbalanced expression of Bmal1 and its regulated dysfunction of the circadian rhythm.

Transcutaneous auricular vagus nerve stimulation ameliorates adolescent depressive- and anxiety-like behaviors via hippocampus glycolysis and inflammation response

BACKGROUND

Transcutaneous auricular vagus nerve stimulation (taVNS) is a crucial neuromodulation therapy for depression, yet its molecular mechanism remains unclear. Here, we aim to unveil the underlying mechanisms of antidepression by systematically evaluating the change of gene expression in different brain regions (i.e., hippocampus, anterior cingulate cortex, and medial prefrontal cortex).

METHODS

The adolescent depression rat model was established by chronic unpredictable mild stress (CUMS), followed by the taVNS treatment for 3 weeks. The open field test (OFT), forced swimming test (FST), elevated plus maze test (EPM), and new object recognition (NOR) test were used to evaluate depressive- and anxiety-like behaviors. Gene expression analysis of three brain regions was conducted by RNA sequencing (RNA-seq) and further bioinformatics methods.

RESULTS

The depressive- and anxiety-like behaviors in CUMS-exposed rats were manifested by decreased spontaneous locomotor activity of OFT, increased immobility time of FST, increased entries and time in the closed arms of EPM, and decreased new object index of NOR. Furthermore, CUMS exposure also led to alterations in gene expression within the hippocampus (HIP), anterior cingulate cortex (ACC), and medial prefrontal cortex (mPFC), suggesting a potential link between adolescent stress and pathological changes within these brain regions. TaVNS could significantly ameliorate depressive- and anxiety-like behaviors. Its effects on these three brain regions were found related to regulation of the metabolism, and there were some brain region-specific findings. Compared with ACC and mPFC, taVNS has a more concrete effect on HIP by regulating the inflammation response and glycolysis.

CONCLUSION

taVNS is capable of ameliorating adolescent depressive- and anxiety-like behaviors by regulating plenty of genes in the three brain regions. Suppressed level of inflammatory response and enhanced glycolysis manifests the dominant role of taVNS in HIP, which provides a theoretical foundation and data support for the molecular mechanism of antidepression by taVNS.

The rapid antidepressant effect of acupuncture on two animal models of depression by inhibiting M1-Ach receptors regulates synaptic plasticity in the prefrontal cortex

BACKGROUND

It is unclear whether acupuncture has a rapid antidepressant effect and what is the main mechanism.

METHODS

In this study, forced swimming stress test (FST) in mice were divided into five groups: control group, acupuncture group, scopolamine group, arecoline group, and acupuncture + arecoline group. Chronic unpredictable mild stress (CUMS) model rats were divided into six groups: naïve (non-CUMS) group, CUMS group, acupuncture group, scopolamine group, arecoline group, and acupuncture + arecoline group. Twenty-four hours after the end of treatment, FST was conducted in mice and rats. The expression of M1-AchR, AMPA receptors (GluR1 and GluR2), BDNF, mTOR, p-mTOR, synapsin I, and PSD95 in the prefrontal cortex was determined by western blot. The spine density of neurons in the prefrontal cortex was detected by golgi staining.

RESULTS

The results showed that acupuncture reduced the immobility time of FST in two depression models. Acupuncture inhibited the expression of M1-AchR and promoted the expression of GluR1, GluR2, BDNF, p-mTOR, synapsin I, PSD95, and increased the density of neuron dendritic spine in the prefrontal cortex.

CONCLUSIONS

The rapid antidepressant effect of acupuncture may be activating the "glutamate tide" - AMPA receptor activation - BDNF release - mTORC1 pathway activation through inhibiting the expression of M1-AchR in the prefrontal cortex, thereby increasing the expression of synaptic proteins and regulating synaptic plasticity.

Neuroproteomics: Unveiling the Molecular Insights of Psychiatric Disorders with a Focus on Anxiety Disorder and Depression

Anxiety and depression are two of the most common mental disorders worldwide, with a lifetime prevalence of up to 30%. These disorders are complex and have a variety of overlapping factors, including genetic, environmental, and behavioral factors. Current pharmacological treatments for anxiety and depression are not perfect. Many patients do not respond to treatment, and those who do often experience side effects. Animal models are crucial for understanding the complex pathophysiology of both disorders. These models have been used to identify potential targets for new treatments, and they have also been used to study the effects of environmental factors on these disorders. Recent proteomic methods and technologies are providing new insights into the molecular mechanisms of anxiety disorder and depression. These methods have been used to identify proteins that are altered in these disorders, and they have also been used to study the effects of pharmacological treatments on protein expression. Together, behavioral and proteomic research will help elucidate the factors involved in anxiety disorder and depression. This knowledge will improve preventive strategies and lead to the development of novel treatments.

Smooth muscle contraction of the fundus of stomach, duodenum and bladder from mice exposed to a stress-based model of depression

Several reports have demonstrated that depressive disorder is related to somatic symptoms including gastrointestinal or genitourinary alterations. The pathophysiological mechanisms underlying the gastrointestinal or genitourinary alterations associated with the depression are still not fully understood. Therefore, this study aimed to evaluate the motor activity of gastrointestinal (fundus of stomach and duodenum) and genitourinary tract (bladder) in a stress-based animal model of depression. Adult male mice were submitted to uncontrollable and unpredictable stress (learned helplessness model), controllable stress and non-stressful situations (control). Then, animals were euthanized and the fundus of stomach, duodenum segments or whole bladder were isolated and mounted in a standard organ bath preparation. We evaluated the contractile effects induced by KCl 80 mM for 5 min or carbachol (acetylcholine receptor agonist). The relaxant effects of isoproterenol (β-adrenoceptor agonist) were also checked. Animals submitted to the learned helplessness model developed a helpless (depressive-like behavior) or resilient (does not exhibit depressive-like behavior) phenotype. The contractions induced by carbachol were diminished in fundus of stomach isolated from helpless and resilient animals. The isoproterenol-induced fundus of stomach relaxation was reduced in resilient but not helpless mice. The contractions/relaxation of duodenum segments isolated from helpless or resilient animals were not altered. Both helpless and resilient animals showed an increase in the bladder contractions induced by carbachol while the relaxant effects of isoproterenol were reduced when compared to control. Conversely, mice underwent a controllable stress situation did not exhibit alterations in the fundus of stomach or duodenum contraction/relaxation induced by pharmacological agents although a decrease in the bladder contraction induced by carbachol was found. In conclusion, incontrollable and unpredictable stress and not depressive phenotype (helpless animals) or controllable stress could be related to the alterations in motor activity of the fundus of stomach and bladder.

Neuroinflammation, memory, and depression: new approaches to hippocampal neurogenesis

As one of most common and severe mental disorders, major depressive disorder (MDD) significantly increases the risks of premature death and other medical conditions for patients. Neuroinflammation is the abnormal immune response in the brain, and its correlation with MDD is receiving increasing attention. Neuroinflammation has been reported to be involved in MDD through distinct neurobiological mechanisms, among which the dysregulation of neurogenesis in the dentate gyrus (DG) of the hippocampus (HPC) is receiving increasing attention. The DG of the hippocampus is one of two niches for neurogenesis in the adult mammalian brain, and neurotrophic factors are fundamental regulators of this neurogenesis process. The reported cell types involved in mediating neuroinflammation include microglia, astrocytes, oligodendrocytes, meningeal leukocytes, and peripheral immune cells which selectively penetrate the blood-brain barrier and infiltrate into inflammatory regions. This review summarizes the functions of the hippocampus affected by neuroinflammation during MDD progression and the corresponding influences on the memory of MDD patients and model animals.

Potential value of Interleukin-6 as a diagnostic biomarker in human MDD and the antidepressant effect of its receptor antagonist tocilizumab in lipopolysaccharide-challenged rats

Depression is a common mental disease with disastrous effect on the health and wealth globally. Focusing on the role for inflammation and immune activation in the pathogenesis of depression, many tries have been taken into effect targeting at the blockage of inflammatory cytokines, among which interleukin- 6 (IL-6) and its receptor antagonist tocilizumab attracts more attention, with inconsistent findings. Moderate to severe depressive disorder (MSDD) patients were enrolled and the serum concentrations of IL-6 and tumor necrosis factor-α (TNF-α) measured, their correlation with the Hamilton Depression Rating Scale-24 (HAMD-24) scores was analyzed, and their role in discriminating MSDD patients from the health controls were evaluated. Meanwhile, a depression rat model was established by intraperitoneal injection of LPS, and tocilizumab was administrated doing 50 mg/kg via intravenous injection. The behavioral performance was observed, the serum concentration of IL-6, TNF-α, and C-reactive protein (CRP) was measured, and the protein expression of IL-6 and TNF-α in the hippocampus were also detected. The activity of the Hypothalamic-pituitary-adrenal (HPA) axis was observed, and the protein expression levels in the hippocampus were detected via western blot. Moreover, the immunofluorescence staining (IF) technique was used to investigate the co-location of IL-6 and neuron (MAP2), astrocyte (GFAP), or microglial (IBA-1). The results showed that the serum IL-6 level was significantly increased in the MSDD patients and lipopolysaccharide (LPS)-challenged rats, with a significant correlation with the HAMD-24 scores or struggling time in the FST and corticosterone (CORT) abundance. Results of ROC analysis showed a significant diagnosis value of IL-6 in discriminating MSDD patients or depression rats from the controls in the present study. Tocilizumab could relieve the depression-like behaviors induced by LPS, together with a normal abundance of serum CORT and hypothalamic CRH expression. Moreover, tocilizumab could alleviate the "inflammatory storm" and impaired hippocampal synaptic plasticity in LPS-challenged depression rats, inhibiting the hyperactivation of astrocyte and microglia, decreasing the peripheral and central abundance of IL-6, CRP, and TNF-α, and balancing the hippocampal expression levels of synaptic plasticity-associated proteins and key molecular in Wnt/β-catenin signaling pathway. These results indicated a predictive role of IL-6 in discriminating depression from controls, and demonstrated an antidepressant effect of tocilizumab in LPS-challenged rats, targeting at the inflammatory storm and the subsequent impairments of hippocampal synaptic plasticity.

Cherry leaf decoction inhibits NMDAR expression and thereby ameliorates CUMS- induced depression-like behaviors through downregulation of α2δ-1

Depression is a complex and prevalent mental illness. Cherry leaf is a traditional Chinese herbal medicine, which has confirmed to exert a certain antidepressant effect, but its potential neural regulation mechanism is not clear. This paper aims to investigate the improved action of cherry leaf decoction (CLD) on chronic unpredictable mild stress (CUMS) rats and its potential neural regulation mechanism by verifying the role and function of NMDAR regulatory target α2δ-1 in depression due to CUMS. Male SD rats were subjected to random stressors persisting for 5 weeks to establish the CUMS depression rat model. CLD could effectively alleviate depression-like behaviors of CUMS rats in behavioral tests including sucrose preference test, forced swimming test, tail suspension test and open field test. After the administration of the CLD, the expression of corticotropic-releasing hormone (CRH) in the hypothalamus was inhibited. Moreover, the levels of CRH, adrenal cortical hormone (ACTH) and corticosterone (CORT) in serum also decreased significantly. CUMS upregulated the expressions of α2δ-1, N-methyl-d-aspartate receptor 1 (NR1), NR2A and NR2B, and enhanced the binding ability to of α2δ-1 and NR1, which were reversed by CLD. The results demonstrated that CLD could ameliorate depression-like behaviors due to CUMS, which was related to the fact that CLD down-regulated α2δ-1 level and interfered with α2δ-1 binding to NR1, thereby reducing NMDAR expression and ultimately inhibiting HPA axis activity.

Review of microbiota gut brain axis and innate immunity in inflammatory and infective diseases

The microbiota gut brain (MGB) axis has been shown to play a significant role in the regulation of inflammatory and infective diseases. Exploring the structure and communication mode of MGB axis is crucial for understanding its role in diseases, and studying the signaling pathways and regulatory methods of MGB axis regulation in diseases is also of profound significance for future clinical research. This article reviews the composition, communication mechanism of MGB axis and its role in inflammatory and infective diseases, including Parkinson's disease (PD), Alzheimer's disease (AD), multiple sclerosis (MS), autism spectrum disorder (ASD), depression, psoriasis, irritable bowel syndrome (IBS), and inflammatory bowel diseases (IBD). In addition, our investigation delved into the regulatory functions of the inflammasome, IFN-I, NF-κB, and PARK7/DJ-1 innate immune signaling pathway in the context of inflammatory and infective diseases. Ultimately, we discussed the efficacy of various interventions, including fecal microbiota transplantation (FMT), antibiotics, probiotics, prebiotics, synbiotics, and postbiotics, in the management of inflammatory and infective diseases. Understanding the role and mechanism of the MGB axis might make positive effects in the treatment of inflammatory and infective diseases.

Isochlorogenic acid B alleviates lead-induced anxiety, depression and neuroinflammation in mice by the BDNF pathway

Lead (Pb) can cause neurobehavioral abnormalities. Isochlorogenic acid B (ICAB), a dietary flavonoid found in tea, sweet potato, artichoke, propolis and several plants, exhibited potential neuroprotective properties. In this study, we aimed to investigate the mechanisms of Pb-induced anxiety, depression and neuroinflammation, and the neuroprotective effect of ICAB in mouse brains. We found that ICAB supplementation significantly improved behavioral abnormalities, neuroinflammation and oxidative stress induced by Pb. ICAB attenuated Pb-induced anxiety and depression behavior in mice, as indicated by decreasing the duration of immobility in tail suspension test and increasing the crossing number, rearing number and time in center in open field test. Accordingly, ICAB inhibited oxidative stress by decreasing malondialdehyde (MDA) level and increasing the antioxidant enzyme activity. ICAB also inhibited Pb-induced inflammation in brain, as indicated by decreasing the tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6) levels. ICAB increased the expression levels of brain derived neurotrophic factor (BDNF) and the phosphorylation of cAMP-responsive element binding protein (CREB), phosphoinositide 3-kinases-protein kinase B (PI3K/AKT). Furthermore, ICAB decreased the levels of Toll-like receptor 4 (TLR4), myeloid differentiation factor 88 (MyD88), glycogen synthase kinase-3 beta (GSK-3β) and p38. Collectively, this study demonstrated that ICAB improved Pb-induced anxiety, depression, neuroinflammation and oxidative stress by regulating the BDNF signaling pathway.

Changes of Serum C-Reactive Protein Level in Patients With Depressive Disorders After Treatment With Agomelatine Combined With Aerobic Exercise and Its Significance

OBJECTIVE

Depressive disorders constitute a series of debilitating diseases. This study investigated the therapeutic effect of agomelatine (AG) combined with aerobic exercise (AE) on patients with moderate-severe depression (MSD) and the changes of the serum C-reactive protein (CRP) level in patients after treatment as well as its significance.

METHODS

A total of 178 MSD patients were randomly assigned to the AG group (N = 90) and AG + AE group (N = 88). The severity of depressive disorders and anhedonia was assessed using the Hamilton Rating Scale for Depression (HAM-D), Beck Depression Inventory, and Snaith-Hamilton Pleasure Scale scores. The serum CRP level in MSD patients was detected by turbidity assay. Patients were defined as remitters, responders, and nonresponders according to the HAM-D 17 score, and the treatment efficacy was analyzed, followed by evaluation of the serum CRP level in patients with different treatment responses. Finally, the adverse reactions of patients during treatment were statistically analyzed.

RESULTS

After treatment, the HAM-D, Beck Depression Inventory, and Snaith-Hamilton Pleasure Scale scores and the serum CRP level of the 2 groups were reduced, and changes in the AG + AE group was more significant than that in the AG group. The clinical efficacy of the AG + AE group was better than that of the AG group. After treatment, the serum levels of CRP in remitters and responders were reduced, but not significantly in nonresponders. The incidence of adverse events in the AG + AE group was lower than that in the AG group.

CONCLUSION

AG + AE reduced the serum level of CRP in MSD patients and had good therapeutic effects on MSD patients.

Chronic social comparison elicits depression- and anxiety-like behaviors and alterations in brain-derived neurotrophic factor expression in male rats

Social comparison is a fundamental human characteristic; however, long-term social comparison may induce psychological stress and can lead to depression and anxiety. Recent studies have shown that nonhuman primates compare themselves with others; however, no studies have investigated whether social comparisons exist among rodents. In the present study, we established a rat model of social comparison. This model was subsequently used to examine the effects of the differential environment of a partner on depression- and anxiety-like behaviors in male rats, as well as to assess the changes in serum, medial prefrontal cortex (mPFC), and dorsal hippocampus brain-derived neurotrophic factor (BDNF) levels induced by long-term social comparison. Compared to rats whose partners were exposed to the same environment, rats whose partners were exposed to two combined enriched environmental stimuli for 14 days showed significantly decreased social novelty preference and sucrose consumption. No anxiety-like behaviors were observed. Rats whose partners were exposed to one enriched environment for 31 days showed significantly increased immobility time in the forced swimming test, and significantly decreased time spent in the center area in the open-field test. Further, rats whose partners were exposed to one enriched environment for 31 days showed lower BDNF levels in the mPFC and dorsal hippocampus, but not following partner exposure for 14 days. These results suggest that social comparisons exist in rats and can induce psychosocial stress and other negative affect. This model will not only provide the possibility to reveal the neurobiological basis of the emotional impact of social comparison, but could also be used to confirm the conservative evolutionary characteristics of social comparison as a behavioral attribute.

Sex difference in prebiotics on gut and blood-brain barrier dysfunction underlying stress-induced anxiety and depression

BACKGROUND

Most of the previous studies have demonstrated the potential antidepressive and anxiolytic role of prebiotic supplement in male subjects, yet few have females enrolled. Herein, we explored whether prebiotics administration during chronic stress prevented depression-like and anxiety-like behavior in a sex-specific manner and the mechanism of behavioral differences caused by sex.

METHODS

Female and male C57 BL/J mice on normal diet were supplemented with or without a combination of fructo-oligosaccharides (FOS) and galacto-oligosaccharides (GOS) during 3- and 4-week chronic restraint stress (CRS) treatment, respectively. C57 BL/J mice on normal diet without CRS were used as controls. Behavior consequences, gut microbiota, dysfunction of gut and brain-blood barriers, and inflammatory profiles were measured.

RESULTS

In the 3rd week, FOS + GOS administration attenuated stress-induced anxiety-like behavior in female, but not in male mice, and the anxiolytic effects in males were observed until the 4th week. However, protective effects of prebiotics on CRS-induced depression were not observed. Changes in the gene expression of tight junction proteins in the distal colon and hippocampus, and decreased number of colon goblet cells following CRS were restored by prebiotics only in females. In both female and male mice, prebiotics alleviated stress-induced BBB dysfunction and elevation in pro-inflammatory cytokines levels, and modulated gut microbiota caused by stress. Furthermore, correlation analysis revealed that anxiety-like behaviors were significantly correlated with levels of pro-inflammatory cytokines and gene expression of tight junction proteins in the hippocampus of female mice, and the abundance of specific gut microbes was also correlated with anxiety-like behaviors, pro-inflammatory cytokines, and gene expression of tight junction proteins in the hippocampus of female mice.

CONCLUSION

Female mice were more vulnerable to stress and prebiotics than males. The gut microbiota, gut and blood-brain barrier, and inflammatory response may mediate the protective effects of prebiotics on anxiety-like behaviors in female mice.

Cardamom oil ameliorates behavioral and neuropathological disorders in a rat model of depression induced by reserpine

ETHNOPHARMACOLOGICAL RELEVANCE

Depression is a public health problem. Despite the availability of treatment options, its prevalence is increasing. A high rate of treatment failure is often reported, along with considerable side effects associated with synthetic antidepressants. Therefore, developing effective and safe antidepressants from traditional herbs or natural products as an alternative strategy is warranted to avoid side effects and increase drug efficacy. In traditional medicine, cardamom has traditionally been used to treat conditions like asthma, tooth and gum infections, cataracts, nausea, diarrhea, and even depression and anxiety as well as some problems with the heart, kidneys, and digestive system.

AIM OF THE STUDY

The current study aimed to evaluate the antidepressant activity of cardamom oil in a rat model of depression induced by reserpine and compare it with the activity of the antidepressant drug fluoxetine.

MATERIALS AND METHODS

Depression-like symptoms were induced in male rats by daily i. p. injection of reserpine (0.2 mg/kg/d for 15 d followed by 0.1 mg/kg/d for 21 d to maintain the depressive state), and the rats were treated with cardamom oil (oral dose = 200 mg/kg/d) for 21 d along with the maintenance dose of reserpine. We performed behavioral tests (forced swimming test and open-field test) and evaluated biochemical markers of depression.

RESULTS

Our findings revealed that cardamom oil attenuated depression-like symptoms in reserpine-injected rats by improving the behavioral changes measured by the forced swimming test and the locomotor activities measured by the open-field test. In reserpine-injected rats, cardamom oil exerted antidepressant-like effects by modulating lower levels of brain monoamine neurotransmitters (serotonin, norepinephrine, and dopamine), GSH, and higher oxido-nitrosative stress parameters (malondialdehyde and nitric oxide). Moreover, cardamom oil alleviated depression-like behaviors by lowering monoamine oxidase activity and raising the activities of Na⁺/K⁺-ATPase and acetylcholinesterase and levels of a brain-derived neurotrophic factor in the cortex and hippocampus.

CONCLUSION

We recommend the use of cardamom oil as a safe and reliable treatment or an adjuvant for preventing depression-like symptoms in patients suffering from depression.

Transcriptome comparative analysis of amygdala-hippocampus in depression: A rat model induced by chronic unpredictable mild stress (CUMS)

BACKGROUND

Depression is a common and complex mental disease, and its pathogenesis involves several brain regions. Abnormalities in the amygdala-hippocampal neural circuits have been shown to be involved in depression. However, the underlying molecular mechanisms remain unclear.

METHODS

A rat model was used to determine the transcriptome changes in the amygdala-hippocampal neural network under chronic unpredictable mild stress (CUMS). Depression-related modules in this neural network were identified using weighted gene co-expression network analysis (WGCNA). Difference and enrichment analyses were used to determine differential gene expression in the two brain regions.

RESULTS

The modules in the amygdala and hippocampus associated with depression-like behavior contained 363 and 225 genes, respectively. Forty-two differentially expressed genes were identified in the amygdala candidate module and 37 in the hippocampus. Enrichment analysis showed that candidate genes in the amygdala were associated with neuronal myelination and candidate genes in the hippocampus were associated with synaptic transmission. Finally, based on module hub gene statistics, differential gene expression, and protein-protein interaction networks, 11 central genes were found in the amygdala candidate module, and one central gene was found in the hippocampal module.

LIMITATIONS

Our study was based on a rat CUMS model. Further evidence is needed to prove that our results are applicable to patients with depression.

CONCLUSION

This study identified critical modules and central genes involved in the amygdala-hippocampal circuit in the context of depression, and may provide further understanding of the pathogenesis of depression and help identify potential targets for antidepressant therapy.

The Role of Gasotransmitter-Dependent Signaling Mechanisms in Apoptotic Cell Death in Cardiovascular, Rheumatic, Kidney, and Neurodegenerative Diseases and Mental Disorders

Cardiovascular, rheumatic, kidney, and neurodegenerative diseases and mental disorders are a common cause of deterioration in the quality of life up to severe disability and death worldwide. Many pathological conditions, including this group of diseases, are based on increased cell death through apoptosis. It is known that this process is associated with signaling pathways controlled by a group of gaseous signaling molecules called gasotransmitters. They are unique messengers that can control the process of apoptosis at different stages of its implementation. However, their role in the regulation of apoptotic signaling in these pathological conditions is often controversial and not completely clear. This review analyzes the role of nitric oxide (NO), carbon monoxide (CO), hydrogen sulfide (H₂S), and sulfur dioxide (SO₂) in apoptotic cell death in cardiovascular, rheumatic, kidney, and neurodegenerative diseases. The signaling processes involved in apoptosis in schizophrenia, bipolar, depressive, and anxiety disorders are also considered. The role of gasotransmitters in apoptosis in these diseases is largely determined by cell specificity and concentration. NO has the greatest dualism; scales are more prone to apoptosis. At the same time, CO, H₂S, and SO₂ are more involved in cytoprotective processes.

StressMatic: A Novel Automated System to Induce Depressive- and Anxiety-like Phenotype in Rats

Major depressive disorder (MDD) is a multidimensional psychiatric disorder that is estimated to affect around 350 million people worldwide. Generating valid and effective animal models of depression is critical and has been challenging for neuroscience researchers. For preclinical studies, models based on stress exposure, such as unpredictable chronic mild stress (uCMS), are amongst the most reliable and used, despite presenting concerns related to the standardization of protocols and time consumption for operators. To overcome these issues, we developed an automated system to expose rodents to a standard uCMS protocol. Here, we compared manual (uCMS) and automated (auCMS) stress-exposure protocols. The data shows that the impact of the uCMS exposure by both methods was similar in terms of behavioral (cognition, mood, and anxiety) and physiological (cell proliferation and endocrine variations) measurements. Given the advantages of time and standardization, this automated method represents a step forward in this field of preclinical research.

Postsynaptic Proteins at Excitatory Synapses in the Brain—Relationship with Depressive Disorders

Depressive disorders (DDs) are an increasingly common health problem that affects all age groups. DDs pathogenesis is multifactorial. However, it was proven that stress is one of the most important environmental factors contributing to the development of these conditions. In recent years, there has been growing interest in the role of the glutamatergic system in the context of pharmacotherapy of DDs. Thus, it has become increasingly important to explore the functioning of excitatory synapses in pathogenesis and pharmacological treatment of psychiatric disorders (including DDs). This knowledge may lead to the description of new mechanisms of depression and indicate new potential targets for the pharmacotherapy of illness. An excitatory synapse is a highly complex and very dynamic structure, containing a vast number of proteins. This review aimed to discuss in detail the role of the key postsynaptic proteins (e.g., NMDAR, AMPAR, mGluR5, PSD-95, Homer, NOS etc.) in the excitatory synapse and to systematize the knowledge about changes that occur in the clinical course of depression and after antidepressant treatment. In addition, a discussion on the potential use of ligands and/or modulators of postsynaptic proteins at the excitatory synapse has been presented.

Olfactory loss is a predisposing factor for depression, while olfactory enrichment is an effective treatment for depression

The loss of olfactory stimulation correlates well with at least 68 widely differing neurological disorders, including depression, and we raise the possibility that this relationship may be causal. That is, it seems possible that olfactory loss makes the brain vulnerable to expressing the symptoms of these neurological disorders, while daily olfactory enrichment may decrease the risk of expressing these symptoms. This situation resembles the cognitive reserve that is thought to protect people with Alzheimer’s neuropathology from expressing the functional deficit in memory through the cumulative effect of intellectual stimulation. These relationships also resemble the functional response of animal models of human neurological disorders to environmental enrichment, wherein the animals continue to have the induced neuropathology, but do not express the symptoms as they do in a standard environment with restricted sensorimotor stimulation.

Antidepressant Effect of Neuropeptide Y in Models of Acute and Chronic Stress

The search for potential effective antidepressants with minimal side effects is necessary. Peptides are possible applicants for this role. We investigated the antidepressant effect of neuropeptide Y (NY), alone and in combination with clomipramine, in models of acute and chronic stress induced by ultrasound of variable frequencies. Rats were divided into the following groups: the control group, stress group, and stress groups with intranasal administration of NY (100 μg/kg) or clomipramine (7.5 mg/kg), or their combination. Rat behavior was evaluated using a sucrose preference test and forced swimming test in an acute stress model, and a sucrose preference test, forced swimming test, social interaction test, open field test, and Morris water maze test in a chronic stress model. The results of our experiment demonstrated a protective effect of intranasal NY in a model of acute stress, which was comparable to the antidepressant effect of clomipramine. When the same dose was chronically administered, NY also demonstrated an antidepressant action, although expressed in a lesser degree than clomipramine. The combination of NY and clomipramine was much less effective in the chronic stress paradigm compared to the separated drug administration, but was just as effective in the acute stress paradigm. Until now, there was no convincing evidence for the efficacy of the chronic administration of neuropeptide Y; we demonstrated its effectiveness in the animal model of depressive-like behavior. However, our hypothesis that neuropeptide Y can enhance the effect of a classical antidepressant was not confirmed.

Pharmacological activities and pharmacokinetics of liquiritin: A review

ETHNOPHARMACOLOGICAL RELEVANCE

Liquiritin is a flavonoid derived from Radix et Rhizoma Glycyrrhizae, which is a widely used traditional Chinese medicine with the effects of invigorating spleen qi, clearing heat, resolving toxins, and dispelling phlegm to stop coughs.

AIM OF THE STUDY

In this review,the pharmacokinetics and pharmacological activities of liquiritin have been summarized.

MATERIALS AND METHODS

The information on liquiritin up to 2021 was collected from PubMed, Web of Science, Springer Link, and China National Knowledge Infrastructure databases. The key words were "liquiritin", "nerve", "tumor", "cardiac", etc. RESULTS: The absorption mechanism of liquiritin conforms to the passive diffusion and first-order kinetics while with low bioavailability. Liquiritin can penetrate the blood-brain-barrier. Besides, liquiritin displays numerous pharmacological effects including anti-Alzheimer's disease, antidepressant, antitumor, anti-inflammatory, cardiovascular protection, antitussive, hepatoprotection, and skin protective effects. In addition, the novel preparations, new pharmacological effects,and cdusafty of liquiritin are also discussed in this review.

CONCLUSION

This review provides a comprehensive state of knowledge on the pharmacokinetics and pharmacological activities of liquiritin, and makes a forecast for its research directions and applications in clinic.

Integrative multi-omics landscape of fluoxetine action across 27 brain regions reveals global increase in energy metabolism and region-specific chromatin remodelling

Depression and anxiety are major global health burdens. Although SSRIs targeting the serotonergic system are prescribed over 200 million times annually, they have variable therapeutic efficacy and side effects, and mechanisms of action remain incompletely understood. Here, we comprehensively characterise the molecular landscape of gene regulatory changes associated with fluoxetine, a widely-used SSRI. We performed multimodal analysis of SSRI response in 27 mammalian brain regions using 310 bulk RNA-seq and H3K27ac ChIP-seq datasets, followed by in-depth characterisation of two hippocampal regions using single-cell RNA-seq (20 datasets). Remarkably, fluoxetine induced profound region-specific shifts in gene expression and chromatin state, including in the nucleus accumbens shell, locus coeruleus and septal areas, as well as in more well-studied regions such as the raphe and hippocampal dentate gyrus. Expression changes were strongly enriched at GWAS loci for depression and antidepressant drug response, stressing the relevance to human phenotypes. We observed differential expression at dozens of signalling receptors and pathways, many of which are previously unknown. Single-cell analysis revealed stark differences in fluoxetine response between the dorsal and ventral hippocampal dentate gyri, particularly in oligodendrocytes, mossy cells and inhibitory neurons. Across diverse brain regions, integrative omics analysis consistently suggested increased energy metabolism via oxidative phosphorylation and mitochondrial changes, which we corroborated in vitro; this may thus constitute a shared mechanism of action of fluoxetine. Similarly, we observed pervasive chromatin remodelling signatures across the brain. Our study reveals unexpected regional and cell type-specific heterogeneity in SSRI action, highlights under-studied brain regions that may play a major role in antidepressant response, and provides a rich resource of candidate cell types, genes, gene regulatory elements and pathways for mechanistic analysis and identifying new therapeutic targets for depression and anxiety.