Attenuation of Chronic Stress-Induced Depressive-like Symptoms by Fish Oil via Alleviating Neuroinflammation and Impaired Tryptophan Metabolism in Aging Rats

Harmonizing the inner orchestra: the impact of urbanization and evolution of stress, inflammation, diet, and lifestyles in depression

PURPOSE OF REVIEW

This review explores the intersection of urbanization, stress, inflammation, diet, lifestyle changes, and digital evolution as key factors influencing depression, emphasizing the necessity for integrative and evolutionary perspectives in mental health and intervention.

RECENT FINDINGS

Epidemiological studies reveal a dramatic increase in common mental disorders, particularly depression, alongside parallel increases in suicide, unemployment, and divorce rates. Evolutionary perspectives suggest that mechanisms once advantageous for survival, such as stress responses and inflammatory processes, may contribute to mental health challenges in modern urban environments. Moreover, the mental health crisis among generation Z underscores the impact of digital evolution, where the shift from play-based to phone-based childhood contributes significantly to rising depression rates. Recent research highlights the significant role of omega-3 fatty acids, circadian rhythm regulation, mindfulness, and anti-inflammatory lifestyle interventions in mitigating depressive symptoms.

SUMMARY

The interplay between our evolutionary heritage and rapid societal changes has created a "symphony" of factors contributing to depression. Understanding these evolutionary mismatches in stress responses, inflammatory processes, dietary shifts, circadian disruptions, and digitalization provides new insights into the etiology of depression. This holistic approach, conceptualized as "harmonizing the inner orchestra," offers promising avenues for prevention and treatment strategies that address the multifaceted nature of depression in our modern world.

Novel insights into dietary bioactive compounds and major depressive disorders: evidence from animal studies and future perspectives

Clinical depression, including major depressive disorder (MDD), is a chronic mental illness characterized by persistent sadness and indifference. Depression is associated with neuroinflammation, oxidative stress, and neuronal apoptosis in the brain, resulting in microglial overactivation, decreased neuronal and glial proliferation, monoamine depletion, structural abnormalities, and aberrant biochemical activity via the hypothalamic-pituitary-adrenal axis. Recent studies have exhibited the role of dietary bioactive compounds in the mitigation of MDD progression. Here, in this narrative review, we reported the effects of commonly consumed bioactive compounds (curcumin, saffron, garlic, resveratrol, omega-3 fatty acids, ginger, blueberry, tea, and creatine) on MDD and MDD-related neuroinflammation and oxidative stress. The evidence reviewed here is almost exclusively from animal studies and strongly suggest that these commonly consumed bioactive compounds have anti-MDD effects as shown in anti-depression-like behaviors, such as increased immobility, sucrose preference, and social interaction. Based on the literature/studies reviewed, the proposed molecular mechanisms include (i) the reduction of neuroinflammation activation and oxidative stress, (ii) the enhancement of anti-inflammatory and anti-oxidant properties, (iii) the reduction of monoamine oxidase-A production, and (iv) the elevation of brain-derived neurotropic factor and neurogenesis. In the future, dietary bioactive compounds on clinical randomized controlled trials are warranted to confirm the findings of preclinical efficacies using bioactive compounds in individuals with MDD.

Xiao-Chai-Hu-Tang Ameliorates Depressive Symptoms via Modulating Neuro-Endocrine Network in Chronic Unpredictable Mild Stress-Induced Mice

OBJECTIVE

Xiao-Chai-Hu-Tang (XCHT) has been demonstrated to exert an antidepressant effect during long-term clinical practices. However, the potential mechanisms of XCHT remain unknown. This study aims to investigate the effect of XCHT on chronic unpredictable mild stress-induced mice with depressive-like behaviors and to explore the underlying mechanisms.

METHODS

The active compositions and potential related targets of XCHT in the brain were obtained through UPLC-Q-TOF-MS, network pharmacology, and bioinformatics analyses, verified by experimental validation. Then, the protein-protein interaction (PPI), Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses, and molecular docking were used to predict the core targets and mechanisms of XCHT on depression. After being treated with XCHT standard decoction, based on enzyme-linked immunosorbent assay (ELISA), non-targeted metabolism, targeted LC-MS analyses, RNA-seq, quantitative RT-PCR, immunofluorescence, and western blotting were determined to clarify the mechanism of XCHT in the treatment of anxiety and depression disorder.

RESULTS

In total, 166 active ingredients and 525 related targets of XCHT were detected and selected from the network databases. The inflammatory response and metabolism of neurotransmitters were the main related signaling pathways predicted by KEGG enrichment analyses. Behavioral testing shows that XCHT has antidepressant effects, and untargeted metabolomic studies showed it significantly reduced levels of the neurotoxic substance quinoline acid. Combining the results of molecular docking, RNA-seq, and western blot revealed that XCHT regulated nerve regeneration via BDNF/TrkB/CREB and PI3K/AKT signaling pathways. Immunofluorescence analysis revealed that XCHT downregulated the chronic stress-induced activation of microglia and astrocytes in the hippocampus.

CONCLUSION

XCHT exerts antidepressant functions by modulating neuroinflammation and neuroregeneration.

Ginsenoside Rk3 Regulates Tryptophan Metabolism along the Brain-Gut Axis by Targeting Tryptophan Hydroxylase and Remodeling the Intestinal Microenvironment to Alleviate Depressive-Like Behavior in Mice

Depression is a neuropsychiatric disease that significantly impacts the physical and mental health of >300 million people worldwide and places a major burden on society. Ginsenosides are the main active ingredient in ginseng and have been proven to have various pharmacological effects on the nervous system. Herein, we investigated the antidepressant effect of ginsenoside Rk3 and its underlying mechanism in a murine model of depression. Rk3 significantly improved depression-like behavior in mice, ameliorated the disturbance of the hypothalamus-pituitary-adrenal axis, and alleviated neuronal damage in the hippocampus and prefrontal cortex of mice. Additionally, Rk3 improved the abnormal metabolism of tryptophan in brain tissue by targeting tryptophan hydroxylase, thereby reducing neuronal apoptosis and synaptic structural damage in the mouse hippocampus and prefrontal cortex. Furthermore, Rk3 reshaped the composition of the gut microbiota of mice and regulated intestinal tryptophan metabolism, which alleviated intestinal barrier damage. Thus, this study provides valuable insights into the role of Rk3 in the tryptophan metabolic cycle along the brain-gut axis, suggesting that Rk3 may have the potential for treating depression.

Gut microbiota promotes macrophage M1 polarization in hepatic sinusoidal obstruction syndrome via regulating intestinal barrier function mediated by butyrate

BACKGROUND

The intestinal-liver axis is associated with various liver diseases. Here, we verified the role of the gut microbiota and macrophage activation in the progression of pyrrolizidine alkaloids-induced hepatic sinusoidal obstruction syndrome (PA-HSOS), and explored the possible mechanisms and new treatment options.

METHODS

The HSOS murine model was induced by gavage of monocrotaline (MCT). An analysis of 16S ribosomal DNA (16S rDNA) of the feces was conducted to determine the composition of the fecal microbiota. Macrophage clearance, fecal microbiota transplantation (FMT), and butyrate supplementation experiments were used to assess the role of intestinal flora, gut barrier, and macrophage activation and to explore the relationships among these three variables.

RESULTS

Activated macrophages and low microflora diversity were observed in HSOS patients and murine models. Depletion of macrophages attenuated inflammatory reactions and apoptosis in the mouse liver. Moreover, compared with control-FMT mice, the exacerbation of severe liver injury was detected in HSOS-FMT mice. Specifically, butyrate fecal concentrations were significantly reduced in HSOS mice, and administration of butyrate could partially alleviated liver damage and improved the intestinal barrier in vitro and in vivo. Furthermore, elevated lipopolysaccharides in the portal vein and high proportions of M1 macrophages in the liver were also detected in HSOS-FMT mice and mice without butyrate treatment, which resulted in severe inflammatory responses and further accelerated HSOS progression.

CONCLUSIONS

These results suggested that the gut microbiota exacerbated HSOS progression by regulating macrophage M1 polarization via altered intestinal barrier function mediated by butyrate. Our study has identified new strategies for the clinical treatment of HSOS.

Melatonin Ameliorates Neuropsychiatric Behaviors, Gut Microbiome, and Microbiota-Derived Metabolites in Rats with Chronic Sleep Deprivation

With the increasing prevalence of sleep deprivation (SD)-related disorders, the effective treatment of sleep disorders has become a critical health research topic. Thus, we hypothesized and investigated the effectiveness of a 3-week melatonin intervention on neuropsychiatric behavioral responses mediated throughout melatonin receptors, gut microbiota, and lipid metabolites in rats with chronic SD. Eighteen 6-week-old Wistar rats were used and divided into the control grup (C, n = 6), SD group (n = 6), and melatonin-supplemented group (SDM, n = 6). During weeks 0 to 6, animals were provided with the AIN-93M diet and free access to water. Four-week chronic SD was conducted from weeks 7 to 10. Exogenous melatonin administration (10 mg/kg BW) was injected intraperitoneally 1 h before the daily administration of SD for 3 weeks in the SDM group. SD rats exhibited anxiety-like behavior, depression-like behavior, and cognitive impairment. Exogenous melatonin administration ameliorated neuropsychiatric behaviors induced by chronic SD. Analysis of fecal metabolites indicated that melatonin may influence brain messaging through the microbiota-gut-brain axis by increasing the production of short-chain fatty acids (SCFA) and decreasing the production of secondary bile acids (SBA). Four-week SD reduced the cerebral cortex expression of MT1, but not in the colon. Chronic SD led to anxiety and depression-like behaviors and cognitive decline, as well as the reduced intestinal level of SCFAs and the enhanced intestinal level of SBAs in rats. In this work, we confirmed our hypothesis that a 3-week melatonin intervention on neuropsychiatric behavioral response mediated throughout melatonin receptors, gut microbiota, and lipid metabolites in rats with chronic SD.