Role of PPAR-Allopregnanolone Signaling in Behavioral and Inflammatory Gut-Brain Axis Communications

The Ferroptosis-Mitochondrial Axis in Depression: Unraveling the Feedforward Loop of Oxidative Stress, Metabolic Homeostasis Dysregulation, and Neuroinflammation

Emerging evidence links ferroptosis-mitochondrial dysregulation to depression pathogenesis through an oxidative stress-energy deficit-neuroinflammation cycle driven by iron overload. This study demonstrates that iron accumulation initiates ferroptosis via Fenton reaction-mediated lipid peroxidation, compromising neuronal membrane integrity and disabling the GPx4 antioxidant system. Concurrent mitochondrial complex I/IV dysfunction impairs ATP synthesis, creating an AMPK/mTOR signaling imbalance and calcium dyshomeostasis that synergistically impair synaptic plasticity. Bidirectional crosstalk emerges: lipid peroxidation derivatives oxidize mitochondrial cardiolipin, while mitochondrial ROS overproduction activates ACSL4 to amplify ferroptotic susceptibility, forming a self-reinforcing neurodegenerative loop. Prefrontal-hippocampal metabolomics reveal paradoxical metabolic reprogramming with glycolytic compensation suppressing mitochondrial biogenesis (via PGC-1α/TFAM downregulation), trapping neurons in bioenergetic crisis. Clinical data further show that microglial M1 polarization through cGAS-STING activation sustains neuroinflammation via IL-6/TNF-α release. We propose a "ferroptosis-mitochondrial fragmentation-metabolic maladaptation" triad as mechanistic subtyping criteria for depression. Preclinical validation shows that combinatorial therapy (iron chelators + SIRT3 agonists) rescues neuronal viability by restoring mitochondrial integrity and energy flux. This work shifts therapeutic paradigms from monoaminergic targets toward multimodal strategies addressing iron homeostasis, organelle dynamics, and metabolic vulnerability-a framework with significant implications for developing neuroprotective antidepressants.

From bugs to brain: unravelling the GABA signalling networks in the brain-gut-microbiome axis

Convergent data across species paint a compelling picture of the critical role of the gut and its resident microbiota in several brain functions and disorders. The chemicals mediating communication along these sophisticated highways of the brain-gut-microbiome (BGM) axis include both microbiota metabolites and classical neurotransmitters. Amongst the latter, GABA is fundamental to brain function, mediating most neuronal inhibition. Until recently, GABA's role and specific molecular targets in the periphery within the BGM axis had received limited attention. Yet, GABA is produced by neuronal and non-neuronal elements of the BGM, and recently, GABA-modulating bacteria have been identified as key players in GABAergic gut systems, indicating that GABA-mediated signalling is likely to transcend physiological boundaries and species. We review the available evidence to better understand how GABA facilitates the integration of molecularly and functionally disparate systems to bring about overall homeostasis and how GABA perturbations within the BGM axis can give rise to multi-system medical disorders, thereby magnifying the disease burden and the challenges for patient care. Analysis of transcriptomic databases revealed significant overlaps between GABAAR subunits expressed in the human brain and gut. However, in the gut, there are notable expression profiles for a select number of subunits that have received limited attention to date but could be functionally relevant for BGM axis homeostasis. GABAergic signalling, via different receptor subtypes, directly regulates BGM homeostasis by modulating the excitability of neurons within brain centres responsible for gastrointestinal (GI) function in a sex-dependent manner, potentially revealing mechanisms underlying the greater prevalence of GI disturbances in females. Apart from such top-down regulation of the BGM axis, a diverse group of cell types, including enteric neurons, glia, enteroendocrine cells, immune cells and bacteria, integrate peripheral GABA signals to influence brain functions and potentially contribute to brain disorders. We propose several priorities for this field, including the exploitation of available technologies to functionally dissect components of these GABA pathways within the BGM, with a focus on GI and brain-behaviour-disease. Furthermore, in silico ligand-receptor docking analyses using relevant bacterial metabolomic datasets, coupled with advances in knowledge of GABAAR 3D structures, could uncover new ligands with novel therapeutic potential. Finally, targeted design of dietary interventions is imperative to advancing their therapeutic potential to support GABA homeostasis across the BGM axis.

The role of short-chain fatty acid in metabolic syndrome and its complications: focusing on immunity and inflammation

Metabolic syndrome (Mets) is an important contributor to morbidity and mortality in cardiovascular, liver, neurological, and reproductive diseases. Short-chain fatty acid (SCFA), an organismal energy donor, has recently been demonstrated in an increasing number of studies to be an important molecule in ameliorating immuno-inflammation, an important causative factor of Mets, and to improve lipid distribution, blood glucose, and body weight levels in animal models of Mets. This study reviews recent research advances on SCFA in Mets from an immune-inflammatory perspective, including complications dominated by chronic inflammation, as well as the fact that these findings also contribute to the understanding of the specific mechanisms by which gut flora metabolites contribute to metabolic processes in humans. This review proposes an emerging role for SCFA in the inflammatory Mets, followed by the identification of major ambiguities to further understand the anti-inflammatory potential of this substance in Mets. In addition, this study proposes novel strategies to modulate SCFA for the treatment of Mets that may help to mitigate the prognosis of Mets and its complications.

Alterations in fecal bacteriome virome interplay and microbiota-derived dysfunction in patients with schizophrenia

Rising studies have consistently reported gut bacteriome alterations in schizophrenia (SCZ). However, little is known about the role of the gut virome on shaping the gut bacteriome in SCZ. Here in, we sequenced the fecal virome, bacteriome, and host peripheral metabolome in 49 SCZ patients and 49 health controls (HCs). We compared the gut bacterial community composition and specific abundant bacteria in SCZ patients and HCs. Specific gut viruses and host peripheral metabolites co-occurring with differential bacteria were identified using Multiple Co-inertia Analysis (MCIA). Additionally, we construct a latent serial mediation model (SMM) to investigate the effect of the gut virome on SCZ through the bacteriome and host metabolic profile. SCZ patients exhibited a decreased gut bacterial β-diversity compared to HCs, with seven differentially abundant bacteria, including Coprobacillaceae, Enterococcaceae etc. Gut viruses including Suoliviridae and Rountreeviridae, co-occur with these SCZ-related bacteria. We found that the viral-bacterial transkingdom correlations observed in HCs were dramatically lost in SCZ. The altered correlations profile observed in SCZ may impact microbiota-derived peripheral metabolites enriched in the bile acids pathway, eicosanoids pathway, and others, contributing to host immune dysfunction and inflammation. The SMM model suggested potential causal chains between gut viruses and SCZ, indicating that the effect of gut virome on SCZ is significantly mediated by bacteriome and metabolites. In conclusion, these findings provide a comprehensive perspective on the role of gut microbiota in the pathogenesis of SCZ. They reveal that patients with schizophrenia harbor an abnormal virome-bacteriome ecology, shedding light on the potential development of microbial therapeutics.

Trends in research on novel antidepressant treatments

Mood disorders, such as major depressive disorder and bipolar disorder, are among the most common mental illnesses and a leading cause of disability worldwide. Key symptoms of these conditions include a depressed mood or anhedonia, sleep and psychomotor disturbances, changes in appetite or weight, and fatigue or loss of energy. Prolonged cognitive disturbances further impair the ability to think or concentrate and are often accompanied by persistent feelings of worthlessness or excessive guilt. Collectively, these symptoms underscore depression as a serious, long-term global health issue. In addition, clinical studies indicate a growing number of patients experiencing difficulties in responding to treatment, even in the long term. This phenomenon poses significant challenges for healthcare professionals, families, and patients alike. As a result, there is an urgent need for therapies that are both rapid-acting and safe. This review aims to summarize the prevailing trends in research on novel antidepressants, emphasizing their diversity and multi-directional mechanisms of action. The development of rapid-acting drugs is increasingly focused on achieving high efficacy, particularly for treatment-resistant depression. Such advances offer the potential for rapid therapeutic effects without the prolonged and often tedious administration of older generation antidepressants. Findings from studies using animal models of depression continue to play a crucial role in predicting and designing new therapeutic strategies. These models remain indispensable for understanding the physiological effects of newly developed compounds, thereby guiding the creation of innovative treatments.

CXCR4 influences PUFA desaturation and oxidative stress injury in experimental prostatitis mice by activating Fads2 via PPARγ

Chronic prostatitis-induced excessive inflammation and oxidative stress (OS) damage substantially affect men's quality of life. However, its treatment remains a major clinical challenge. Therefore, the identification of drugs that can decrease chronic prostatitis and oxidative stress targets is urgent and essential. CXCR4 is a classic chemokine receptor that is crucially associated with the occurrence and development of inflammation. This investigation aimed to elucidate how CXCR4 affects prostatitis regression and progression. The effect of CXCR4 on chronic prostatitis was evaluated by HE staining, immunohistochemistry, immunofluorescence, PCR, and TUNEL analyses. Furthermore, CXCR4 influence on metabolism was also evaluated by monitoring body weight, body temperature, food intake, and LC/MS. Additionally, chromatin immunoprecipitation, Western blot, and double luciferase reporter gene assays were carried out to elucidate the mechanism by which CXCR4 modulates Fads2 transcription by PPARγ. Lastly, ROS, DHE, mito-tracker, and ATP were utilized to validate the α-linolenic acid's protective effect against OS in prostate epithelial cells. It was revealed that the inhibition of CXCR4 can effectively alleviate prostatitis in mice. Furthermore, downregulating CXCR4 expression can markedly reduce the inflammatory cell infiltration in mouse prostates, decrease the elevated levels of DNA damage markers,MDA and 4-HNE, and mitigate apoptosis of prostatic epithelial cells. Moreover, treatment of CXCR4 knockdown mice with a PPARγ inhibitor revealed different degrees of changes in the above phenotypes. Mechanistically, the PPARγ protein translocates to the nucleus and serves as a transcription factor to regulate Fads2 expression, thereby altering PUFA metabolism. Additionally, in vitro experiments indicated that α-linolenic acid can effectively alleviate OS damage and RWPE-1 cell apoptosis by protecting mitochondrial function and enhancing the antioxidant capacity of prostatic epithelial cells. In conclusion, reducing the levels of CXCR4 can alleviate inflammation and OS damage in chronic prostatitis.

Current View on PPAR-α and Its Relation to Neurosteroids in Alzheimer's Disease and Other Neuropsychiatric Disorders: Promising Targets in a Therapeutic Strategy

Peroxisome proliferator-activated receptors (PPARs) may play an important role in the pathomechanism/pathogenesis of Alzheimer's disease (AD) and several other neurological/neuropsychiatric disorders. AD leads to progressive alterations in the redox state, ion homeostasis, lipids, and protein metabolism. Significant alterations in molecular processes and the functioning of several signaling pathways result in the degeneration and death of synapses and neuronal cells, leading to the most severe dementia. Peroxisome proliferator-activated receptor alpha (PPAR-α) is among the processes affected by AD; it regulates the transcription of genes related to the metabolism of cholesterol, fatty acids, other lipids and neurotransmission, mitochondria biogenesis, and function. PPAR-α is involved in the cholesterol transport to mitochondria, the substrate for neurosteroid biosynthesis. PPAR-α-coding enzymes, such as sulfotransferases, which are responsible for neurosteroid sulfation. The relation between PPAR-α and cholesterol/neurosteroids may have a significant impact on the course and progression of neurodegeneration/neuroprotection processes. Unfortunately, despite many years of intensive studies, the pathogenesis of AD is unknown and therapy for AD and other neurodegenerative diseases is symptomatic, presenting a significant goal and challenge today. This review presents recent achievements in therapeutic approaches for AD, which are targeting PPAR-α and its relation to cholesterol and neurosteroids in AD and neuropsychiatric disorders.

Characterizing defective lipid metabolism in the lateral septum of mice treated with olanzapine: implications for its side effects

Schizophrenia significantly impacts cognitive and behavioral functions and is primarily treated with second-generation antipsychotics (SGAs) such as olanzapine. Despite their efficacy, these drugs are linked to serious metabolic side effects which can diminish patient compliance, worsen psychiatric symptoms and increase cardiovascular disease risk. This study explores the hypothesis that SGAs affect the molecular determinants of synaptic plasticity and brain activity, particularly focusing on the lateral septum (LS) and its interactions within hypothalamic circuits that regulate feeding and energy expenditure. Utilizing functional ultrasound imaging, RNA sequencing, and weighted gene co-expression network analysis, we identified significant alterations in the functional connection between the hypothalamus and LS, along with changes in gene expression in the LS of mice following prolonged olanzapine exposure. Our analysis revealed a module closely linked to increases in body weight and adiposity, featuring genes primarily involved in lipid metabolism pathways, notably Apoa1, Apoc3, and Apoh. These findings suggest that olanzapine may influence body weight and adiposity through its impact on lipid metabolism-related genes in the LS. Therefore, the neural circuits connecting the LS and LH, along with the accompanying alterations in lipid metabolism, are likely crucial factors contributing to the weight gain and metabolic side effects associated with olanzapine treatment.

Allopregnanolone and its antagonist modulate neuroinflammation and neurological impairment

Neuroinflammation accompanies several brain disorders, either as a secondary consequence or as a primary cause and may contribute importantly to disease pathogenesis. Neurosteroids which act as Positive Steroid Allosteric GABA-A receptor Modulators (Steroid-PAM) appear to modulate neuroinflammation and their levels in the brain may vary because of increased or decreased local production or import from the systemic circulation. The increased synthesis of steroid-PAMs is possibly due to increased expression of the mitochondrial cholesterol transporting protein (TSPO) in neuroinflammatory tissue, and reduced production may be due to changes in the enzymatic activity. Microglia and astrocytes play an important role in neuroinflammation, and their production of inflammatory mediators can be both activated and inhibited by steroid-PAMs and GABA. What is surprising is the finding that both allopregnanolone, a steroid-PAM, and golexanolone, a novel GABA-A receptor modulating steroid antagonist (GAMSA), can inhibit microglia and astrocyte activation and normalize their function. This review focuses on the role of steroid-PAMs in neuroinflammation and their importance in new therapeutic approaches to CNS and liver disease.

Latest advances on new promising molecular-based therapeutic approaches for Huntington's disease

Huntington's disease (HD) is a devastating, autosomal-dominant inherited, neurodegenerative disorder characterized by progressive motor deficits, cognitive impairments, and neuropsychiatric symptoms. It is caused by excessive cytosine-adenine-guanine (CAG) trinucleotide repeats within the huntingtin gene (HTT). Presently, therapeutic interventions capable of altering the trajectory of HD are lacking, while medications for abnormal movement and psychiatric symptoms are limited. Numerous pre-clinical and clinical studies have been conducted and are currently underway to test the efficacy of therapeutic approaches targeting some of these mechanisms with varying degrees of success. In this review, we update the latest advances on new promising molecular-based therapeutic strategies for this disorder, including DNA-targeting techniques such as zinc-finger proteins, transcription activator-like effector nucleases, and CRISPR/Cas9; post-transcriptional huntingtin-lowering approaches such as RNAi, antisense oligonucleotides, and small-molecule splicing modulators; and novel methods to clear the mHTT protein, such as proteolysis-targeting chimeras. We mainly focus on the ongoing clinical trials and the latest pre-clinical studies to explore the progress of emerging potential HD therapeutics.

Integrated metabolomics and transcriptomics revealed the anti-constipation mechanisms of xylooligosaccharides from corn cobs

Xylooligosaccharides (XOSs) have recently garnered interest for their potential as an anti-constipation agent. In this study, we investigated the effects of XOSs derived from corn cobs on constipation in mice through a comprehensive analysis of both the metabolome and transcriptome. Our multi-omics approach revealed that XOSs primarily modulated butanoate metabolism and steroid hormone biosynthesis pathways, as well as key signaling pathways such as PPAR and NF-kappa B. Notably, we observed a decrease in inflammatory biomarker expression and an elevation of butyric acid metabolite levels with XOSs treatment. A deeper analysis of gene expression and metabolite alterations highlighted significant changes in genes encoding critical enzymes and metabolites involved in these pathways. Overall, these findings underscore the considerable potential of XOSs derived from corn cobs as a dietary supplement for effectively alleviating constipation.

Research progress on pleiotropic neuroprotective drugs for traumatic brain injury

Traumatic brain injury (TBI) has become one of the most important causes of death and disability worldwide. A series of neuroinflammatory responses induced after TBI are key factors for persistent neuronal damage, but at the same time, such inflammatory responses can also promote debris removal and tissue repair after TBI. The concept of pleiotropic neuroprotection delves beyond the single-target treatment approach, considering the multifaceted impacts following TBI. This notion embarks deeper into the research-oriented treatment paradigm, focusing on multi-target interventions that inhibit post-TBI neuroinflammation with enhanced therapeutic efficacy. With an enriched comprehension of TBI's physiological mechanisms, this review dissects the advancements in developing pleiotropic neuroprotective pharmaceuticals to mitigate TBI. The aim is to provide insights that may contribute to the early clinical management of the condition.