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Chronic stress is increasingly acknowledged as a pivotal precipitating factor in the pathogenesis of neuropsychiatric and neurodegenerative disorders, notably including depression and Alzheimer's disease (AD). Astrocytes, which constitute the predominant population of glial cells involved in the maintenance of synaptic homeostasis, the recycling of neurotransmitters, and the provision of metabolic support, display a pronounced susceptibility to sustained exposure to stress. The deleterious effects of astrocytic dysfunction instigate a series of neuroinflammatory and synaptic modifications that undermine both cognitive and emotional resilience. This review articulates the mechanistic interactions between stress-induced astrocyte dysfunction, neuroinflammatory signaling, and compromised neuroplasticity, underscoring the converging pathways that are implicated in both depression and AD. A thorough synthesis of the literature from 2020 to 2025 was conducted utilizing databases such as PubMed, Scopus, and Web of Science, with an emphasis on molecular, in vitro, in vivo, and translational studies that examine the modulation of astrocytic function under conditions of chronic stress and its pertinence to depression and AD. The chronic activation of the hypothalamic-pituitary-adrenal (HPA) axis precipitates morphological alterations, diminished expression of glutamate transporters (GLT-1/EAAT2), disrupted brain-derived neurotrophic factor (BDNF) signaling, and an augmented release of pro-inflammatory cytokines (IL-1β, IL-6, TNF-α) from astrocytes. These biochemical alterations exacerbate excitotoxicity, disturb monoaminergic and glutamatergic neurotransmission, and hasten synaptic degeneration. In the context of depression, this phenomenon is manifested as impaired mood regulation and a decline in neurogenesis. In AD, it synergistically interacts with amyloid-beta and tau pathologies to facilitate progressive cognitive impairment. Both conditions exhibit a common feature of diminished neurosignaling plasticity, which limits the brain's capacity for adaptation and repair. Astrocyte dysfunction constitutes a central mechanistic nexus wherein chronic stress, neuroinflammation, and synaptic pathology intersect to promote the progression of depression and AD. The targeting of astrocytic health via the modulation of reactive astrocyte phenotypes, the restoration of glutamate homeostasis, and the enhancement of neurotrophic signaling emerges as a promising therapeutic avenue for alleviating stress-related neurodegeneration and mood disorders. Show less

Astroglia, often called as astrocytes, play a crucial role in protecting neurons and preserved the neurophysiological functions. Astrocytes' dysfunction contributes to numerous neurological disorders. Astrocytes are involved in the regulation of oxidative stress and inflammatory process within Central nervous system. Developments in specific transcriptomic and genomics have initiated the discovery of new mechanisms governing astrocyte during oxidative and inflammatory process. Despite the advancements in existing diagnostic and therapeutic methods like targeted ultrasound and NPs mediated administration, these methods still pose risks and have drawbacks. Aptamers, artificial single stranded oligonucleotides have the ability to specific target cells and exhibit strong binding affinity and enhance the administration of therapeutic agents. Research over the last few years has demonstrated that the ability to target specific molecules/intermediates such as reactive oxygen species, interleukins, tumor necrotic factor, vascular endothelial growth factor, brain-derived neurotrophic factor and penetrate the blood brain barrier makes aptamers ideal candidates for addressing the oxidative and inflammatory intermediaries within astrocytes. Present review explores the emerging applications of aptamers in cytoprotection specially focus on their potential to combat oxidative stress and inflammation in astrocytes. We also discuss the capability of aptamers as cell specific molecular probes for advancing tailored diagnostic and therapeutic interventions. Present article also addresses future directions and significant issues. Show less

The number of people living with Alzheimer's disease (AD) is increasing worldwide as populations age. A hallmark of AD is the accumulation of amyloid-β (Aβ) in the brain, and pathways regulating amyloid-β precursor protein (AβPP) processing are of major interest for disease-modifying and preventive strategies such as exercise. Regular exercise is associated with a reduced risk of AD, potentially through limiting Aβ accumulation, yet the underlying cellular mechanisms remain unclear. Acute bouts of exercise induce the release of circulating signalling molecules that may influence AβPP metabolism. To investigate the effects of exercise on AβPP processing, human induced pluripotent stem cell (iPSC)-derived neurons and astrocytes were treated with serum collected before and immediately after high-intensity exercise. Both healthy control and familial AD (PSEN1 A246E) neurons and astrocytes were independently exposed to 10 % pre- or post-exercise serum for 30 min, after which markers of AβPP processing were quantified. Post-exercise serum contained increased amounts of Lacate, BDNF, IL-6, sAβPPα, and Aβ₁-₄₂, and reduced neprilysin activity (p < 0.05). Treatment with post-exercise serum acutely elevated ADAM10 activity in neurons, which was replicated by spiking lactate in pre-exercise serum. sAβPPα was also increased in PSEN1 neurons following post exercise serum treatment with increased Aβ₁-₄₂ secretion in both PSEN1 neurons and astrocytes (p < 0.05). These findings demonstrate that human post-exercise serum can modulate AβPP processing in iPSC-derived neural cells. This supports the concept that circulating exercise-induced factors can influence neuronal pathways relevant to AD pathology. Show less

Disruption of metabolic interactions between astrocytes and neurons, in particular of the lactate shuttle, may contribute to neurodevelopmental and psychiatric disorders such as autism spectrum disorder (ASD) and schizophrenia. The enzyme glycine decarboxylase (GLDC), predominantly expressed in astrocytes, degrades glycine and plays a critical role in regulating NMDA receptor function and cellular metabolism. Here, we investigated whether administration of lactate would reverse schizophrenia-like phenotypes in a mouse model for psychosis with 4 copies of the Gldc gene (4cG mice). Adult male and female 4cG and wildtype mice were subjected to acute L-lactate intraperitoneal administration one hour before behavioral testing and brain collection for biochemical assays. Y-maze spontaneous alternation test, prepulse inhibition of acoustic startle test, and the three-chamber social interaction test were performed for behavioral analysis, and Western blots for protein estimations. In 4cG mice, acute lactate administration one hour before assessment rescued short-term memory deficits, acoustic startle habituation deficits, and normalized deficits in social preference behavior. Furthermore, lactate treatment restored the expression of PGC1α, a master regulator of mitochondrial biogenesis, and brain-derived neurotrophic factor (BDNF), a protein essential for synaptic plasticity. The results suggest a role for astrocytic metabolism in modulating neuronal function, and potential molecular mechanisms underlying the reversal of behavioral phenotypes. The results indicate that exogenous lactate may reverse key pathophysiological and behavioral deficits in a mouse model for schizophrenia and that lactate supplementation may be useful as a therapeutic strategy for schizophrenia and related disorders. Show less

Brain-derived neurotrophic factor (BDNF) is a neurotrophin that, through the activation of its full length receptor, TrkB-FL, plays a pivotal role in neuroprotection, namely against neuronal toxicity mediated by amyloid-β peptide (Aβ). In astrocytes, the increase of calcium (Ca Show less

Depression is a major mental illness, and its underlying mechanisms remain unclear. Emerging evidence suggests that astrocytes, which play a crucial role in brain function, may be involved in the pathophysiology of depression. We previously showed that downregulation of astrocytic connexin43 (Cx43) enhances the antidepressant effect of amitriptyline. However, the precise molecular mechanisms underlying this phenomenon remain unknown. In the present study, we investigated the signaling pathways involved in the antidepressant action of amitriptyline using an in vitro model involving Cx43-knockdown astrocytes. We found that amitriptyline potentiated the expression of brain-derived neurotrophic factor (BDNF), a key neurotrophic factor, in Cx43-knockdown astrocytes. This potentiation was mediated by the activation of Gq protein-coupled lysophosphatidic acid (LPA) receptors, a pathway that was sensitized by Cx43 downregulation. We further demonstrated that this signaling cascade involved the activation of Protein Kinase C (PKC) δ and transcription factor NF-κB, but not the conventional BDNF transcription factor CREB. We propose that Cx43 downregulation enhances the antidepressant effect of amitriptyline by specifically engaging the Gq-PKCδ-NF-κB pathway. These findings suggest that Cx43 downregulation in astrocytes, which has been considered a pathological feature of depression, may paradoxically contribute to the therapeutic efficacy of antidepressants by sensitizing a specific signaling pathway. Our study provides new insights into the molecular mechanism of antidepressant action and highlights the potential role of astrocytic Cx43 in modulating therapeutic responses. Show less