Microglia-mediated neuroinflammation is one of the most remarkable hallmarks of neurodegenerative diseases (NDDs), including AD, PD, and ALS. Accumulating evidence indicates that microglia play both neuroprotective and detrimental roles in the onset and progression of NDDs. Yet, the specific mechanisms of action surrounding microglia are not clear. Modulation of microglia function and phenotypes appears to be a potential strategy to reverse NDDs. Until recently, research into the epigenetic mechanisms of diseases has been gradually developed, making it possible to elucidate the molecular mechanisms underlying the epigenetic regulation of microglia in NDDs. This review highlights the function and phenotypes of microglia, elucidates the relationship between microglia, epigenetic modifications, and NDDs, as well as the possible mechanisms underlying the epigenetic modulation of microglia in NDDs with a focus on potential intervention strategies.

Background: Alzheimer’s disease (AD) lacks effective therapeutic strategies. Electroacupuncture (EA) offers promising neuroprotective effects, but its underlying mechanisms remain unclear. Objective: To explore the mechanisms of EA’s neuroprotective effects on AD via microbiome and metabolome integration. Methods: Utilizing a well-established model of AD, Senescence-Accelerated Mouse Prone 8 (SAMP8), EA intervention was performed. 16S ribosomal RNA (rRNA) sequencing and serum metabolomics were conducted on SAMP8 mice, SAMP8 mice after EA intervention, and their normal control group Senescence-Accelerated Mouse Resistant 1 (SAMR1) mice. Results: SAMP8 mice were subjected to electroacupuncture (EA) treatment at the Baihui (GV20) and Shenshu (BL23) acupoints for 15 min daily over a period of four weeks. EA enhanced cognitive function and reduced neuronal damage in AD models. The treatment lowered pro-inflammatory cytokines (TNF-α, IL-1β) and AD-related pathologies (tau, Aβ_1-42). EA also rebalanced gut microbiota by increasing beneficial Gastranaerophilales while decreasing harmful Proteobacteria. Additionally, it restored purine and phenylpropanoid metabolism by regulating key metabolites. Importantly, EA reduced levels of specific metabolites linked to pro-inflammatory bacteria (Sphingomonas, Massilia, Escherichia-Shigella), simultaneously decreasing their abundance. These findings highlight EA’s multi-target effects on neuroinflammation, gut microbiota, and metabolic pathways in AD. Notably, the interactions between EA-regulated key metabolites and AD-related targets, predicted via PubChem and ChEMBL databases, remain computational and have not been validated by experimental studies. Conclusions: EA exerts neuroprotective effects in AD via modulation of gut microbiota and metabolic pathways, representing a novel non-pharmacological therapeutic strategy.

Microglial responses to mitochondrial protein stress are best evaluated by connecting the initiating protein burden to its processing and functional consequences. This review develops an outcome-based failed-resolution framework that integrates burden trajectory, clearance or repair, and lesion-relevant functional recovery. Stress-response activation is evaluated separately from successful proteostasis restoration. Failed resolution requires persistent initiating burden AND insufficient corresponding processing AND inadequate functional recovery after a defined withdrawal or rescue interval; these are measurement domains, not obligatory biological stages. Matched human induced pluripotent stem cell-derived neural cultures show preferential microglial aggregate-associated signals and multidomain senescence-associated changes under common exposure, while vulnerability at an equivalent intracellular burden remains to be tested. Substrate-resolved turnover and functional measurements anchor the interpretation of stress markers, bulk autophagy and extracellular-cargo uptake. Proteostasis status, functional adequacy and cell fate are assessed independently, allowing a persistent phenotype after burden clearance to be distinguished from ongoing unresolved stress. Resource competition between mitochondrial maintenance and phagolysosomal work is a testable hypothesis supported by component findings. Human cellular, organoid and animal studies define these components; their complete integration in adult microglia in vivo remains untested. The framework provides falsifiable comparisons and selective-rescue tests for linking protein handling to cell-specific recovery.

Estrogen deficiency is an established risk factor for menopausal brain dysfunctions in women. Urgent exploration of drugs is needed to improve estrogen deficiency-related brain dysfunctions without the side effects of estrogen supplements. Three-month-old rats had bilateral ovariectomy (OVX) performed and were treated with emodin (EMO, 80 mg/kg/day) and 17 β-estradiol (EST, 0.5 mg/kg/day). Brain functions were evaluated by cognition and emotion-related behavioral tests. Levels of glucagon-like peptide-1 (GLP-1) and estrogen in blood, mRNA levels of estrogen receptor (ER) α, ERβ, GLP-1 receptor (GLP-1R), proprotein convertase subtilisin/kexin type 1 (PCSK1) and proglucagon (proGCG) in intestinal segments, and brain ERα and GLP-1R levels were evaluated. Contractions of isolated intestinal segments were recorded. Additionally, an ERβ antagonist, PHTPP (200 μg/kg/day), was used to clarify the role of ERβ. EST and EMO significantly ameliorated cognition deficit and depressive behaviors in OVX rats, and reduced neuronal loss and synaptic abnormalities in the hippocampus and prefrontal cortex. The blood GLP-1 levels of sham operation rats (sham, 3.09 pg/mL), EMO-treated (2.57 pg/mL) and EST-treated OVX rats (2.64 pg/mL), were higher than that of OVX rats (1.03 pg/mL). EMO had no effect on the blood estrogen level. Furthermore, EMO up-regulated mRNA levels of ERβ in ileum, colon, and cerebral GLP-1R level, while EST increased mRNA levels of ERβ in colon and cerebral ERα level. In vitro intestinal segment spontaneous contraction tests revealed that EMO reduced contraction amplitudes in isolated intestinal segments from OVX rats, with the ileum and proximal colon showing greater sensitivity to EMO. The ileum and colon segments from OVX rats were less sensitive to EST as compared to those of normal rats. Upon PHTPP intervention, the up-regulated intestinal mRNA levels of ERβ, PCSK1, proGCG, blood GLP-1 level by EMO, and the beneficial effects of EMO in abnormal behaviors of OVX rats were significantly inhibited. Overall, it was found that EMO up-regulated blood GLP-1 level via intestinal Erβ-dependent mechanism and increased brain GLP-1R level, which may be involved in the neuroprotection of EMO in OVX animals.