ObjectiveTo investigate the mechanisms by which Huanglian Jiedutang （HLJDT） modulates microglial （MG） phenotypes through the sialic acid-binding Ig-like lectin 2 （SIGLEC2/CD22）/Src-homology-2-domain-containing protein tyrosine phosphatase-1 （SHP-1）/phosphorylated protein kinase B （p-Akt） signaling pathway， thereby promoting myelin repair and alleviating agitation-like behaviors in vascular dementia （VAD）. MethodsSixty C57BL/6J mice were randomly assigned to a sham （normal） group， model group， HLJDT low-， medium-， and high-dose groups （2.5， 5， and 10 g·kg^-1·d^-1）， and a risperidone group （2 mg·kg^-1·d^-1）， with 10 mice per group. VAD was induced by bilateral common carotid artery stenosis （BCAS）. From day 42， mice received drug interventions for 2 weeks. Agitation-like behaviors were assessed using the resident-intruder test. After behavioral testing， ventrolateral part of the ventromedial hypothalamus （VMHvl） tissues were collected. Western blot was used to measure protein levels of myelin oligodendrocyte glycoprotein （MOG）， myelin basic protein （MBP）， proteolipid protein （PLP）， inducible nitric oxide synthase （iNOS）， arginase-1 （Arg1）， CD86， CD206， and CD22， SHP-1， and p-Akt. Immunofluorescence was used to evaluate myelin-associated glycoprotein （MAG） intensity and the proportion of iNOS⁺/ionized calcium-binding adapter molecule 1 （Iba1）⁺ cells. ELISA was used to detect tumor necrosis factor-α （TNF-α）， interleukin （IL）-6， and IL-1β. ResultsCompared with the normal group， the model group exhibited markedly increased biting and aggressive behaviors and shortened attack latency （P<0.01）. MOG， MBP， and PLP protein levels and MAG fluorescence intensity were significantly reduced （P<0.05， P<0.01）. INOS and CD86 expression and TNF-α， IL-6， and IL-1β levels were significantly elevated （P<0.01）. CD22 and SHP-1 expression increased significantly （P<0.01）， whereas p-Akt expression decreased （P<0.01）. Compared with the model group， the medium- and high-dose HLJDT groups and the risperidone group showed markedly reduced biting and aggression （P<0.05， P<0.01） and prolonged attack latency （P<0.01）. MOG， MBP， and PLP levels and MAG fluorescence intensity were significantly increased （P<0.05， P<0.01）. INOS， CD86， TNF-α， IL-6， and IL-1β levels decreased significantly （P<0.05， P<0.01）. CD22 and SHP-1 expression decreased， while p-Akt expression increased significantly （P<0.05， P<0.01）. ConclusionHLJDT may modulate CD22/SHP-1/p-Akt signaling in the VMHvl， promote the shift of MG toward an anti-inflammatory and phagocytic phenotype， enhance myelin repair， and improve agitation-like behaviors in VAD mice.

ObjectiveTo investigate the ameliorative effects of quercetin on neuropsychiatric symptoms associated with vascular dementia （VaD） and to elucidate the molecular mechanism， specifically whether quercetin inhibits pro-inflammatory activation of microglia by modulation of the receptor-interacting serine/threonine-protein kinase 1 （RIPK1）/NOD-like receptor protein 3 （NLRP3）/Caspase-1 signaling pathway， thereby promoting myelin repair in the medial prefrontal cortex （mPFC）. MethodsA C57BL/6J mouse model of VaD with neuropsychiatric symptoms was established by bilateral common carotid artery stenosis （BCAS） combined with chronic restraint stress （CRS）. Mice were randomly divided into a sham group， a model group， low-dose， medium-dose， and high-dose quercetin groups （30， 60， 120 mg·kg^-1·d^-1）， and a fluoxetine group （10 mg·kg^-1·d^-1）. After intervention， depressive- and anxiety-like behaviors were assessed by the sucrose preference test （SPT）， forced swim test （FST）， open field test （OFT）， and elevated plus maze （EPM）. mPFC tissue was collected. Immunofluorescence （IF） was used to detect myelin basic protein （MBP） expression and microglial morphology. Western blot was used to measure the protein level of MBP， myelin oligodendrocyte glycoprotein （MOG）， myelin-associated glycoprotein （MAG）， inducible nitric oxide synthase （iNOS）， CD86， RIPK1， phosphorylated RIPK1 （Ser166）， NLRP3， and Caspase-1. Enzyme-linked immunosorbent assay （ELISA） was used to determine the level of tumor necrosis factor-alpha （TNF-α）， interleukin-6 （IL-6）， and interleukin-1β （IL-1β）. ResultsCompared with the sham group， the model group exhibited significant depressive- and anxiety-like behaviors （P<0.01）， significantly decreased protein expression of MBP， MOG， and MAG in the mPFC （P<0.01）， activated microglia （characterized by enlarged cell bodies， reduced protrusions， and upregulated iNOS and CD86 expressions， P<0.01）， and significantly elevated p-RIPK1/RIPK1 ratio， NLRP3， Caspase-1 protein expression， and level of TNF-α， IL-6， and IL-1β （P<0.01， P<0.05）. Compared with the model group， the quercetin treatment （especially at medium and high doses） significantly ameliorated these behavioral abnormalities （P<0.05， P<0.01）， increased the expression of MBP （protein and fluorescence intensity）， MOG， and MAG in the mPFC （P<0.05， P<0.01）， suppressed excessive microglial activation （characterized decreased cell bodies， increased protrusions， and downregulated iNOS and CD86 expressions， P<0.01）， and significantly reduced the p-RIPK1/RIPK1 ratio， NLRP3， Caspase-1 protein expression， and inflammatory cytokine levels （P<0.01）. ConclusionQuercetin effectively alleviates neuropsychiatric symptoms in VaD mice. Its mechanism may be associated with the inhibition of microglial inflammatory activation mediated by the RIPK1/NLRP3/Caspase-1 signaling pathway， thereby promoting myelin repair in the mPFC region.