Molecular Brain最新文献

Secondary injuries from ischemia‒reperfusion in stroke, such as edema and hemorrhagic transformation, can significantly impact brain function. This study investigated the effects of intermittent theta burst stimulation (iTBS) on neurological function and cerebral blood flow in a mouse model of ischemia‒reperfusion injury. Laser speckle flowmetry was used to assess changes in cortical blood flow before and after ischemia‒reperfusion. Behavioral assessments were conducted to evaluate motor function recovery. The impact of iTBS on neuronal damage and apoptosis in the peri-infarct area was evaluated via Nissl staining and a TUNEL assay. RNA transcriptome sequencing and immunofluorescence staining were performed to investigate the effects of iTBS on microglial and astrocyte activation and the associated inflammatory response. Our findings demonstrated that iTBS significantly mitigated abnormal perfusion in the infarcted hemisphere, reduced neuronal damage and apoptosis in the peri-infarct area, and enhanced motor function in ischemic mice. Furthermore, iTBS promoted the polarization of microglia and astrocytes toward the anti-inflammatory M2 and A2 phenotypes. Therefore, iTBS provides neurovascular protection by modulating microglial and astrocyte activation and regulating the inflammatory response in the peri-infarct area, thereby improving abnormal cerebral blood flow in both the acute and subacute phases after ischemic brain injury.

In the synaptic junction, pre-and post compartments are anchored to each other through trans-synaptic bridges spanning the synaptic cleft. Here we demonstrate that mild mechanical disturbance through sonication dissociates the synaptic cleft, and releases PSDs adjoined to the postsynaptic membrane, but devoid of presynaptic elements. It is the first time, to our knowledge, that dissection of the synaptic cleft has been achieved without the use of chemical/enzymatic treatments. This observation suggests that some of the protein-protein interactions involved in the anchoring of pre- and postsynaptic compartments are relatively weak non-covalent associations. We describe a method for the further fractionation of PSDs with the associated postsynaptic membrane. This PSD preparation provides a valuable tool for studies of postsynaptic membrane components, such as glutamatergic receptors, in an environment closer to their native state.

Ischemic stroke remains a leading cause of mortality and long-term disability, with reperfusion injury contributing significantly to poor clinical outcomes. Microglia, the primary immune cells of the central nervous system, play a dual role in ischemic stroke by both exacerbating injury through neuroinflammation and supporting recovery through neuroprotection. This study aimed to explore the role of CD74, a gene upregulated in microglia following ischemia-reperfusion injury. Using single-cell RNA sequencing and bulk RNA sequencing, we identified CD74 as a potential target involved in microglial-mediated neuroinflammation. We observed a significant increase in CD74 expression in microglia following middle cerebral artery occlusion/reperfusion (MCAO/R), which correlated with pro-inflammatory cytokine production and neuroinflammation. Targeted knockdown of CD74 in microglia using CX3CR1Cre/ERT2 mice led to a reduction in infarct volume, inflammatory cytokine levels, and long-term neurological deficits. Behavioral tests showed improved motor coordination, sensory function, and exploratory behavior in CD74 knockdown mice. These results suggest that CD74 is a critical mediator of microglia-driven neuroinflammation, and targeting CD74 may represent a promising therapeutic strategy for reducing ischemic brain injury and promoting recovery after stroke.

Fear memory formation is crucial for survival, with the hippocampus playing a central role. This study investigates the behavioral and molecular aspects of fear memory formation, focusing on Dual-specificity tyrosine phosphorylation-regulated kinase 1 A (DYRK1A), a protein known to be critical for cognitive functions. Our results demonstrate that DYRK1A expression in hippocampal CA1 pyramidal neurons is downregulated after contextual fear conditioning (CFC). We also observed a decrease in DYRK1A binding to the Maoa promoter, suggesting its involvement in transcriptional regulation during fear memory formation. In subsequent experiments, we modulated DYRK1A expression using viral vectors. DYRK1A overexpression reduced freezing behavior, while knockdown enhanced it. At the molecular level, DYRK1A overexpression resulted in elevated H3K4me3 levels, while knockdown decreased it. These findings indicate that DYRK1A regulates fear memory formation via epigenetic modifications, altering H3K4me3 levels and influencing Maoa transcription in the hippocampus. This research highlights the nuclear role of DYRK1A and suggests its potential as a therapeutic target for neuropsychiatric disorders related to fear and memory.

Cytoskeletal remodeling drives morphological changes. Septin cytoskeleton assembles into hetero-oligomers. We previously demonstrated that late-phase long-term potentiation (L-LTP) induces smooth endoplasmic reticulum (sER) extension into dendritic spines via septin 3 (SEPT3), contributing to greater postsynaptic Ca²⁺ responses and enhanced activation of synaptically induced Ca²⁺ signaling. Sept3^-/- mice exhibit a reduced number of sER-containing spines and show impaired long-term spatial/object memory despite normal short-term memory. Additionally, SEPT3 binds the motor protein myosin-Va (MYO5A) upon elevated Ca²⁺ concentrations, facilitating sER extension from the dendritic shaft into the spine. MYO5A localizes on the sER membrane, while SEPT3 remains at the spine base, accumulating on sER upon electroconvulsive stimulation (ECS). However, the mechanism underlying SEPT3's delocalization from the spine base and its cooperative role with MYO5A in sER extension remains unclear. In this study, we demonstrate that SEPT3 is phosphorylated in a stimulation-dependent manner. Phosphorylation at Thr211 releases SEPT3 from the spine base, enabling sER extension with constitutively active MYO5A mutant (MYO5A-CCtr). These findings provide molecular insight into the role of SEPT3 phosphorylation in regulating sER dynamics that sustain long-term spine activation.

Fear generalization, which allows animals to respond adaptively to cues similar to original threatening ones, is generally beneficial for survival. However, an inability to distinguish between threat and safety, leading to the overgeneralization of fear to non-threatening stimuli, is maladaptive and is implicated in anxiety disorders such as post-traumatic stress disorder (PTSD). The neuropeptide gastrin-releasing peptide (GRP) is known to modulate fear memory under stress, yet its role in response to intense aversive stimuli remains less understood. In this study, we used GRP knockout (Grp^-/-) mice to examine the role of GRP in enhancing fear responses to conditioned stimulus (10 kHz tone, CS+) and non-conditioned stimulus (2 kHz tone, CS-) in a model of auditory fear conditioning with high-intensity footshocks following single acute restraint stress (RS). Our findings reveal that GRP is required not only for enhanced response to CS+ but also for generalized fear responses to CS-. Furthermore, we observed that infusion of GRP into the auditory cortex (AC) of Grp^-/- mice restores freezing behavior in response to CS- and fear generalization. Additionally, GRP in the AC is essential for the generalization of CS+ responsive neurons to respond to CS- during fear memory retrieval. These results highlight a novel role for GRP in the mechanisms underlying maladaptive fear in highly stressful situations, offering potential new targets for treating anxiety-related disorders.

Exercise evokes many physiological changes, including the release of hormones and growth factors that are known to improve cognition via unknown mechanisms. Here, we have compared the ability of two physiologically relevant factors, corticosterone (CORT) and brain-derived neurotrophic factor (BDNF), to affect long-term potentiation (LTP) in the hippocampus. Using a compressed theta-burst stimulation (cTBS) protocol, we found that CORT has no effect on LTP, BDNF enhances LTP and combined CORT + BDNF treatment results in significantly greater LTP. We also find that CORT + BDNF, but not either compound alone, results in phosphorylation of protein kinase A (PKA). These findings show that BDNF and CORT act synergistically to enhance LTP at these synapses, potentially via a PKA-dependent mechanism. Such a synergistic action could underlie the positive cognitive effects of exercise.

Kv1.3 channels in microglia are pivotal in regulating neuroinflammation. The antipsychotic chlorpromazine (CPZ) demonstrates anti-inflammatory effects by decreasing Kv1.3 activity in mPFC microglia. However, the precise mechanism of CPZ's effect in the mPFC remains unclear, given that CPZ is known to inhibit dopamine receptors and the mPFC contains various cell types with dopamine receptors. In this study, we investigate how CPZ inhibits Kv1.3 channels using human Kv1.3 channel-expressing Xenopus laevis oocytes. CPZ directly inhibits Kv1.3 channel currents in a concentration-dependent manner. The CPZ-mediated Kv1.3 channel inhibition is not voltage-dependent, and CPZ accelerates Kv1.3 channel inactivation without significantly affecting its activation. Our findings suggest that CPZ directly blocks Kv1.3 channels without involving other ion channels or receptors, including dopamine receptors, thereby contributing to the understanding of its neuroinflammation-suppressing mechanism.

Hypoxic-ischemic brain damage (HIBD) is a significant cause of neonatal death and neurological dysfunction. Following this injury, activated microglia can lead to a series of inflammatory responses. Gastrodin (GAS), a polyphenol extracted from the Chinese herbal medicine Gastrodia elata Blume, has demonstrated antioxidant and anti-inflammatory effects. This study investigated the neuroprotective impact of GAS in HIBD mice model and in BV2 cells subjected to oxygen-glucose deprivation (OGD) treatment. Expression of various members of the Ccr2/Akt/Gsk-3β, including Ccl2, Ccr2, Akt, p-Akt, Gsk-3β, p-Gsk-3β and inflammatory factors TNF-α and IL-1β in activated microglia was assessed by Western blotting, immunofluorescence, and qRT-PCR in HIBD in postnatal mice, and in OGD-induced BV2 microglia in vitro with or without GAS treatment. The present results showed that GAS effectively reduces the expression of Ccl2 and Ccr2, increases the phosphorylation levels of Akt and Gsk-3β, and decreases the expression of the TNF-α and IL-1β. Additionally, we have shown that inhibition of Ccr2 by RS102895 increased the expression of p-Akt and p-Gsk-3β, and attenuate production of proinflammatory mediators in activated microglia. Of note, the expression of p-Akt, p-Gsk-3β, TNF-α and IL-1β remained unchanged after the combination of gastrodin and RS102895. Taken together, we conclude that GAS can play a protective role in reducing the neuroinflammatory response after HIBD. It is suggested that this is mainly through up-regulating the Akt/Gsk-3β signaling pathway via the Ccr2 receptor in the present experimental paradigm.

Astrocytes are critical in regulating synaptic transmission in the central nervous system (CNS). The spinal dorsal horn (SDH) is a crucial region that processes and integrates somatosensory information from the periphery and transmits it to the brain. Our previous work demonstrated that stimulation of an astrocyte population in the SDH, characterized by the expression of hairy and enhancer of split 5 (Hes5), causes pain hypersensitivity. However, the mechanism by which Hes5⁺ astrocytes modulate synaptic transmission in the SDH remains unclear. In this study, using electrophysiological and cell type-specific functional manipulation approaches, we found that chemogenetic stimulation of Hes5⁺ SDH astrocytes enhanced Aδ and C fiber-mediated excitatory postsynaptic currents in lamina I neurons. A pharmacological blockade of the glycine binding site of N-methyl-D-aspartate (NMDA) receptors prevented the astrocytic enhancement. These findings suggest that Hes5⁺ astrocytes in the SDH enhance synaptic transmission from primary afferent nociceptors to lamina I neurons by potentiating NMDA receptor activity.