Experimental Neurology最新文献

Interictal epileptiform discharges refer to aberrant brain electrographic signals between seizures and feature intermittent interictal spikes (ISs), sharp waves, and/or abnormal rhythms. Recognition of these epileptiform activities by electroencephalographic (EEG) examinations greatly aids epilepsy diagnosis and localization of the seizure onset zone. ISs are a major form of interictal epileptiform discharges recognized in animal models of epilepsy. Progressive changes in IS waveforms, IS rates, and/or associated fast ripple oscillations have been shown to precede the development of spontaneous recurrent seizures (SRS) in various animal models. IS expressions in the kindling model of epilepsy have been demonstrated but IS changes during the course of SRS development in extended kindled animals remain to be detailed. We hence addressed this issue using a mouse model of kindling-induced SRS. Adult C57 black mice received twice daily hippocampal stimulations until SRS occurrence, with 24-h EEG monitoring performed following 50, 80, and ≥ 100 stimulations and after observation of SRS. In the stimulated hippocampus, increases in spontaneous ISs rates, but not in IS waveforms nor IS-associated fast ripples, along with decreased frequencies of hippocampal delta and theta rhythms, were observed before SRS onset. Comparable increases in IS rates were further observed in the unstimulated hippocampus, piriform cortex, and entorhinal cortex, but not in the unstimulated parietal cortex and dorsomedial thalamus. These data provide original evidence suggesting that increases in hippocampal IS rates, together with reductions in hippocampal delta and theta rhythms are closely associated with development of SRS in a rodent kindling model.

Interleukin-17 A (IL-17 A) contributes to inflammation and causes secondary injury in post-stroke patients. However, little is known regarding the mechanisms that IL-17 A is implicated in the processes of neuronal death during ischemia. In this study, the mouse models of middle cerebral artery occlusion/reperfusion (MCAO/R)-induced ischemic stroke and oxygen-glucose deprivation/reoxygenation (OGD/R)-simulated in vitro ischemia in neurons were employed to explore the role of IL-17 A in promoting neuronal apoptosis. Mechanistically, endoplasmic reticulum stress (ERS)-induced neuronal apoptosis was accelerated by IL-17 A activation through the caspase-12-dependent pathway. Blocking calpain or phospholipase Cγ (PLCγ) inhibited IL-17 A-mediated neuronal apoptosis under ERS by inhibiting caspase-12 cleavage. Src and IL-17 A are linked, and PLCγ directly binds to activated Src. This binding causes intracellular Ca²⁺ flux and activates the calpain-caspase-12 cascade in neurons. The neurological scores showed that intracerebroventricular (ICV) injection of an IL-17 A neutralizing mAb decreased the severity of I/R-induced brain injury and suppressed apoptosis in MCAO mice. Our findings reveal that IL-17 A increases caspase-12-mediated neuronal apoptosis, and IL-17 A suppression may have therapeutic potential for ischemic stroke.

The activation of glial cells is intimately associated with the pathophysiology of neuroinflammation and white matter injury (WMI) during both acute and chronic phases following subarachnoid hemorrhage (SAH). The complement C3a receptor (C3aR) has a dual role in modulating inflammation and contributes to neurodevelopment, neuroplasticity, and neurodegeneration. However, its impact on WMI in the context of SAH remains unclear. In this study, 175 male C57BL/6J mice underwent SAH through endovascular perforation. Oxyhemoglobin (oxy-Hb) was employed to simulate SAH in vitro. A suite of techniques, including immunohistochemistry, transcriptomic sequencing, and a range of molecular biotechnologies, were utilized to evaluate the activation of the C3-C3aR pathway on microglial polarization and WMI. Results revealed that post-SAH abnormal activation of microglia was accompanied by upregulation of complement C3 and C3aR. The inhibition of C3aR decreased abnormal microglial activation, attenuated neuroinflammation, and ameliorated WMI and cognitive deficits following SAH. RNA-Seq indicated that C3aR inhibition downregulated several immune and inflammatory pathways and mitigated cellular injury by reducing p53-induced death domain protein 1 (Pidd1) and Protein kinase RNA-like ER kinase (Perk) expression, two factors mainly function in sensing and responding to cellular stress and endoplasmic reticulum (ER) stress. The deleterious effects of the C3-C3aR axis in the context of SAH may be related to endoplasmic reticulum (ER) stress-dependent cellular injury and inflammasome formation. Agonists of Perk can exacerbate the cellular injury and neuroinflammation, which was attenuated by C3aR inhibition after SAH. Additionally, intranasal administration of C3a during the subacute phase of SAH was found to decrease astrocyte reactivity and alleviate cognitive deficits post-SAH. This research deepens our understanding of the complex pathophysiology of WMI following SAH and underscores the therapeutic potential of C3a treatment in promoting white matter repair and enhancing functional recovery prognosis. These insights pave the way for future clinical application of C3a-based therapies, promising significant benefits in the treatment of SAH and its related complications.

Neuroinflammation is a common pathological feature and onset in multiple cognitive disorders, including postoperative cognitive dysfunction (POCD). Iron deposition was proved to participate in this process. But how iron mediates inflammation-induced cognitive deficits remains unknown. This study aimed to investigate the mechanism of iron through the neuroprotective effect of the iron chelator deferoxamine (DFO) in a mouse model of lipopolysaccharide (LPS)-induced cognitive impairment. Adult C57BL/6 mice were pretreated with 0.5 μg of DFO three days before intracerebroventricular microinjection of 2 μg of LPS. The mice showed memory deficits by showing decreased percentage of distance and the time within the platform-site quadrant, fewer platform-site crossings, and shortened swimming distance around the platform in the Morris water maze test, which were significantly mitigated by DFO pretreatment. Mechanistically, DFO prevented LPS-induced iron accumulation and modulated the imbalance of proteins expression related to iron metabolism, including elevated transferrin (TF) levels and reduced ferritin (Fth) caused by LPS. DFO attenuated the LPS-induced lipid peroxidation and oxidative stress, which is evidenced by the decrease of malondialdehyde (MDA) and lipid peroxidation (LPO) levels and the increase of superoxide dismutase (SOD) activity and glutathione (GSH) concentration. Moreover, DFO ameliorated ferroptosis-like mitochondrial damages in the hippocampus and also alleviated the expression of ferroptosis-related proteins in the hippocampus. Additionally, DFO attenuated microglial activation, alleviated LPS-induced inflammation, and reduced elevated levels of IL-6 and TNF-α in the hippocampus. Taken together, our findings suggested that DFO exerts neuroprotective effects by alleviating excessive iron participation in lipid peroxidation, reducing the occurrence of ferroptosis, inhibiting the vicious cycle between oxidative stress and inflammation, and ultimately ameliorating LPS-induced cognitive dysfunction, providing novel insights into the immunopathogenesis of inflammation-related cognitive dysfunction and future potential prevention options targeting iron.

Platelet-derived growth factor receptor β positive (PDGFRβ⁺) pericytes detach from the microvascular wall and migrate into the injury center following spinal cord injury (SCI), which has been widely regarded as the main source of fibrotic scar, but the mechanism of migration and fibroblast transition remains elusive. Here we show the associated spatiotemporal distribution between microglia and pericytes at three and seven days post-injury (dpi). The increased expression of Sphingosine kinase-1 (SPHK1) in microglia significantly raised the concentration of Sphingosine-1-phosphate (S1P) in the spinal cord, which promotes migration and fibroblast transition of pericyte. In vitro experiments, we found the elevated Sphingosine 1-phosphate receptor 3 (S1P3), the S1P/S1PR3 axis inhibited the phosphorylation of YAP and promoted its nuclear translocation, which contributed to the formation of alpha-smooth muscle actin (α-SMA) and collagen type I (COL1) protein, This process can be blocked by an S1P3 specific inhibitor TY52156 in vitro. The S1P/S1P3/YAP pathway might be a potential target for treatment in SCI.

In intracerebral hemorrhage (ICH), the mechanical brain injury is a considerable and indispensable factor determining the neurological functions and poor outcomes. Previous studies indicate the mechanically gated ion channel-Piezo1 can transduce mechanical effects following ICH. Isoquercitrin (ISQ) is a well-studied ion channel inhibitor. Furthermore, whether the following Piezo1-mediated neurological impairment can be ameliorated by ISQ remains unclear. Herein, we constructed the hydrostatic pressure model and ICH rat model. Firstly, we found that Piezo1 agonists Yoda1 and Jedi1 facilitated extracellular calcium influx dramatically, but ISQ could depress intracellular Ca²⁺ overload under hydrostatic pressure in primary neurons. Then we detected the expression profile of Piezo1, NLRP3 and NF-κB p-p65 after ICH, and found that the expression of Piezo1 was much earlier than NLRP3 and NF-κB p-p65. Furthermore, by western blot and immunofluorescence, ISQ decreased the expression of Piezo1 and NLRP3 dramatically like GsMTx4, but Nigericin as a NLRP3 agonist failed to affect Piezo1. Besides, both ISQ and interfering Piezo1 suppressed the upregulated caspase-1, NF-κB p-p65, p-IκBα, Tunel-positive cells and inflammatory factors (IL-1β, IL-6 and TNF-α) in ICH. At last, the hydrostatic pressure or hematoma induced disturbed neural viability, disordered neural cytomorphology, and increased neurobehavioral and cognitive deficits, but they were improved by ISQ and GsMTx4 strongly. Therefore, ISQ could alleviate neurological injuries induced by Piezo1 via NLRP3 pathway. These observations indicated that Piezos might be the new therapeutic targets, and blocking Piezos/NLRP3 pathway by ISQ could be an auspicious strategy for the treatment of ICH.

Cerebral ischemic stroke is a serious disease with high mortality and disability rates. However, few neuroprotective drugs have been used for ischemic stroke in the clinic. Two main reasons may be responsible for this failure: difficulty in penetrating the blood-brain barrier (BBB) and easily inactivated in the blood circulation. Ferroptosis, a lipid oxidation-related cell death, plays significant roles in cerebral ischemia-reperfusion injury. We utilized RVG29, a peptide derived from Rabies virus glycoprotein, to obtain BBB-targeted lipid nanoparticles (T-LNPs) in order to investigate whether T-LNPs improved the neuroprotective effects of Ferrostatin-1 (Fer1, an inhibitor of ferroptosis) against cerebral ischemic damage. T-LNPs significantly increased BBB penetration following oxygen/glucose deprivation exposure in an in vitro BBB model and enhanced the fluorescence distribution in brain tissues at 6 h post-administration in a cerebral ischemic murine model. Moreover, T-LNPs encapsulated Fer1 (T-LNPs-Fer1) significantly enhanced the inhibitory effects of Fer1 on ferroptosis by maintaining the homeostasis of NADPH oxidase 4 (NOX4) and glutathione peroxidase 4 (GPX4) signals in neuronal cells after cerebral ischemia. T-LNPs-Fer1 significantly suppressed oxidative stress [heme oxygenase-1 expression and malondialdehyde (the product of lipid ROS reaction)] in neurons and alleviated ischemia-induced neuronal cell death, compared to Fer1 alone without encapsulation. Furthermore, T-LNPs-Fer1 significantly reduced cerebral infarction and improved behavior functions compared to Fer1-treated cerebral ischemic mice after 45-min ischemia/24-h reperfusion. These findings showed that the T-LNPs helped Fer1 penetrate the BBB and improved the neuroprotection of Fer1 against cerebral ischemic damage in experimental stroke, providing a feasible translational strategy for the development of clinical drugs for the treatment of ischemic stroke.

Impaired sensorimotor functions are prominent complications of spinal cord injury (SCI). A clinically important but less obvious consequence is development of metabolic syndrome (MetS), including increased adiposity, hyperglycemia/insulin resistance, and hyperlipidemia. MetS predisposes SCI individuals to earlier and more severe diabetes and cardiovascular disease compared to the general population, which trigger life-threatening complications (e.g., stroke, myocardial infarcts). Although each comorbidity is known to be a risk factor for diabetes and other health problems in obese individuals, their relative contribution or perceived importance in propagating systemic pathology after SCI has received less attention. This could be explained by an incomplete understanding of MetS promoted by SCI compared with that from the canonical trigger diet-induced obesity (DIO). Thus, here we compared metabolic-related outcomes after SCI in lean rats to those of uninjured rats with DIO. Surprisingly, SCI-induced MetS features were equal to or greater than those in obese uninjured rats, including insulin resistance, endotoxemia, hyperlipidemia, liver inflammation and steatosis. Considering the endemic nature of obesity, we also evaluated the effect of premorbid obesity in rats receiving SCI; the combination of DIO + SCI exacerbated MetS and liver pathology compared to either alone, suggesting that obese individuals that sustain a SCI are especially vulnerable to metabolic dysfunction. Notably, premorbid obesity also exacerbated intraspinal lesion pathology and worsened locomotor recovery after SCI. Overall, these results highlight that normal metabolic function requires intact spinal circuitry and that SCI is not just a sensory-motor disorder, but also has significant metabolic consequences.

The establishment of reliable human brain models is pivotal for elucidating specific disease mechanisms and facilitating the discovery of novel therapeutic strategies for human brain disorders. Human induced pluripotent stem cell (iPSC) exhibit remarkable self-renewal capabilities and can differentiate into specialized cell types. This makes them a valuable cell source for xenogeneic or allogeneic transplantation. Human-mouse chimeric brain models constructed from iPSC-derived brain cells have emerged as valuable tools for modeling human brain diseases and exploring potential therapeutic strategies for brain disorders. Moreover, the integration and functionality of grafted stem cells has been effectively assessed using these models. Therefore, this review provides a comprehensive overview of recent progress in differentiating human iPSC into various highly specialized types of brain cells. This review evaluates the characteristics and functions of the human-mouse chimeric brain model. We highlight its potential roles in brain function and its ability to reconstruct neural circuitry in vivo. Additionally, we elucidate factors that influence the integration and differentiation of human iPSC-derived brain cells in vivo. This review further sought to provide suitable research models for cell transplantation therapy. These research models provide new insights into neuropsychiatric disorders, infectious diseases, and brain injuries, thereby advancing related clinical and academic research.

Aims

Matrix metalloproteinases 9 (MMP9) plays a role in the destruction of blood–brain barrier (BBB) and cell death after cerebral ischemic/reperfusion (I/R). Esculentoside H (EH) is a saponin found in Phytolacca esculenta. It can block JNK1/2 and NF-κB signal mediated expression of MMP9. In this study, we determined whether EH can protect against cerebral I/R injury by inhibiting MMP9 and elucidated the underlying mechanism.

Main methods

Male SD rats were used to construct middle cerebral artery occlusion (MCAO) models. We determined the effect of EH on MMP9 inhibition, BBB destruction, neuronal death, PANoptosis, infarct volume, and the protective factor TLE1. Adeno-associated virus (AAV) infection was used to establish TLE1 gene overexpression and knockdown rats, which were used to determine the function. LY294002 was used to determine the role of PI3K/AKT signaling in TLE1 function.

Key findings

After EH treatment, MMP9 expression, BBB destruction, neuronal death, and infarct volume decreased. We found that TLE1 expression decreased obviously after cerebral I/R. TLE1-overexpressing rats revealed distinct protective effects to cerebral I/R injury. After treatment with LY294002, the protective effect was inhibited. The curative effect of EH also decreased when TLE1 was knocked down.

Significance

EH alleviates PANoptosis and protects BBB after cerebral I/R via the TLE1/PI3K/AKT signaling pathway. Our findings reveal a novel strategy and new target for treating cerebral I/R injury.