Sepsis-associated encephalopathy (SAE) is a severe and frequent complication of sepsis causing delirium, coma, and long-term cognitive dysfunction. We identified microglia and C1q complement activation in hippocampal autopsy tissue of patients with sepsis and increased C1q-mediated synaptic pruning in a murine polymicrobial sepsis model. Unbiased transcriptomics of hippocampal tissue and isolated microglia derived from septic mice revealed an involvement of the innate immune system, complement activation, and up-regulation of lysosomal pathways during SAE in parallel to neuronal and synaptic damage. Microglial engulfment of C1q-tagged synapses could be prevented by stereotactic intrahippocampal injection of a specific C1q-blocking antibody. Pharmacologically targeting microglia by PLX5622, a CSF1-R inhibitor, reduced C1q levels and the number of C1q-tagged synapses, protected from neuronal damage and synapse loss, and improved neurocognitive outcome. Thus, we identified complement-dependent synaptic pruning by microglia as a crucial pathomechanism for the development of neuronal defects during SAE.

Background: High-resolution nerve ultrasound (HRUS) has been proven to be a valuable tool in the diagnosis of immune-mediated neuropathies, such as chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). POEMS syndrome (polyneuropathy, organomegaly, endocrinopathy, M-protein, skin changes) is an important differential diagnosis of CIDP. Until now, there have been no studies that could identify specific HRUS abnormalities in POEMS syndrome patients. Thus, the aim of this study was to assess possible changes and compare findings with CIDP patients. Methods: We retrospectively analyzed HRUS findings in three POEMS syndrome and ten CIDP patients by evaluating cross-sectional nerve area (CSA), echogenicity and additionally calculating ultrasound pattern scores (UPSA, UPSB, UPSC and UPSS) and homogeneity scores (HS). Results: CIDP patients showed greater CSA enlargement and higher UPSS (median 14 vs. 11), UPSA (median 11.5 vs. 8) and HS (median 5 vs. 3) compared with POEMS syndrome patients. However, every POEMS syndrome patient illustrated enlarged nerves exceeding reference values, which were not restricted to entrapment sites. In CIDP and POEMS syndrome, heterogeneous enlargement patterns could be identified, such as inhomogeneous, homogeneous and regional nerve enlargement. HRUS in CIDP patients visualized both increased and decreased echointensity, while POEMS syndrome patients pictured hypoechoic nerves with hyperechoic intraneural connective tissue. Discussion: This is the first study to demonstrate HRUS abnormalities in POEMS syndrome outside of common entrapment sites. Although nerve enlargement was more prominent in CIDP, POEMS syndrome patients revealed distinct echogenicity patterns, which might aid in its differentiation from CIDP. Future studies should consider HRUS and its possible role in determining diagnosis, prognosis and treatment response in POEMS syndrome.

Neuronal ischemia results in chloride gradient alterations which impact the excitatory–inhibitory balance, volume regulation, and neuronal survival. Thus, the Na⁺/K⁺/Cl⁻ co-transporter (NKCC1), the K⁺/ Cl⁻ co-transporter (KCC2), and the gamma-aminobutyric acid A (GABA_A) receptor may represent therapeutic targets in stroke, but a time-dependent effect on neuronal viability could influence the outcome. We, therefore, successively blocked NKCC1, KCC2, and GABA_A (with bumetanide, DIOA, and gabazine, respectively) or activated GABA_A (with isoguvacine) either during or after oxygen-glucose deprivation (OGD). Primary hippocampal cultures were exposed to a 2-h OGD or sham normoxia treatment, and viability was determined using the resazurin assay. Neuronal viability was significantly reduced after OGD, and was further decreased by DIOA treatment applied during OGD (p < 0.01) and by gabazine applied after OGD (p < 0.05). Bumetanide treatment during OGD increased viability (p < 0.05), while isoguvacine applied either during or after OGD did not influence viability. Our data suggests that NKCC1 and KCC2 function has an important impact on neuronal viability during the acute ischemic episode, while the GABA_A receptor plays a role during the subsequent recovery period. These findings suggest that pharmacological modulation of transmembrane chloride transport could be a promising approach during stroke and highlight the importance of the timing of treatment application in relation to ischemia-reoxygenation.

Long-term consequences of stroke significantly impair the quality of life in a growing population of stroke survivors. Hippocampal adult neurogenesis has been hypothesized to play a role in the pathophysiology of cognitive and neuropsychiatric long-term sequelae of stroke. Reliable animal models of stroke are paramount to understanding their biomechanisms and to advancing therapeutic strategies. We present a detailed protocol of a transient cerebral ischemia model which does not cause direct ischemic damage in the hippocampus, allowing investigations into the pathophysiology of long-term neurocognitive deficits of stroke. Furthermore, we describe a protocol for obtaining acute hippocampal slices for the purpose of electrophysiological and morphological characterization of adult-borne granule cells. Particularities relating to performing electrophysiological recordings from small cells, such as immature adult-borne granule cells, are also discussed. The present protocol may be complemented by multi-modal investigations (behavioral, morpho-structural, biochemical), to hopefully facilitate research and advances into the long-term sequelae of stroke and the discovery of new therapeutic opportunities., [摘要]中风的长期后果严重损害了越来越多的中风幸存者的生活质量。假定海马成年神经发生在中风的认知和神经精神病学长期后遗症的病理生理学中起作用。可靠的中风动物模型对于理解其生物机制和推进治疗策略至关重要。我们提出 暂时性脑缺血模型的详细协议，该模型不会在海马体中引起直接缺血损伤，从而可以研究中风的长期神经认知缺陷的病理生理学。此外，我们描述了一种用于获取成人海马颗粒细胞的电生理学和形态学特征的急性海马切片的协议。还讨论了与从小细胞（例如未成熟的成年颗粒细胞）进行电生理记录有关的特殊性。本协议可以通过多模式研究（行为，形态结构，生化）加以补充，以期有希望促进研究和中风的长期后遗症的发展以及发现新的治疗机会。[背景]中风是在发达国家发病率和死亡率的重要原因引起急性和延迟赤字。虽然针对缺血性中风恢复血流的干预策略在降低急性发病率和死亡率方面已经变得更加有效，但中风的长期后果（如中风后抑郁和中风后认知功能障碍和痴呆症）目前正在逃避临床治疗（Wang等。，2010; Loubinoux等人，2012; Mijajlovic 。等人，2017）。这些迟发性神经认知功能障碍的病理生理学尚不充分了解。假定成人传播的颗粒细胞在中风的认知和神经精神后遗症中起作用，但是，在这一领域的研究已经落后于涉及成人神经发生的其他疾病的研究，例如癫痫病（Jakubs等，2006； Jessberger等。 。，2007）。存在几种脑缺血的动物模型，范围从可逆的全局缺血模型到永久性局灶性缺血模型，甚至是由光血栓形成引起的局部局限性皮层梗死（Sicard and Fisher，2009）。但是，整体缺血模型可能会直接影响（成人传播的）海马颗粒细胞的活力，从而诱发与神经认知功能障碍的病理生理学有关的混杂因素，而局灶性梗塞则可能导致大脑中较弱的继发性变化。确实，先前的研究发现，梗死面积与在成人传播的颗粒细胞中观察到的形态变化程度有关，短暂性大脑中动脉闭塞（MCAO）模型比皮质梗塞具有更深远的影响（例如，通过光血栓形成，Niv等）等人，2012年）。因此，我们提出了一种灵活的MCAO模型，该模型可以可靠地诱发广泛的皮质-皮层下皮质缺血模式，但不会对海马体造成直接缺血性损害（Sicard和Fisher，2009）。本方法的优点是梗塞体积随缺血时间而变化（更大的梗塞体积在成年神经发生过程中引起更广泛的扰动），从而高比例的动物存活以允许行为，电生理，形态学和中风后延迟时间点的生化特征。可以使用转基因模型（Couillard-Despres等，2006）或使用逆转录病毒标记技术（Niv等，2012）对成人传播的颗粒细胞进行荧光标记。转基因DCX / DsRed小鼠（Couillard-Despres等，2006）在双皮质素（DCX）启动子的控制下表达红色荧光蛋白DsRed 。DCX是一种迁移蛋白，大约在有丝分裂后的第四周，在突触整合和固有成熟时在未成熟的神经元中表达。或者，逆转录病毒标记可用于追踪海马内注射病毒时出生的齿状颗粒细胞的成熟（Niv等，2012）。

Perinatal asphyxia (PA) and hypoxic-ischemic encephalopathy can result in severe, long-lasting neurological deficits. In vitro models, such as oxygen–glucose deprivation (OGD), are used experimentally to investigate neuronal response to metabolic stress. However, multiple variables can affect the severity level of OGD/PA and may confound any measured treatment effect. Oxytocin (OXT) has emerged as a potential neuroprotective agent against the deleterious effects of PA. Previous studies have demonstrated OXT’s potential to enhance neuronal survival in immature hippocampal cultures exposed to OGD, possibly by modulating gamma-aminobutyric acid-A receptor activity. Moreover, OXT’s precise impact on developing hippocampal neurons under different severities of OGD/PA remains uncertain. In this study, we investigated the effects of OXT (0.1 µM and 1 µM) on 7-day-old primary rat hippocampal cultures subjected to 2 h OGD/sham normoxic conditions. Cell culture viability was determined using the resazurin assay. Our results indicate that the efficacy of 1 µM OXT treatment varied according to the severity of the OGD-induced lesion, exhibiting a protective effect (p = 0.022) only when cellular viability dropped below 49.41% in non-treated OGD cultures compared to normoxic ones. Furthermore, administration of 0.1 µM OXT did not yield significant effects, irrespective of lesion severity (p > 0.05). These findings suggest that 1 µM OXT treatment during OGD confers neuroprotection exclusively in severe lesions in hippocampal neurons after 7 days in vitro. Further research is warranted to elucidate the mechanisms involved in OXT-mediated neuroprotection.