The effects of preweaning manganese exposure on spatial learning ability and p-CaMKIIα level in the hippocampus

BackgroundThe effects and mechanisms of preweaning Manganese (Mn) exposure on cognitive dysfunction remain unclear.ObjectiveThis study evaluated the effects of preweaning Mn exposure on spatial learning and memory as well as the protein expression of CaMKIIα and p-CaMKIIα.MethodsWe treated neonate rats with Mn²⁺ doses of 0 (control group), 10, 20 and 30 mg of Mn²⁺ per kg body weight (Mn-exposed groups) over postnatal day (PND) 1–21 by intraperitoneal injection. The ability of spatial learning and memory was tested on PND 22 using the Morris water maze (MWM), while the protein expressions of CaMKIIα and p-CaMKIIα in the hippocampus were evaluated by Western blotting. The levels of Mn in the blood and hippocampus were measured by inductively coupled plasma-mass spectrometry (ICP-MS).ResultsThe rats in Mn-exposed groups showed a significant delay in spatial learning ability on the third day of the MWM without dose-dependent differences, but there was no effect on the spatial memory ability. p-CaMKIIα, but not CaMKIIα protein expression significantly reduced in the Mn-exposed group.ConclusionThese findings suggested that the inhibition of p-CaMKIIα could be one of the mechanisms involved in the occurrence of Mn-induced cognitive impairments.     

TNF-α from hippocampal microglia induces working memory deficits by acute stress in mice

The role of microglia in stress responses has recently been highlighted, yet the underlying mechanisms of action remain unresolved. The present study examined disruption in working memory due to acute stress using the water-immersion resistant stress (WIRS) test in mice. Mice were subjected to acute WIRS, and biochemical, immunohistochemical, and behavioral assessments were conducted. Spontaneous alternations (working memory) significantly decreased after exposure to acute WIRS for 2 h. We employed a 3D morphological analysis and site- and microglia-specific gene analysis techniques to detect microglial activity. Morphological changes in hippocampal microglia were not observed after acute stress, even when assessing ramification ratios and cell somata volumes. Interestingly, hippocampal tumor necrosis factor (TNF)-α levels were significantly elevated after acute stress, and acute stress-induced TNF-α was produced by hippocampal-ramified microglia. Conversely, plasma concentrations of TNF-α were not elevated after acute stress. Etanercept (TNF-α inhibitor) recovered working memory deficits in accordance with hippocampal TNF-α reductions. Overall, results suggest that TNF-α from hippocampal microglia is a key contributor to early-stage stress-to-mental responses.     

Increased irritability,anxiety, and immune reactivity in transgenic Huntington’s disease monkeys

Although the most notable clinical symptoms of Huntington’s disease (HD) are motor disturbances and brain atrophy, other symptoms include cognitive dysfunction, emotional and hormonal dysregulation. Emotional dysregulation (irritability, anger/aggression, and anxiety) and increased inflammation are early emerging symptoms which can be detected decades before the onset of motor symptoms in HD patients. Despite the advances in understanding the genetic causes of HD there is still no cure or preventative treatment. Thus, to better understand the pathogenesis of HD and develop effective treatments, a holistic understanding of HD is needed, as well as animal models that replicate the full spectrum of HD symptoms. The current study examined the emotional, hormonal, and gene expression responses to an acute stressor of adult male transgenic HD rhesus monkeys (n = 2) as compared to wild-type controls (n = 2). Results revealed that HD monkeys expressed increased anxiety and irritability/aggression as compared to controls. Reactive cortisol response to the stressor was similar between groups. However, HD monkeys exhibited increased pro-inflammatory cytokines and higher induction of immune pathway genes as compared to controls. Overall, results reveal that HD monkeys exhibit these early emerging symptoms of HD and may be an effective animal model to facilitate the development of new therapeutics for HD patients.     

Temporal control of glucocorticoid neurodynamics and its relevance for brain homeostasis,neuropathology and glucocorticoid-based therapeutics

Glucocorticoids mediate plethora of actions throughout the human body. Within the brain, they modulate aspects of immune system and neuroinflammatory processes, interfere with cellular metabolism and viability, interact with systems of neurotransmission and regulate neural rhythms. The influence of glucocorticoids on memory and emotional behaviour is well known and there is increasing evidence for their involvement in many neuropsychiatric pathologies. These effects, which at times can be in opposing directions, depend not only on the concentration of glucocorticoids but also the duration of their presence, the temporal relationship between their fluctuations, the co-influence of other stimuli, and the overall state of brain activity. Moreover, they are region- and cell type-specific. The molecular basis of such diversity of effects lies on the orchestration of the spatiotemporal interplay between glucocorticoid- and mineralocorticoid receptors, and is achieved through complex dynamics, mainly mediated via the circadian and ultradian pattern of glucocorticoid secretion. More sophisticated methodologies are therefore required to better approach the study of these hormones and improve the effectiveness of glucocorticoid-based therapeutics.     

二甲氧乙二酰甘氨酸对缺血性急性肾衰竭小鼠的保护作用

目的 观察二甲氧乙二酰甘氨酸(DMOG)对小鼠缺血性急性肾衰竭的影响及其与低氧诱导因子1α(HIF-1α)活化之间的关系.方法 雄性C57/BL小鼠25只,随机分为5组:正常对照组(Control组),DMOG组(20 mg/kg,ip),假手术组(Sham组)及肾缺血-再灌注组(I/R组)和DMOG预处理组(DMOG+I/R组).采用夹闭双侧肾蒂30 min的方法建立小鼠缺血性急性.肾衰竭模型,DMOG注射6 h或缺血-再灌注24 h后采血并处死小鼠,全自动生化分析仪检测小鼠的肾功能,通过HE染色对肾组织病理学进行评分,免疫组织化学染色检测肾组织中波形蛋白的表达,TUNEL法检测细胞凋亡,Western blot方法检测肾HIF-1α活化情况.结果 DMOG组小鼠肾组织中HIF-1α的表达明显高于正常对照组(P＜0.01);DMOG+I/R组小鼠.肾功能病理学评分明显低于I/R未处理组[BUN,(26.3±6.5) vs (65.8±2.6);Scr,(27.0±14.1) vs (229.5±11.2),P＜0.01],DMOG+I/R组细胞凋亡程度和小管波形蛋白的表达较I/R组明显减少[(5.7±1.5) vs (23.3±2.1),P＜0.05;(12.9±5.7) vs (69.6±22.7),P＜0.01].结论 DMOG可通过诱导HIF-1α活化对缺血性急性肾衰竭小鼠发挥保护作用.     

Deferoxamine preconditioning activated hypoxia-inducible factor-1α and MyD88-dependent Toll-like receptor 4 signaling in intestinal stem cells

Background/Purpose

Toll-like receptors (TLRs) are important regulators of innate immunity, and TLR4 pathway can regulate the survival, migration, and differentiation of stem cells, including intestinal stem cells (ISCs). Deferoxamine (DFO), a hypoxia-mimic compound, can activate the proliferation of ISCs. In this study, we investigated the response of TLR4 signaling to DFO-induced hypoxia in cultured ISCs in vitro.

TNFα-在小鼠叶酸诱导肾病中的致病作用及其机理研究

目的研究TNF-α在小鼠叶酸诱导肾病中的致病作用及其机制。方法建立小鼠叶酸诱导肾病模型,运用抗TNF-α多克隆抗体及对照抗体干预治疗,检测小鼠血清以及肾组织中TNF-α水平,肾小管上皮细胞凋亡情况以及凋亡相关蛋白的表达水平。结果在CD1小鼠叶酸诱导肾病模型中,尿素氮水平显著升高,肾小管上皮细胞坏死和凋亡增加,小鼠血清以及肾组织中TNF-α水平显著升高,肾皮质组织中Bcl-xL表达水平显著下降,运用抗TNF-α多克隆抗体干预治疗可保持Bcl-xL在肾组织中的表达水平,减少肾小管上皮细胞凋亡,有效减轻小鼠肾功能损害。结论TNF-α在小鼠叶酸诱导肾病发病机制中具有重要作用,阻断TNF-α是治疗急性肾衰的一种潜在有效手段。     

Fibroblast-derived exosomal miRNA-133 promotes cardiomyocyte-like differentiation

ObjectiveTo investigate the role of exosomal miRNA-133 secreted by cardiac fibroblasts (CFs) in promoting cardiomyocyte differentiation.MethodsNeonatal rat CFs were cultured in vitro, and the cultured CFs were divided into three groups as follows: induction, miRNA-133 high expression, and miRNA-133 inhibition. miRNA-133 was transfected into CFs with lentivirus as a vector. CFs were transfected with the miRNA-133 inhibitor, and the markers of cardiomyocyte were detected through immunofluorescence staining, Western blotting, and real-time quantitative polymerase chain reaction (qRT-PCR) at 3, 8, and 14 days, respectively. The expression levels of cardiac troponin T (cTnT) and cardiac actin (α-actin) were determined, and qRT-PCR was used to detect the expression of miRNA-133 in the fibroblast exosomes.ResultsCFs subjected to immunofluorescence staining expressed vimentin and discoid domain receptor 2. The exosomes secreted by CFs were observed as small vesicles of 30–100 nm via transmission electron microscopy, and Western blotting was used to detect exosome-specific protein CD63 and CD9 expression. The expression levels of cTnT, α-actin, and exosomal miRNA-133 secreted into the supernatant of the miRNA-133 high-expression group increased gradually at different time points and reached the highest level at 14 days. The expression levels of cTnT, α-actin, and exosome miRNA-133 in the miRNA-133 inhibition group were the lowest.ConclusionThe exosomal miRNA-133, which is derived from CFs, can promote the differentiation of fibroblasts into cardiomyocyte-like cells.