Chronic Stress Remodels Synapses in an Amygdala Circuit–Specific Manner

Background

Chronic stress exposure increases the risk of developing various neuropsychiatric illnesses. The behavioral sequelae of stress correlate with dendritic hypertrophy and glutamate-related synaptic remodeling at basolateral amygdala projection neurons (BLA PNs). Yet, though BLA PNs are functionally heterogeneous with diverse corticolimbic targets, it remains unclear whether stress differentially impacts specific output circuits.

肿瘤抑制因子PTEN亚细胞定位与缺血-缺氧性脑损伤

第10号染色体缺失的磷酸酶和张力蛋白同源等位基因(PTEN)具有脂质和蛋白双重磷酸酶活性。脑组织缺血-缺氧后PTEN发生活化并向线粒体或胞核内转移,而这种在神经元内的不同亚细胞定位可能最终决定细胞命运。因此,阐明PTEN在脑缺血-缺氧后的亚细胞定位机制,将为各种急慢性神经退行性变疾病的靶向治疗和药物研发提供新思路。     

成人起病散发性下运动神经元病基因检测的相关研究

目的探讨成人散发起病的下运动神经元病(lower motor neuron disease,LMND)患者铜锌超氧化物歧化酶1(superoxide dismutase 1,SOD1)基因、运动神经元存活基因(survive motor neuron,SMN)及雄激素受体(androgen receptor,AR)基因对明确诊断疾病类型的作用。方法收集43例成人散发起病表现为LMND的患者取外周血提取基因组DNA,分别进行聚合酶链式反应(PCR)扩增SOD1基因外显子1-5,SMN基因外显子7及男性LMND患者AR基因外显子1,对产物进行高分辨熔解曲线分析、变性聚丙烯酰胺凝胶电泳分析及测序。结果在43例成年LMND患者中,未发现SOD1基因突变。2例男性患者有SMN1外显子7的纯合缺失,诊断为Ⅲ、Ⅳ型脊髓性肌萎缩(SMA)。在31例男性患者中发现3例AR基因外显子1的CAG三核苷酸重复序列数分别为49、50、52,可诊断肯尼迪病。结论对LMND患者进行SMN1基因外显子7及AR基因外显子1检测,可使部分散发或无明确家族史的患者明确诊断,并可对病情及预后进行评估。     

脊髓损伤(SCI)后呼吸运动功能的恢复

 高颈段脊髓损伤(spinal cord injury,SCI)往往导致膈肌麻痹,了解如何恢复SCI患者膈神经的节律活动至关重要。控制膈运动神经元(phrenic motor neuron,PhMn)的兴奋性前运动神经元主要起源于同侧延髓,因此,当C2脊髓半离断(spinal cord hemisection,SH)后,损伤侧的下行冲动中断,同侧膈神经的节律消失。随后,潜在的对侧下行冲动逐渐增强(神经可塑性),使PhMn的节律性活动恢复。众多证据表明神经营养因子(如脑源性神经营养因子,brain derived neurotrophic factor, BDNF)通过原肌球蛋白相关激酶受体(如TrkB)在神经可塑性中发挥重要作用。我们的实验结果表明,在鞘膜内注射BDNF能促进PhMn节律性的恢复,而注射TrkB-Fc(一种可抑制细胞外BDNF的融合蛋白)则延迟恢复。应用腺病毒载体(adeno-associated viral vector,AVV)靶向诱导PhMn中TrkB的表达也可促进PhMn节律性的恢复,而Si-RNA诱导的PhMn中TrkB表达抑制则延缓恢复。总之,增强PhMn的BDNF-TrkB信号通路可能是促进SCI后功能恢复的有效治疗手段。     

纳洛酮对缺氧诱导大鼠神经元损伤的抑制作用及其机制

目的探讨纳洛酮对缺氧诱导大鼠神经元损伤的作用及其可能的机制。方法体外培养大鼠神经元，将其分为正常对照组、缺氧诱导组、缺氧诱导＋纳洛酮干预组。应用流式细胞术测定大鼠神经元损伤；应用荧光探针2，7-二氯二氢荧光素乙酰乙酸（DCFDA）检测细胞内活性氧的变化；应用比色法检测超氧化物歧化酶（SOD）的活性；应用Westernblot检测NF—KB的活化。结果（1）纳洛酮抑制缺氧诱导的大鼠神经元凋亡，缺氧组大鼠神经元细胞凋亡明显增加，为对照组的3．54倍，纳洛酮干预组为对照组的1．35倍（均P〈0．05）。（2）纳洛酮抑制缺氧诱导的活性氧生成，缺氧诱导大鼠神经元活性氧生成，为对照组的2．66倍，纳洛酮干预组为对照组的1．24倍（均P〈0．05）。（3）纳洛酮抑制缺氧诱导的NF—KB活化（P〈0．05）。（4）抗氧化剂NAC抑制缺氧诱导的NF—KB活化，抑制率达49％（P〈0．05）。结论纳洛酮抑制缺氧诱导的活性氧生成，进而抑制NF—KB活化，从而抑制缺氧诱导的大鼠神经元凋亡。     

Arimoclomol: a potential therapy under development for ALS

Arimoclomol, an amplifier of heat shock protein expression involved in cellular stress response, has emerged as a potential therapeutic candidate in amyotrophic lateral sclerosis (ALS) in recent years. Treatment with arimoclomol was reported to improve survival and muscle function in a mouse model of motor neuron disease. Several single- and multiple-dose safety studies have been completed in healthy control subjects. A 3-month Phase IIa study in people with ALS demonstrated safety at dosages up to 300 mg/day and another study is currently recruiting participants with familial ALS caused by mutations in the superoxide dismutase gene. We review the rationale for testing arimoclomol in sporadic and familial ALS in the context of available safety and pharmacokinetic data. Published and unpublished literature relative to the drug in the past two decades is discussed. The current review attempts to bring together our existing understanding of the actions of arimoclomol with the disease profile of ALS. The pharmacological profile of arimoclomol and the available preclinical data make it a promising therapeutic possibility in ALS.     

Treatment of transected peripheral nerves with artemin improved motor neuron regeneration,but did not reduce nerve injury-induced pain behaviour

Incomplete recovery of function and neuropathic pain are common problems after peripheral nerve injury. To develop new treatment strategies for peripheral nerve injuries we investigated whether the neurotrophic factor artemin could improve outcome after sciatic nerve injuries in rats. Artemin is a member of the glial cell line-derived neurotrophic factor (GDNF) family and exerts neuroprotective effects on sensory neurons as well as influencing behavioural thermal sensitivity. We additionally evaluated if fibrin sealant, which is sometimes used as a nerve glue, had any effects on neuropathic pain-related behaviour. After the sciatic nerve had been transected, 30 animals were randomised to one of three groups: treatment with a fibrin sealant that contained artemin in conjunction with sutures; fibrin sealant with no artemin (sham) in conjunction with sutures; or sutures alone (n=10 in each group). Motor function, sensory function, and autotomy were evaluated from 1 to 12 weeks after injury. Retrograde flourogold tracing 12 weeks after injury showed that the addition of artemin increased the number of regenerating motor neurons. However, it did not improve their performance, as measured by the Sciatic Function Index, compared with sham or suture alone. Animals treated with artemin had a non-significant increase in motor nerve conduction velocity compared with sham. However, artemin did not reverse nerve injury-induced pain behaviour such as cold or heat hypersensitivity. Fibrin sealant in itself did not ameliorate motor performance, or regeneration of motor neurons, or give rise to nerve injury-induced pain behaviour. The results indicate that artemin is of value as a treatment for peripheral nerve injuries, although the effects were limited. As the artemin high-affinity receptor GFRα-3 is present in Schwann cells and not in motor neurons, the effect on motor neuron axon regeneration may result from an indirect effect through Schwann cells in the injured nerve.