Effects of metformin on recognition memory and hippocampal neuroplasticity in rats with metabolic syndrome

Metabolic syndrome (MS) is a health problem that is characterized by body fat accumulation, hypertension, dyslipidemia, and hyperglycemia; recently, it has been demonstrated that MS also damages memory processes. The first-line drug in the treatment of MS and type 2 diabetes mellitus is metformin, which is an antihyperglycemic agent. This drug has been shown to produce neuroprotection and to improve memory processes. However, the mechanism involved in this neuroprotection is unknown. A 90-day administration of metformin improved the cognitive processes of rats with MS as evaluated by the novel object recognition test, and this finding could be explained by an increase in the neuronal spine density and spine length. We also found that metformin increased the immunoreactivity of synaptophysin, sirtuin-1, AMP-activated protein kinase, and brain-derived neuronal factor, which are important plasticity markers. We conclude that metformin is an important therapeutic agent that increases neural plasticity and protects cognitive processes. The use of this drug is important in the minimization of the damage caused by MS.     

Lateral ventricular liponeurocytoma: Review of literature and case illustration

BackgroundLiponeurocytoma is an uncommon tumor of the central nervous system. It is very rare for this tumor to originate within the lateral ventricle. In the context of the rarity of this tumor entity, this review article aims to summarize the clinical, radiological, and pathological features of lateral ventricular liponeurocytoma to facilitate its diagnosis and management.MethodsHere, we conduct a systematic literature review using the Pubmed, Scopus, and Cochrane Library database for all cases of lateral ventricular liponeurocytoma. A case illustration complements this review.ResultsThe described cases from 1997 onward include 14 cases that have been published in full papers in the English literature. Six additional cases are reported in short English abstracts in full non-English papers, and one case was described in a central neurocytoma report. There is a definite male predominance of 70% (14 male) and a mean age of 37 years (range 24–62). Heterogenous enhancement and signals in magnetic resonant images (MRI) are the radiological characteristics. In all reported cases, the presence of lipocytes and fat vacuoles is considered the paramount histopathological feature. Total surgical resection was achieved in 80% (12 out of 15) of the cases. Only two cases (including ours) received radiation therapy. Recurrence was seen in two patients during follow-up that was treated by radiation therapy in one and surgery in the other. The proliferation index is mostly below 5% in all cases, with the Ki-67 range between < 1% to 10%.ConclusionsLateral ventricular liponeurocytoma has been treated effectively by surgical resection in a limited number of cases. The decision for radiation therapy is based on a high proliferation index and tumor recurrence.     

Clinicopathological features of low-grade malignant endolymphatic sac tumors

Background

Low-grade malignant endolymphatic sac tumor (ELST) is a rare neoplasm, occurring in the inner ear and invading the temporal bone. This study aims to investigate the clinicopathological features of low-grade malignant ELSTs.

跑台训练对脑缺血大鼠脑组织超微结构及突触素表达的影响

目的:研究运动训练对局灶性脑缺血大鼠脑组织超微结构及突触素表达的影响。方法:选取健康雄性SD大鼠37只,随机分为假手术组、缺血对照组和缺血加跑台训练组。线栓法阻断动物大脑中动脉血流2h制备局灶性脑缺血模型。术后2周,采用Western blot测定脑组织中突触素的表达;术后4周,透射电镜观察各组实验动物脑组织超微结构改变情况。结果:①与假手术组相比,缺血组和缺血加跑台训练组大鼠脑额顶叶皮质半暗区突触素含量显著升高(P<0.01);其中跑台训练组升高明显,两组差异有显著性意义(P<0.05)。②电镜观察显示缺血加跑台训练组大鼠脑组织超微结构损伤较轻,突触数目较多,突触形态基本正常。结论:运动训练可以减轻脑缺血性损伤程度,并可能通过增加脑组织突触素的表达,促进脑缺血性损伤后新生突触的形成。     

环境噪音对新生大鼠身长体质量及学习记忆的影响

目的研究环境噪音对新生大鼠身长体质量及学习记忆的影响。方法选用7 d SD大鼠16只,分为高噪音组和对照组,每组8只,高噪音组的平均噪音为90 db(A)、对照组50 db(A)。分别在P10、P15、P20时进行身长、体质量的测量,P20时利用Morris水迷宫观察学习记忆功能、ELISA检测生长激素,RT-PCR、Western blot观察突触素表达。结果高噪音组身长、体质量低于同年龄对照组大鼠[身长(cm):P10(9.54±0.1)vs(9.98±0.1),P15(10.24±0.1)vs(10.79±0.1),P20(10.59±0.1)vs(11.68±0.1);体质量(g):P10(14.33±0.02)vs(14.51±0.02),P15(15.31±0.02)vs(15.68±0.02),P20(16.63±0.02)vs(16.76±0.02),P<0.05];与对照组比较,高噪音组学习能力下降,生长激素、突触素(synaptophysin,SYP)mRNA、SYP表达水平低于同年龄对照组大鼠[生长激素(pg/ml):(299.7±4.9)vs(504.9±13.14),SYP mRNA:(0.182±0.008)vs(1.056±0.011),SYP:(0.168±0.007)vs(0.432±0.025),P<0.05]。结论高噪音环境下新生SD大鼠的身长、体质量增长缓慢,学习记忆能力下降。     

神经生长因子对大鼠缺血性脑损伤急性期的疗效研究

目的:观察神经生长因子(NGF)对脑缺血急性期大鼠脑组织超微结构及突触素(Syp)表达的影响。方法:健康雄性SD大鼠36只,随机分为假手术组、缺血组和NGF组各12只,后2组线栓法制备MCAO模型,NGF组给予NGF腹腔注射治疗14d,其余2组腹腔注射等量生理盐水治疗14d。术后14d,WesternBlot测定各组脑组织中Syp的表达;术后28d,透射电镜观察各组脑组织超微结构。结果:术后14d,缺血组和NGF组脑组织Syp蛋白含量均显著高于假手术组(P<0.01),NGF组脑组织Syp蛋白含量高于缺血组(P<0.05);术后28d,电镜显示NGF组脑组织超微结构损伤较轻,突触数目较多,突触形态基本正常。结论:急性期腹腔注射NGF可减轻大鼠脑缺血性损伤程度,可能通过增加脑组织Syp的表达来促进脑缺血性损伤后突触的形成。     

灵芝三萜对癫痫大鼠学习记忆损伤的效果

目的 研究灵芝三萜对戊四氮致痫大鼠认知功能的影响及其作用机制。方法 75只Sprague-Dawley大鼠随机分为空白对照组、癫痫模型组、灵芝三萜组、外源性单唾液酸四己糖神经节苷脂(GM1)组和灵芝三萜联合GM1组,每组15只。除空白对照组外,其余各组用戊四氮35 mg/kg腹腔注射,每天1次,持续28 d。各用药组在每天腹腔注射戊四氮的同时进行相应给药。造模后,行Morris水迷宫测试;HE染色及透射电镜观察海马神经元;实时定量聚合酶链反应检测大鼠海马肌动蛋白结合蛋白(Cofilin)、突触素(SYN)、神经生长相关蛋白43 (GAP-43)的mRNA表达水平。结果 与空白对照组比较,各时间点癫痫模型组逃避潜伏期延长(P < 0.05);与癫痫模型组比较,各用药组逃避潜伏期均缩短,部分时间点有显著性差异( P < 0.05)。与癫痫模型组比较,各用药组穿越平台次数明显增多( P < 0.01),在目标象限停留时间明显延长( P < 0.01)。各用药组海马神经元数增加,核溶解碎裂减少,核膜结构较清楚,突触小泡增多,突触数量增加,细胞器结构有所改善。与空白对照组相比,癫痫模型组Cofilin mRNA水平上调( P < 0.05),SYN mRNA和GAP-43 mRNA水平降低( P < 0.05);与癫痫模型组比较,各用药组Cofilin mRNA表达水平降低( P < 0.05),SYN mRNA表达水平升高( P < 0.05),仅灵芝三萜联合GM1组GAP-43 mRNA升高( P < 0.05)。 结论 灵芝三萜和GM1及两者联合用药均可改善癫痫大鼠的学习记忆能力及神经元形态结构,其机制可能与影响海马突触生长重塑相关基因表达有关,以达到保护大脑神经元的作用。     

Expression of mGluR5 and Synaptophysin Genes after Injury to the Dorsal Hippocampus,Inflicted by Cainic Acid

The expression of synaptophysin (vesicular protein) and mGluR5 (metabotropic glutamate receptor) genes was studied 3, 7, and 20 days after cainic acid injury of the dorsal hippocampal area in Wistar rats. The expression of both genes was characteristically reduced in the hippocampus. Twenty days after the exposure the expression of mGluR5 in this brain area reached the control level, while synaptophysin expression remained low. An opposite trend was observed in the frontal cortex: synaptophysin expression 20 days after exposure did not differ from the control, while mGluR5 expression was reduced. The peculiar time course of both genes’ expression in the hippocampus and frontal cortex indicates the involvement of the frontal cortex in mechanisms of functional recovery after hippocampal injuries. Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 147, No. 2, pp. 197-200, February, 2009     

Granulocyte colony stimulating factor decreases brain amyloid burden and reverses cognitive impairment in Alzheimer's mice

Granulocyte colony stimulating factor (G-CSF) is a multi-modal hematopoietic growth factor, which also has profound effects on the diseased CNS. G-CSF has been shown to enhance recovery from neurologic deficits in rodent models of ischemia. G-CSF appears to facilitate neuroplastic changes by both mobilization of bone marrow–derived cells and by its direct actions on CNS cells. The overall objective of the study was to determine if G-CSF administration in a mouse model of Alzheimer's disease (AD) (Tg APP/PS1) would impact hippocampal-dependent learning by modifying the underlying disease pathology. A course of s.c. administration of G-CSF for a period of less than three weeks significantly improved cognitive performance, decreased β-amyloid deposition in hippocampus and entorhinal cortex and augmented total microglial activity. Additionally, G-CSF reduced systemic inflammation indicated by suppression of the production or activity of major pro-inflammatory cytokines in plasma. Improved cognition in AD mice was associated with increased synaptophysin immunostaining in hippocampal CA1 and CA3 regions and augmented neurogenesis, evidenced by increased numbers of calretinin-expressing cells in dentate gyrus. Given that G-CSF is already utilized clinically to safely stimulate hematopoietic stem cell production, these basic research findings will be readily translated into clinical trials to reverse or forestall the progression of dementia in AD. The primary objective of the present study was to determine whether a short course of G-CSF administration would have an impact on the pathological hallmark of AD, the age-dependent accumulation of Aβ deposits, in a transgenic mouse model of AD (APP+ PS1; Tg). A second objective was to determine whether such treatment would impact cognitive performance in a hippocampal-dependent memory paradigm. To explain the G-CSF triggered amyloid reduction and associated reversal of cognitive impairment, several mechanisms of action were explored. (1) G-CSF was hypothesized to increase activation of resident microglia and to increase mobilization of marrow-derived microglia. The effect of G-CSF on microglial activation was examined by quantitative measurements of total microglial burden. To determine if G-CSF increased trafficking of marrow-derived microglia into brain, bone marrow–derived green fluorescent protein-expressing (GFP+) microglia were visualized in the brains of chimeric AD mice. (2) To assess the role of immune-modulation in mediating G-CSF effects, a panel of cytokines was measured in both plasma and brain. (3) To test the hypothesis that reduction of Aβ deposits can affect synaptic area, quantitative measurement of synaptophysin immunoreactivity in hippocampal CA1 and CA3 sectors was undertaken. (4) To learn whether enhanced hippocampal neurogenesis was induced by G-CSF treatment, numbers of calretinin-expressing cells were determined in dentate gyrus.