耐药性杏仁核点燃癫痫模型海马组织中γ-氨基丁酸受体表达变化

目的 建立多药耐药性癫痫模型,观察海马组织γ-氨基丁酸(GABA)受体表达变化从而探讨其在耐药性杏仁核点燃癫痫形成中的作用.方法 选用Wistar大鼠100只制作慢性杏仁核点燃癫痫模型,模型制作成功(n=52)后用经典抗癫痫药苯妥英钠和苯巴比妥进行筛选,根据大鼠对苯妥英钠和苯巴比妥的反应区别出耐药癫痫大鼠(n=8)及药物敏感大鼠(n=8),然后处死动物留取脑组织标本,用免疫组织化学染色方法观察海马组织内GABAA受体表达变化,用蛋白质印迹法检测GABAA受体含量,观察耐药癫痫大鼠和药物敏感大鼠之间的不同.结果 耐药癫痫性颞叶大鼠海马细胞变性坏死,排列紊乱,结构特征消失;耐药性颞叶癫痫大鼠海马组织内GABAA受体阳性表达细胞的灰度值(141.15±14.72)比药物敏感大鼠增高(92.56 ±5.17;t =3.380,P=0.006);蛋白质印迹方法提示受体条带变淡变窄,蛋白含量明显减少(0.38 ±0.08),与药物敏感大鼠(0.88 ±0.18)比较,差异具有统计学意义(t=5.420,P=0.002);但两组间GABAA受体阳性细胞数百分率比较差异无统计学意义.结论 耐药性颞叶癫痫大鼠海马组织内GABA受体表达明显减少,这可能在耐药性颞叶癫痫的形成过程中发挥部分作用.     

建立杏仁核电刺激慢点燃和匹罗卡品化学点燃耐药性颞叶癫痫模型并对比癫痫发作和海马超微结构的变化

目的用两种方法建立颞叶耐药癫痫模型,探讨哪种方法更适合建立多药耐药颞叶癫痫模型。方法选用SD大鼠130只,10只作为正常组,120只分别制作杏仁核和匹罗卡品模型,模型成功后用抗癫痫药苯巴比妥和苯妥英钠或卡马西平进行筛选,分别选择10只杏仁核模型和匹罗卡品模型比较两种方法建立的模型癫痫发作持续时间、发作频率、发作级别、脑电图及电镜下超微结构的变化。结果成功制作杏仁核模型31只,匹罗卡品模型29只,匹罗卡品模型癫痫发作频率(2. 09±0. 044)高于杏仁核组(1. 01±0. 037),持续时间(61. 37±4. 22)长于杏仁核组(43. 16±5. 91),而癫痫发作的级别无明显差异;经过耐药性癫痫模型的筛选,选出杏仁核耐药模型8只,匹罗卡品耐药模型12只。匹罗卡品模型与杏仁核模型相比脑电频率更高,波幅增宽,超微结构的损伤更严重。结论匹罗卡品模型自发性率高,耐药率高,脑电变化明显,超微结构损伤重,更适合耐药性癫痫机制的研究。     

泛素特异性蛋白酶25在颞叶癫痫大鼠颞叶皮质中表达变化的实验研究

目的探讨海人酸点燃杏仁核大鼠颞叶癫痫模型颞叶皮质中泛素特异性蛋白酶25(USP25)的表达情况。方法将52只SD雄性大鼠按随机数字表法分为癫痫模型组(共39只)和假手术对照组(简称对照组,13只)。癫痫模型组建立海人酸点燃杏仁核大鼠颞叶癫痫模型,再按构建成功的时间分为3组(构建成功1 d为急性期组、构建成功7 d为潜伏期组、构建成功30 d为慢性期组,每组各13只),在观察结束时取材。对照组在杏仁核注入生理盐水,与癫痫模型组伴随取材。免疫组织化学染色及免疫荧光双标法检测USP25在颞叶皮质中的表达及与神经元(NeuN)和星形胶质细胞(GFAP)的共定位情况;实时荧光定量PCR法和蛋白免疫印迹法检测USP25在颞叶皮质中的表达变化。结果在注药侧颞叶皮质中,癫痫模型组USP25与NeuN的共定位阳性细胞在癫痫后期增加,USP25 mRNA及蛋白水平在癫痫发作不同时期的表达差异均有统计学意义(F值分别为25.48、7.68,均P<0.05)。与对照组(mRNA:1.00±0.36;蛋白:1.00±0.46)比较,潜伏期组(mRNA:10.80±4.82;蛋白:1.88±0.32)和慢性期组(mRNA:12.97±4.48;蛋白:1.92±0.26)的表达水平显著增加,差异均有统计学意义(均P<0.05)。在未注药侧皮质中,USP25 mRNA及蛋白水平在癫痫发作不同时期的表达差异也均有统计学意义(F值分别为86.86、6.65,均P<0.05)。结论颞叶皮质中USP25的表达在癫痫大鼠潜伏期后增加,提示去泛素化通路参与颞叶癫痫的慢性病理过程。     

海马硬化致颞叶癫癎的SPECT与MRI研究

目的探讨SPECT脑血流灌注显像结合MRI测量海马体积对海马硬化致颞叶癫癎患者致灶的定位价值。方法采用99Tcm-双半胱乙酯(99Tcm-ECD)SPECT脑血流灌注显像对双侧海马血流灌注进行定性和半定量分析,MRI测量双侧海马体积,分析海马硬化致颞叶癫癎(颞叶癫癎组)患者患侧海马相对脑血流量与相应区域海马体积的相关性。结果颞叶癫癎组患者患侧海马相对脑血流量[(46.04±7.94)ml/(100 g·min)]低于对侧[(54.76±9.62)ml/(100 g·min);t=-2.966,P=0.005]和正常对照者[(64.87±7.28)ml/(100 g·min);t=-4.824,P=0.000],且海马体积[(1.69±0.39)cm3]小于对侧[(2.68±0.41)cm3;t=-7.410,P=0.000]和正常对照者[(3.50±0.39)cm3;t=-16.340,P=0.000]。海马硬化致颞叶癫癎患者患侧海马相对脑血流量与相应区域海马体积呈正相关(r=0.394,P=0.017)。结论海马硬化致颞叶癫癎患者患侧海马相对脑血流量降低、海马体积缩小,二者呈正相关。SPECT脑血流灌注显像结合MRI测量海马体积,可以作为致灶切除术前准确定位的参考依据。     

海人酸致难治性癫痫大鼠脑组织及外周血P糖蛋白表达趋势相关性研究

目的 研究难治性癫痫大鼠脑组织及外周血中P糖蛋白表达的相关性,探讨难治性癫痫可能的耐药机制,并比较海人酸在不同核团致痫后P糖蛋白表达的差异.方法 用海人酸分别于大鼠杏仁核及海马进行化学点燃,制作难治性癫痫模型.采用免疫组化方法,分析比较难治性癫痫大鼠脑组织及外周血中P糖蛋白的表达.结果 杏仁核点燃组与海马点燃组大鼠脑组织及外周血P糖蛋白表达高于与其相对应的生理盐水卡马西平组及生理盐水对照组,有统计学意义(P＜0.05);杏仁核生理盐水卡马两平组及海马生理盐水卡马西平组大鼠脑组织及外周血P糖蛋白的表达高于杏仁核生理盐水对照组及海马生理盐水对照组,有统计学意义(P＜0.05);杏仁核点燃组和海马点燃组大鼠脑组织及外周血P糖蛋白的表达相近,无统计学意义(P＞0.05).结论 难治性癫痫大鼠外周血及脑组织中P糖蛋白的表达具有一定的相关性,难治性癫痫的耐药机制可能是癫痫本身、服用抗癫痫药物等多因素作用的结果.杏仁核点燃模型及海马点燃模型均可诱导相近似的P糖蛋白的表达.     

耐药性内侧颞叶癫痫患者的功能影像磁共振研究

目的采用功能磁共振功能连接密度(FCD)探索耐药与否的内侧颞叶癫痫患者脑功能活动的差异,并分析其与病程的相关性。方法采用回顾性研究方法,收集从2009年7月至2019年2月在东部战区总医院(南京大学医学院附属金陵医院)就诊的单侧海马硬化的内侧颞叶癫痫患者共146例,根据2010年国际抗癫痫联盟对耐药性癫痫的定义将其分为药物控制组(73例)和耐药组(73例)。对所有受试者均进行3.0 T静息态功能磁共振扫描,比较两组患者FCD的差异,并计算两组患者FCD差异脑区FCD值和病程的相关性。结果药物控制组和耐药组内侧颞叶癫痫患者的FCD显示出广泛差异。相比于药物控制组,耐药组在致痫灶侧岛叶、豆状核、丘脑、海马、中央前回FCD值明显降低。耐药组致痫灶侧楔前叶FCD值与病程呈负相关(r=-0.30,P=0.010)。结论耐药性内侧颞叶癫痫患者较药物控制组FCD值广泛降低,此外大脑可能存在进行性损伤,影像学差异有利于探究内侧颞叶癫痫患者耐药相关的病理生理机制,寻找可靠的耐药相关的神经影像标志物。     

大鼠颞叶癫痫点燃后海马zif268mRNA及其蛋白的时空表达变化

目的 探讨海马zif268mRNA及其蛋白的时空表达变化与颞叶癫痫脑损伤的关系. 方法 将雄性Wistar大鼠随机分为3组:其中正常组6只,假手术对照组(Sham组)和海人酸(KA)颞叶癫痫点燃组(TLE组)各36只,后两组按点燃后6h、24h、3d、7d、14d、21d时间点各分为6小组,每小组6只.采用KA杏仁核点燃建立经典颞叶癫痫模型,应用原位杂交和免疫组织化学方法分别检测海马神经元zif268mRNA及其蛋白的表达.结果 TLE组zif268mRNA表达在总体上和点燃后远期21d海马CA1、CA3区和齿状同(DG)均高于Sham组(P＜0.05).TLE组Zif268蛋白表达在总体上和远期21d海马DG表达低于Sham组(P＜0.05).回归分析提示颞叶癫痫与海马zif268mRNA表达呈正相关(β=0.286,P＜0.001),与Zif268蛋白表达呈负相关(β=-0.153,P＜0.001).结论 颞叶癫痫大鼠海马zif268mRNA及其蛋白的时空表达变化可能参与颞叶癫痫发病及其脑损伤过程.     

锂-匹罗卡品致痫大鼠脑组织中驱动蛋白家族成员17的表达情况

目的 观察驱动蛋白家族成员17 (KIF17)在锂-匹罗卡品致痫大鼠海马和颞叶皮质表达的变化,探讨其在癫痫发生、发展中的作用.方法 采用氯化锂-匹罗卡品诱导癫痫大鼠模型,将49只雄性正常Wistar大鼠采用随机数字表法分成实验组(n=42)和对照组(n=7),实验组又分为6个亚组(n=7):包括癫痫后24h、72 h、7d、14 d、1个月、2个月组.运用蛋白质印迹法检测KIF17在致痫大鼠海马和颞叶皮质的表达变化,免疫荧光双标染色法确定KIF17的表达部位.结果 大鼠海马KIF17蛋白表达在癫痫持续状态(SE)后开始增高[积分吸光度(L4)比值:24 h 0.516±0.196、72 h0.742±0.313],在癫痫后7d时达到高峰(0.888±0.319),之后逐渐降低(14 d 0.770±0.271、1个月0.742±0.261、2个月0.714±0.271),但均显著高于对照组(0.495±0.203),差异均有统计学意义(t=7.051、4.974、7.419、8.795、8.264、6.676,均P＜0.05).大鼠颞叶皮质KIF17蛋白的表达在SE后24h时开始持续增高,并在30 d时达到高峰,且IA比值均明显高于对照组.免疫荧光双标染色法显示KIF17蛋白主要存在于神经元,包括兴奋性神经元和抑制性神经元,而在星形胶质细胞中不表达.结论 KIF17在锂-匹罗卡品致癫痫模型的发生发展过程中可能起着重要的作用.     

低频经颅磁刺激对颞叶癫痫大鼠颞叶和海马细胞凋亡的影响

目的　 探讨低频经颅磁刺激对颞叶癫痫大鼠病灶区颞叶和海马的细胞凋亡有无抑制作用。 方法　 制作氯化锂 匹罗卡品所致的慢性期颞叶癫痫大鼠动物模型 ,分为两组 ,一组给予磁场强度 0 .4T ,刺激时程 0 .2ms的低频 (0 .5Hz)经颅磁刺激 ,另一组给予“假性”刺激。以原位末端标记法 (TUNEL)标记DNA片段 ,电子显微镜检测两组颞叶和海马的细胞凋亡情况 ,并分别与对照组进行比较。结果　 在慢性期颞叶癫痫大鼠的颞叶和海马均可见大量凋亡细胞。在给予适量的低频经颅磁刺激后 ,相应脑部的凋亡细胞数均明显减少 (P <0 .0 5 )。 结论　适量的低频经颅磁刺激能抑制颞叶癫痫大鼠的细胞凋亡 ,对癫痫所致的脑部损伤有修复作用 ,是一种有前途的治疗癫痫的新疗法。     

颞叶癫痫对前瞻性记忆的影响

目的 探讨颞叶癫痫对基于事件的前瞻性记忆(event-based prospective memory,EBPM)和基于时间的前瞻性记忆(time-based prospective memory,TBPM)的影响,验证颞叶参与前瞻性记忆的神经机制假说.方法 采用McDaniel等建立的前瞻性记忆神经心理学试验方法,测试62例颞叶癫痫患者(33例服用抗癫痫药物和29例未服用药物,颞叶癫痫组)和年龄、教育程度相匹配的30名健康者(健康对照组)的EBPM和TBPM.结果 颞叶癫痫组简易精神状态检查(MMSE)、数字广度测试(DS)、词汇流畅性测试(VFT)的成绩均低于健康对照组,且MMSE、VFT两组间差异有统计学意义.与健康对照组[ EBPM测试(6.83±1.34)分,TBPM测试(5.00±1.70)分]相比,颢叶癫痫组的EBPM测试[(3.95±2.77)分]和TBPM测试[(3.08±2.42)分]的成绩差异均有统计学意义(t=6.72、4.39,均P＜0.01),且TBPM测试得分均低于EBPM.其中服药和未服药两组间EBPM测试成绩[(3.82±2 70)、(4.10±2.90)分]差异无统计学意义(t=-0.40,P ＞0.05),两组间TBPM测试成绩[(2.55±2.20)、(3.69±2.55)分]差异亦无统计学意义(t=-1.90,P＞0.05).结论 颞叶癫痫患者存在前瞻性记忆损害,提示颞叶参与前瞻性记忆的神经机制过程;与EBPM相比,TBPM损害更明显,提示TBPM需要更多的自我发动过程.     

Norharman-induced motoric impairment in mice: neurodegeneration and glial activation in substantia nigra

Summary. The β-carboline norharman is present in cooked food and tobacco smoke and show structural resemblance to the neurotoxicant 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine. C57BL/6 mice were injected subcutaneously with norharman (3 and 10 mg/kg) twice per day for five consecutive days. Eighteen hours after the last dose an increased expression of glial fibrillary acidic protein and fluoro-jade staining were demonstrated whereas the number of tyrosine hydroxylase positive cells were unchanged in the substantia nigra. Two weeks after the last treatment a decreased motor activity was observed whereas cognitive functions remained intact. In cultured PC12 cells norharman treatment induced mitochondrial dysfunction and increased the number of caspase-3 and TUNEL-positive cells. The results demonstrate that norharman induced apoptosis in cultured cells as well as early neurodegeneration, glial activation and sustained motor deficits in mice and suggest that exposure to norharman may contribute to idiopathic Parkinson’s disease.     

Sex differences in estrogen receptor promoter expression in the area postrema

Estrogen receptor α is widely distributed in the rat brain, but the tissue- or target-specificity of the estrogen receptor α gene promoters remains unknown. In the present study, we used transgenic rats expressing enhanced green fluorescent protein under the control of the estrogen receptor α 0/B promoter to examine expression driven by this promoter in two significant nuclei that regulate cardiovascular activity, the area postrema and the nucleus tractus solitarius. Immunohistochemistry showed that enhanced green fluorescent protein-labeled cells were distributed in the area postrema and the nucleus tractus solitarius of both female and male transgenic rats, and a neural network of enhanced green fluorescent protein-positive fibers was seen between the area postrema and the nucleus tractus solitarius. The number of enhanced green fluorescent protein-labeled cells in the area postrema of female rats was significantly higher than in the males, but no significant difference was found in the number of enhanced green fluorescent protein-labeled cells in the nucleus tractus solitarius. The sex differences in the number of enhanced green fluorescent protein-labeled cells in the area postrema was not affected after ovariectomy or 17β-estradiol benzoate treatment in adult rats. Our results suggest that the effects of estrogen in the area postrema are related to the expression of estrogen receptor α under the control of the 0/B promoter, and changes in the sex hormone environment in the adult period do not affect estrogen receptor α expression in the area postrema or the nucleus tractus solitarius.     

Potential therapeutic effects of polyphenols in Parkinson’s disease: in vivo and in vitro pre-clinical studies

Parkinson’s disease is a neurodegenerative disorder characterized by a combination of severe motor and non-motor symptoms. Over the years, several factors have been discovered to play a role in the pathogenesis of this disease, in particular, neuroinflammation and oxidative stress. To date, the pharmacological treatments used in Parkinson’s disease are exclusively symptomatic. For this reason, in recent years, the research has been directed towards the discovery and study of new natural molecules to develop potential neuroprotective therapies against Parkinson’s disease. In this context, natural polyphenols have raised much attention for their important anti-inflammatory and antioxidant properties, but also for their ability to modulate protein misfolding. In this review, we propose to summarize the relevant in vivo and in vitro studies concerning the potential therapeutic role of natural polyphenols in Parkinson’s disease.     

A review of SPECT studies in psychiatry in China

Background

Studies of mental disorders using single photon emission computed tomography (SPECT) have been done for many years in China. Many results have been obtained. We review these findings and introduce them to the outside world.

Methods

SPECT papers available on the Chinese Biomedical Bibliographic Database, focusing on depression, schizophrenia, Alzheimer’s disease (AD), vascular dementia (VD), anxiety disorder, and obsessive compulsive disorder (OCD) in China, were reviewed and the results were compared with those obtained outside China.

Results

We found that regional cerebral blood flow (rCBF) was abnormal in mental disorders, but the specificity of the abnormality is not yet consistent. Lower perfusion of rCBF could be seen in frontal, temporal, and parietal lobes of patients with depression, AD, schizophrenia, and VD. It seems that abnormality of the frontal lobe is more common in depression and schizophrenia, but temporal lobe abnormalities are more common in AD and VD. The perfusion of rCBF in the parietal lobe seems to be related to aging. Abnormalities in the occipital lobe and basal ganglia seem to be more associated with vascular problems. Thalamic dysfunction was mainly correlated with VD, and that of the cingulate largely with depression and schizophrenia. Hippocampal abnormalities were associated with AD. There were few reports on changes in anxiety disorders and other mental problems.

Conclusion

There is no specific biological marker of SPECT for individual mental disorders. Further study is needed to provide more specific information on the pathophysiology of mental disorders. It seems that brain abnormalities are similar in Chinese and non Chinese psychiatric patients.     

缺血性卒中并发2型糖尿病患者颈动脉斑块内新生血管分布特点的超声造影研究

目的 应用超声造影观察缺血性卒中并发2型糖尿病患者颈动脉斑块内新生血管分布情况,明确其 斑块内新生血管分布特征。 方法 病例组选取因急性缺血性卒中住院的糖尿病患者40例（入组前未服用降糖药）,卒中同侧颈 动脉斑块形成;对照组为同期门诊就诊的颈动脉斑块形成患者,无卒中病史,性别及年龄匹配的非 糖尿病患者32例。两组患者行弓上计算机断层扫描血管造影（computed tomography angiography,CTA） 检查排除主动脉弓斑块及颅内动脉病变,排除卵圆孔未闭及心房颤动等。对所有患者均行常规超声 及超声造影检查。常规超声观察斑块厚度及内部回声,超声造影观察斑块增强情况,横切面多角度 观察,将超声造影结果分为近内膜处有增强（代表新生血管）及近内膜处无增强两种。 结果 两组患者颈动脉斑块厚度及回声情况差异无统计学意义。超声造影结果显示病例组颈动脉 斑块近内膜处增强者34例（85%）,对照组近内膜处增强12例（37.5%）,差异有统计学意义（χ 2=17.38, P＜0.01）。 结论 未服用降糖药的2型糖尿病并发急性缺血性卒中的患者颈动脉粥样硬化斑块内近内膜处新生 血管增生多于无糖尿病患者,提示血糖升高与颈动脉斑块内血管新生有关。     

急性缺血性卒中血管再通治疗不良预后的预测研究进展

急性缺血性卒中（acute ischemic stroke,AIS）治疗的关键在于早期血管再通,挽救缺血半 暗带。然而早期再通的效果存在个体差异,难以早期预测,且增加了脑梗死后出血转化的风险。为了 能够早期判断AIS患者早期血管再通的预后及出血转化风险,多年来国内外学者一直致力于这方面预 测模型的研发及应用,相关评分预测模型也层出不穷。本文对近年一些相关预测模型的研究进展进 行回顾,以期待对未来的临床工作及科学研究提供帮助和启示。     

Effects of mild intrauterine hypoperfusion in the second trimester on memory and learning function in rat offspring

Mild intrauterine hypoperfusion(MIUH) is a serious pathological event that affects the growth and development of fetuses and offspring. MIUH can lead to growth restriction, low birth weight, neurodevelopmental disorders, and other adverse clinical outcomes. To study the effects of MIUH on learning and memory function in offspring, a model of MIUH was established by placing a coil(length 2.5 mm, diameter 0.24 mm) on the uterine artery and ovarian uterine artery of Sprague-Dawley rats in the second trimester of pregnancy(day 17). Next, 120 mg/kg lithium chloride(the MIUH + Li group) or normal saline(the MIUH group) was injected intraperitoneally into these rats. In addition, 120 mg/kg lithium chloride(the Li group) or normal saline(the SHAM group) was injected intraperitoneally into pregnant rats without coil placement. The Morris water maze was used to detect changes in learning and memory ability in the offspring at 4 weeks after birth. In the MIUH group, the escape latency and journey length before reaching the platform were both increased, and the number of times that the platform was crossed and the activity time in the target quadrant within 90 seconds were both decreased compared with the SHAM group. Immunofluorescence double staining and western blot assays demonstrated that hippocampal nestin and Ki67(both cell-proliferation-related proteins) expression was significantly downregulated in the MIUH group compared with the SHAM group. Furthermore, western blot assays were conducted to investigate changes in related signaling pathway proteins in the brains of offspring rats, and revealed that glycogen synthase kinase 3β(GSK3β) expression was upregulated and β-catenin expression was downregulated in the MIUH group compared with the SHAM group. In addition, compared with the MIUH group, the expression levels of p-GSK3β and β-catenin were upregulated in the MIUH + Li group. These results suggest that MIUH may affect learning and memory function in rat offspring by regulating the GSK3β signaling pathway. The experimental procedures were approved by Animal Ethics Committee of Shengjing Hospital of China Medical University(approval No. 2018 PS07 K) in June 2018.     

Predicting individual variability in task‐evoked brain activity in schizophrenia

What goes wrong in a schizophrenia patient''s brain that makes it so different from a healthy brain? In this study, we tested the hypothesis that the abnormal brain activity in schizophrenia is tightly related to alterations in brain connectivity. Using functional magnetic resonance imaging (fMRI), we demonstrated that both resting‐state functional connectivity and brain activity during the well‐validated N‐back task differed significantly between schizophrenia patients and healthy controls. Nevertheless, using a machine‐learning approach we were able to use resting‐state functional connectivity measures extracted from healthy controls to accurately predict individual variability in the task‐evoked brain activation in the schizophrenia patients. The predictions were highly accurate, sensitive, and specific, offering novel insights regarding the strong coupling between brain connectivity and activity in schizophrenia. On a practical perspective, these findings may allow to generate task activity maps for clinical populations without the need to actually perform any tasks, thereby reducing patients inconvenience while saving time and money.     

Developmental patterns of DR6 in normal human hippocampus and in Down syndrome

Background

Death receptor 6 (DR6) is highly expressed in the human brain: it has been shown to induce axon pruning and neuron death via distinct caspases and to mediate axonal degeneration through binding to N-terminal β amyloid precursor protein (N-APP).

Methods

We investigated the expression of DR6 during prenatal and postnatal development in human hippocampus and temporal cortex by immunocytochemistry and Western blot analysis (118 normal human brain specimens; 9 to 41 gestational weeks; 1 day to 7 months postnatally; 3 to 91 years). To investigate the role of N-APP/DR6/caspase 6 pathway in the development of hippocampal Alzheimer’s disease (AD)-associated pathology, we examined DR6 immunoreactivity (IR) in the developing hippocampus from patients with Down syndrome (DS; 48 brain specimens; 14 to 41 gestational weeks; 7 days to 8 months postnatally; 15 to 64 years) and in adults with DS and AD.

Results

DR6 was highly expressed in human adult hippocampus and temporal cortex: we observed consistent similar temporal and spatial expression in both control and DS brain. Western blot analysis of total homogenates of temporal cortex and hippocampus showed developmental regulation of DR6. In the hippocampus, DR6 IR was first apparent in the stratum lacunosum-moleculare at 16 weeks of gestation, followed by stratum oriens, radiatum, pyramidale (CA1 to CA4) and molecular layer of the dentate gyrus between 21 and 23 gestational weeks, reaching a pattern similar to adult hippocampus around birth. Increased DR6 expression in dystrophic neurites was detected focally in a 15-year-old DS patient. Abnormal DR6 expression pattern, with increased expression within dystrophic neurites in and around amyloid plaques was observed in adult DS patients with widespread AD-associated neurodegeneration and was similar to the pattern observed in AD hippocampus. Double-labeling experiments demonstrated the colocalization, in dystrophic neurites, of DR6 with APP. We also observed colocalization with hyper-phosphorylated Tau and with caspase 6 (increased in hippocampus with AD pathology) in plaque-associated dystrophic neurites and within the white matter.

Conclusions

These findings demonstrate a developmental regulation of DR6 in human hippocampus and suggest an abnormal activation of the N-APP/DR6/caspase 6 pathway, which can contribute to initiation or progression of hippocampal AD-associated pathology.     

Glial dysfunction in abstinent methamphetamine abusers

Persistent neurochemical abnormalities in frontal brain structures are believed to result from methamphetamine use. We developed a localized ¹³C magnetic resonance spectroscopy (MRS) assay on a conventional MR scanner, to quantify selectively glial metabolic flux rate in frontal brain of normal subjects and a cohort of recovering abstinent methamphetamine abusers. Steady-state bicarbonate concentrations were similar, between 11 and 15 mmol/L in mixed gray-white matter of frontal brain of normal volunteers and recovering methamphetamine-abusing subjects (P>0.1). However, glial ¹³C-bicarbonate production rate from [1-¹³C]acetate, equating with glial tricarboxylic acid (TCA) cycle rate, was significantly reduced in frontal brain of abstinent methamphetamine-addicted women (methamphetamine 0.04 μmol/g per min (N=5) versus controls 0.11 μmol/g per min (N=5), P=0.001). This is equivalent to 36% of the normal glial TCA cycle rate. Severe reduction in glial TCA cycle rate that normally comprises 10% of total cerebral metabolic rate may impact operation of the neuronal glial glutamate cycle and result in accumulation of frontal brain glutamate, as observed in these recovering methamphetamine abusers. Although these are the first studies to define directly an abnormality in glial metabolism in human methamphetamine abuse, sequential studies using analogous ¹³C MRS methods may determine ‘cause and effect'' between glial failure and neuronal injury.