ApoE and TDP-43 neuropathology in two siblings with familial FTLD-motor neuron disease

Frontotemporal lobar degeneration with motor neuron disease (FTLD-MND) is characterized by neuronal cytoplasmic inclusions containing TDP-43. Apolipoprotein E4 (apoE4), derived from the apoE ?4 allele, enhances brain atrophy in FTLD through unknown mechanisms. Here, we studied two siblings with C9ORF72-linked familial FTLD-MND, an apoE ?4 homozygote and an apoE ?3 homozygote. The apoE ?4 homozygote had more cognitive-behavioral symptoms, fronto-insulo-temporal atrophy, and apoE fragments and aggregates in the anterior cingulate cortex. ApoE formed complexes with TDP-43 that were more abundant in the apoE ?4 homozygote. Although differences seen in a sibling pair could arise due to chance, these findings raise the possibility that apoE4 exacerbates brain pathology in FTLD through formation of neurotoxic apoE fragments and interactions with TDP-43.     

The mechanism of astragaloside IV promoting sciatic nerve regeneration

3-O-beta-D-xylopyranosyl-6-O-beta-D-glucopyranosyl-cycloastragenol (astragaloside Ⅳ), the main active component of the traditional Chinese medicine astragalus membranaceus, has been shown to be neuroprotective. This study investigated whether astragaloside Ⅳ could promote the repair of injured sciatic nerve. Denervated sciatic nerve of mice was subjected to anastomosis. The mice were intraperitoneally injected with 10, 5, 2.5 mg/kg astragaloside Ⅳ per day for 8 consecutive days. Western blot assay and real-time PCR results demonstrated that growth-associated protein-43 expression was upregulated in mouse spinal cord segments L4-6 after intervention with 10, 5, 2.5 mg/kg astragaloside Ⅳ per day in a dose-dependent manner. Luxol fast blue staining and electrophysiological detection suggested that astragaloside Ⅳ elevated the number and diameter of myelinated nerve fibers, and simultaneously increased motor nerve conduction velocity and action potential amplitude in the sciatic nerve of mice. These results indicated that astragaloside Ⅳ contributed to sciatic nerve regeneration and functional recovery in mice. The mechanism underlying this effect may be associated with the upregulation of growth-associated protein-43 expression.     

Nuclear TAR DNA-binding protein 43 A new target for amyotrophic lateral sclerosis treatment

Abnormal TAR DNA-binding protein 43 （TDP-43） inclusion bodies can be detected in the degen- erative neurons of amyotrophic lateral sclerosis. In this study, we induced chronic oxidative stress injury by applying malonate to cultured mouse cortical motor neurons. In the later stages of the malonate insult, TDP-43 expression reduced in the nuclei and transferred to the cytoplasm. This was accompanied by neuronal death, mimicking the pathological changes in TDP-43 that are seen in patients with amyotrophic lateral sclerosis. Interestingly, in the early stages of the response to malonate treatment, nuclear TDP-43 expression increased, and neurons remained relatively intact, without inclusion bodies or fragmentation. Therefore, we hypothesized that the increase of nuclear TDP-43 expression might be a pro-survival factor against oxidative stress injury. This hypothesis was confirmed by an in vitro transgenic experiment, in which overexpression of wild type mouse TDP-43 in cultured cortical motor neurons significantly reduced malonate-induced neuronal death. Our findings suggest that the loss of function of TDP-43 is an important cause of neuronal degen- eration, and upregulation of nuclear TDP-43 expression might be neuroprotective in amyotrophic lateral sclerosis.     

Maturational changes in connexin 43 expression in the seminiferous tubules may depend on thyroid hormone action

Introduction

Connexin 43 (Cx43) mediates the effect of thyroid hormone on Sertoli cell maturation in vitro. We investigated the influence of triiodothyronine (T3) administration on Cx43 expression in relation to the progress in seminiferous tubule maturation.

Material and methods

Male rats were daily injected with 100 µg T3/kg body weight from birth until postnatal day (pnd) 5 (transient treatment – tT3) or until pnd 15 (continuous treatment – cT3) or solvent – control (C). On pnd 16 serum hormone levels, body and testes weight, seminiferous tubule morphometry, Cx43 immunostaining and germ cell degeneration were investigated. Cx43 expression was also assessed in six 50-day-old adult untreated rats.

Result

tT3 increased 2.6-fold serum level of T3, testes weight, and seminiferous tubule diameter, and induced maturation-like dislocation of Cx43 expression from the apical to the peripheral region of Sertoli cell cytoplasm. In addition, incidence of Cx43-positive tubules declined from 86% in C to 46% after tT3, being similar to the adult value (30% of tubules Cx43-positive). In turn, cT3 increased serum T3 level 12-fold, and decreased body weight. Seminiferous tubules became shortened and distended, Sertoli cell cytoplasm vacuolated, Cx43 expression had minimal intensity and germ cell degeneration increased.

Conclusions

Cx43 might intermediate a short and transient stimulatory effect of T3 on seminiferous tubule maturation that disappeared together with exposure to the toxic effect of a continuously high level of the hormone.     

RNA quality control and protein aggregates in amyotrophic lateral sclerosis: A review

Amyotrophic lateral sclerosis (ALS) is the most common motor neuron disease in adults. The biologic basis of ALS remains unknown. However, ALS research has taken a dramatic turn over the past 4 years. Ground breaking discoveries of mutations of genes that encode RNA processing proteins, and demonstration that abnormal aggregates of these and other proteins precede motor neuron loss in familial and sporadic ALS, have initiated a paradigm shift in understanding the pathogenic mechanisms of ALS. Curiously, some of these RNA binding proteins have prion‐like domains, with a propensity to self‐aggregation. The emerging hypothesis that a focal cascade of toxic protein aggregates, and their consequent non–cell‐autonomous spread to neighborhood groups of neurons, fits the classical temporo‐spatial progression of ALS. This article reviews the current research efforts toward understanding the role of RNA‐processing regulation and protein aggregates in ALS. Muscle Nerve 47:330‐338, 2013     

Exposure to female estrous is beneficial for male mice against transient ischemic stroke

ABSTRACT

Objective: Exposure to female estrous, a natural rewarding experience, alleviates anxiety and depression, and the contribution of this behavior to stroke outcome is unknown. The aim of this study was to evaluate whether exposure to female estrous is beneficial to recovery following transient ischemic stroke in male mice.

Methods: Cerebral ischemia was induced in male ICR mice with thread occlusion of the middle cerebral artery (MCAO) for 30 min followed by reperfusion. MCAO mice were randomly divided into MCAO group and Estrous Female Exposure (EFE) group. The mice in the EFE group were subjected to estrous female mouse interaction from day 1 until the end of the experiment. Mortality was recorded during the investigation. Behavioral functions were assessed by a beam-walking test and corner test from day 1 to day 10 after MCAO. Serum testosterone levels were analyzed with ELISA, and the expression levels of growth-associated protein-43 (GAP-43) and synaptophysin in the cortex of the ischemic hemisphere were determined by western blot on day 7 after MCAO.

Results: Exposure to female estrous reduced the mortality induced by cerebral ischemic lesions. The beam-walking test demonstrated that exposure to female estrous significantly improved motor function recovery. The serum testosterone levels and ischemic cortex GAP-43 expression were significantly higher in MCAO male mice exposed to female estrous.

Conclusion: Exposure to female estrous reduces mortality and improves functional recovery in MCAO male mice. The study provides the first evidence to support the importance of female interaction to male stroke rehabilitation.

Abbreviations: GAP-43: growth-associated protein-43; SYP: Synaptophysin; MCAO: middle cerebral artery occlusion; OVXs: ovariectomies; CCA: common carotid artery; ECA: external carotid artery; EFE: estrous female exposure; TTC: 2,3,5-triphenyltetrazolium chloride; PAGE: polyacrylamide gel electrophoresis; PVDF: polyvinylidene difluoride; ANOVA: analysis of variance; LSD: least significant difference     

Neuropathology of the hippocampus in FTLD‐Tau with Pick bodies: a study of the BrainNet Europe Consortium

G. G. Kovacs, A. J. M. Rozemuller, J. C. van Swieten, E. Gelpi, K. Majtenyi, S. Al‐Sarraj, C. Troakes, I. Bódi, A. King, T. Hortobágyi, M. M. Esiri, O. Ansorge, G. Giaccone, I. Ferrer, T. Arzberger, N. Bogdanovic, T. Nilsson, I. Leisser, I. Alafuzoff, J. W. Ironside, H. Kretzschmar and H. Budka (2013) Neuropathology and Applied Neurobiology 39, 166–178 Neuropathology of the hippocampus in FTLD‐Tau with Pick bodies: a study of the BrainNet Europe Consortium Aims: Frontotemporal lobar degeneration with Pick bodies (Pick's disease) is characterized by the presence of tau immunoreactive spherical structures in the cytoplasm of neurones. In view of confusion about the molecular pathology of Pick's disease, we aimed to evaluate the spectrum of tau pathology and concomitant neurodegeneration‐associated protein depositions in the characteristically affected hippocampus. Methods: We evaluated immunoreactivity (IR) for tau (AT8, 3R, 4R), α‐synuclein, TDP43, p62, and ubiquitin in the hippocampus, entorhinal and temporal cortex in 66 archival cases diagnosed neuropathologically as Pick's disease. Results: Mean age at death was 68.2 years (range 49–96). Fifty‐two (79%) brains showed 3R immunoreactive spherical inclusions in the granule cells of the dentate gyrus. These typical cases presented mainly with the behavioural variant of frontotemporal dementia, followed by progressive aphasia, mixed syndromes or early memory disturbance. α‐Synuclein IR was seen only in occasional spherical tau‐positive inclusions, TDP‐43 IR was absent, and 4R IR was present only as neurofibrillary tangles in pyramidal neurones. Aβ IR was observed in 16 cases; however, the overall level of Alzheimer's disease‐related alterations was mainly low or intermediate (n = 3). Furthermore, we identified six cases with unclassifiable tauopathy. Conclusions: (i) Pick's disease may occur also in elderly patients and is characterized by a relatively uniform pathology with 3R tau inclusions particularly in the granule cells of dentate gyrus; (ii) even minor deviation from these morphological criteria suggests a different disorder; and (iii) immunohistological revision of archival cases expands the spectrum of tauopathies that require further classification.     

Blocking brain‐derived neurotrophic factor inhibits injury‐induced hyperexcitability of hippocampal CA3 neurons

Brain trauma can disrupt synaptic connections, and this in turn can prompt axons to sprout and form new connections. If these new axonal connections are aberrant, hyperexcitability can result. It has been shown that ablating tropomyosin‐related kinase B (TrkB), a receptor for brain‐derived neurotrophic factor (BDNF), can reduce axonal sprouting after hippocampal injury. However, it is unknown whether inhibiting BDNF‐mediated axonal sprouting will reduce hyperexcitability. Given this, our purpose here was to determine whether pharmacologically blocking BDNF inhibits hyperexcitability after injury‐induced axonal sprouting in the hippocampus. To induce injury, we made Schaffer collateral lesions in organotypic hippocampal slice cultures. As reported by others, we observed a 50% reduction in axonal sprouting in cultures treated with a BDNF blocker (TrkB‐Fc) 14 days after injury. Furthermore, lesioned cultures treated with TrkB‐Fc were less hyperexcitable than lesioned untreated cultures. Using electrophysiology, we observed a two‐fold decrease in the number of CA3 neurons that showed bursting responses after lesion with TrkB‐Fc treatment, whereas we found no change in intrinsic neuronal firing properties. Finally, evoked field excitatory postsynaptic potential recordings indicated an increase in network activity within area CA3 after lesion, which was prevented with chronic TrkB‐Fc treatment. Taken together, our results demonstrate that blocking BDNF attenuates injury‐induced hyperexcitability of hippocampal CA3 neurons. Axonal sprouting has been found in patients with post‐traumatic epilepsy. Therefore, our data suggest that blocking the BDNF–TrkB signaling cascade shortly after injury may be a potential therapeutic target for the treatment of post‐traumatic epilepsy.     

电针对脑出血大鼠神经功能、学习记忆能力及GAP-43表达的影响

目的研究电针对脑出血大鼠神经功能、学习记忆能力及GAP-43表达的影响。方法将40只雄性SD大鼠随机分为正常组、模型组、假手术组及电针组,每组各10只大鼠,模型组及电针组大鼠采用Rosenberg法制备大鼠脑出血模型,电针组于制备模型后24h给予电针治疗,连续治疗21d后采用NSS神经缺损体征评分法检测大鼠神经功能,水迷宫检测大鼠学习记忆能力,免疫组化法检测出血周边区GAP-43的表达水平。结果与模型组比较,电针组大鼠神经功能缺损评分明显降低,逃避潜伏期显著缩短,而出血周边区GAP-43表达显著增加（P均〈0．01）。结论电针可能通过增加大鼠出血周边区GAP-43表达而促进神经元重塑,进而改善其神经功能及学习记忆能力。     

Reduced expression of BTBD10 in anterior horn cells with Golgi fragmentation and pTDP‐43‐positive inclusions in patients with sporadic amyotrophic lateral sclerosis

Overexpression of BTBD10 (BTB/POZ domain‐containing protein 10) suppresses G93A‐superoxide dismutase 1 (SOD1)‐induced motor neuron death in a cell‐based amyotrophic lateral sclerosis (ALS) model. In the present study, paraffin sections of spinal cords from 13 patients with sporadic ALS and 10 with non‐ALS disorders were immunostained using a polyclonal anti‐BTBD10 antibody. Reduced BTBD10 expression in the anterior horn cells was more frequent in spinal cords from ALS patients than in cords from patients with non‐ALS disorders. We further investigated the relationship between the level of BTBD10 immunoreactivity and the morphology of the Golgi apparatus (GA) and the presence of phosphorylated TAR‐DNA‐binding protein 43 (pTDP‐43). Mirror sections of spinal cords from five sporadic ALS cases were immunostained with antibodies against BTBD10 and trans‐Golgi‐network (TGN)‐46 or pTDP‐43. Whereas 89.7–96.5% of the neurons with normal BTBD10 immunoreactivity showed normal GA morphology and no pTDP‐43 cytoplasmic aggregates, 86.2–94.3% of the neurons with reduced BTBD10 expression showed GA fragmentation and abnormal pTDP‐43 aggregates. These findings suggest that reduced BTBD10 expression is closely linked to the pathogenesis of sporadic ALS.