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.     

New routes in frontotemporal dementia drug discovery

Introduction: Research into the pathogenic mechanisms behind frontotemporal dementia (FTD) has yielded several new targets for therapeutic intervention; such targets include specific new pathways uncovered by mutations as well as targets involving the modulation, formation and degradation of protein aggregates.

Areas covered: Herein, the authors outline the principal molecular causes underlying FTD to date and the research that has been performed in these areas with respect to an eventual corrective strategy.

Expert opinion: While it is worthwhile targeting pathways affected by specific mutations with a causative loss of function linked to FTD, research still has to contend with issues including the remaining presence of protein aggregates or that treatments are rarely universally applicable. Aiming to recover function in a downstream target caused by the protein aggregates will likely be insufficient due to the large cascade of events affected. It is our belief that the clearance of these aggregates and the inhibition of protein misfolding are more appropriate and direct routes to an eventual therapy.     

连接蛋白43在骨关节炎发病机制中的研究进展

骨关节炎(osteoarthritis,OA)是常见的关节疾病,也是导致残疾的主要原因之一,给患者及家庭带来巨大的经济生活负担。虽然OA的发病机制至今尚未完全明确,但关节软骨代谢平衡的破坏被认为与骨关节炎的发生息息相关。研究发现连接蛋白43(connexin43)在维持关节软骨代谢平衡的稳态中发挥着至关重要的作用,它所参与形成的半通道(hemichannels)和缝隙连接(gap junctions)在细胞与细胞外基质,以及细胞之间建立起直接的物质信号交换通道。同时,连接蛋白43的高表达和(或)分布的变化都将影响软骨细胞结构和功能的完整性。因此,连接蛋白43被认为与骨关节炎的发生有着密切关系。本文就连接蛋白43与骨关节炎发病机制的研究进展做一综述。     

Mechanism of Regulatory Effect of MicroRNA-206 on Connexin 43 in Distant Metastasis of Breast Cancer

Background:

MicroRNA-206 (miR-206) and connexin 43 (Cx43) are related with the distant metastasis of breast cancer. It remains unclear whether the regulatory effect of miR-206 on Cx43 is involved in metastasis of breast cancer.

Methods:

Using quantitative real-time polymerase chain reaction and Western blot, the expressions of miR-206 and Cx43 were determined in breast cancer tissues, hepatic and pulmonary metastasis (PM), and cell lines (MCF-10A, MCF-7, and MDA-MB-231). MCF-7/MDA-M-231 cells were transfected with lentivirus-shRNA vectors to enhance/inhibit miR-206, and then Cx43 expression was observed. Cell counting kit-8 assay and Transwell method were used to detect their changes in proliferation, migration, and invasion activity. The mutant plasmids of Cx43-3’ untranslated region (3’UTR) at position 478–484 and position 1609–1615 were constructed. Luciferase reporter assay was performed to observe the effects of miR-206 on luciferase expression of different mutant plasmids and to confirm the potential binding sites of Cx43.

Results:

Cx43 protein expression in hepatic and PM was significantly higher than that in the primary tumor, while no significant difference was showed in messenger RNA (mRNA) expression. MiR-206 mRNA expression in hepatic and PM was significantly lower than that in the primary tumor. Cx43 mRNA and protein levels, as well as cell proliferation, migration, and invasion capabilities, were all significantly improved in MDA-MB-231 cells after reducing miR-206 expression but decreased in MCF-7 cells after elevating miR-206 expression, which demonstrated a significantly negative correlation between miR-206 and Cx43 expression (P = 0.03). MiR-206 can drastically decrease Cx43 expression of MCF-7 cells but exerts no effects on Cx43 expression in 293 cells transfected with the Cx43 coding region but the lack of Cx43-3’UTR, suggesting that Cx43-3’UTR may be the key in Cx43 regulated by miR-206. Luciferase expression showed that the inhibition efficiency was reduced by 46.80% in position 478–484 mutant, 16.72% in position 1609–1615 mutant; the inhibition was totally disappeared in double mutant (P = 0.02).

Conclusions:

MiR-206 can regulate the expression of Cx43, the cytobiological activity, and the metastasis of breast cancer through binding to the two binding sites in Cx43-3’UTR: position 478–484 and position 1609–1615.     

Chronic antidepressant treatment selectively increases expression of plasticity-related proteins in the hippocampus and medial prefrontal cortex of the rat

Antidepressants protect against hippocampal volume loss in humans and reverse stress-induced atrophic changes in animals thus supporting the hypothesis that the pathophysiology of stress-related disorders such as depression involves reductions in neuronal connectivity and this effect is reversible by antidepressant treatment. However, it is unclear which brain areas demonstrate such alterations in plasticity in response to antidepressant treatment. The aim of the present study was to examine the effect of antidepressant treatment on the expression of three plasticity-associated marker proteins, the polysialylated form of nerve cell adhesion molecule (PSA-NCAM), phosphorylated cyclic-AMP response element binding protein (pCREB) and growth-associated protein 43 (GAP-43), in the rat brain. To this end, rats were treated either acutely (60 min) or chronically (21 days) with imipramine (30 and 15 mg/kg, respectively) and the expression of PSA-NCAM, pCREB, and GAP-43 was assessed using immunohistochemistry. Initial mapping revealed that chronic imipramine treatment increased expression of these plasticity-associated proteins in the hippocampus, medial prefrontal cortex and piriform cortex but not in the other brain regions examined. Since PSA-NCAM and pCREB are expressed in recently-generated neurons in the dentate gyrus, it is likely that chronic imipramine treatment increased their expression in the hippocampus at least partially by increasing neurogenesis. In contrast, since chronic imipramine treatment is not associated with neurogenesis in the medial prefrontal cortex, increased expression of PSA-NCAM and pCREB in the prelimbic cortex implicates changes in synaptic connectivity in this brain region. Acute treatment with imipramine increased the number of pCREB positive nuclei in the hippocampus and the prefrontal cortex but did not alter expression of GAP-43 or PSA-NCAM in any of the brain regions examined. Taken together, the results of the present study suggest that antidepressant treatment increases synaptic plasticity and connectivity in brain regions associated with mood disorders.     

Connexin 43 Is Necessary for Murine Tendon Enthesis Formation and Response to Loading

The enthesis is a mineralized fibrocartilage transition that attaches tendon to bone and is vital for musculoskeletal function. Despite recent studies demonstrating the necessity of muscle loading for enthesis formation, the mechanisms that regulate enthesis formation and mechanoresponsiveness remain unclear. Therefore, the current study investigated the role of the gap junction protein connexin 43 in these processes by deleting Gja1 (the Cx43 gene) in the tendon and enthesis. Compared with their wild-type (WT) counterparts, mice lacking Cx43 showed disrupted entheseal cell alignment, reduced mineralized fibrocartilage, and impaired biomechanical properties of the supraspinatus tendon entheses during postnatal development. Cx43-deficient mice also exhibited reduced ability to complete a treadmill running protocol but no apparent deficits in daily activity, metabolic indexes, shoulder muscle size, grip strength, and major trabecular bone properties of the adjacent humeral head. To examine enthesis mechanoresponsiveness, young adult mice were subjected to modest treadmill exercise. Gja1 deficiency in the tendon and enthesis reduced entheseal anabolic responses to treadmill exercise: WT mice had increased expression of Sox9, Ihh, and Gli1 and increased Brdu incorporation, whereas Cx43-deficient mice showed no changes or decreased levels with exercise. Collectively, the results demonstrated an essential role for Cx43 in postnatal tendon enthesis formation, function, and response to loading; results further provided evidence implicating a link between Cx43 function and the hedgehog signaling pathway. © 2020 American Society for Bone and Mineral Research.