Environmental enrichment delays the onset of memory deficits and reduces neuropathological hallmarks in a mouse model of Alzheimer-like neurodegeneration

Alzheimer's disease (AD) is a devastating neurodegenerative disorder characterized by progressive memory deficits and cognitive decline. We explored the possibility that Environmental Enrichment (EE) may reduce the disease progression in a comprehensive mouse model for AD like neurodegeneration, the AD11 mice. AD11 mice, which express anti nerve growth factor (NGF) antibodies, develop an age dependent neurodegeneration which encompasses all hallmarks of human AD. We have tested the efficacy of EE starting from 2 months of age, that is before the onset of behavioural deficits in AD11 mice. At 7 months of age, visual recognition memory was tested with the Object Recognition Test (ORT), spatial memory with the Morris Water Maze (MWM) and the presence of AD pathological hallmarks (Abeta clusters, presence of hyperphosphorylated tau and cholinergic deficit) was assessed immunohistochemically. We found that in AD11 mice exposed to EE from 2 to 7 months of age performance in both memory tests was significantly better than in non EE AD11 mice and indistinguishable from that in wild-type mice of the same age. Exposure to EE from 2 to 7 months significantly reduce the appearance of AD neuropathological hallmarks. A group of AD11 mice was tested also at 12 months of age: we found that 12 months old AD11 mice exposed to EE from 2 to 7 months of age performed significantly better than non EE AD11 mice of the same age and did not differ from 12 months old wt mice. Thus, EE is able to prevent the onset of memory deficits up to at least 12 months of age and to restrain the progression of neurodegeneration in a mouse model of AD.     

Neural substrates of verbal memory impairments in adults with type 2 diabetes mellitus

Background: Verbal memory impairment is well documented in type 2 diabetes mellitus (T2DM) but, to date, the neural substrates remain unclear. The present study evaluated verbal memory and ascertained the degree of frontal and temporal lobe involvement in the anticipated verbal memory impairment among adults with T2DM. Method: Forty-six late-middle-aged and elderly adults with T2DM and 50 age-, sex-, and education-matched adults without T2DM underwent medical evaluation, verbal memory assessment, and brain magnetic resonance imaging (MRI) evaluations. Results: As anticipated, participants with T2DM had clear verbal memory impairments. Consistent with prior reports, we found volume reductions restricted to the hippocampus. Our diffusion tensor imaging analysis revealed that participants with T2DM had extensive cerebral gray and white matter microstructural abnormalities predominantly in the left hemisphere, with a larger concentration present in the temporal lobe. In contrast, we uncovered mostly nonspecific microstructural abnormalities in the absence of tissue loss in the frontal lobe. Of great importance, we present the first evidence among participants with T2DM linking verbal memory impairment and compromised microstructural integrity of the left parahippocampal gyrus, a key memory-relevant structure. Conclusions: Our results suggest that the hippocampus and parahippocampal gyrus may be particularly vulnerable to the deleterious effects of T2DM. The parahippocampal gyrus in particular may play a crucial role in the verbal memory impairments frequently reported in T2DM. Future studies should employ methods such as resting state functional magnetic resonance imaging and diffusion tensor imaging tractography to better characterize network connectivity, which may help further characterize the verbal memory impairment frequently reported in T2DM.     

食源性肥胖大鼠2型糖尿病模型的建立

背景：高脂饮食加小剂量链脲佐菌素是目前国内最常用的2型糖尿病大鼠造模方式,但高脂饮食仅能诱导50%大鼠发生胰岛素抵抗,因此还需寻找更理想的2型糖尿病大鼠建模方法。目的：选择食源性肥胖大鼠进行小剂量链脲佐菌素腹腔注射,建立更理想的2型糖尿病动物模型。方法：将SD大鼠随机分成对照组和高脂饮食组。4周后,据大鼠体质量将高脂饮食组分为食源性肥胖组和食源性肥胖抵抗组。8周后,所有大鼠均给予小剂量链脲佐菌素(30 mg/kg)腹腔注射,将注射10 d后空腹血糖> 7.8 mmol/L且稳定2周以上者纳为2型糖尿病大鼠模型。检测各组大鼠的空腹血糖、血脂、胰岛素;评价各组大鼠的胰岛素抵抗程度;比较各组大鼠的2型糖尿病成模率。结果与结论：与对照组及食源性肥胖抵抗组相比,食源性肥胖组大鼠出现明显的体质量增加、高血脂、高胰岛素血症及胰岛素抵抗(P < 0.01)。注射链脲佐菌素后食源性肥胖组2型糖尿病成模率高达100%,食源性肥胖抵抗组成模率仅为12.5%。由结果可知选择食源性肥胖组大鼠作为2型糖尿病造模对象,是2型糖尿病造模方法的成功改良。     

Cognitive functioning and brain MRI in patients with type 1 and type 2 diabetes mellitus: a comparative study

BACKGROUND/AIMS: Diabetes mellitus (DM) may affect the central nervous system, resulting in cognitive impairments. It has been suggested that cognitive impairments are more pronounced in DM2 than in DM1, but studies that directly compare the effects of these 2 types of DM on cognition are lacking. METHODS: Forty patients with DM1 (mean duration: 34 years) were compared with 40 age- and education-matched patients who were known to have DM2 (mean duration: 7 years). Extensive neuropsychological assessment focussed on abstract reasoning, memory, attention and executive function, visuoconstruction and information processing speed. Psychological well-being was measured and brain MRIs were obtained. RESULTS: No systematic between-group differences were observed in neuropsychological measures or levels of psychological well-being. DM2 patients showed significantly more deep white matter lesions and cortical atrophy on MRI (p < 0.01). CONCLUSION: DM1 patients with more than 30 years of DM have a similar cognitive profile and better MRI ratings than age- and education-matched DM2 patients with only 7 years of DM.     

Protective effects of Purendan superfine powder on retinal neuron apoptosis in a rat model of type 2 diabetes mellitus

This study sought to investigate the effects of Purendan superfine powder comprised of Momordica charantia, Radix Ginseng, and Radix Salviae Miltiorrhiae on neuronal apoptosis and expression of bcl-2, bax, and caspase-3, which are retinal apoptosis-associated factors in rats with diabetes mellitus induced by continuous intraperitoneal injection of streptozotocin. The results showed that Purendan superfine powder could upregulate the expression of bcl-2 protein and mRNA, and downregulate the expression of bax and caspase-3 in the retina of diabetes mellitus rats. In addition, Purendan superfine powder was shown to reduce the number of apoptotic neurons. Our experimental findings indicate that Purendan superfine powder can inhibit neuronal apoptosis in the retina of diabetes mellitus rats and has protective effects on diabetic retinopathy.     

2型糖尿病伴抑郁症状患者的脑诱发电位研究

目的了解2型糖尿病伴抑郁症状患者的认知功能及脑诱发电位的变化。方法102例2型糖尿病患者,按照汉密尔顿抑郁量表（HAMD）评分结果,50例合并抑郁症状者为研究组,52例不合并抑郁症状者为对照组,比较2组脑诱发电位P300、失匹配负波（MMN）、血脂及脑部核磁共振显像检查。结果2组患者血脂、脑部核磁共振显像及脑诱发电位P300无统计学差异。与对照组比较,研究组脑诱发电位失匹配负波潜伏期延长,波幅降低。结论抑郁症状进一步加重糖尿病患者认知功能及脑诱发电位改变,MMN是敏感的早期检测手段。     

Oxidative stress biology and cell injury during type 1 and type 2 diabetes mellitus

Diabetes mellitus (DM) affects approximately 170 million individuals worldwide and is expected to alter the lives of at least 366 million individuals within a future span of 25 years. Of even greater concern is the premise that these projections are underestimated since they assume obesity levels will remain constant. Type 1 insulin-dependent DM accounts for only 5-10 percent of all diabetics but represents a highly significant health concern, since this disorder begins early in life and leads to long-term complications. In contrast, Type 2 DM is recognized as the etiology of over 80 percent of all diabetics and is dramatically increasing in incidence as a result of changes in human behavior and increased body mass index. Yet, the pathological consequences of these disorders that involve the both the neuronal and vascular systems are intimately linked through the pathways that mediate oxidative stress. Here we highlight some of the relevant oxidative pathways that determine insulin resistance through reactive oxygen species, mitochondrial dysfunction, uncoupling proteins, and endoplasmic reticulum stress. These pathways are ultimately linked to protein kinase B (Akt) and the insulin signaling pathways that determine the initial onset of glucose intolerance and the subsequent course to apoptotic cell injury. Through the elucidation of these targets, improvement in current strategies as well as the development of future clinical applications can move forward for both the prevention and treatment of Type 1 and Type 2 DM.     

Cerebrovascular disease in type 2 diabetes mellitus

Incidence of CVD in diabetic men was reported to be twice as that of non-diabetics and almost three times greater in diabetic women in the Framingham Study. It is postulated that excessive glycation and oxidation, endothelial dysfunction and increased platelet aggregation may be responsible for endothelial proliferation and thickening of plasmatic membrane in small blood vessels ('lipohyalinosis') leading to lacunar infarction. Prothrombotic state may precipitate a stroke, however, platelet aggregability, elevated fibrinopeptide A (FPA) and D-dimer were not significantly related to stroke in diabetic mellitus (DM), whereas suppressed fibrinolytic activity was a common finding. Of many unknown factors in pathogenesis, the deficient insulin secretion, resistance to action of insulin at level of 'insulin receptors', changes in counter regulatory hormones (e.g. glucagon, pancreatic polypetides, growth hormone, catecholamines, etc.) and decrease in the hepatic sensitivity to insulin action in suppressing glucose output have received more attention. Hyperosmolar state can simulate stroke syndromes. Early recognition and treatment of risk factors such as hypertension or better glycemic control, correction of hyperlipidemia or obesity in diabetic population are important. In diabetic subjects already showing recurrent transient cerebral ischemic attacks (TIAs) or minor strokes, the benefit of antiplatelet agents or antithrombotic therapy in prevention of major strokes is well established. Ramipril has been found to be effective in reducing stroke risk by 33% in diabetic patinets in HOPE study.     

Cognitive deficits in spinocerebellar ataxia type 1, 2, and 3

Cognitive impairment was studied in distinct types of spinocerebellar ataxia (SCA): eleven SCA1, 14 SCA2, and 11 SCA3 individuals and 8 age- and IQ- matched controls. All were submitted to a neuropsychological test battery that comprised tests for IQ, attention, executive function, verbal and visuospatial memory. Executive dysfunction was prominent in SCA1 as compared with controls and all other SCA types. Mild deficits of verbal memory were present in SCA1, SCA2 and SCA3. The neuropathological pattern in different SCA types suggests that these cognitive deficits are not likely to be contingent upon cerebellar degeneration but to result from disruption of a cerebrocerebellar circuitry presumably at the pontine level. Received: 26 November 2002, Received in revised form: 13 September 2002, Accepted: 24 September 2002 Correspondence to K. Bürk, MD     

Cognitive deficits in a mouse model of pre-manifest Parkinson's disease

Early cognitive deficits are increasingly recognized in patients with Parkinson's disease (PD), and represent an unmet need for the treatment of PD. These early deficits have been difficult to model in mice, and their mechanisms are poorly understood. α-Synuclein is linked to both familial and sporadic forms of PD, and is believed to accumulate in brains of patients with PD before cell loss. Mice expressing human wild-type α-synuclein under the Thy1 promoter (Thy1-aSyn mice) exhibit broad overexpression of α-synuclein throughout the brain and dynamic alterations in dopamine release several months before striatal dopamine loss. We now show that these mice exhibit deficits in cholinergic systems involved in cognition, and cognitive deficits in domains affected in early PD. Together with an increase in extracellular dopamine and a decrease in cortical acetylcholine at 4-6 months of age, Thy1-aSyn mice made fewer spontaneous alternations in the Y-maze and showed deficits in tests of novel object recognition (NOR), object-place recognition, and operant reversal learning, as compared with age-matched wild-type littermates. These data indicate that cognitive impairments that resemble early PD manifestations are reproduced by α-synuclein overexpression in a murine genetic model of PD. With high power to detect drug effects, these anomalies provide a novel platform for testing improved treatments for these pervasive cognitive deficits.     

Cognitive deficits precede motor deficits in a slowly progressing model of parkinsonism in the monkey

Five adult Macaca fascicularis monkeys were trained to perform tests of cognitive and motor functioning that included a complex visual pattern discrimination task, an object retrieval task, a test of task persistence, and a timed motor task. Once stable baseline performance was achieved, monkeys were administered 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) at doses of 0.05 to 0.075 mg/kg, 2 to 3 times per week for a total of 24 weeks. Animals were assessed weekly for performance on the previously learned tasks. All monkeys developed performance deficits in a predictable pattern with behavioural and cognitive deficits (i.e. deficits in task persistence and the cognitive component of object retrieval) appearing in advance of measurable motor deficits. Deficits in visual pattern discrimination never appeared. These results show that specific cognitive dysfunction pre-dates motor dysfunction in a chronic, slowly progressing parkinson model in monkeys and support the contention that cognitive deficits in Parkinson's disease may precede the motor signs of the disorder and may not be caused by them.     

2型糖尿病患者实施人工关节置换围手术期的风险探讨

人工关节置换并发症主要有感染、无菌性松动、假体的脱位、断裂、深静脉血栓形成。2型糖尿病导致微血管病变,组织血供减少,造成全身和局部抵抗力降低,多合并心肾脑血管并发症,行人工关节置换感染概率高,并发症多,易发生伤口愈合障碍。术后肺部感染、尿路感染也较一般人群发病率增加,创口愈合时间均有不同程度的延迟。深静脉血栓形成也是2型糖尿病人工关节置换术的常见并发症之一,增加了围手术期治疗的复杂性。血糖的不稳定易触发循环功能的不稳定,使麻醉过程中的不确定因素增加,因此有效地控制血糖是降低2型糖尿病人工关节置换术风险的关键。     

Cerebrolysin reverses hippocampal neural atrophy in a mice model of diabetes mellitus type 1

The animal model of streptozotocin‐induced diabetes mellitus type 1 (DM1) is used to study neuronal and behavioral changes produced by an increase in blood‐glucose levels. Our previous report showed that chronic streptozotocin administration induced atrophy of dendritic morphology of pyramidal neurons of the CA1 dorsal hippocampus. In addition, we showed that Cerebrolysin (Cbl), a neurotrophic peptide mixture, reduces the dendritic atrophy in animal models of aging. This study aimed to determine whether Cbl was capable of reducing behavioral and neuronal alterations, after 6 weeks of hyperglycemia in mice (streptozotocin‐induced DM1). The levels of glucose in the blood were evaluated before and after streptozotocin administration and only animals with more than 240 mg/dL of blood‐levels of glucose were used. After streptozotocin treatment, the mice received 6 weeks of Cbl, locomotor activity was measured and dendritic morphological changes were evaluated using Golgi‐Cox stain procedure, and analyzed by the Sholl method. In mice treated with streptozotocin there was a clear reduction in the dendritic length of pyramidal neurons of the CA1 and granular cells of the dental gyrus of the dorsal hippocampus. Interestingly, Cbl reversed the morphological changes induced by streptozotocin. Our results extend the list of abnormal morphological changes detected in this model of DM, and support the possibility that Cbl may have beneficial effects in the management of brain alterations induced by DM. Synapse 69:326–335, 2015. © 2015 Wiley Periodicals, Inc.     

Limited Alzheimer-type neurodegeneration in experimental obesity and type 2 diabetes mellitus

Alzheimer's disease (AD) is associated with brain insulin resistance and insulin deficiency, whereas Type 2 diabetes mellitus (T2DM) is associated with peripheral insulin resistance. This study assesses the degree to which T2DM causes AD-type neurodegeneration. In a C57BL/6 mouse model of obesity and T2DM, we characterized the histopathology, gene expression, and insulin and insulin-like growth factor (IGF)-receptor binding in temporal lobe. High fat diet (HFD) feeding for 16 weeks doubled mean body weight, caused T2DM, and marginally reduced mean brain weight. These effects were associated with significantly increased levels of tau, IGF-I receptor, insulin receptor substrate-1 (IRS-1), IRS-4, ubiquitin, glial fibrillary acidic protein, and 4-hydroxynonenol, and decreased expression of beta-actin. HFD feeding also caused brain insulin resistance manifested by reduced BMAX for insulin receptor binding, and modestly increased brain insulin gene expression. However, HFD-fed mouse brains did not exhibit AD histopathology, increases in amyloid-beta or phospho-tau, or impairments in IGF signaling or acetylcholine homeostasis. Obesity and T2DM cause brain atrophy with insulin resistance, oxidative stress, and cytoskeleton degradation, but the absence of many features that typify AD suggests that obesity and T2DM may contribute to, but are not sufficient to cause AD.     

Hydrogen-rich water ameliorates neuropathological impairments in a mouse model of Alzheimer's disease through reducing neuroinflammation and modulating intestinal microbiota

Hydrogen exhibits the potential to treat Alzheimer's disease. Stereotactic injection has been previously used as an invasive method of administering active hydrogen, but this method has limitations in clinical practice. In this study, triple transgenic(3×Tg) Alzheimer's disease mice were treated with hydrogen-rich water for 7 months. The results showed that hydrogen-rich water prevented synaptic loss and neuronal death, inhibited senile plaques, and reduced hyperphosphorylated tau and neurofibrillary tangles in 3×Tg Alzheimer's disease mice. In addition, hydrogen-rich water improved brain energy metabolism disorders and intestinal flora imbalances and reduced inflammatory reactions. These findings suggest that hydrogen-rich water is an effective hydrogen donor that can treat Alzheimer's disease. This study was approved by the Animal Ethics and Welfare Committee of Shenzhen University, China(approval No. AEWC-20140615-002) on June 15, 2014.