载脂蛋白E基因敲除小鼠冠状动脉内粥样硬化病灶的研究

目的：研究载脂蛋白E基因敲除( apoE-/-)小鼠冠状动脉内粥样硬化病灶的分布和组成；探讨病灶发生和发展的机理。方法：取60周龄和112周龄的apoE-/-小鼠心脏作连续切片，从冠状动脉在主动脉开口处连续追踪冠状动脉主干和心肌内冠状动脉小分支，行Movat特殊染色，寻找病灶。根据组织切片数计算病灶离冠状动脉开口处的距离和病灶的长度；根据病灶的长度将病灶分为大、中、小3类病灶；用图像分析仪测量血管口径；根据Movat染色结果观察病灶内组成成分。结果：在apoE-/-小鼠冠状动脉内发现从主动脉内直接延续的延伸病灶和在冠状动脉分支内形成的原位病灶；在60周龄和112周龄小鼠冠状动脉延伸病灶的发生率分别为60%和80%；有延伸病灶的冠状动脉外膜有大量炎性细胞浸润。每只apoE-/-小鼠均有原位病灶；原位病灶多发生在左室壁心肌内血管分支处和乳头肌附近；随着原位病灶增大，蛋白聚糖成分减少，细胞内外脂质成分增多；增大的原位病灶可堵塞小血管；在有原位病灶的冠状动脉外膜常可发现有增多的炎性细胞。112周龄apoE-/-小鼠大原位病灶多于60周龄小鼠 (P＜0.05)。结论：apoE-/-小鼠冠状动脉主干和心肌小分支内分别存在着延伸和原位的粥样硬化病灶，随着小鼠周龄增加，病灶增大。动脉外膜炎症和心肌收缩对血管的挤压与病灶的发生和发展有密切关系。     

Impact of aging on hippocampal function: plasticity,network dynamics,and cognition

Aging is associated with specific impairments of learning and memory, some of which are similar to those caused by hippocampal damage. Studies of the effects of aging on hippocampal anatomy, physiology, plasticity, and network dynamics may lead to a better understanding of age-related cognitive deficits. Anatomical and electrophysiological studies indicate that the hippocampus of the aged rat sustains a loss of synapses in the dentate gyrus, a loss of functional synapses in area CA1, a decrease in the NMDA-receptor-mediated response at perforant path synapses onto dentate gyrus granule cells, and an alteration of Ca(2+) regulation in area CA1. These changes may contribute to the observed age-related impairments of synaptic plasticity, which include deficits in the induction and maintenance of long-term potentiation (LTP) and lower thresholds for depotentiation and long-term depression (LTD). This shift in the balance of LTP and LTD could, in turn, impair the encoding of memories and enhance the erasure of memories, and therefore contribute to cognitive deficits experienced by many aged mammals. Altered synaptic plasticity may also change the dynamic interactions among cells in hippocampal networks, causing deficits in the storage and retrieval of information about the spatial organization of the environment. Further studies of the aged hippocampus will not only lead to treatments for age-related cognitive impairments, but may also clarify the mechanisms of learning in adult mammals.     

Impact of ApoB-100 expression on cognition and brain pathology in wild-type and hAPPsl mice

During their lifetime, people are commonly exposed to several vascular risk factors that may affect brain ageing and cognitive function. In the last few years, increasing evidence suggests that pathological plasma lipid profiles contribute to the pathogenesis of late-onset Alzheimer's disease. Importantly, hypercholesterolemia, especially elevated low-density lipoprotein cholesterol values, that is, increased apolipoprotein B-100 (ApoB-100) levels, represents an independent risk factor. In this study, the effects of ApoB-100 overexpression, either alone or in combination with cerebral expression of human amyloid precursor protein (hAPP), on cognitive functions and brain pathology were assessed. Our results show that ApoB-100 overexpression induces memory decline and increases cerebral lipid peroxidation and amyloid beta levels compared to those in wild-type animals. Although double-transgenic ApoBxAPP animals did not develop more distinct behavioral deficits than single-transgenic hAPP littermates, hApoB-100 expression caused additional pathophysiological features, such as high LDL and low HDL-cholesterol levels, increased lipid peroxidation, and pronounced ApoB-100 accumulation in cerebral vessels. Thus, our results indicate that ApoBxAPP mice might better reflect the situation of elderly humans than hAPPsl overexpression alone.     

apoE基因敲除小鼠主动脉尾加压素Ⅱ受体GPR14表达的变化

目的：观察apoE敲除小鼠主动脉组织尾加压素Ⅱ受体-GPR14表达的变化，以探讨UⅡ及其受体系统在动脉粥样硬化发病中的作用。 方法： 取不同周龄（18、28 和38周）的apoE基因敲除及同龄对照C57BL/6J小鼠（各亚组n=6只），取主动脉，提取mRNA，行竞争RT-PCR。 结果： apoE敲除小鼠GPR14表达分别较同龄对照增加54.2%（18周，P<0.05）、50.0%（28周，P<0.05）、97.0%（38周，P<0.01）。取28周apoE基因敲除及同龄对照小鼠（各8只）主动脉行［125I］-尾加压素Ⅱ放射性配基实验，apoE基因敲除组最大结合力（Bmax）较对照组增大64%（P<0.01），而解离常数Kd值无明显变化（P>0.05）。 结论： 尾加压素Ⅱ/GPR14通路可能参与动脉粥样硬化的发病过程。     

Early postnatal plasticity in neocortex of Fmr1 knockout mice

Fragile X syndrome is produced by a defect in a single X-linked gene, called Fmr1, and is characterized by abnormal dendritic spine morphologies with spines that are longer and thinner in neocortex than those from age-matched controls. Studies using Fmr1 knockout mice indicate that spine abnormalities are especially pronounced in the first month of life, suggesting that altered developmental plasticity underlies some of the behavioral phenotypes associated with the syndrome. To address this issue, we used intracellular recordings in neocortical slices from early postnatal mice to examine the effects of Fmr1 disruption on two forms of plasticity active during development. One of these, long-term potentiation of intrinsic excitability, is intrinsic in expression and requires mGluR5 activation. The other, spike timing-dependent plasticity, is synaptic in expression and requires N-methyl-d-aspartate receptor activation. While intrinsic plasticity was normal in the knockout mice, synaptic plasticity was altered in an unusual and striking way: long-term depression was robust but long-term potentiation was entirely absent. These findings underscore the ideas that Fmr1 has highly selective effects on plasticity and that abnormal postnatal development is an important component of the disorder.     

Glucose-dependent insulinotropic polypeptide receptor knockout mice are impaired in learning, synaptic plasticity, and neurogenesis

Glucose-dependent insulinotropic polypeptide (GIP) is a key incretin hormone, released from intestine after a meal, producing a glucose-dependent insulin secretion. The GIP receptor (GIPR) is expressed on pyramidal neurons in the cortex and hippocampus, and GIP is synthesized in a subset of neurons in the brain. However, the role of the GIPR in neuronal signaling is not clear. In this study, we used a mouse strain with GIPR gene deletion (GIPR KO) to elucidate the role of the GIPR in neuronal communication and brain function. Compared with C57BL/6 control mice, GIPR KO mice displayed higher locomotor activity in an open-field task. Impairment of recognition and spatial learning and memory of GIPR KO mice were found in the object recognition task and a spatial water maze task, respectively. In an object location task, no impairment was found. GIPR KO mice also showed impaired synaptic plasticity in paired-pulse facilitation and a block of long-term potentiation in area CA1 of the hippocampus. Moreover, a large decrease in the number of neuronal progenitor cells was found in the dentate gyrus of transgenic mice, although the numbers of young neurons was not changed. Together the results suggest that GIP receptors play an important role in cognition, neurotransmission, and cell proliferation.     

Glycerol homeostasis and metabolism in glycerol kinase carrier mice

To examine glycerol homeostasis and metabolism is essential for understanding of pathogenesis and evaluation of treatment efficacy in disorders of glycerol metabolism. In this study, we designed the intraperitoneal glycerol tolerance test (IPGlyTT) and studied glycerol tolerance in vivo using glycerol kinase (Gyk) carrier (C) and wild type (WT) mice. Serum glycerol concentrations in WT almost normalized at 90 min after injection, whereas Gyk C mice retained high serum glycerol concentrations at least until 180 min after injection. These results showed that glycerol tolerance was impaired in Gyk C mice compared to WT mice. The IPGlyTT is useful in accessing glycerol homeostasis and metabolism in animal models such as Gyk C mice and will be valuable in assessing therapeutic interventions in Gyk KO mice.     

Pklr基因敲除小鼠的构建及其糖脂代谢研究

目的 丙酮酸激酶(pyruvate kinase,PK)作为糖酵解途径的关键限速酶之一,主要在肝脏和红细胞中表达,在糖脂代谢过程中发挥着重要作用.对于PK的研究目前主要集中在细胞实验与临床观察水平,动物模型的缺乏限制了对其进一步研究.因此该研究目的在于建立Pklr基因缺陷小鼠模型,并探索该酶在机体中与糖脂代谢的关系.方法 本研究利用CRISPR/Cas9系统,设计引物sgRNA1与sgRNA2,分别靶向LPK外显子1和共用外显子3.通过测序、实时定量PCR、Western印迹及PK活性测定试剂盒检测小鼠Pklr基因在转录、蛋白质和酶活性等不同层面上的变化,之后通过正常与高脂饮食,检测小鼠体重、白色脂肪及脾脏变化验证PK与糖脂代谢的关系.结果 经过检测发现,小鼠Pklr基因双位点发生基因编辑,与野生型小鼠相比,转录水平下降至24％,LPK蛋白几乎不表达,酶活性下降至33％,在基因、转录、蛋白质和酶活性不同层面上证明成功获得了Pklr基因缺陷小鼠模型,并且发现该基因突变纯合子小鼠在高脂饮食条件下显示出体重下降和白色脂肪积累(P值分别为0.0040、0.0200),同时两种饮食条件下脾脏重量都显著上升(P =0.0003).结论 利用CRISPR/Cas9系统成功构建了Pklr基因缺陷小鼠,并且该基因缺陷会导致异常的糖脂代谢.Pklr基因敲除小鼠模型为进一步探索PK在机体内调控机制与糖脂代谢的关系提供了平台.     

硫化氢抑制apoE基因敲除小鼠动脉粥样硬化中ICAM-1的表达

目的　探讨硫化氢(H2S)对apoE基因敲除小鼠(apoE-/-小鼠)动脉粥样硬化中细胞间黏附分子-1 (ICAM-1)的调节作用。方法　6周龄雄性C57BL/6J和apoE-/-小鼠分为C57BL/6对照组、apoE-/-组、apoE-/-+硫氢化钠(NaHS)组和apoE-/-+炔丙基甘氨酸(PPG)组,每组各8只,普通饮食饲养10周。硫电极法测定血清中H2S的含量;ELISA法测定血清中ICAM-1的含量;荧光实时定量RT-PCR法测定主动脉组织中ICAM-1 mRNA的表达。油红O染色观察小鼠主动脉根部斑块面积的变化。结果 与C57BL/6J小鼠相比,apoE-/-小鼠血清中H2S的含量明显下降(P 0.01),血清中ICAM-1的含量和主动脉组织中ICAM-1 mRNA的表达明显升高(P 0.01),主动脉根部出现明显斑块;给予NaHS后,apoE-/-小鼠血清中H2S的含量明显升高(P 0.05),血清和主动脉组织中ICAM-1的表达明显降低(P 0.01和P 0.05),动脉粥样斑块明显缩小(P 0.05);给予PPG后,apoE-/-小鼠血清中H2S的含量明显降低(P 0.05),血清和主动脉组织中ICAM-1的表达明显增高(P 0.05和P 0.01),动脉粥样斑块明显增大(P 0.01)。结论　气体信号分子H2S可明显抑制动脉粥样斑块形成过程中ICAM-1的表达与分泌。     

Age-appropriate cognition and subtle dopamine-independent motor deficits in aged Tau knockout mice

The microtubule-associated protein tau is expressed throughout the nervous system, most highly in neurons but also in glial cells. Its functions in adult and aging mammals remain to be defined. Previous studies in mouse models found either protective or detrimental effects of genetic tau ablation. Though tau ablation prevented synaptic, network, and cognitive dysfunctions in several models of Alzheimer's disease and made mice more resistant to epileptic seizures, a recent study described a parkinsonian phenotype in aging Tau knockout mice. Here we tested cognition and motor functions in Tau^+/+, Tau^+/−, and Tau^−/− mice at approximately 1 and 2 years of age. Tau ablation did not impair cognition and caused only minor motor deficits that were much more subtle than those associated with the aging process. Tau ablation caused a mild increase in body weight, which correlated with and might have contributed to some of the motor deficits. However, tau ablation did not cause significant dopaminergic impairments, and dopamine treatment did not improve the motor deficits, suggesting that they do not reflect extrapyramidal dysfunction.     

Absence of an hypoxic depression of metabolism in preproenkephalin knockout mice

Opioids inhibit breathing in mammals, especially in newborns, and are also implicated in the control of hypoxic anapyrexia. We measured breathing patterns and metabolic responses to 12% oxygen in six adult male wildtype C57B/6J mice and six preproenkephalin knockout (PPNK-/-) mice in a flow-through respirometer and barometric plethysmograph with ambient temperature maintained in the thermoneutral zone. Breathing air, there was no significant difference between the two groups of mice in ventilation ((.)V), oxygen consumption ((.)V(O(2)), convection requirement ((.)V/(.)V(O(2)), tidal volume (V(t)), frequency (f), or inspiratory time (T(i)); however, PPNK-/- mice had a significantly shorter expiratory time (T(e)). The breathing pattern response to 5% CO(2) was the same between wildtype and PPNK-/- in terms of absolute values, but the % change in V(t) was greater in the wildtype. Breathing 12% O(2), there was no significant difference in V , V(t), f, T(i), T(e) or body temperature between groups, but there was a significant difference in (.)V(O(2) (PPNK-/- 1.24+/-0.05 ml O(2)min(-1) versus 0.91+/-0.05 for wildtype, P<0.001) and % change in (.)V(O(2), (2.3+/-6.6% for PPNK-/- versus -28+/-3.8% for wildtype); in ((.)V/(.)V(O(2)), (54+/-4 versus 78+/-10, P<0.05) and the % change in (.)V/(.)V(O(2), (37+/-9 versus 131+/-28, P<0.01). These data implicate enkephalin as a signaling molecule in the control of hypoxic depression of metabolism in mice.     

SETD4基因敲除小鼠的构建及鉴定

目的　构建并鉴定SETD4基因敲除小鼠,为研究SETD4的生物学功能提供动物模型。 方法　将引进的SETD4flox/+小鼠与EIIa-Cre小鼠进行杂交繁殖,得到基因型为SETD4+/-.EIIa-Cre的小鼠;再与C57BL/6小鼠杂交去除Cre酶,获得杂合子SETD4+/-小鼠;该小鼠自交获得纯合子SETD4-/-小鼠。通过PCR法鉴定子代小鼠的基因型;RT-PCR、荧光定量PCR方法鉴定纯合子的SETD4基因敲除小鼠SETD4 mRNA表达情况;HE染色观察小鼠肝、肺组织的形态学变化。 结果　PCR结果表明子代小鼠的基因型符合SETD4-/-;纯合子基因敲除小鼠SETD4 mRNA水平显著低于野生型小鼠;SETD4基因敲除小鼠肝、肺组织的形态学特征与野生型小鼠相比无明显差异。 结论　本研究基于Cre/loxp系统,成功构建并鉴定了SETD4基因敲除小鼠。     

Genes,cognition and brain through a COMT lens

Various genes are known to modulate the delicate balance of dopamine in prefrontal cortex and influence cortical information processing. Catechol-O-methyltransferase (COMT) on chromosome 22q11 is the most widely studied of these genes. Val158Met, a common, functional variant in the coding sequence that increases or decreases the enzymatic activity of the gene has been shown to impact the efficiency of prefrontally-mediated cognition, specifically executive functioning, working memory, fluid intelligence and attentional control. We review the rapidly evolving literature exploring the association between COMT genotype and cognitive performance, and illustrate how this polymorphism has served a pivotal role in characterizing various interacting dimensions of complexity in the relationship between genes and cognition. We review how Val158Met has been used to help develop and validate behavioral and neurophysiological phenotypes, as a critical tool in dissecting overlapping neural functional systems and exploring interactions within and between genes, and in exploring how gene effects on cognition are modulated by environmental, demographic and developmental factors. Despite the impressive range of findings, the COMT story is also a bracing reminder of how much work remains to translate this knowledge into practical clinical applications.     

身体活动对海马体可塑性和认知功能的影响

背景:身体活动作为一种实用模型,可以从各个方面来研究运动与大脑健康之间的关联,从而更清楚地认识运动对大脑的促进作用,特别是身体活动对海马体结构和功能的改变。目的:综述身体活动与海马体和认知方面的研究,并提出目前研究和实际应用方面许多亟待解决的问题。方法:以"Physical activity,Exercise,Hippocampal,Cognition,Neuroplasticity,Adaptive,Mechanisms"为检索词,检索PubMed数据库1995至2019年发表的相关文章,文献检索语种限制为英文。纳入身体活动和海马、认知调节机制和应用方面的相关内容。结果与结论:计算机初检得到142篇文献,排除无关和重复的文献,保留89篇进行综述。海马体齿状回具有神经再生的能力。规律性身体活动对身体和大脑健康产生深远的影响,运动可促进海马体齿状回的神经再生,可增加两三倍,此类神经主要发生在齿状回背侧。此外,运动对神经元的成熟、形态和连接性等特性的改变也十分重要,并能改变新神经元的整合通路,增加传入新生神经元和传入细胞突触的数量。海马体齿状回的神经再生与运动诱导的多种因素有关,新生神经元的发育和整合需要多个神经递质的参与,而运动可通过调节兴奋性和抑制性神经递质,促进海马体突触可塑性的变化;运动诱导的血清脑源性神经营养因子水平升高则可减缓海马体体积的变化;运动的持续时间和强度可差异性地调节脑血流量,进而影响神经元活动,而长期运动后血管内皮生长因子的过表达,则可促进海马体的血管增殖,增加海马体的神经发生。此外,运动也可改变成人新生神经元的突触可塑性和连接网络,增强成人新生神经元与现有海马-内嗅通路的整合。     

髓样细胞特异性SETD4基因敲除小鼠的构建与鉴定

目的　利用FLP/FRT、Cre/Loxp重组酶系统构建并鉴定髓样细胞特异性SETD4基因敲除小鼠,为深入研究SETD4的生物学功能奠定基础。 方法　将引进的Setd4flox/+小鼠自交,筛选出子代基因型为Setd4flox/flox的小鼠;与FLP小鼠交配,得到Setd4fl/+/flp小鼠;然后分别与C57BL/6小鼠交配去除FLP酶,筛选出Setd4fl/+小鼠;与Lyz2-Cre小鼠交配,筛选出Setd4fl/+/Lyz2-Cre小鼠;将得到的Setd4fl/+和Setd4fl/+/Lyz2-Cre小鼠交配,筛选出Setd4-/-/Lyz2-Cre小鼠,即髓样细胞特异性SETD4基因敲除小鼠。利用PCR技术鉴定小鼠基因型;实时荧光定量PCR技术检测小鼠腹腔巨噬细胞及肝组织中SETD4 的mRNA表达水平验证敲除情况。 结果　髓样细胞特异性SETD4基因敲除小鼠腹腔巨噬细胞中SETD4 mRNA水平较野生型小鼠显著降低;而在肝组织中无显著差异。 结论　利用FLP/FRT、Cre/Loxp系统成功构建髓样细胞特异性SETD4基因敲除小鼠,为后续的功能学研究提供了动物模型。     

Aquaporin-4 knockout regulated cocaine-induced behavior and neurochemical changes in mice

Aquaporin-4 (AQP4) is the predominant water channel of brain, which mediates transmembrane water movement at the blood-brain barrier and at the brain-cerebrospinal fluid interface. It has been reported that AQP4 deletion results in an increase of amino acid and monoamine levels in some brain regions of mice, suggesting that AQP4 may participate in region-specific alterations in brain amino acid and monoamine metabolism. In the present study, we examined whether AQP4 affects neurotransmission in acute and chronic cocaine exposure mice. For this purpose, both wild-type and AQP4 knockout mice were used with locomotor activity evaluation and microdialysis methods. The results reveal that AQP4 deletion attenuated locomotor activity in acute and repeated cocaine exposure mice, and induced a decrease of extracellular dopamine and glutamate levels in the nucleus accumbens (NAc), a brain region known to be critically involved in the addictive properties of cocaine. Therefore, AQP4 may play a role in regulating extracellular cocaine-induced dopamine and glutamate release in the brain reward center, and in turn AQP4 deletion may attenuate cocaine reinforcement and dependence.     

Mutation theory of aging,assessed in transgenic mice and knockout mice

A vital question in the mutation theory of aging is whether mutation accumulates with age. If it does, what are the causes and consequences of the accumulation of mutation? The recent development of transgenic mice has made it possible to study mutation in different kinds of tissues and at a molecular level. An application of these mice to the study of age-dependent alteration has revealed that mutation does accumulate in the aging process. Studies have also revealed several important characteristics of mutation associated with aging. (1) The rate of age-dependent increase of mutant frequency varies among different types of tissue. (2) The rate is not in parallel with the cell proliferation rate of the tissue. (3) Some types of mutation are unique to specific tissues, suggesting the presence of a mechanism of mutation relative to tissue type. On the other hand, several kinds of knockout mice defective in DNA repair have been shown to exhibit tissue lesions and shortened life span. These characteristics provide a new view on the relationship between aging and the genome maintenance system. Here we review the current status of research on the correlation between mutation and aging undertaken by the use of transgenic and knockout mice.     

Overexpression of peroxiredoxin 4 attenuates atherosclerosis in apolipoprotein e knockout mice

Abstract Aim: A growing body of evidence has shown that increased formation of oxidized molecules and reactive oxygen species within the vasculature (i.e., the extracellular space) plays a crucial role in the initiation and progression of atherosclerosis and in the formation of unstable plaques. Peroxiredoxin 4 (PRDX4) is the only known secretory member of the antioxidant PRDX family. However, the relationship between PRDX4 and susceptibility to atherosclerosis has remained unclear. Results: To define the role of PRDX4 in hyperlipidemia-induced atherosclerosis, we generated hPRDX4 transgenic (Tg) and apolipoprotein E (apoE) knockout mice (hPRDX4(+/+)/apoE(-/-)). After feeding the mice a high-cholesterol diet, they showed fewer atheromatous plaques, less T-lymphocyte infiltration, lower levels of oxidative stress markers, less necrosis, a larger number of smooth muscle cells, and a larger amount of collagen, resulting in thickened fibrous cap formation and possible stable plaque phenotype as compared with apoE(-/-) mice. We also detected greater suppression of apoptosis and decreased Bax expression in hPRDX4(+/+)/apoE(-/-) mice than in apoE(-/-) mice. Bone marrow transplantation from hPRDX4(+/+) donors to apoE(-/-) mice confirmed the antiatherogenic aspects of PRDX4, revealing significantly suppressed atherosclerotic progression. Innovation: In this study, we demonstrated for the first time that PRDX4 suppressed the development of atherosclerosis in apoE(-/-) mice fed a high-cholesterol diet. Conclusion: These data indicate that PRDX4 is an antiatherogenic factor and, by suppressing oxidative damage and apoptosis, that it may protect against the formation of vulnerable (unstable) plaques. Antioxid. Redox Signal. 17, 1362-1375.     

Effects of high cholesterol diet on gliosis in apolipoprotein E knockout mice. Implications for Alzheimer's disease and stroke

Hypercholesterolemia has been suggested as a risk factor for Alzheimer's disease (AD). A genetic risk factor for AD is the E4 allele of apolipoprotein E (apoE). ApoE is the major lipoprotein transporter in the brain, and is mainly produced by glial cells. The present study is focussed on analysing the effects of high cholesterol (HC) diet, duration 9 months, on glial activation in the brain, both in wild type (WT) mice and in mice with a null mutation in the apoE gene (knock-out, KO) mice. The activation of astrocytes and microglia was analysed after immunohistochemical labelling of glial fibrillary acidic protein (GFAP), and F4/80, respectively. In addition, the expression of the antioxidant enzyme NAD(P)H:quinone oxidoreductase (NQO1) was analysed. There was a marked stimulation of astrocyte and microglial activation as well as induced expression of NQO1 in the hippocampus and cerebral cortex upon HC diet. Furthermore, there was significant astrocyte activation in the apoE KO mice, as compared to the WT mice, on ND. The long time exposure to HC diet combined with apoE deficiency resulted in a synergistic effect on the expression of NQO1 in the brain.