Effects of Treadmill Exercise on Cell Proliferation and Differentiation in the Subgranular Zone of the Dentate Gyrus in a Rat Model of Type II Diabetes

In the present study, we investigated the effects of a treadmill exercise on serum glucose levels and Ki67 and doublecortin (DCX) immunoreactivity, which is a marker of cell proliferation expressed during cell cycles except G0 and early G1 and a marker of progenitors differentiating into neurons, respectively, in the subgranular zone of the dentate gyrus (SZDG) using a type II diabetic model. At 6 weeks of age, Zucker lean control (ZLC) and Zucker diabetic fatty (ZDF) rats were put on a treadmill with or without running for 1 h/day/5 consecutive days at 22 m/min for 5 weeks. Body weight was significantly increased in the control (without running)-ZDF rats compared to that in the other groups. In the control groups blood glucose levels were increased by 392.7 mg/dl in the control-ZDF rats and by 143.3 mg/dl in the control-ZLC rats. However, in the exercise groups, blood glucose levels were similar between the exercise-ZLC and ZDF rats: The blood glucose levels were 110.0 and 118.2 mg/dl, respectively. Ki67 positive nuclei were detected in the SZDG in control and exercise groups. The number of Ki67 positive nuclei was significantly high in exercise groups compared to that in the control groups. In addition, Ki67 positive cells were abundant in ZLC groups compared to those in ZDF groups. DCX-immunoreactive structures in the control-ZDF rats were lower than that in the control-ZLC rats. In the exercise groups, DCX-immunoreactive structures (somata and processes with tertiary dendrites) and DCX protein levels were markedly increased in both the exercise-ZLC and ZDF rats compared to that in the control groups. These results suggest that a treadmill exercise reduces blood glucose levels in ZDF rats and increases cell proliferation and differentiation in the SZDG in ZLC and ZDF rats compared to those in control groups.     

Age-related Differentiation in Newly Generated DCX Immunoreactive Neurons in the Subgranular Zone of the Gerbil Dentate Gyrus

In the present study, we investigated age-related changes of newborn neurons in the gerbil dentate gyrus using doublecortin (DCX), a marker of neuronal progenitors which differentiate into neurons in the brain. In the postnatal month 1 (PM 1) group, DCX immunoreactivity was detected in the subgranular zone of the dentate gyrus, but DCX immunoreactive neurons did not have fully developed processes. Thereafter, DCX immunoreactivity and its protein levels in the dentate gyrus were found to decrease with age. Between PM 3 and PM 18, DCX immunoreactive neuronal progenitors showed well-developed processes which projected to the granular layer of the dentate gyrus, but at PM 24, a few DCX immunoreactive neuronal progenitors were detected in the subgranular zone of the dentate gyrus. DCX protein level in the dentate gyrus at PM 1 was high, thereafter levels of DCX were decreased with time. The authors suggest that a decrease of DCX immunoreactivity and its protein level with age may be associated with aging processes in the hippocampal dentate gyrus.     

Differences in Doublecortin Immunoreactivity and Protein Levels in the Hippocampal Dentate Gyrus Between Adult and Aged Dogs

Doublecortin (DCX), a microtubule-associated protein, specifically expresses in neuronal precursors. This protein has been used as a marker for neuronal precursors and neurogenesis. In the present study, we observed differences in DCX immunoreactivity and its protein levels in the hippocampal dentate gyrus between adult and aged dogs. In the adult dog, DCX immunoreactive cells with well-stained processes were detected in the subgranular zone of the dentate gyrus. Numbers of DCX immunoreactive cells in the dentate gyrus of the aged dog were significantly decreased compared to those in the adult dog. DCX immunoreactive cells in both adult and aged dog did not show NeuN (a marker for mature neurons) immunoreactivity. NeuN immunoreactivity in the aged dog was poor compared to that in the adult dog. DCX protein level in the aged dentate gyrus was decreased by 80% compared to that in the adult dog. These results suggest that the reduction of DCX in the aged hippocampal dentate gyrus may be involved in some neural deficits related to the hippocampus.     

Glucocorticoid Receptor Changes Associate with Age in the Paraventricular Nucleus of Type II Diabetic Rat Model

Diabetes is a metabolic disorder that is associated with the dysregulation of a number of systems within the body. In the present study, we investigated glucocorticoid receptor (GR) immunoreactivity and its protein levels in the paraventricular nuclei of 4-, 12-, 20- and 30-week-old Zucker diabetic fatty (fa/fa, ZDF) and in Zucker lean control (fa/+ or +/+, ZLC) rats, because the progressive induction of diabetes is detectable in this model after 7 weeks of age and chronic diabetic conditions are maintained after 12 weeks of age. GR immunoreactivity was detected in parvocellular paraventricular nuclei and this and GR protein levels were exponentially increased according to the ages. In particular, GR immunoreactivities and protein levels were markedly more increased in 30-week-old ZDF rats than in age-matched ZLC group and in younger ZDF group. The present study suggests that GR immunoreactivity and its protein level is associated with a degenerative phenotype in the hypothalamus of from 12-weeks old in the ZDF rat type II diabetes model.     

雌激素在脑缺血诱导的大鼠齿状回神经再生中的作用

为研究雌激素对成年动物局灶性脑缺血诱导成年动物海马齿状回神经元再生的影响,将雄性SD大鼠分为假手术 雌激素组(SE)、假手术 生理盐水替代组(SN)、缺血 雌激素组(ME)和缺血 生理盐水替代组(MN),右侧大脑中动脉闭塞(MCAO)建立脑缺血模型。在缺血90min后恢复供血再灌注,分别于再灌注后1、3、12、24和28h处死老鼠并检测各组大鼠脑梗死体积、细胞凋亡以及脑缺血诱导的成年动物海马齿状回神经元再生的情况。在5个时间点的检测中,ME组脑梗死体积显著小于SE组(P<0.05);在MCAO大鼠中,海马齿状回区域并未发现有神经元丢失及凋亡的现象。同时,MN组与SN组相比较,损伤侧齿状回新生神经元数目明显增多(P<0.05),说明这种缺血诱导的神经元再生并不依赖于齿状回区域神经细胞的死亡;ME组与MN组相比较,损伤侧新生神经元数目显著增多(P<0.05);SE与SN组相比较,手术侧和对侧的新生神经元数目都显著增加(P<0.05)。结果提示雌激素对局灶性脑缺血后海马齿状回神经元再生具有促进作用,且这种促进作用与海马缺血损伤程度无关。     

Metformin Normalizes Type 2 Diabetes-Induced Decrease in Cell Proliferation and Neuroblast Differentiation in the Rat Dentate Gyrus

In this study, we observed the effects of metformin, one of the most widely prescribed drugs for the treatment of type 2 diabetes, on cell proliferation and neuroblast differentiation in the subgranular zone of the hippocampal dentate gyrus (SZDG) in Zucker diabetic fatty (ZDF) rats, which are a model for type 2 diabetes. For this, metformin was administered orally once a day to 14-week-old ZDF rats for 2 weeks and the animals were sacrificed at 16 weeks of age. During this period, blood glucose levels were higher in the vehicle-treated ZDF rats than in the Zucker lean control (ZLC) rats. Metformin treatment significantly decreased the blood glucose levels from 15.5 weeks of age. In the SZDG, Ki67 (a marker for cell proliferation)- and doublecortin (DCX, a marker for differentiated neuroblasts)-immunoreactive cells were much lower in the vehicle-treated ZDF rats than in the ZLC rats. In the metformin-treated ZDF group, Ki67- and DCX-immunoreactive cells were significantly increased in the SZDG compared to those in the vehicle-treated ZDF group. These results suggest that diabetes significantly reduces cell proliferation and neuroblast differentiation in the SZDG and that metformin treatment normalizes the reduction of cell proliferation and neuroblast differentiation in the SZDG in diabetic rats.     

Content and Concentration of Taurine,Hypotaurine, and Zinc in the Retina,the Hippocampus,and the Dentate Gyrus of the Rat at Various Postnatal Days

Taurine and zinc possess neurotrophic and neuroprotective properties, and they have been demonstrated to interact in the central nervous system (CNS). The aim of this work was to determine taurine, hypotaurine, and zinc levels during postnatal development and any possible significant correlation between them in selective areas of the CNS with differential taurine level regulation and intrinsic capacity to proliferate. Taurine and hypotaurine content (nM/region) and concentration (nM/mg protein) and total zinc levels were determined in the retina, hippocampus, and dentate gyrus of the rat at postnatal days 5, 10, 15, 20, 30, and 50. Taurine and hypotaurine increased during development in the retina without significant correlation between them. In the hippocampus there was a progressive decrease, and in the dentate gyrus there was an initial increase and a posterior decrease of taurine and hypotaurine levels. Correlation between the two amino acids was observed at P10, P15, and P50 for the hippocampus and at P15, P30, and P50 for the dentate gyrus. The variations in total zinc levels followed a biphasic behavior, with an early decrease and later increase. Significant and positive correlation of zinc and taurine was only observed in the hippocampus at P30 and P50 and negative in the dentate gyrus at P30. No significant correlation was obtained for the retina. The maintenance of taurine levels in specific CNS areas does not seem to be related to the availability of the precursor, hypotaurine, which might have a role by itself. There are critical postnatal periods during which there is a preservation of taurine, hypotaurine, or zinc levels. It seems that these requirements could be related to zinc-taurine interactions.     

Effects of Treadmill Exercise on Neural Stem Cells, Cell Proliferation, and Neuroblast Differentiation in the Subgranular Zone of the Dentate Gyrus in Cyclooxygenase-2 Knockout Mice

Cyclooxygenase-2 (COX-2) function has been implicated in a number of physiological processes, including inflammatory responses, synaptic transmission, and synaptic plasticity in the brain. However, the specific role of COX-2 in exercise-induced neurogenesis is still debatable. Here, we assessed the role of COX-2 in exercise-induced plasticity by comparing COX-2 knockout mice to wild-type control littermates. We investigated the number of neural stem cells, and the degree of cell proliferation and neuronal differentiation in COX-2 knockout and its wild-type mice that either exercised or remained inactive. Wild-type and COX-2 knockout mice were put on a treadmill and were either sedentary or were forced to run 1 h/day for five consecutive days at a pace of 10–12 m/min for 5 weeks. Loss of COX-2 expression in the knockout mice was confirmed with two measures: (1) COX immunolabeling in the hippocampus, and (2) the identification of abnormal kidney development using hematoxylin and eosin staining, including subcapsular glomerular hypoplasia and hypertrophy of the deeper cortical glomeruli. Compared to wild-type mice, COX-2 knockout mice exhibited a significant reduction in the neural stem cells (nestin-positive cells), cell proliferation (Ki67-positive cells), and neuroblast differentiation (doublecortin-positive cells). In contrast, exercise significantly increased the neural stem cells, cell proliferation, and neuroblast differentiation in both the wild-type and COX-2 knockout mice although the NeuN-immunoreactive neurons were similar in all groups. Expression of phosphorylated cAMP-response element binding protein was decreased in knockout mice. Exercise increased its expression in the subgranular zone of the dentate gyrus in both wild-type and knockout mice. These results suggest that the COX-2 pathway is one of important factors on neural stem cells, cell proliferation and neuroblast differentiation in sedentary mice. The ability of exercise to increase these types of neural plasticity, regardless of COX-2 signaling, suggests that the effects of exercise on neural stem cells, cell proliferation, and neuroblast differentiation are induced via a pathway that is independent of COX-2.     

Memory Consolidation Induces a Transient and Time-Dependent Increase in the Frequency of Neural Cell Adhesion Molecule Polysialylated Cells in the Adult Rat Hippocampus

Abstract: Animals trained in a passive avoidance task exhibit a transient time-dependent increase in hippocampal neural cell adhesion molecule (NCAM) polysialylation at 12–24 h following the initial learning trial. Using immunocytochemical techniques with a monoclonal antibody that specifically recognises NCAM-polysialic acid homopolymers, a distinct population of granule-like cells, at the border of the granule cell layer and the hilus in the dentate gyrus of the adult rat hippocampus, has been demonstrated to exhibit time-dependent change in frequency at 10–12 h following the initial learning of a one-trial, step-through, passive avoidance response. These changes were paradigm specific as they failed to occur in those animals rendered amnesic with scopolamine. These polysialylated dentate neurons are not de novo granule cell precursors as administration of 5-bromo-2'-deoxyuridine every 2 h from the point of learning to the 12-h posttraining time showed no significant difference between trained and passive animals in the small number of heterogeneously distributed, labelled cells. These findings directly identify a morphological substrate of memory, implied by previous correlative and interventive studies on NCAM function.     

GK糖尿病大鼠生物学特性观察

目的了解2型糖尿病模型GK大鼠生长曲线、主要脏器重量、糖代谢等生物学特性,评价GK大鼠葡萄糖刺激的胰岛素分泌能力。方法采用51只雄性GK大鼠及15只年龄性别匹配的Wistar大鼠作为研究对象。测定13周龄GK、Wistar大鼠空腹血糖、23周龄GK大鼠空腹及随机血糖。随访GK及Wistar大鼠生长曲线,34～46周龄期间血糖、糖化血红蛋白。46周龄时行腹腔葡萄糖耐量实验（IPGTT）,计算相关参数评价β细胞葡萄糖刺激的胰岛素分泌能力;之后处死大鼠,脏器称重。比较GK及Wistar大鼠间上述各指标差异。结果13周龄GK大鼠空腹血糖4．74±0．41mmol／L,对照Wistar大鼠1．85±0．44mmol／L（P〈0．001）。23周龄GK大鼠空腹血糖7．88±1．96mmol／L,随机血糖9．91±3．52～13．46±4．13mmol／L。7～20及34～45周龄期间GK大鼠体重高于对照Wistar大鼠（P〈0．05）,46周龄时无显著性差异。34～45周龄期间GK大鼠空腹血糖、进食后血糖、HbAlc均高于对照Wistar大鼠（P〈0．05）。IPGTT曲线下面积分析示GK大鼠胰岛素曲线下面积（AUCi）、葡萄糖曲线下面积（AUCg）高于对照Wistar大鼠,胰岛素与葡萄糖曲线下面积比值（AUCi／AUCg）低于对照Wistar大鼠,差异均有显著性（P〈0．05）。GK大鼠肾脏重量高于对照Wistar大鼠（P〈0．05）,余主要脏器重量差异无显著性。结论GK大鼠空腹血糖、进食后血糖、HbAlc水平升高,葡萄糖刺激的胰岛素分泌能力（GSIS）减退,葡萄糖刺激后胰岛素分泌早期相消失,晚期相代偿性增加,具有2型糖尿病特点;体重、血糖等生物学特性稳定。     

Effects of Adrenalectomy and Replacement Therapy of Corticosterone on Cell Proliferation and Neuroblast Differentiation in the Rat Dentate Gyrus

Newly generated neurons in the dentate gyrus differentiate into mature granule cells. In the present study, we observed the effects of adrenalectomy (ADX) and corticosterone replacement therapy (CRT) on cell death, cell proliferation and neuroblast differentiation in the subgranular zone of the hippocampal dentate gyrus (SZDG). For this, the animals received vehicle or CRT after ADX, and were sacrificed 5 or 42 days later. Plasma corticosterone levels were very low in the adrenalectomized groups, whereas CRT after ADX significant increased serum corticosterone levels at 42 days, not 5 days, after ADX. ADX induced some neuronal damage in the dentate gyrus at 5 days post-ADX. CRT did not significantly reduce the neuronal damage at 5 days post-ADX; however, neuronal damage was not shown at 42 post-ADX with CRT. Ki67 (a marker for cell proliferation) and doublecortin (DCX, a marker for neuronal differentiation) immunoreaction was detected in the SZDG. ADX transiently increased cell proliferation and neuroblast differentiation 5 days after ADX, not 42 days, after ADX, and the CRT 42 days after ADX prominently decreased cell proliferation and neuroblast differentiation in the dentate gyrus. These results suggest that adrenal corticosteroid hormone is not essential for cell proliferation and neuroblast differentiation in long-term period after ADX.     

链尿佐菌素加高糖高脂饮食复制大鼠2型糖尿病模型

目的链尿佐菌素加高糖高脂饮食诱导大鼠2型糖尿病模型的建立。方法SD雄性大鼠高糖高脂饲料喂养3周后,采血检测空腹血糖及血清胰岛素,按25mg/g体重剂量一次性腹腔内注射链尿佐菌素,3d后,行糖耐量实验,对糖耐量异常大鼠继续喂以高糖高脂饲料,在第2、第4周再两次采血检测糖尿病鼠空腹血糖及血清胰岛素。结果与对照组比较,高糖高脂喂养大鼠血清胰岛素明显上升（P〈0.01）,但血糖无变化（P〉0.05）,糖尿病鼠血糖及血清胰岛素均显著的高于对照组（P〈0.01）。结论高糖高脂喂养能致大鼠明显的高胰岛素血症,辅以小剂量一次性注射链尿佐菌素而造成的糖耐量异常,可成功复制出2型糖尿病大鼠模型。     

2型糖尿病大鼠模型制备的影响因素及其特点

目的探讨高脂喂养联合低剂量链脲佐菌素(Streptozotocin,STZ)制备2型糖尿病大鼠模型的造模方法和影响因素。方法4周龄雄性Sprague Dawley(SD)大鼠45只随机分为三组:(1)正常组(normal control,NC),9只,普通饲料喂养。(2)高脂组(high fat,HF),9只,高脂饲料喂养。(3)糖尿病模型组,根据高脂喂养时间差异和STZ剂量不同设计了3种模型制备方法:A组,9只,高脂喂养满4周,注射STZ 30 mg/kg;B组,9只,高脂喂养满8周,注射STZ 20 mg/kg;C组,9只,高脂喂养满8周,注射STZ 30 mg/kg。所有大鼠于48h、2周和4周后行灌胃葡萄糖耐量试验(OGTT)评价成模率和血糖波动情况。实验结束时测定血清胰岛素、甘油三酯(TG)和胆固醇(TC),RT-PCR测定胰腺内胰岛素mRNA表达水平,免疫组化染色观察胰岛细胞形态学特点,用彩色图像分析系统进行定量比较。结果糖尿病C组血糖显著升高,成模后2周血糖下降,4周后又上升到基线水平,成模率100%。糖尿病A组、B组在4周后血糖逐渐降低到接近正常水平,成模率分别为55.6%、11.1%。C组与HF组相比,胰岛素敏感性显著下降(P<0.01)。β细胞内胰岛素水平下降39.3%(P<0.01),胰岛内β细胞所占比例下降了79.2%(P<0.01),胰腺内胰岛素mRNA表达水平减少19.2%(P<0.01),α细胞升高了1倍(P<0.01)。结论高脂喂养8周后腹腔注射低剂量STZ(30 mg/kg)制备的2型糖尿病大鼠模型,成模率高,模型稳定。     

高脂高糖饮食结合链脲佐菌素建立2型糖尿病大鼠模型的改良

目的对目前常用的高脂高糖饮食结合链脲佐菌素建（STZ）建立2型糖尿病大鼠模型的方法进行改良。方法选择40只雄性SD幼鼠,对传统方法进行改良。改良的方法包括：1.采用幼鼠（4周龄）造模;2.用实验方法确定STZ致糖尿病的亚致病剂量;3.大鼠生化指标检测根据用血量不同采取尾静脉、尾动脉和摘除眼球取血等多种取血方式。结果实验组大鼠血糖明显升高（13.7±1.57 mmol/L）。大鼠肝脏、胰腺、脑组织和肾脏等多个器官出现了病变,实验大鼠生存时间较长（9个月以上）。结论本研究完善了2型糖尿病的建模方法。     

Effects of a new synthetic butyrylcholinesterase inhibitor, HBU-39, on cell proliferation and neuroblast differentiation in the hippocampal dentate gyrus in a scopolamine-induced amnesia animal model

In this study, we synthesized [1-(4-(benzo[d][1,3]dioxol-5-ylmethyl)piperazin-1-yl)-5-(1,2-dithiolan-3-yl)pentan-1-one, HBU-39], a (α)-lipoic acid derivative, and found this compound strongly inhibited butyrylcholinesterase (BuChE) in an in vitro experiment. We also examined the effects of HBU-39 on cell proliferation and neuroblast differentiation using the specific markers Ki67 and doublecortin (DCX), respectively, in the hippocampal dentate gyrus of a rat model of scopolamine-induced amnesia. For this, scopolamine was subcutaneously administered for 28 days by an ALzet osmotic minipump (44 mg/mL delivered at 2.5 μL/h). HBU-39 (1 mg/kg per day) and galantamine (an acetylcholinesterase inhibitor used as a control; 5 mg/kg per day) were intraperitoneally administered for 28 days. The administration of scopolamine significantly decreased the mean number of Ki67- and DCX-immunoreactive cells in the dentate gyrus. However, treatment with both HBU-39 and galantamine significantly ameliorated the reductions in cell proliferation and neuroblast differentiation. In particular, the mean number of Ki67- and DCX-immunoreactive cells was prominently abundant in the HBU-treated group compared to that in the galantamine-treated group. These results suggest that the BuChE inhibitor, HBU-39, can ameliorate the scopolamine-induced reductions of cell proliferation and neuroblast differentiation, and HBU-39 may be applicable to amnesia patients to promote memory functions.     

Enhanced Expressions of Arginine Vasopressin (Avp) in the Hypothalamic Paraventricular and Supraoptic Nuclei of Type 2 Diabetic Rats

Arginine vasopressin (AVP) is known to a neuropeptide that plays important roles in water conservation, sodium homeostasis, and in the regulation of serum osmolality. Several studies have reported that the elevated AVP level is related with diabetes mellitus as an acute or chronic stressor using type 1 diabetes mellitus animal models. However, it is unclear as to how the immunoreactivity and protein level of AVP in the brain is regulated in animal models of type 2 diabetes mellitus. In the present study, Zucker diabetic fatty (ZDF) rats were employed as a type 2 diabetes mellitus model and were compared with Zucker lean control (ZLC) rats with respect to AVP protein expression. Furthermore, in order to verify the regulation of AVP expression before and after the onset of diabetes mellitus, pre-diabetic rats (4 week-old) and obese-diabetic rats (12 week-old) were used. Blood glucose levels and water consumption were also measured and the results showed significantly high in 12 week-old ZDF than any other groups. AVP expression levels in the paraventricular nucleus and supraoptic nucleus were found to be significantly higher in 12 week-old ZDF rats than in 12 week-old ZLC rats and than in 4 week-old rats by immunostaining and western blotting. Enhanced expression of AVP in these animals may be associated with type 2 diabetes mellitus. Special issue article in honor of George Fink.     

豚鼠齿状回颗粒细胞在追踪性眨眼条件反应巩固过程中的活动

海马在追踪性眨眼条件反应的巩固过程中发挥重要作用,但解剖学上与其紧密联系的齿状回在此过程中的作用尚不清楚. 实验拟观察齿状回颗粒细胞在追踪性眨眼条件反应巩固过程中的放电活动,阐明齿状回在此海马依赖任务中所发挥的作用. 条件反射组动物 (n=8) 首先接受 200 ms 声音条件刺激,间隔 600 ms 后,再被给予 200 ms 吹气非条件刺激,多次重复配对,建立追踪性眨眼条件反应. 对照组动物 (n=8) 接受非配对出现的上述两种刺激. 采用在体单细胞外记录技术,研究习得条件反应豚鼠的齿状回颗粒细胞在条件反应巩固过程中的放电活动. 结果显示:a. 通过 14 天的训练,条件反射组动物均建立了追踪性眨眼条件反应,而非配对组动物则没有建立该条件反应;b. 齿状回颗粒细胞在追踪性眨眼条件反应的巩固过程中表现出不同的活动模式,如在声音条件刺激、间隔期或吹气非条件刺激出现后活动的增强. 这些结果提示:齿状回可能参与巩固追踪性眨眼条件反应所需的神经环路,其颗粒细胞在追踪性眨眼条件反应巩固过程中可能编码不同的信息.     

Effects of Cu,Zn-Superoxide Dismutase on Cell Proliferation and Neuroblast Differentiation in the Mouse Dentate Gyrus

Oxidative stress is one of the most important factors in reducing adult hippocampal neurogenesis in the adult brain. In this study, we observed the effects of Cu,Zn-superoxide dismutase (SOD1) on lipid peroxidation, cell proliferation, and neuroblast differentiation in the mouse dentate gyrus using malondialdehyde (MDA), Ki67, and doublecortin (DCX), respectively. We constructed an expression vector, PEP-1, fused PEP-1 with SOD1, and generated PEP-1-SOD1 fusion protein. We administered PEP-1 and 100 or 500 μg PEP-1-SOD1 intraperitoneally once a day for 3 weeks and sacrificed at 30 min after the last administrations. PEP-1 administration did not change the MDA levels compared to those in the vehicle-treated group, while PEP-1-SOD1 treatment significantly reduced MDA levels compared to the vehicle-treated group. In the PEP-1-treated group, the number of Ki67-positive nuclei was similar to that in the vehicle-treated group. In the 100 μg PEP-1-SOD1-treated group, the number of Ki67-positive nuclei was slightly decreased; however, in the 500 μg PEP-1-SOD1-treated group, Ki67-positive nuclei were decreased to 78.5% of the vehicle-treated group. The number of DCX-positive neuroblasts in the PEP-1-treated group was similar to that in the vehicle-treated group. However, the arborization of DCX-positive neuroblasts was significantly decreased in both the 100 and 500 μg PEP-1-SOD1-treated groups compared to that in the vehicle-treated group. The number of DCX-positive neuroblasts with tertiary dendrites was markedly decreased in the 500 μg PEP-1-SOD1-treated group. These results suggest that a SOD1 supplement to healthy mice may not be necessary to modulate cell proliferation and neuroblast differentiation in the dentate gyrus.     

Pre- and Posttreatment With Edaravone Protects CA1 Hippocampus and Enhances Neurogenesis in the Subgranular Zone of Dentate Gyrus After Transient Global Cerebral Ischemia in Rats

Edaravone is clinically used for treatment of patients with acute cerebral infarction. However, the effect of double application of edaravone on neurogenesis in the hippocampus following ischemia remains unknown. In the present study, we explored whether pre- and posttreatment of edaravone had any effect on neural stem/progenitor cells (NSPCs) in the subgranular zone of hippocampus in a rat model of transient global cerebral ischemia and elucidated the potential mechanism of its effects. Male Sprague-Dawley rats were divided into three groups: sham-operated (n = 15), control (n = 15), and edaravone-treated (n = 15) groups. Newly generated cells were labeled by 5-bromo-2-deoxyuridine. Immunohistochemistry was used to detect neurogenesis. Terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end labeling was used to detect cell apoptosis. Reactive oxygen species (ROS) were detected by 2,7-dichlorofluorescien diacetate assay in NSPCs in vitro. Hypoxia-inducible factor-1α (HIF-1α) and cleaved caspase-3 proteins were quantified by western blot analysis. Treatment with edaravone significantly increased the number of NSPCs and newly generated neurons in the subgranular zone (p < .05). Treatment with edaravone also decreased apoptosis of NSPCs (p < .01). Furthermore, treatment with edaravone significantly decreased ROS generation and inhibited HIF-1α and cleaved caspase-3 protein expressions. These findings indicate that pre- and posttreatment with edaravone enhances neurogenesis by protecting NSPCs from apoptosis in the hippocampus, which is probably mediated by decreasing ROS generation and inhibiting protein expressions of HIF-1α and cleaved caspase-3 after cerebral ischemia.     

Combination Effects of Sodium Butyrate and Pyridoxine Treatment on Cell Proliferation and Neuroblast Differentiation in the Dentate Gyrus of d-Galactose-Induced Aging Model Mice

We previously reported that sodium butyrate (SB), a histone deacetylase inhibitor, robustly increased pyridoxine-induced cell proliferation and neuroblast differentiation in the dentate gyrus of the adult mouse. In this study, we investigated the effects of treatment with SB combined with pyridoxine on cell proliferation and neuroblast differentiation in the dentate gyrus of a mouse model of aging induced by d-galactose (d-gal). d-gal was administered to 20-week-old male mice (d-gal mice) for 10 weeks to induce changes that resemble natural aging in animals. Seven weeks after d-gal (100 mg/kg) treatment, vehicle (physiological saline; d-gal-vehicle mice) and SB (300 mg/kg) combined with pyridoxine (Pyr; 350 mg/kg) were administered to the mice (d-gal-Pyr-SB mice) for 3 weeks. Escape latency under water maze in the d-gal mice was longer than that in the control mice. In the d-gal-Pyr-SB mice, escape latency was similar to that in the control mice. In the d-gal mice, many cells in the granule cell layer of the dentate gyrus showed pyknosis and condensation of the cytoplasm. However, in the d-gal-Pyr-SB mice, such cellular changes were rarely found. Furthermore, the d-gal mice showed a great reduction in cell proliferation (Ki67-positive cells) and neuroblast differentiation (doublecortin-positive neuroblasts) in the dentate gyrus compared to control mice. However, in the d-gal-Pyr-SB mice, cell proliferation and neuroblast differentiation were markedly increased in the dentate gyrus. Furthermore, the administration of pyridoxine with sodium butyrate significantly increased Ser133-phosphorylated cyclic AMP response element binding protein in the dentate gyrus. These results indicate that the combination treatment of Pyr with SB in d-gal mice ameliorated the d-gal-induced reduction in cell proliferation, neuroblast differentiation, and memory deficits.