缺血缺氧新生大鼠脑内原位神经干细胞的增殖与分化：可通过针刺任脉、督脉及膀胱经实现？

[摘要] 目的 检测针刺任脉、督脉及膀胱经对新生儿缺血缺氧性脑病模型鼠脑内神经干细胞的影响,分析针刺诱导神经干细胞增殖、分化的机制,为临床针刺治疗新生儿缺血缺氧性脑病提供新的细胞学理论依据。方法 新生7天SD大鼠结扎左侧颈总动脉并缺氧2小时制作新生鼠缺血缺氧性脑病模型。实验动物共分三组：针刺组、对照组和正常组。针刺组每天针刺任脉、督脉及膀胱经治疗一次。对照组及正常组不作针刺处理。各组动物每天两次腹腔注射Brdu用于标记脑内神经干细胞增殖情况。分别于模型建立后3d、7d、14d和28d取脑组织行抗Brdu的免疫组化染色,并于模型建立后40d行免疫荧光双标,分别观察各组动物海马及皮层Brdu阳性细胞数目、形态、分布以及分化情况; 并比较他们之间的差异。结果 抗Brdu的免疫组化染色显示针刺任脉、督脉及膀胱经治疗第3天及第7天时针刺组动物皮层及海马的Brdu阳性细胞数目和对照组相比,差别无统计学意义;针刺治疗第14天及第28天时针刺组动物皮层及海马的Brdu阳性细胞数目明显比对照组多,差别有统计学意义。针刺后第40天免疫荧光双标显示大部分Brdu阳性细胞和神经元标记物NSE共存,少部分和星形胶质细胞标记物GFAP共存。结论 针刺任脉、督脉及膀胱经能促进HIE模型鼠皮层及海马神经干细胞的增殖潜能;针刺任脉、督脉及膀胱经治疗后新生的神经干细胞大部分分化为神经元,提示针刺后新生的神经细胞有可能有效地补充在缺血缺氧中丧失的神经元,并能促进HIE动物功能的恢复。     

针刺任脉、督脉及膀胱经促进新生儿缺血缺氧性脑病鼠模型脑内神经干细胞增殖

目的检测针刺任脉、督脉及膀胱经对新生儿缺血缺氧性脑病（HIE）鼠模型脑内神经干细胞的影响，分析针刺诱导神经干细胞增殖的机制。方法新生7dSD大鼠结扎左侧颈总动脉并缺氧2h制作HIE鼠模型。动物分为针刺组和对照组。针刺组每天针刺任脉、督脉及膀胱经一次。对照组不作处理。各组动物每天两次腹腔注射BrdU用于标记脑内神经干细胞增殖情况，分别于模型建立后3d、7d、14d和28d取脑组织行抗BrdU的免疫组化染色。分别观察各组动物海马及皮层BrdU阳性细胞数目、形态以及分布情况：并比较他们之间的差异。结果抗BrdU的免疫组化染色显示针刺治疗第3天及第7天时针刺组动物皮层及海马的BrdU阳性细胞数目和对照组相比。差别无统计学意义；针刺治疗第14天及第28天时针刺组动物皮层及海马的BrdU阳性细胞数目明显比对照组多．差别有统计学意义。结论针刺任脉、督脉及膀胱经能促进HIE模型鼠皮层及海马神经干细胞的增殖潜能。     

补阳还五汤对老龄大鼠脑缺血再灌注海马齿状回细胞增殖分化的影响

BACKGROUND： The mobilization of endogenous stem cells is an effective way to promote repair following ischemic brain damage. Buyang Huanwu decoction （BHD） can effectively improve cerebral blood flow and protect against cerebral ischemia/reperfusion damage. OBJECTIVE： To study the effects of BHD on cell proliferation and differentiation in the hippocampal dentate gyrus of rats following cerebral infarction, to investigate the protective effects of BHD against cerebral infarction, and to analyze the dose-effect relationship. DESIGN, TIME AND SETTING： This randomized, controlled, animal study was performed at the Laboratory of Department of Physiology, Henan College of Traditional Chinese Medicine, China from June 2007 to February 2008. MATERIALS： A total of 36 male, Sprague Dawley rats, aged 20-21 months, were equally and randomly assigned to the following groups： sham operation, model control, and nimodipine, as well as high-dose, moderate-dose, and low-dose BHD. BHD was composed of milkvetch root, Chinese angelica, red peony root, earthworm, peach seed, safflower, and Szechwan Iovage rhizome, which were provided by the Outpatient Department, Henan College of Traditional Chinese Medicine, China. METHODS： The Chinese medicinal ingredients described above were decocted. The external carotid artery was ligated in rats from the sham operation group. Rat models of focal cerebral infarction were established by middle cerebral artery occlusion in the model control and nimodipine groups, as well as the high-dose, moderate-dose, and low-dose BHD groups. The drugs were administered by gavage 5 days, as well as 2 hours, prior to model induction. Rats in the nimodipine group were daily administered a 6 mg/kg nimodipine suspension by gavage. Rats in the high-dose, moderate-dose, and low-dose BHD groups were administered daily 26, 13, and 6.5 g/kg BHD, respectively. Rats in the sham operation and model control groups were treated with an equal volume of saline. MAIN OUTCOME MEASURES： The effects of BHD on neurological dysfunction score, brain water content, cell proliferation and differentiation in the hippocampal dentate gyrus, and pathological changes in the ischemic brain hemisphere were measured in cerebral infarction rats. RESULTS： Compared with the sham operation group, the neurological dysfunction score, brain water content, number of BrdU-positive cells, BrdU/NeuN-positive cells, and BrdU/GFAP-positive cells in the hippocampal dentate gyrus significantly increased in the model control group （P 〈 0.01 ）. Compared with the model control group, neurological dysfunction score and brain water content were significantly decreased （P 〈 0.01 or 0.05）, as were the number of BrdU-positive and BrdU/NeuN-positive cells （P 〈 0.01 or 0.05）. The number of BrdU/GFAP-positive cells was significantly reduced （P 〈 0.05） in the nimodipine group, high-dose, moderate-dose, and low-dose BHD groups. Compared with the nimodipine group, the neurological dysfunction score was significantly reduced in the moderate-dose BHD group （P 〈 0.05）. However, the number of BrdU-positive cells was significantly increased in the rat hippocampal dentate gyrus in the high-dose and moderate-dose BHD groups （P 〈 0.01 or 0.05）. The following was determined by microscopy： slightly disarranged neural cells, mild vascular dilatation, inflammatory cell infiltration, and light tissue edema were observed in the nimodipine group; inflammatory celt infiltration was reduced in the low-dose BHD group; cerebral edema and inflammatory cell infiltration were significantly reduced in the high-dose and in the moderate-dose BHD group. Electron microscopy revealed lipofuscin, slightly swollen mitochondria, and normal rough endoplasmic reticulum in the high-dose and moderate-dose BHD groups. Improvement was best in the moderate-dose BHD group. CONCLUSION： Cerebral ischemia activated proliferation of neural stem cells in the rat hippocampal dentate gyrus. The actions of BHD against cerebral ischemia/reperfusion damage correlated with proliferation and differentiation of neural stem cells in the hippocampal dentate gyrus. A moderate-dose of BHD resulted in the most effective outcome.     

Cholinergic activation of hippocampal neural stem cells in aged dentate gyrus

Adult hippocampal neurogenesis contributes to the hippocampal circuit's role in cognitive functioning. New neurons are generated from hippocampal neural stem cells (NSCs) throughout life, but their generation is substantially diminished in aged animals due to a decrease in NSC proliferation. Because acetylcholine (ACh) is an important neurotransmitter released in the hippocampus during learning and exercise that is known to decrease with aging, we investigated whether aged NSCs can respond to ACh. In this study, we found that cholinergic stimulation has a positive effect on NSC proliferation in both young adult (8–12 weeks old) and aged mice (>2 years old). In fresh hippocampal slices, we observed a rapid calcium increase in NSCs in the dentate gyrus after muscarinic cholinergic stimulation, in both age groups. Furthermore, we found that the exercise‐induced promotion of aged NSC proliferation was abrogated by the specific lesioning of the septal cholinergic system. In turn, cholinergic activation by either eserine (physostigmine) or donepezil treatment promoted the proliferation of NSCs in aged mice. These results indicate that NSCs respond to cholinergic stimulation by proliferating in aged animals. Physiological and/or pharmacological cholinergic stimulation(s) may ameliorate cognitive decline in aged animals, by supporting adult hippocampal neurogenesis. © 2010 Wiley‐Liss, Inc.     

Regeneration of granule neurons after lesioning of hippocampal dentate gyrus: evaluation using adult mice treated with trimethyltin chloride as a model

The hippocampal dentate gyrus in adult animals is known to contain neural progenitors that proliferate and differentiate into neurons in response to brain injury. Little has been observed, however, on regeneration of the granule cell layer of the dentate gyrus that has been directly injured. Using trimethyltin (TMT)-treated mice as an in vivo model, we evaluated the ability of this layer to regenerate after injury. The administration of TMT induced neuronal death in the dentate gyrus selectively 2 days later, with recovery of granule neurons on day 14 and thereafter. At an early stage (days 2-5) after the damage by TMT treatment, 5-bromo-2'-deoxyuridine (BrdU) incorporation into at least two different types of cells was facilitated in the dentate gyrus: BrdU-positive/neuronal nuclear antigen (NeuN)-negative cells were found predominantly in the subgranular zone and granule cell layer, whereas BrdU-positive/NeuN-positive cells were numerous in the dentate molecular layer and hilus. In addition, expression of proliferating cell nuclear antigen, nestin, NeuroD3, and doublecortin, which are markers for proliferating cells and neural progenitors/neuronal precursors, was extremely enhanced in the dentate gyrus at the early stage after treatment. Double staining revealed that BrdU was colocalized with nestin and doublecortin in the subgranular zone. Behavioral analysis revealed that TMT-induced cognition impairment was ameliorated by day 14 after the treatment. Taken together, our data indicate that the hippocampal dentate gyrus itself is capable of regenerating the neuronal cell layer through rapid enhancement of neurogenesis after injury.     

Sleep restriction by forced activity reduces hippocampal cell proliferation

Mounting evidence suggests that sleep loss negatively affects learning and memory processes through disruption of hippocampal function. In the present study, we examined whether sleep loss alters the generation, differentiation, and survival of new cells in the dentate gyrus. Rats were sleep restricted by keeping them awake in slowly rotating drums for 1 day or repeatedly for 20 h/day over a period of 8 days. In addition to home cage controls, we included forced activity controls which, compared to sleep restricted rats, walked at double speed for half the time. These animals thus walked the same distance but had sufficient time to sleep. The results show that a single day of sleep deprivation significantly reduced hippocampal cell proliferation in the hilus of the dentate gyrus as measured by immunostaining for the proliferation marker Ki-67. Repeated partial sleep deprivation reduced cell proliferation in both the hilus and the subgranular zone. However, the latter was also found after chronic forced activity, and may not have been specific for sleep loss. To study neuronal survival, rats received a single intraperitoneal injection of 5-bromo-2'-deoxyuridine (BrdU) 5 days before the experiment. The number of surviving, BrdU-positive cells was not affected by sleep restriction. Also, the differentiation of BrdU-positive new cells into NeuN-positive neuronal and GFAP-positive glial phenotypes was not significantly altered by sleep loss. In conclusion, since new cells in the hilus mostly differentiate into glia, our findings indicate that sleep loss may reduce hippocampal gliogenesis.     

NSCs promote hippocampal neurogenesis,metabolic changes and synaptogenesis in APP/PS1 transgenic mice

Adult neurogenesis and synaptic remodeling persist as a unique form of structural and functional plasticity in the hippocampal dentate gyrus (DG) and subventricular zone (SVZ) of the lateral ventricles due to the existence of neural stem cells (NSCs). Transplantation of NSCs may represent a promising approach for the recovery of neural circuits. Here, we aimed to examine effects of highly neuronal differentiation of NSCs transplantation on hippocampal neurogenesis, metabolic changes and synaptic formation in APP/PS1 mice. 12‐month‐old APP/PS1 mice were used for behavioral tests, immunohistochemistry, western blot, transmission electron microscopy and proton magnetic resonance spectroscopy (1H‐MRS). The results showed that N‐acetylaspartate (NAA) and Glutamate (Glu) levels were increased in the Tg‐NSC mice compared with the Tg‐PBS and Tg‐AD mice 10 weeks after NSCs transplantation. NSC‐induced an increase in expression of synaptophysin and postsynaptic protein‐95, and the number of neurons with normal synapses was significantly increased in Tg‐NSC mice. More doublecortin‐, BrdU/NeuN‐ and Nestin‐positive neurons were observed in the hippocampal DG and SVZ of the Tg‐NSC mice. This is the first demonstration that engrafted NSCs with a high differentiation rate to neurons can enhance neurogenesis in a mouse model of AD and can be detected by 1H‐MRS in vivo. It is suggested that engraft of NSCs can restore memory and promote endogenous neurogenesis and synaptic remodeling, moreover, 1H‐MRS can detect metabolite changes in AD mice in vivo. The observed changes in NAA/creatine (Cr) and glutamate (Glu)/Cr may be correlated with newborn neurons and new synapse formation.     

β1‐integrin restricts astrocytic differentiation of adult hippocampal neural stem cells

Integrins are transmembrane receptors that mediate cell‐extracellular matrix and cell–cell interactions. The β1‐integrin subunit is highly expressed by embryonic neural stem cells (NSCs) and is critical for NSC maintenance in the developing nervous system, but its role in the adult hippocampal niche remains unexplored. We show that β1‐integrin expression in the adult mouse dentate gyrus (DG) is localized to radial NSCs and early progenitors, but is lost in more mature progeny. Although NSCs in the hippocampal subgranular zone (SGZ) normally only infrequently differentiate into astrocytes, deletion of β1‐integrin significantly enhanced astrocyte differentiation. Ablation of β1‐integrin also led to reduced neurogenesis as well as depletion of the radial NSC population. Activation of integrin‐linked kinase (ILK) in cultured adult NSCs from β1‐integrin knockout mice reduced astrocyte differentiation, suggesting that at least some of the inhibitory effects of β1‐integrin on astrocytic differentiation are mediated through ILK. In addition, β1‐integrin conditional knockout also resulted in extensive cellular disorganization of the SGZ as well as non‐neurogenic regions of the DG. The effects of β1‐integrin ablation on DG structure and astrogliogenesis show sex‐specific differences, with the effects following a substantially slower time‐course in males. β1‐integrin thus plays a dual role in maintaining the adult hippocampal NSC population by supporting the structural integrity of the NSC niche and by inhibiting astrocytic lineage commitment. GLIA 2016;64:1235–1251     

Temporal profile of neurogenesis in the subventricular zone,dentate gyrus and cerebral cortex following transient focal cerebral ischemia

Abstract

Background: In the adult mammalian brain, it is considered that neurogenesis persists in limited regions such as the hippocampal dentate gyrus (DG) and the subventricular zone (SVZ) of the lateral ventricle. On the other hand, neurogenesis in the cortex after cerebral ischemia and its role in post-stroke recovery have not been clarified yet. In this study, we investigated neurogenesis in the cortex and the spatiotemporal profile of neural progenitors in SVZ and DG of rats subjected to transient focal cerebral ischemia.

Materials and methods: Male Sprague–Dawley rats (270–300 g) were subjected to 60 minute middle cerebral artery occlusion. Proliferating cells were labeled by the cumulative administration of BrdU 1, 2, 3, 4, 6 and 8 weeks after ischemia induction (at weeks 1–4, 6 and 8). Double labeling was also performed with antibodies against BrdU and NeuN.

Results: BrdU-positive cells proliferated in DG and SVZ of the bilateral hemispheres, and their proliferation peaked at week 3 in SVZ and at week 4 in DG. In the peri-infarct zone of cerebral cortex, BrdU-positive cells co-expressed NeuN from weeks 3 to 8.

Conclusion: Neurogenesis was observed in the cerebral cortex and proliferation of neural progenitors occurred in SVZ and DG of rats subjected to transient focal cerebral ischemia. Our data might indicate that endogenous dormant neural stem cells residing in the cortex were activated by ischemic insult to induce the proliferation of neural progenitors and differentiation into mature neurons.     

Antidepressant drugs reverse the loss of adult neural stem cells following chronic stress

In rodents, adult neurogenesis occurs in the olfactory bulb and the dentate gyrus of the hippocampus. It has been shown that exposure to psychosocial stress reduces cell proliferation in the dentate gyrus. However, little is known about how stress affects the proliferation kinetics of neural stem cells (NSCs) in the subventricular zone (SVZ), which provide new neurons to the olfactory bulb. We utilized a forced-swim model of stress in the mouse and found that chronic stress decreased the number of NSCs in the SVZ. The reduction of NSC number persisted for weeks after the cessation of stress but was reversed by treatment with the antidepressant drugs fluoxetine and imipramine. We demonstrated by in vitro colony-forming neurosphere assay that corticosterone attenuated neurosphere formation by adult NSCs and, in contrast, that serotonin increased the survival of NSCs. In addition, serotonin expanded the size of the NSC pool in the SVZ when it was infused into the lateral ventricle in vivo. These results suggest that, under chronic stress conditions, the number of NSCs is regulated by the actions of glucocorticoids and serotonin. These data provide insights into the molecular mechanisms underlying the pharmacological actions of antidepressant drugs.     

Derivation of neural stem cells from an animal model of psychiatric disease

Several psychiatric and neurological diseases are associated with altered hippocampal neurogenesis, suggesting differing neural stem cell (NSC) function may play a critical role in these diseases. To investigate the role of resident NSCs in a murine model of psychiatric disease, we sought to isolate and characterize NSCs from alpha-calcium-/calmodulin-dependent protein kinase II heterozygous knockout (CaMK2α-hKO) mice, a model of schizophrenia/bipolar disorder. These mice display altered neurogenesis, impaired neuronal development and are part of a larger family possessing phenotypic and behavioral correlates of schizophrenia/bipolar disorder and a shared pathology referred to as the immature dentate gyrus (iDG). The extent to which NSCs contribute to iDG pathophysiology remains unclear. To address this, we established heterogeneous cultures of NSCs isolated from the hippocampal neuropoietic niche. When induced to differentiate, CaMK2α-hKO-derived NSCs recapitulate organotypic hippocampal neurogenesis, but generate larger numbers of immature neurons than wild-type (WT) littermates. Furthermore, mutant neurons fail to assume mature phenotypes (including morphology and MAP2/calbindin expression) at the same rate observed in WT counterparts. The increased production of immature neurons which fail to mature indicates that this reductionist model retains key animal- and iDG-specific maturational deficits observed in animal models and human patients. This is doubly significant, as these stem cells lack several developmental inputs present in vivo. Interestingly, NSCs were isolated from animals prior to the emergence of overt iDG pathophysiology, suggesting mutant NSCs may possess lasting intrinsic alterations and that altered NSC function may contribute to iDG pathophysiology in adult animals.     

The duration of sustained convulsive seizures determines the pattern of hippocampal neurogenesis and the development of spontaneous epilepsy in rats

The duration of sustained seizures (SS) plays a crucial role in the occurrence of spontaneous recurrent seizures (SRS) in experimental animals. We tested whether rats with varying durations of initial convulsive SS exhibited differential neurogenesis patterns in the hippocampal dentate gyrus that may be related to subsequent epileptogenesis. Sprague-Dawley rats with pilocarpine-induced convulsive SS were divided into short SS (30 min) and long SS (2 h) groups. Their behavior was monitored to identify convulsive SRS. From 1 to 28 days post-SS, cell proliferation was evaluated by 5'-bromo-2'-deoxyuridine (BrdU) labeling and immature neuroblasts in the dentate gyrus were identified by doublecortin immunohistochemistry. Convulsive SRS was detected in 8 out of the 9 long SS rats, but not in the 9 short SS rats. During day 1-3, proliferative cells were diffusely localized throughout the hippocampus in the long SS rats but were primarily confined within the subgranular zone in the short SS rats. Within the subgranular zone, a significant increase in the number of BrdU-positive cells was found at days 3 and 7 after the long SS and on day 1 after the short SS. Notably, abnormal dendritic outgrowth and hilar-ectopic localization of doublecortin-positive cells were present in the long SS rats. In conclusion, aberrant hippocampal neurogenesis following long SS may contribute to the development of SRS.     

Use of bromodeoxyuridine-immunohistochemistry to examine the proliferation, migration and time of origin of cells in the central nervous system

The use of an exogenously administered thymidine analog, 5-bromo-2'-deoxyuridine (BrdU), for studies of the proliferation, migration and time of origin of cells in the cerebral cortex was investigated and compared with [3H]thymidine [( 3H]dT) autoradiography. Pregnant rats or mice were injected with BrdU and/or [3H]dT and processed by standard immunohistochemical techniques using a primary antibody directed against BrdU in single-stranded DNA, autoradiographic methods, or both. In animals that survived only 1 h after the injection, BrdU-positive cells were distributed in the proliferative zones throughout the central nervous system (CNS). In animals killed 1-3 days after the BrdU injection, intensely immunoreactive cells were in the superficial cortical plate and less intensely labeled cells were scattered throughout the deep cortical plate, the intermediate zone, and the germinal zones. In adult animals, 60 days or more after an injection of BrdU on GD 19, BrdU-positive cells were located in layer II/III of neocortex, the hippocampal pyramidal layer, and the granule layer of the dentate gyrus. In the double-labeling studies, the distribution of BrdU-immunoreactive cells was identical to that of autoradiographically labeled cells, and all autoradiographically labeled neurons were BrdU positive. Thus, BrdU immunohistochemistry is suitable for developmental studies of the CNS; moreover, it provides several advantages over [3H]dT autoradiography.     

Depletion of norepinephrine decreases the proliferation,but does not influence the survival and differentiation,of granule cell progenitors in the adult rat hippocampus

The dentate gyrus region retains the ability to generate neurons throughout adulthood. A few studies have examined the neurotransmitter regulation of adult hippocampal neurogenesis and have shown that this process is regulated by serotonin and glutamate. Given the strong noradrenergic innervation of the adult hippocampus and the ability of norepinephrine to influence proliferation during development, we examined the influence of norepinephrine on adult hippocampal neurogenesis. Our study indicates that depletion of norepinephrine by the selective noradrenergic neurotoxin, N-(2-chloroethyl)-N-ethyl-2-bromo benzylamine hydrochloride (DSP-4), results in a 63% reduction in the proliferation of dentate gyrus progenitor cells identified through 5-bromo-2'-deoxyuridine (BrdU) labelling. In contrast, the survival of BrdU-positive cells labelled prior to treatment with DSP-4 is not influenced by norepinephrine depletion. The differentiation of BrdU labelled progenitors into neurons or glia was also not sensitive to noradrenergic depletion. These results indicate that the proliferation, but not the survival or differentiation, of adult hippocampal granule cell progenitors is affected by norepinephrine depletion.     

慢性应激抑制卒中后大鼠海马内源性神经干细胞增殖和分化研究

目的 观察慢性应激对卒中后海马内源性神经干细胞增殖和分化的影响。方法 将雄性SD大鼠分为正常、卒中、慢性应激组。建立左侧大脑中动脉闭塞卒中动物模型并予以慢性不可预见温和应激刺激结合孤养。经溴脱氧尿苷嘧啶（BrdU）标记，免疫组化、荧光双标染色及共聚焦成像动态检测并比较各研究组大鼠左侧海马齿状回BrdU及其与神经元核性蛋白（NeuN）共表达。结果 与卒中组相比，慢性应激组大鼠病灶侧海马齿状回BrdU+细胞数在脑梗死后第7天未见减少，第21天明显减少（28.5±1.9 vs 72.2±1.4），差异有统计学意义（P<0.001）。与卒中组相比，慢性应激组大鼠病灶侧海马齿状回BrdU+/NeuN+细胞比例在脑梗死后30 d[（69.0±3.4）%）]和45 d[（78.3±2.4）%]均明显减少，差异有统计学意义（P<0.001； P<0.01）。结论 慢性应激能明显抑制卒中后海马内源性神经干细胞的增殖和分化，可能是卒中后抑郁发病的因素之一。     

Decreased cell proliferation in the dentate gyrus of rats after repeated administration of cocaine

Cell proliferation in the dentate gyrus of hippocampus was assessed using in vivo labeling with 5-bromo-2'-deoxyuridine (BrdU) in adult rats that were administered cocaine (20 mg/kg) for 14 consecutive days. Rats showed increased stereotypy at a challenge dose of cocaine after 1 week of withdrawal, suggesting the acquisition of behavioral sensitization. Twenty-four hours after final injection of repetitive cocaine administration, a 26% decrease in BrdU-positive cells was observed, compared with control rats. However, this returned to control level within 1 week. No differences were observed in rats that received a single injection of cocaine. Differentiation of newly formed cells was not influenced. These data imply that the regulation of hippocampal cell proliferation by cocaine may be involved in the development of certain symptoms of addiction, such as cognitive impairment and acquisition of behavioral sensitization.     

A ginkgo biloba extract promotes proliferation of endogenous neural stem cells in vascular dementia rats

The ginkgo biloba extract EGb761 improves memory loss and cognitive impairments in patients with senile dementia. It also promotes proliferation of neural stem cells in the subventricular zone in Parkinson’s disease model mice and in the hippocampal zone of young epileptic rats. However, it remains unclear whether EGb761 enhances proliferation of endogenous neural stem cells in the brain of rats with vascular dementia. In this study, a vascular dementia model was established by repeatedly clipping and reperfusing the bilateral common carotid arteries of rats in combination with an intraperitoneal injection of a sodium nitroprusside solution. Seven days after establishing the model, rats were intragastrically given EGb761 at 50 mg/kg per day. Learning and memory abilities were assessed using the Morris water maze and proliferation of endogenous neural stem cells in the subventricular zone and dentate gyrus were labeled by 5-bromo-2-deoxyuridine immunofluorescence in all rats at 15 days, and 1, 2, and 4 months after model establishment. The escape latencies in Morris water maze tests of rats with vascular dementia after EGb761 treatment were significantly shorter than the model group. Immunofluorescence staining showed that the number and proliferation of 5-bromo-2-deoxyuridine-positive cells in the subventricular zone and dentate gyrus of the EGb761-treated group were significantly higher than in the model group. These experimental findings suggest that EGb761 enhances proliferation of neural stem cells in the subventricular zone and dentate gyrus, and significantly improves learning and memory in rats with vascular dementia.     

Effects of CXCR7-neutralizing antibody on neurogenesis in the hippocampal dentate gyrus and cognitive function in the chronic phase of cerebral ischemia

Stromal cell-derived factor-1 and its receptor CXCR4 are essential regulators of the neurogenesis that occurs in the adult hippocampal dentate gyrus.However,the effects of CXCR7,a new atypical receptor of stromal cell-derived factor-1,on hippocampal neurogenesis after a stroke remain largely unknown.Our study is the first to investigate the effect of a CXCR7-neutralizing antibody on neurogenesis in the dentate gyrus and the associated recovery of cognitive function of rats in the chronic stage of cerebral ischemia.The rats were randomly divided into sham,sham+anti-CXCR7,ischemia and ischemia+anti-CXCR7 groups.Endothelin-1 was injected in the ipsilateral motor cortex and striatum to induce focal cerebral ischemia.Sham group rats were injected with saline instead of endothelin-1 via intracranial injection.Both sham and ischemic rats were treated with intraventricular infusions of CXCR7-neutralizing antibodies for 6 days 1 week after surgery.Immunofluorescence staining with doublecortin,a marker for neuronal precursors,was performed to assess the neurogenesis in the dentate gyrus.We found that anti-CXCR7 antibody infusion enhanced the proliferation and dendritic development of doublecortin-labeled cells in the dentate gyrus in both ischemic and sham-operated rats.Spatial learning and memory functions were assessed by Morris water maze tests 30-32 days after ischemia.CXCR7-neutralizing antibody treatment significantly reduced the escape latency of the spatial navigation trial and increased the time spent in the target quadrant of spatial probe trial in animals that received ischemic insult,but not in sham operated rats.These results suggest that CXCR7-neutralizing antibody enhances the neurogenesis in the dentate gyrus and improves the cognitive function after cerebral ischemia in rats.All animal experimental protocols and procedures were approved by the Institutional Animal Care and Use Committee of China Medical University(CMU16089 R)on December 8,2016.