Impairment of the nerve growth factor pathway driving amyloid accumulation in cholinergic neurons the incipit of the Alzheimer's disease story?

The current idea behind brain pathology is that disease is initiated by mild disturbances of common physiological processes. Overtime, the disruption of the neuronal homeostasis will determine irreversible degeneration and neuronal apoptosis. This could be also true in the case of nerve growth factor （NGF） al- terations in sporadic Alzheimer＇s disease （AD）, an age-related pathology characterized by cholinergic loss, amyloid plaques and neurofibrillary tangles. In fact, the pathway activated by NGF, a key neurotrophin for the metabolism of basal forebrain cholinergic neurons （BFCN）, is one of the first homeostatic systems affected in prodromal AD. NGF signaling dysfunctions have been thought for decades to occur in AD late stages, as a mere consequence of amyloid-driven disruption of the retrograde axonal transport of neuro- trophins to BFCN. Nowadays, a wealth of knowledge is potentially opening a new scenario： NGF signaling impairment occurs at the onset of AD and correlates better than amyloid load with cognitive decline. The recent acceleration in the characterization of anatomical, functional and molecular profiles of early AD is aimed at maximizing the efficacy of existing treatments and setting novel therapies. Accordingly, the elucidation of the molecular events underlying APP metabolism regulation by the NGF pathway in the sep- to-hippocampal system is crucial for the identification of new target molecules to slow and eventually halt mild cognitive impairment （MCI） and its progression toward AD.

Wnt3a expression during the differentiation of adipose-derived stem cells into cholinergic neurons

The present study analyzed changes in Wnt3a expression during differentiation of adipose-derived stern cells into cholinergic neurons. Immunocytochemistry and immunofluorescence revealed significantly increased nestin, neuron-specific enolase, microtubule-associated protein 2, and choline acetyltransferase expression in adipose-derived stem cells isolated from Sprague-Dawley rats and cultured in vitro in neural-induced medium. These expressions increased with prolonged induction time. Real-time reverse transcription-PCR and western blot assay results demonstrated significantly increased choline acetyltransferase and Wnt3a protein and mRNA expressions, respectively, in adipose-derived stem cells following induction. Choline acetyltransferase expression positively correlated with Wnt3a protein and mRNA expressions. These results demonstrated that neural-induced medium induced differentiation of adipose-derived stem cells into cholinergic neuronal-like cells, with subsequent increased Wnt3a expression.

Age-dependent loss of cholinergic neurons in learning and memory-related brain regions and impaired learning in SAMP8 mice with trigeminal nerve damage

The tooth belongs to the trigeminal sensory pathway. Dental damage has been associated with impairments in the central nervous system that may be mediated by injury to the trigeminal nerve. In the present study, we investigated the effects of damage to the inferior alveolar nerve, an important peripheral nerve in the trigeminal sensory pathway, on learning and memory be-haviors and structural changes in related brain regions, in a mouse model of Alzheimer’s disease. Inferior alveolar nerve transection or sham surgery was performed in middle-aged （4-month-old） or elderly （7-month-old） senescence-accelerated mouse prone 8 （SAMP8） mice. When the middle-aged mice reached 8 months （middle-aged group 1） or 11 months （middle-aged group 2）, and the elderly group reached 11 months, step-down passive avoidance and Y-maze tests of learn-ing and memory were performed, and the cholinergic system was examined in the hippocampus （Nissl staining and acetylcholinesterase histochemistry） and basal forebrain （choline acetyltrans-ferase immunohistochemistry）. In the elderly group, animals that underwent nerve transection had fewer pyramidal neurons in the hippocampal CA1 and CA3 regions, fewer cholinergic ifbers in the CA1 and dentate gyrus, and fewer cholinergic neurons in the medial septal nucleus and vertical limb of the diagonal band, compared with sham-operated animals, as well as showing impairments in learning and memory. Conversely, no signiifcant differences in histology or be-havior were observed between middle-aged group 1 or group 2 transected mice and age-matched sham-operated mice. The present ifndings suggest that trigeminal nerve damage in old age, but not middle age, can induce degeneration of the septal-hippocampal cholinergic system and loss of hippocampal pyramidal neurons, and ultimately impair learning ability. Our results highlight the importance of active treatment of trigeminal nerve damage in elderly patients and those with Alzheimer’s disease, and indicate that tooth extraction should be avoided in these populations.

The synthetic thyroid hormone, levothyroxine, protects cholinergic neurons in the hippocampus of naturally aged mice

The thyroid hormones, triiodothyronine and thyroxine, play important roles in cognitive func- tion during the mammalian lifespan. However, thyroid hormones have not yet been used as a therapeutic agent for normal age-related cognitive deficits. In this study, CD-1 mice （aged 24 months） were intraperitoneally injected with levothyroxine （L-T4; 1.6 gg/kg per day） for 3 consecutive months. Our findings revealed a significant improvement in hippocampal cyto- skeletal rearrangement of actin and an increase in serum hormone levels of L-T4-treated aged mice. Furthermore, the survival rate of these mice was dramatically increased from 60% to 93.3%. The Morris water maze task indicated that L-T4 restored impaired spatial memory in aged mice. Furthermore, level of choline acetyltransferase, acetylcholine, and superoxide dismutase were in- creased in these mice, thus suggesting that a possible mechanism by which L-T4 reversed cognitive impairment was caused by increased activity of these markers. Overall, supplement of low-dosage L-T4 may be a potential therapeutic strategy for normal age-related cognitive deficits.

Activation of medial septum cholinergic neurons restores cognitive function in temporal lobe epilepsy

Cognitive impairment is the most common complication in patients with temporal lobe epilepsy with hippocampal scle rosis.There is no effective treatment for cognitive impairment.Medial septum cholinergic neurons have been reported to be a potential target for controlling epileptic seizures in tempo ral lobe epile psy.However,their role in the cognitive impairment of temporal lobe epilepsy remains unclear.In this study,we found that patients with temporal lobe epile psy with hippocampal sclerosis had a low memory quotient and severe impairment in verbal memory,but had no impairment in nonverbal memory.The cognitive impairment was slightly correlated with reduced medial septum volume and medial septum-hippocampus tra cts measured by diffusion tensor imaging.In a mouse model of chronic temporal lobe epilepsy induced by kainic acid,the number of medial septum choline rgic neurons was reduced and acetylcholine release was reduced in the hippocampus.Furthermore,selective apoptosis of medial septum cholinergic neurons mimicked the cognitive deficits in epileptic mice,and activation of medial septum cholinergic neurons enhanced hippocampal acetylcholine release and restored cognitive function in both kainic acid-and kindling-induced epile psy models.These res ults suggest that activation of medial septum cholinergic neurons reduces cognitive deficits in temporal lobe epilepsy by increasing acetylcholine release via projections to the hippocampus.

Mitochondria Dynamically Transplant into Cells in Vitro and in Mice and Rescue Aerobic Respiration of Mitochondrial DNA-Depleted Motor Neuron NSC-34

It has been reported that transplantation of pheochromocytoma P12 and hepatoma cells’ mitochondria improve the locomotive activity and prevent disease progress in experimental Parkinson’s disease rats. To prepare for mitochondrial transplantation study in human neurodegenerative diseases, we select human fibroblasts as mitochondrial donor because that fibroblasts share many characteristics with mesenchymal stromal cells (MSCs). We isolate human primary fibroblasts and develop a mitochondrial DNA (mtDNA)-depleted mouse motor neuron NSC-34 cells (NSC-34 ρ° cells). Fibroblast and NSC-34 cell’s mitochondria are co-cultured with NSC-34 ρ° cells. Mitochondrial transplantation is observed by fluorescent microscopy. Gene expression is determined by polymerase chain reaction (PCR) and real time PCR (qPCR). Also, mitochondria are injected to mice bearing mammary adenocarcinoma 4T1 cells. We find results as following: 1) There are abundant mitochondria in fibroblasts (337 ± 80 mitochondria per fibroblast). 42.4% of viable mitochondria are obtained by using differential centrifugation. The isolated mitochondria actively transplant into NSC-34 ρ° cells after co-culture. 2) Fibroblasts transfer mitochondria to human mammary adenocarcinoma MCF-7 cells. 3) There is no expression of HLA-I antigen in fibroblast’s mitochondria indicating they can be used for allogeneic mitochondrial transplantation without HLA antigen match. 4) PCR and qPCR show that NSC-34 ρ° cells lose mitochondrially encoded cytochrome c oxidase I (MT-CO1) and mitochondrially encoded NADH dehydrogenase 1 (MT-ND1) and upregulate expression of glycolysis-associated genes hexokinase (HK2), glucose transporter 1 (SLC2A1) and lactate dehydrogenase A (LDHA). 5) Transplantation of NSC-34 mitochondria restores MT-CO1 and MT-ND1 and downregulates gene expression of HK2, SLC2A1 and LDHA. 6) Normal mammary epithelial mitochondria successfully enter to 4T1 cells in mice. Subcutaneous injection of mitochondria is safe for mice. In summary, mitochondrial transplantation replenishes mtDNA and rescues aerobic respiration of diseased cells with mitochondrial dysfunction. Human primary fibroblasts are potential mitochondrial donor for mitochondrial transplantation study in human neurodegenerative diseases.

Cell-based therapy in Alzheimer's disease: can human fetal cholinergic neurons “untangle the skein”?

Alzheimer＇s disease（AD）is a devastating neurodegenerative disorder and the most common form of old-age dementia.The disease is characterized by a progressive decline in cognitive functions,gradual loss of memory and ability to perform everyday activities,and leads to inevitable death within 3 to 9 years atter diagnosis.

Influence of interferon-gamma on the differentiation of cholinergic neurons in rat embryonic basal forebrain and septal nuclei

BACKGROUND： Interferon-gamma （IFN-γ） can make neurons in basal forebrain and septal nuclei differentiate into cholinergic neurons by treating the cells in cerebral cortex of newborn rats, without the inhibition from IFN-γ antibody. The important effect of IFN-γ on the development and differentiation of neurons has been found by some scholars. OBJ EClIVE：To investigate whether IFN-γ has differentiational effect on cholinergic neurons in basal forebrain and septal nuclei, and make clear that the increased number of cholinergic neurons is resulted by cell differentiation or cell proliferation. DESIGN ： Controlled observation trial SETTING： Department of Cell Biology, Medical School, Beijing University MATERIALS： Sixty-eight female Wistar rats at embryonic 16 days, weighing 250 to 350 g, were enrolled in this study, and they were provided by the Experimental Animal Center, Medical School, Beijing University. IFN-γ was the product of Gibco Company. METHODS： This study was carried out in the Department of Cell Biology, Medical School, Beijing University and Daheng Image Company of Chinese Academy of Sciences during September 1995 to December 2002. The female Wistar rats at embryonic 16 days were sacrificed, and their fetuses were taken out. Primary culture of the isolated basal forebrain and septal nuclei was performed. The cultured nerve cells were assigned into 3 groups： control group （nothing added）, IFN-γ group（1×10^5 U/L interferon）, IFN-γ＋ IFN-γ antibody group （1 ×10^5 U/L IFN-γ ＋ IFN-γ antibody）. The specific marker enzyme （choline acetyl transferase） of cholinergic neuron was stained with immunohistochemical method. Choline acetyl transferase positive cells were counted, and ^14C-acetyl CoA was used as substrate to detect the activity of choline acetyl transferase, so as to reflect the differentiational effect of IFN-γ on cholinergic neuron in basal forebrain and septal nuclei. Flow cytometry was used to analyze cell circle and detect the proliferation of nerve cells. Nerve cells were marked with MAP2 and counted to evaluate the neuronal proliferation in basal forebrain and septal nuclei. MAIN OUTCOME MEASURES： Effect of interferon-γ on the number and activity of choline acetyl transferase-positive ceils in basal forebrain and septal nuclei as well as the effect on neuronal proliferation. RESULTS ： ① Nerve cells in the basal forebrain and septal nuclei of IFN-γ group grew well compared with control group.②The differentiation of cholinergic neurons： The number and activity of choline acetyl transferase positive cells in IFN-γ group were significantly higher than those in the control group [（49.30 ±4.92） /100 cells vs （7.50±1.58） /100 cells; （2 049.00±12.30） min^-1 vs （1 227.30±12.59） min^-1, p 〈 0.01], while there was no significant difference in the number and activity of choline acetyl transferase positive cells between IFN-γ ＋ IFN-γ antibody group and control group（P 〉 0.05）. ③The proliferation of cholinergic neurons： Cell percentage was 17.2% and 19.8% at S-stage, 6.2% and 6.1% at G2＋M stage in the control group and IFN-γ group respectively, without significant difference （P 〉 0.05）. CONCLUSION ： IFN-γ does not promote the neuronal proliferation in basal forebrain and septal nuclei, and the increased expression of cholinergic neurons is not resulted by the increase in the number of neurons, but its differentiation.

切割穹窿海马伞海马提取液和银杏叶提取物联合诱导海马NSCs向胆碱能神经元的分化

为探讨切割穹窿海马伞海马提取液和银杏叶提取物(extract of ginkgo bilobo,EGb)在海马NSCs向胆碱能神经元定向分化中的作用,分别制备大鼠穹窿海马伞切割侧和正常侧海马提取液;将从鼠胚海马中分离扩增的NSCs球分成4组,应用不同的培养液促其分化:(1)联合组:含切割侧海马提取液和银杏内酯的DMEM/F12培养基;(2)提取液组:含切割侧海马提取液的DMEM/F12培养基;(3)EGb组:含银杏内酯的DMEM/F12培养基;(4)对照组:含正常侧海马提取液的DMEM/F12培养基。培养14d后行ChAT免疫荧光检测,计算ChAT阳性神经元的分化率,图像处理细胞面积和周长。结果显示联合组各项指标均明显优于其它各组(P<0.01);提取液组、EGb组各项指标也均优于对照组(P<0.05);细胞面积提取液组优于EGb组(P<0.05),细胞周长EGb组优于提取液组(P<0.05),两组ChAT阳性神经元分化率无明显差异(P>0.05)。上述提示切割穹窿海马伞的海马提取液和EGb联合应用可诱导海马NSCs分化为更多、更为成熟的胆碱能神经元。

Lhx8基因沉默抑制NGF诱导的海马NSCs向胆碱能神经元分化的研究

目的:明确Lhx8在神经生长因子(nerve growth factors,NGF)促进海马神经干细胞向胆碱能神经元分化中的作用。方法:体外培养海马神经干细胞并应用NGF促进其向胆碱能神经元分化的过程中,将构建的Lhx8干扰慢病毒加入至培养液中,7 d后应用免疫荧光标记技术检测分化所得胆碱乙酰转移酶(choline acetyltransferase,Ch AT)和微管相关蛋白-2(microtubule-associated protein 2,MAP-2)双标阳性细胞。结果:在空白对照组中,仅检测到少量的Ch AT/MAP-2双标阳性细胞;在NGF组或是NGF联合阴性对照慢病毒组中则可检测到较多的Ch AT/MAP-2双标阳性细胞;在加入Lhx8干扰慢病毒的实验组中,分化所得的Ch AT/MAP-2双标阳性细胞数较NGF组或是NGF联合阴性慢病毒组明显减少。结论:Lhx8基因沉默抑制了NGF诱导的海马神经干细胞向胆碱能神经元的分化。

3D打印支架联合iPSCs-NSCs对大鼠脊髓损伤后神经细胞凋亡及运动功能的影响

目的探讨3D打印支架载重编程诱导性多能干细胞(iPSCs)-神经干细胞(NSCs)移植对大鼠脊髓损伤的作用机制。方法制备3D脊髓支架,将人尿液细胞来源iPSCs分化为NSCs,选择成年雄性SD大鼠42只,按随机数字表法分为假手术组、模型组、iPSCs-NSCs组,每组14只。采用改良Allen’s重物打击法制作脊髓损伤大鼠模型,1周后假手术组不做处理,模型组植入DMEM培养液0.2mL,i PSCs-NSCs组植入载iPSCs-NSCs的2~3mm支架预处理。于实验干预后1、3、7、14、28天采用BBB评分评估大鼠运动能力,28天后处死大鼠,苏木精-伊红(HE)染色观察伤段脊髓组织改变;免疫组化与RT-PCR检测脊髓组织中Bax、Bcl-2、Caspase-3的表达。结果(1)BBB评分:术后7、14、28天iPSCs-NSCs组与模型组下肢功能均有恢复(P<0.05),且iPSCs-NSCs组较模型组恢复更明显[(3.76±0.65)分比(2.22±0.46)分,(7.02±0.68)分比(4.41±0.42)分,(11.72±0.81)分比(7.52±0.53)分,P<0.05]。(2)HE染色:假手术组脊神经生长良好;模型组脊神经受损,组织水肿,细胞稀疏,细胞之间的间隙增大;iPSCs-NSCs组细胞生长较模型组紧密,各组织生长间隙缩小,空泡减小,组织水肿消失。(3)免疫组化检测:iPSCs-NSCs组Bcl-2阳性细胞的表达较模型组增加[(0.32±0.02)个/mm^(2)比(0.14±0.01)个/mm^(2),P<0.05],Bax阳性细胞的表达较模型组减少[(0.08±0.00)个/mm^(2)比(0.23±0.02)个/mm^(2),P<0.05];(4)RT-PCR检测:iPSCs-NSCs组Caspase-3 mRNA表达较模型组减少[(0.96±0.07)比(1.33±0.03),P<0.05]。结论3D打印支架联合iPSCs-NSCs移植可以显著改善脊髓损伤引起的运动功能下降,其机制可能与上调Bcl-2表达及下调Bax、Caspase-3表达,降低脊髓神经元细胞凋亡相关。

大鼠NSCs向多巴胺能神经元分化研究

目的:探讨IL-1β对神经干细胞(NSCs)分化为多巴胺能神经元作用。方法:体外培养和鉴定中脑来源NSCs,用免疫学方法检测分化细胞酪氨酸羟化酶(TH)表达。结果:血清组、IL-1β10pg/ml组、IL-1β120pg/ml组、IL-1β150pg/ml组、IL-1β200pg/ml组诱导7d后TH细胞分别平均为0.45%、0.6%、7.2%、12.5%、8.75%。结果显示IL-1β诱导NSCs明显提高TH细胞表达率,与血清组比较有显著性差异(P<0.05),在IL-1β150pg/ml剂量范围内TH细胞表达率与剂量呈正相关。结论:IL-1β有诱导NSC向多巴胺能神经元分化的显著作用。

EGFP示踪NSCs海马移植对APP/PS1转基因鼠认知功能及基底前脑胆碱能神经元的影响

目的观察神经干细胞(NSCs)移植对APP/PS1双转基因小鼠认知功能及基底前脑胆碱能神经元的影响,并探讨其可能机制。方法体外分离培养EGFP转基因小鼠胎脑来源NSCs,24只12月龄雄性APP/PS1双转基因小鼠随机分入实验组(Tg-NSCs组)和AD对照组(Tg-AD组),每组12只,12只同月龄雄性野生型小鼠作为正常对照组(WT组),Tg-NSCs组进行EGFP示踪NSCs移植,其余两组进行等量磷酸盐缓冲液注射,移植部位为双侧海马区。移植4周后采用Morris水迷宫检测三组小鼠学习记忆功能,免疫荧光组化法和Western blot检测基底前脑胆碱能神经元的变化情况;Q-PCR检测海马神经营养因子NGF、BDNF、NT3的mRNA水平的变化。结果①体外悬浮培养的神经球表达EGFP阳性,免疫荧光检测显示神经干细胞特异性标志物Nestin阳性。移植4周后,可见EGFP阳性NSCs在海马注射移植部位存活并向胼胝体,海马深部和齿状回迁移,基底前脑未见EGFP阳性细胞。②与Tg-AD组相比,Tg-NSCs组基底前脑ChAT神经元及蛋白水平均增加(P<0.05),但ChAT蛋白表达低于WT组水平(P<0.05)。③Tg-NSCs组海马区神经营养因子NGF、BDNF、NT3的mRNA表达增加,高于Tg-AD组(P<0.05),且与WT组相比差异无统计学意义(P>0.05)。④水迷宫结果显示Tg-NSCs组学习记忆功能改善优于Tg-AD组(P<0.05),但仍低于WT组水平(P<0.05)。结论 NSCs海马移植并不能对该转基因鼠基底前脑胆碱能神经元丢失产生直接的替代与补充,可能通过分泌神经营养因子对基底前脑胆碱能神经元起到保护作用,从而促进其认知功能的恢复。

Selective loss of basal forebrain cholinergic neurons in APP_(770) transgenic mice

To determine whether cholinergic neurons in the basal nucleus magnocellularis (NBM) and the medial septum are affected in transgenic mice overexpressing human amyloid precursor protein 770 (APP 770 ) Methods Eight age groups, from 3 months old to 10 months old, of either heterozygous transgenic or non transgenic mice were used for choline acetyltransferase (ChAT) staining using immunohistochemistry The number of ChAT positive neurons was counted on the MCID Image Analysis System Neurons in the cerebral cortex and area CA1 of hippocampus were also stained with cresyl violet and counted using optical dissector technique Results There is no change in the number of forebrain cholinergic neurons in the transgenic mice up to 9 months of age A loss of these cholinergic neurons starts in 9 months old transgenic mice, with a further decrease in the number of NBM and medial septum neurons in 10 month old transgenic mice On the other hand, the number of neurons in the cerebral cortex and hippocampal area CA1 remained unchanged Conclusion These results demonstrate a selective loss of basal forebrain cholinergic neurons in APP 770 transgenic mice

Scopolamine causes delirium-like brain network dysfunction and reversible cognitive impairment without neuronal loss

Delirium is a severe acute neuropsychiatric syndrome that commonly occurs in the elderly and is considered an independent risk factor for later dementia.However,given its inherent complexity,few animal models of delirium have been established and the mechanism underlying the onset of delirium remains elusive.Here,we conducted a comparison of three mouse models of delirium induced by clinically relevant risk factors,including anesthesia with surgery(AS),systemic inflammation,and neurotransmission modulation.We found that both bacterial lipopolysaccharide(LPS)and cholinergic receptor antagonist scopolamine(Scop)induction reduced neuronal activities in the delirium-related brain network,with the latter presenting a similar pattern of reduction as found in delirium patients.Consistently,Scop injection resulted in reversible cognitive impairment with hyperactive behavior.No loss of cholinergic neurons was found with treatment,but hippocampal synaptic functions were affected.These findings provide further clues regarding the mechanism underlying delirium onset and demonstrate the successful application of the Scop injection model in mimicking delirium-like phenotypes in mice.

Disturbance of cholinergic Grb2-associated-binding protein 1 signaling participate in the pathological process of cognitive dysfunction

OBJECTIVE A causal relationshiphas been postulated between cholinergic dysfunction and the progression of cognitive decline in neurodegenerative disorders. However,the cause of the cognitive dysfunction remains unclear. METHODS Gab1^(loxP/loxP) were bred with ChAT-Cre mice to generate ChAT-Cre; Gab1^(f/f) mice. Excitability of cholinergic neurons wererecorded using whole-cel patch clump. A series of behavioral analyses were used to address the changes of cognitive function in ChAT-Cre; Gab1^(f/f) mice. Neurochemical changes on brain of conditional knockout mice were evaluated by using immunohistochemistry and Western blotting analysis. RESULTS Grb2-associated-binding protein 1(Gab1) is adocking/scaffolding molecule known to play an important role in cell growth and survival. Here,wereport that Gab1 is decreased in cholinergic neurons in a mousemodel of AD. We found that selective downregulation of Gab1 in the septum impaired learning and memory and hippocampal long-term potentiation,whereas overexpression of Gab1 in the same area rescued the cognitive deficitsseen in ChAT-Cre; Gab1^(f/f) and APP^(swe)/PS1 mice.^(18)F-FDGmicroP ET imaging data indicated that Gab1 treatment had no effect on metabolic activity of glucose in APPswe/PS1 mice. Moreover,we identify abnormal function of SKchannelscontributes to increased firing in cholinergic neuronsof ChAT-Cre; Gab1^(f/f) mice. CONCLUSION Gab1 signaling may serve as a potential treatment target for neurological disorders involving dysfunction of central cholinergic neurons.

Engrafted newborn neurons could functionally integrate into the host neuronal network

The limited capability to regenerate new neurons following injuries of the central neural system（CNS）still remains a major challenge for basic and clinical neuroscience.Neural stem cells（NSCs）could nearly have the potential to differentiate into all kinds of neural cells in vitro.

Bone morphogenetic protein 4 induces cholinergic differentiation of brain-derived neural stem cells in vivo and in vitro

In vitro studies have demonstrated that many factors of bone morphogenetic proteins （BMPs） induce cholinergic differentiation of neural stem cells. However, BMP retains the potential to induce increased numbers of cholinergic neurons in central nervous system regions that are rich in cholinergic cells, which is an important determinant of BMP. Therefore, BMP-4 was added to neural stem cell culture medium or the adult rat hippocampal dentate gyrus. Results demonstrated that BMP-4 induced cholinergic differentiation of neural stem cells in vitro and increased the number of cholinergic neurons in the adult rat hippocampal dentate gyrus.

Tumor cells undergoing direct lineage conversion to neurons: unnatural but useful?

Dear Editor, In 2011, Son et al. （2011） reported that the forced expression of selected transcription factors is sufficient to convert mouse and human fibroblasts into induced motor neurons （iMNs）. The authors used three factors （Ascll, Brn2, and Mytll） to convert fibroblasts into neuronal-like ceils. After confirming that the cells had neuronal morphology, but with absence of motor neuron markers, eight candidate transcription factors were added, which participate in various stages of motor neuron specification. As expected, a significant number of motor cells emerged with known characteristics of cultured embryonic motor neurons.

中枢胆碱能神经元变性对小鼠肝叶切除术后认知功能的影响

目的观察中枢胆碱能神经元变性对小鼠肝叶切除术后认知功能的影响。方法将C57BL/6小鼠随机分为麻醉组、手术组、多奈哌齐组、mu-p75-sap组、对照组,每组5只。麻醉组动物吸入2.6%七氟烷、30%氧气、70%氮气混合气体6 h麻醉;手术组、多奈哌齐组、mu-p75-sap组采用同法麻醉并接受肝叶切除手术,其中多奈呱齐组术前给予选择性可逆中枢乙酰胆碱酯酶(AChE)抑制剂多奈哌齐5 mg/kg灌胃4周,mu-p75-sap组麻醉后向小鼠各侧脑室双侧各注射免疫毒素mu-p75-sap 0.8μg制作胆碱能神经元变性模型。对照组动物不进行手术和麻醉操作。采用Morris水迷宫实验检测小鼠学习和记忆能力,采用考马斯亮兰蛋白测定试剂盒检测各组海马组织中枢胆碱能神经生物标志物[胆碱乙酰转移酶(ChAT)、AChE、乙酞胆碱(Ach)]。结果与对照组相比,手术组逃逸潜伏期延长,AChE表达增高,停留时间、穿越平台次数和海马组织ChAT、Ach表达减少(P均<0.05)。与手术组相比,多奈哌齐组逃逸潜伏期缩短、停留时间和穿越平台次数增多、AChE表达降低、ChAT和Ach表达增高,mu-p75-sap组小鼠逃逸潜伏期延长、停留时间和穿越平台次数减少、ChAT和Ach表达降低、AChE表达增高(P均<0.05)。结论肝叶切除术可影响小鼠术后认知功能,中枢胆碱能神经元变性可加重对术后认知功能的影响,可能会导致术后认知障碍的发生发展。