GM1 and NGF synergism on choline acetyltransferase and choline uptake in aged brain

In the brain of aged rats high affinity choline uptake (HAChU) of the striatum, hippocampus, and frontal cortex is lower than in young rats, while choline acetyltransferase (ChAT) activity is lower in striatum and frontal cortex. Infusion into the lateral cerebral ventricle with nerve growth factor (NGF) enhances the low values of these cholinergic markers in a dose- and region-dependent manner. GM 1 ganglioside infused into the lateral ventricle, at a dose that is ineffective alone, together with NGF synergistically enhances the effect of NGF on ChAT and HAChU activities in the brain of aged animals. The pharmacology of this GM 1/NGF synergism suggests potentiation of response.     

七氟醚对幼年大鼠空间学习记忆功能及海马区胆碱能神经元活力的影响

目的探讨七氟醚对幼年大鼠空间学习记忆功能及海马区乙酰胆碱酯酶（acetylcholinesterase,AchE）活力、胆碱乙酰转移酶（choline acetyltransferase,ChAT）活力的影响。方法出生7dSD大鼠48只随机分为3组,各16只,吸入体积分数3%七氟醚2h和6h者分别为S1和S2组,不作任何处理者为C组。于出生后第16～20天行Morris水迷宫实验测试3组空间学习记忆功能;于吸入麻醉结束后次日（Ⅰ期）、水迷宫实验结束后次日（Ⅱ期）取大鼠海马组织,比色法测定AchE和ChAT活力。结果 S1组第2～4天和S2组第2～5天逃避潜伏期较C组延长（P〈0.05）,S2组第4～5天逃避潜伏期较S1组延长（P〈0.01）;S1和S2组Ⅰ期AchE活力较C组增加、ChAT活力较C组降低（P〈0.01）;S2组Ⅱ期AchE活力较C组及S1组增加（P〈0.05）,各组间ChAT活力比较差异无统计学意义（P〉0.05）。结论体积分数3%七氟醚通过增加海马AchE活力、降低ChAT活力而降低幼年大鼠空间学习记忆功能,吸入6h较吸入2h影响更明显。     

维生素E对慢性间断性缺氧大鼠学习记忆的作用

目的 探讨不同剂量维生素E(Vitamin，VitE)对慢性间断性缺氧（chronic episodic hypoxia,EHYP)大鼠学习记忆能力和脑内胆碱乙酰转移酶(choline acetyltransferase,ChAT)活性的影响。方法 建立EHYP大鼠模型，并给予大(50IU/250g体重/d)、小(50IU/250g体重/d)剂量VitE干预。用被动避暗回避反射试验评价大鼠学习记忆能力，潜伏期(STL)越长，学习记忆能力越强；用放射化学法测定大鼠皮层、海马和纹状体ChAT活性。结果 EHYP处理后，与对照组相比，EHYP组大鼠STL明显缩短(P＜0．01)，各脑区ChAT活性均显著降低(P＜0．05)。药物干预后，与EHYP组相比，VitE大、小剂量组大鼠STL均显著延长(VitE大剂量组：P＜0.05，VitE小剂量组：P＜0．01)，但大剂量组大鼠STL明显短于小剂量组(P＜0．05)；就ChAT活性而言，小剂量组大鼠各脑区ChAT活性均显著升高(P＜0．05)，而大剂量组大鼠仅海马和纹状体ChAT活性显著升高(P＜0．05)。结论 VitE可改善EHYP大鼠学习记忆能力并提高其脑内ChAT活性，且小剂量优于大剂量。     

血管性痴呆小鼠海马胆碱乙酰转移酶免疫组织化学变化特征

目的　观测血管性痴呆小鼠海马神经元胆碱乙酰转移酶免疫组织化学变化特征。方法　双侧颈总动脉线结 ,反复缺血—再灌注法制备模型 ,利用跳台试验和水迷宫试验观测其行为学改变 ,采用免疫组织化学技术观测小鼠海马神经元胆碱乙酰转移酶的表达变化。结果　模型组小鼠学习、记忆成绩较假手术组明显降低 (P <0 .0 1) ,其海马胆碱乙酰转移酶表达也明显下降 (P <0 .0 1)。结论　血管性痴呆小鼠学习、记忆成绩下降与其海马胆碱乙酰转移酶低水平表达有关。     

补肾醒脑方对血管性痴呆模型大鼠行为学及胆碱乙酰转移酶含量的影响

目的:观察补肾醒脑方对血管性痴呆(VD)模型大鼠胆碱乙酰转移酶(ChAT)与学习记忆功能的影响。方法:双侧颈总动脉结扎并反复缺血再灌注法制模,将大鼠分为模型组、西药组和补肾醒脑方组(中药组),给予相应药物治疗。用跳台实验检测大鼠行为学变化,用酶免法检测血清和海马组织ChAT含量。结果:中药组大鼠跳台检测反应期比模型组缩短(P<0.05);中药组血清和海马ChAT含量比模型组增加(P<0.05)。结论:对血管性痴呆大鼠血清和海马内ChAT含量的改善是补肾醒脑方治疗VD获效的作用机制之一。     

Resequencing and association analysis of arylalkylamine N‐acetyltransferase (AANAT) gene and its contribution to major depression susceptibility

Abstract: Circadian rhythms disruptions, including abnormalities of circadian phase position and melatonin secretion, have been described in major depression (MD). Arylalkylamine N‐acetyltransferase (AANAT) is a key enzyme of the melatonin pathway involved in circadian oscillations of melatonin levels. We assessed the contribution of AANAT gene variability to susceptibility to MD considering common and rare genetic variations through a sequential sequencing and single nucleotide polymorphism (SNP)‐based genotyping approach in a sample of 445 unrelated patients with MD (257 unipolar MD, 188 bipolar depression) and 440 community‐based screened control subjects. We identified 17 sequence changes, thirteen of which represented novel sequence variations. We did not observe an over‐representation of patients carrying rare variants compared with the healthy controls. Common variants (MAF > 2%) were included in a case–control association analysis that showed significant association after multiple testing correction of two SNPs located in the promoter region of AANAT with MD: rs3760138 (P = 0.00006) and rs4238989 (P = 0.005). Multimarker analysis found significant associations between two three‐marker protective haplotypes and a susceptibility three‐marker haplotype containing the rare alleles of rs3760138‐rs4238989‐rs8150 and MD. We present evidence of the association of genetic variability in the AANAT gene with susceptibility to MD. Our results support the hypothesis that the melatonin‐signaling pathway and circadian clock mechanisms may contribute to the pathophysiology of MD.     

Molecular cloning and functional analysis of serotonin N‐acetyltransferase from the cyanobacterium Synechocystis sp. PCC 6803

Serotonin N‐acetyltransferase (SNAT) catalyzes conversion of serotonin into N‐acetylserotonin, which is a direct precursor for melatonin biosynthesis in all organisms. Molecular cloning of plant SNAT from rice led to a screening for SNAT homolog genes in other species. We identified a cyanobacterium SNAT‐like gene (cSNAT) that showed 56% amino acid homology with the rice SNAT. To confirm whether cSNAT encoded SNAT enzyme activity, we expressed cSNAT DNA in Escherichia coli and purified the cSNAT protein as a C‐terminal His‐tagged form. The purified cSNAT protein exhibited SNAT enzyme activities, transferring the acetyl group into either serotonin or tryptamine substrates. The optimum temperature was 55°C, but it was still highly active at 70°C, suggesting that cSNAT is a thermotolerant enzyme. The K_m and V_max were 823 μm and 1.6 nmol/min/mg protein, respectively. The cSNAT gene is highly conserved in all cyanobacterial taxa and seems to be an origin of SNAT in higher plants. The thermotolerance of cSNAT suggests that melatonin plays a role in the response to high‐temperature stress. Further analysis of this role of melatonin in higher plants is needed.     

Microarray analysis of genes differentially expressed in melatonin‐rich transgenic rice expressing a sheep serotonin N‐acetyltransferase

Transgenic rice plants overexpressing a sheep serotonin N‐acetyltransferase led to an enhanced production of melatonin with various physiological effects, including seminal root elongation and resistance against cold and oxidative stress, which raises the possibility that melatonin may alter gene expression profiles in the transgenic rice. Therefore, we performed a microarray analysis to investigate the regulatory role of melatonin using the melatonin‐rich transgenic rice. We identified 260 and 204 genes that were up‐ or downregulated in the melatonin‐rich transgenic rice when compared with the wild type. Of these, 20 upregulated genes were identified in the seedlings of melatonin‐rich rice at more than twice the levels in the wild type (P < 0.05), while 23 downregulated genes were also detected. The representative upregulated genes included caleosin, a Ca²⁺‐binding oil‐body surface protein involved in the degradation of lipids stored in oil bodies and various signaling proteins such as a cyclin F‐box protein and leucine‐rich repeat protein. In contrast, jasmonate‐induced protein, senescence‐associated protein, and polygalacturonase were included in the downregulated gene group. These results suggest that melatonin has an important role in modulating a wide range of gene expression, reflecting its pleiotropic physiological roles in plant growth and development.     

复方脑益康对AD大鼠脑组织ChAT表达的影响

目的:观察中药复方脑益康对阿尔茨海默病(Alzheimer’s disease,AD)大鼠脑组织胆碱乙酰基转移酶(choline acetyltransferase,ChAT)表达的影响。方法:采用大鼠双侧Meynert核(nucleus basalis of Meynert,NBM)注射鹅膏蕈氨酸(ibotenic acid,IBO)建立AD动物模型,灌胃给药28 d后,应用免疫组织化学染色和Western-blot印迹分析观察ChAT在AD大鼠额叶皮层的表达。结果:脑益康改善脑组织ChAT阳性神经元的形态及数量、增加ChAT蛋白的表达。结论:脑益康通过促进ChAT蛋白合成,增加乙酰胆碱(acetylcholine,ACh)的合成,从而保护中枢胆碱能神经元。