Effect of differential rearing environments on nicotine-stimulated locomotor activity and nicotinic acetylcholine receptor subtypes

OBJECTIVE Individuals vary in sensitivity to the behavioral effects of nicotine,resulting in differences in their vulnerability to addiction.The role of rearing environment in determining individual sensitivity to nicotine is unclear.The neuropharmacological mechanisms mediating the effect of rearing environment on the actions of nicotine are also understood.Thus,the contribution of rearing environment in determining the sensitivity to the locomotor effects of nicotine and regulating α4β2*-and α7-nicotinic acetylcholine(n ACh) receptor expressionwas determined in rats reared in isolated(IC) or enriched(EC) conditions.METHODS To measure locomotor activity,adolescent rats(postnatal day 21-51)were injected with saline(1 mL·kg^(-1)) or nicotine(0.3 mg·kg^(-1)) subcutaneously,then placed in chamberswhere ambulatory activity was monitored for 30-min by computer for 14 daily sessions.α4β2*-andα7-n ACh receptor expression in the mesolimbic dopamine pathway was determined by quantitative autoradiography of [125 I]-epibatidine and [125 I]-bungarotoxinbinding,respectively,in 16 μmol·L^(-1) coronal sections.Values for receptor expression in fmol are ±s of 8 brains and compared by two-tailed,unpaired t-test with P<0.05 considered significant.RESULTS EC-rats are similarly sensitive as IC-rats to the locomotor effects of nicotine.[125 I]-epibatidine binding in the ventral tegmental area of EC-rats was reduced(2.8±0.3 fmo L) compared to IC-rats(4.0±0.4 fmo L);there was no difference in the nucleus accumbens.There was no difference between EC-and IC-rats in α7-n ACh receptor expression in the mesolimbic dopamine pathway.CONCLUSION Rearing environment differentially regulates n ACh receptor subtypes in EC and IC rats.These data suggest regulation of n ACh receptors by environmental factors may be a mechanism for the protective effect of enrichment against altered sensitivity to nicotine in genetically vulnerable individuals.The characterization of these mechanisms will aid in development of novel pharmacological tools mimicking the protection afforded by environmental enrichment in nicotine-sensitive individuals.

Vagus nerve stimulation protects against cerebral injury after cardiopulmonary resuscitation by inhibiting inflammation through the TLR4/NF-κB and α7nAChR/JAK2 signaling pathways

BACKGROUND: Our previous research proved that vagus nerve stimulation(VNS) improved the neurological outcome after cardiopulmonary resuscitation(CPR) by activating α7 nicotinic acetylcholine receptor(α7nAChR) in a rat model, but the underlying mechanism of VNS in neuroprotection after CPR remains unclear.METHODS: In vivo, we established a mouse model of cardiac arrest(CA)/CPR to observe the survival rate, and the changes in inflammatory factors and brain tissue after VNS treatment. In vitro, we examined the effects of α7nAChR agonist on ischemia/reperfusion(I/R)-induced inflammation in BV2 cells under oxygen-glucose deprivation/reoxygenation(OGD/R) conditions. We observed the changes in cell survival rate, the levels of inflammatory factors, and the expressions of α7nAChR/Janus kinase 2(JAK2) and toll-like receptor 4(TLR4)/nuclear factor-κB(NF-κB).RESULTS: In vivo, VNS preconditioning enhanced functional recovery, improved the survival rate, and reduced hippocampal CA1 cell damage, and the levels of inflammatory mediators after CA/CPR. The application of α7nAChR agonists provided similar effects against cerebral injury after the return of spontaneous circulation(ROSC), while α7nAChR antagonists reversed these neuroprotective impacts. The in vitro results mostly matched the findings in vivo. OGD/R increased the expression of tumor necrosis factor-alpha(TNF-α), TLR4 and NF-κB p65. When nicotine was added to the OGD/R model, the expression of TLR4, NF-κB p65, and TNF-α decreased, while the phosphorylation of JAK2 increased, which was prevented by preconditioning with α7nAChR or JAK2 antagonists.CONCLUSION: The neuroprotective effect of VNS correlated with the activation of α7nAChR. VNS may alleviate cerebral IR injury by inhibiting TLR4/NF-κB and activating the α7nAChR/JAK2 signaling pathway.

Association of nicotinic acetylcholine receptor subunit alpha-4 polymorphisms with smoking behaviors in Chinese male smokers

Background it has been reported that the nicotinic acetylcholine receptor subunit a4 gene （CHRNA4） might be associated with smoking behaviors in the previous studies. Up to now, there are few reports on the relationship between CHRNA4 and smoking initiation, in this study, we tried to explore the role of two polymorphisms in CHRNA4 （rs1044396 and rs1044397） in smoking initiation and nicotine dependence in Chinese male smokers. Methods Nine hundred and sixty-six Chinese male lifetime nonsmokers and smokers were assessed by the Fagerstr6m test for nicotine dependence （FTND）, smoking quantity （SQ） and the heaviness of smoking index （HSI）.

Nicotinic Acetylcholine Receptor α4 Subunit Gene Variation Associated with Attention Deficit Hyperactivity Disorder

Previous pharmacological, human genetics, and animal models have implicated the nicotinic ace- tylcholine receptor α4 subunit （CHRNA4） gene in the pathogenesis of attention deficit/hyperactivity disorder （ADHD）. The objective of this study is to examine the genetic association between single nucleotide poly- morphisms in the CHRNA4 gene （rs2273502, rs1044396, rs1044397, and rs3827020 loci） and ADHD. Both case-control and family-based designs are used. Children aged 6 to 16 years were interviewed and assessed with the children behavior checklist and the revised conner＇ parent rating scale to identify probands. No significant differences in the frequency distribution of genotypes or alleles were found between the case and control groups. However, further haplotype analyses showed the CCGG haplotype on risk for ADHD in 164 case-control samples and the standard transmission disequilibrium test analyses suggest that the allele C of rs2273502 was over-trensferred in 98 ADHD parent-offspring trios. These findings suggest that the CHRNA4 gene may play a role in the pathogenesis of ADHD.

右美托咪定通过α7nAChR介导的TLR4/NF-κB通路减轻脂多糖诱导的急性肺损伤

目的探讨右美托咪定是否通过α7烟碱乙酰胆碱受体(α7nAChR)介导的Tol l样受体4(TLR4)/核因子-κB(NF-κB)通路减轻脂多糖(LPS)诱导的急性肺损伤(ALI)。方法24只Wistar大鼠随机分为对照组、急性肺损伤组、右美托咪定治疗组与α7nAChR抑制剂α-BGT组,每组6只。麻醉后,对照组腹腔注射生理盐水;急性肺损伤组股静脉注射LPS(10 mg/kg)诱导ALI模型;右美托咪定治疗组给予LPS后即刻股静脉持续输注右美托咪定[5μg/(kg.h)]至实验结束;α7nAChR抑制剂α-BGT组在输注右美托咪定前半小时腹腔注射1μg/kgα-BGT,其余处理同右美托咪定治疗组。LPS注射后12 h处死大鼠,收集血液和肺组织。HE染色观察肺组织病理学变化并进行损伤评分。抽取颈动脉血检测氧分压(PaO_(2))、碳酸氢根(HCO_(3)^(–))及乳酸(Lac)水平;测定肺组织湿/干重比(W/D)和髓过氧化物酶(MPO)活性;计数支气管肺泡灌洗液(BALF)中总细胞、中性粒细胞及巨噬细胞数;ELISA法检测血液中肿瘤坏死因子-α(TNF-α)、白细胞介素-6(IL-6)、IL-10水平;Western blotting检测肺组织中α7nAChR、TLR4、p-NF-κB蛋白表达水平。结果肺组织病理学观察见右美托咪定治疗可明显减轻LPS诱导的肺泡壁和肺组织间隔增厚以及炎性细胞浸润,降低肺损伤病理评分(P<0.01)。与对照组比较,急性肺损伤组PaO_(2)、HCO_(3)^(–)水平降低,Lac、W/D、TNF-α、IL-6、IL-10水平及MPO活性升高,总细胞、中性粒细胞及巨噬细胞计数增多,肺组织中α7nAChR、TLR4、p-NF-κB蛋白表达水平升高(P<0.01);与急性肺损伤组比较,右美托咪定治疗组PaO_(2)、HCO_(3)^(–)、IL-10水平升高,Lac、W/D、TNF-α、IL-6水平及MPO活性降低,总细胞、中性粒细胞及巨噬细胞计数减少,肺组织中α7nAChR蛋白表达水平升高,TLR4、p-NF-κB蛋白表达水平降低(P<0.01)。而右美托咪定的作用可被α7nAChR抑制剂α-BGT部分逆转。结论右美托咪定可能通过α7nAChR介导的TLR4/NF-κB通路减轻LPS诱导的ALI。

汉族儿童热性惊厥与CHRNA4和SYN2基因多态性的关联研究

目的探讨神经元烟碱乙酰胆碱受体α-4亚单位基因（CHRNA4基因）和突触蛋白Ⅱ基因（SYN2基因）的单核苷酸多态性（SNP）是否可作为北方汉族儿童单纯性热性惊厥（FS）发病的基因标志物。方法用SNaPshotSNP分型技术对北方汉族141例单纯性FS患儿（病例组）和130例健康儿童（健康对照组）进行CHRNA4基因rs1044396、SYN2基因rs3773364位点分型，比较SNP基因型和等位基因频率的差异。结果病例组与健康对照组在rs1044396和rs3773364的基因型和等位基因频率的差异均无统计学意义（P均〉0．05）；对CHRNA4基因rsl0443963种基因型A／A、A／G、G／G的Fs患儿的临床资料比较，显示首次惊厥的年龄差异具有统计学意义（x2=17．206，P〈0．001），而SYN2基因rs3773364的3种基因型C／C、C／T、T／T的FS患儿在性别、首次惊厥年龄和首次惊厥时体温的差异均有统计学意义（x2=21．458、8．717、10．424，P均〈0．05）。结论无论CHRNA4基因rs1044396还是SYN2基因rs3773364的多态性可能均与北方汉族儿童FS的发病无关联，但对患儿首次惊厥的年龄和体温有一定影响。

吸烟和CHRNA4基因簇上rs3787140位点多态性与肺癌的关联

目的探讨在中国男性人群中吸烟、烟碱型乙酰胆碱受体亚单位α4（CHRNA4）上rs3787140位点多态性与肺癌的关联。方法采用病例-对照研究设计,共收集204例男性原发性肺癌病例和821名正常健康男性对照者。采用结构式问卷调查人口学特征、吸烟行为及健康相关行为等信息,并采集静脉血检测CHRNA4基因簇上单核苷酸多态性位点rs3787140的多态性。应用Kruskal-Walis检验方法和多因素logistic回归模型分析吸烟、CHRNA4基因簇上的基因多态性与肺癌的关联。结果采用多因素logistic回归校正混杂因素后,rs3787140基因多态性与患者的病理类型及解剖位置无关;rs3787140基因型分布在吸烟与不吸烟的人群中的差异无统计学意义;rs3787140的基因多态性并不增加发生肺癌的风险,未发现rs3787140的多态性和吸烟对肺癌存在交互作用。结论吸烟和CHRNA4rs3787140多态性及其交互作用并非肺癌发生的危险因素。

Vagus nerve stimulation is a potential treatment for ischemic stroke

Microglia are the brain’s primary innate immune cells,and they are activated and affect pro-inflammatory phenotype or regulatory phenotype after ischemic stroke.Vagus nerve stimulation was shown to activate microglial phenotypic changes and exhibit neuroprotective effects in ischemia/reperfusion injury.In this study,we established rat models of ischemic stroke by occlusion of the middle cerebral artery and performed vagus nerve stimulation 30 minutes after modeling.We found that vagus nerve stimulation caused a shift from a pro-inflammatory phenotype to a regulatory phenotype in microglia in the ischemic penumbra.Vagus nerve stimulation decreased the levels of pro-inflammatory phenotype markers inducible nitric oxide synthase and tumor necrosis factorαand increased the expression of regulatory phenotype markers arginase 1 and transforming growth factorβthrough activatingα7 nicotinic acetylcholine receptor expression.Additionally,α7 nicotinic acetylcholine receptor blockade reduced the inhibition of Toll-like receptor 4/nuclear factor kappa-B pathwayassociated proteins,including Toll-like receptor 4,myeloid differentiation factor 88,I kappa B alpha,and phosphorylated-I kappa B alpha,and also weakened the neuroprotective effects of vagus nerve stimulation in ischemic stroke.Vagus nerve stimulation inhibited Toll-like receptor 4/nuclear factor kappa-B expression through activatingα7 nicotinic acetylcholine receptor and regulated microglial polarization after ischemic stroke,thereby playing a role in the treatment of ischemic stroke.Findings from this study confirm the mechanism underlying vagus nerve stimulation against ischemic stroke.

经耳迷走神经刺激对急性创伤性颅脑损伤大鼠神经功能的改善作用及其机制

目的 观察经耳迷走神经刺激(t-VNS)对急性创伤性颅脑损伤大鼠的神经功能改善作用,并探讨其相关机制。方法 成年SD大鼠36只,随机分为假手术组、模型组、治疗组各12只。模型组和治疗组采用改良Feeney自由落体法建立颅脑创伤模型;假手术组仅切开头皮打开骨窗,不实施撞击。治疗组于造模30 min后给予t-VNS(强度1 mA、间期0.5 ms、频率20 Hz),在1 h内每隔5 min刺激1次,每次持续30 s,连续刺激3 d;模型组及假手术组不给予刺激。造模72 h后采用改良神经功能缺损评分(mNSS)评价神经功能;处死大鼠,取脑组织测算脑含水量;分别采用Western blotting法和免疫组化法检测各组大鼠脑组织中的水通道蛋白4(AQP4)、肿瘤坏死因子α(TNF-α)、α7烟碱型乙酰胆碱受体(α7nAChR)。结果 模型组mNSS、脑含水量及AQP4、TNF-α蛋白表达高于假手术组(P均<0.05);治疗组mNSS、脑含水量及AQP4、TNF-α蛋白表达低于模型组,α7nAChR蛋白表达高于模型组(P均<0.05)。结论 t-VNS对急性创伤性颅脑损伤大鼠具有神经保护作用,其机制可能与下调AQP4表达、上调α7nAChR表达、减轻炎症反应有关。

Altered filamin A enables amyloid beta-induced tau hyperphosphorylation and neuroinflammation in Alzheimer's disease

Alzheimer's disease (AD) is a neurodegenerative disease with proteopathy characterized by abnormalities in amyloid beta (Aβ) and tau proteins. Defective amyloid and tau propagate and aggregate, leading to eventual amyloid plaques and neurofibrillary tangles. New data show that a third proteopathy, an altered conformation of the scaffolding protein filamin A (FLNA), is critically linked to the amyloid and tau pathologies in AD. Altered FLNA is pervasive in AD brain and without apparent aggregation. In a striking interdependence, altered FLNA is both induced by Aβ and required for two prominent pathogenic signaling pathways of Aβ. Aβ monomers or small oligomers signal via the α7 nicotinic acetylcholine receptor (α7nAChR) to activate kinases that hyperphosphorylate tau to cause neurofibrillary lesions and formation of neurofibrillary tangles. Altered FLNA also enables a persistent activation of toll-like-receptor 4 (TLR4) by Aβ, leading to excessive inflammatory cytokine release and neuroinflammation. The novel AD therapeutic candidate PTI-125 binds and reverses the altered FLNAconformation to preventAβ's signaling via α7nAChR and aberrant activation of TLR4, thus reducing multiple AD-related neuropathologies. As a regulator of Aβ's signaling via α7nAChR and TLR4, altered FLNA represents a novel AD therapeutic target.