Determination of non-steroidal anti-inflammatory drugs in the environmental water samples by a polyvinylimide-modified magnetic nanoparticles-based solid phase extraction coupled with high-performance liquid chromatography
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摘要:
环境水样中非甾体抗炎药(NSAIDs)的长期存在不仅会影响水生生物的生命安全,扰乱生态系统环境,而且会对人类健康构成严重威胁。采用溶剂热法首先制备了氨基功能化Fe3O4纳米粒子(Fe3O4-NH2)。随后,通过室温下水溶液中的席夫碱反应,以戊二醛为交联剂,将具有支链结构的聚乙烯亚胺(PEI)成功地接枝到Fe3O4纳米粒子上,合成了一种可回收的PEI接枝磁性纳米吸附剂(Fe3O4@PEI)并将其应用于环境水中NSAIDs的检测。通过各种表征手段研究了Fe3O4@PEI的组成特性,并对影响NSAIDs萃取效果的参数进行了优化。Fe3O4@PEI对4种NSAIDs具有高吸附性,与高效液相色谱联用可对环境水样中的酮洛芬、萘普生、双氯芬酸和托芬那酸4种NSAIDs进行定量分析,在1~500 µg/mL范围内,色谱峰面积与质量浓度呈良好的线性关系,样品在3种不同添加水平下的加标回收率在85.6%~107.8%,日内精密度均小于7.8%(n=6),日间精密度均小于9.5%(n=3)。该方法操作简单、准确高效,可用于环境水样中非甾体抗炎药的测定。
Abstract:The long-term presence of non-steroidal anti-inflammatory drugs (NSAIDs) in the environmental water samples not only affects the life safety of aquatic organisms and disturbs the ecoenvironment, but also poses a serious threat to human health. In this study, amino-functionalized Fe3O4 nanoparticles (Fe3O4-NH2) were firstly prepared by solvothermal method. Subsequently, polyethyleneimine (PEI) with a branched chain structure was successfully grafted onto Fe3O4 nanoparticles by Schiff base reaction in aqueous solution at room temperature using glutaraldehyde as a cross-linking agent, and a recyclable PEI-grafted magnetic nano-sorbent (Fe3O4@PEI) was synthesized and applied for the detection of NSAIDs in the environmental water samples. The compositional properties of Fe3O4@PEI were investigated by different characterization methods and the parameters affecting the extraction of NSAIDs were optimized. Due to high adsorption of Fe3O4@PEI for NSAIDs, the quantitative analysis of four NSAIDs in the environmental water samples, ketoprofen, naproxen, diclofenac and tolfenamic acid, was performed in combination with high-performance liquid chromatography. A good linear relationship between the chromatographic peak area and concentration was observed in the range of 1−500 µg/mL. The recoveries of the samples at three different spiked levels ranged from 85.6% to 107.8%; the intra-day precision was less than 7.8% (n=6); and the inter-day precision was less than 9.5% (n=3). The method is simple, rapid, accurate and reliable, and can be used for the analysis of NSAIDs in the environmental water samples.
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氟溴唑仑(flubromazolam,Flub)是通过改造阿普唑仑结构获得的一种新型苯二氮䓬类精神活性物质,其化学结构与阿普唑仑(alprazolam)类似,是在阿普唑仑结构8位添加了一个氟原子,并用溴取代了2′位氯原子。据报道,Flub具有快速且持久的中枢抑制作用,可使人体暂时性遗忘、昏迷、呼吸抑制[1]。2014年,德国首次发现Flub在人群中滥用[2]。2018年,中国也监测到Flub滥用[3]。2019–2021年,美国缉毒局(DEA)报告Flub滥用的案例逐年增加[4−6]。目前,关于Flub研究主要集中在定性定量分析及其代谢动力学等方面[7−10],其成瘾性及其机制尚不清楚。本研究拟建立小鼠条件性位置偏好(CPP)模型,以CPP评分评价Flub的奖赏效应,并检测腹侧被盖区(VTA)多巴胺(DA)能神经元以及喙内侧被盖核(RMTg)→VTA神经环路对Flub奖赏效应调控作用,为深入了解Flub成瘾性、开发安全有效的防治方法奠定基础。
1. 材 料
1.1 药品与试剂
氟溴唑仑(国家禁毒委员会办公室-中国药科大学禁毒关键技术联合实验室提供);羟丙基-β-环糊精,氟马西尼(flumazenil,FMZ)(上海源叶生物科技有限公司);氯氮平-N-氧化物(clozapine-n-oxide,CNO)(美国MCE公司);异氟烷(深圳瑞沃德生命科技有限公司);驴血清(江苏碧云天生物科技有限公司);酪氨酸羟化酶(tyrosine hydroxylase,TH)抗体(美国CST公司);c-Fos抗体(美国 Abcam公司);Alexa Fluor 594标记驴抗兔IgG,Alexa Fluor 488标记山羊抗小鼠IgG(上海翌圣生物科技有限公司);4',6-二脒基-2-苯基吲哚(4',6-diamidino-2-phenylindole,DAPI,北京索莱宝科技有限公司);其他试剂均为市售分析纯。
1.2 工具病毒信息
腺相关病毒包括AAV-TH-hM4Di-mCherry、AAV-GAD67-hM3Dq-mCherry、AAV-GAD67-hM4Di-mCherry、retro-AAV-GAD67-Cre-EGFP、retro-AAV-VGAT1-Cre、AAV-hSyn-DIO-hM3Dq-mCherry,均购自武汉枢密脑科学技术有限公司。AAV-TH-hM4Di-mCherry用于化学遗传调控VTA DA能神经元和相关环路;AAV-hSyn-DIO-hM3Dq-mCherry和retro-AAV-VGAT1-Cre用于化学遗传调控RMTg→VTA环路;AAV-GAD67-hM3Dq-mCherry用于顺向追踪RMTg脑区神经元的投射;retro-AAV-GAD67-Cre-EGFP用于VTA脑区神经元逆向追踪;AAV-GAD67-hM4Di-mCherry用于化学遗传调控RMTg→VTA环路。
1.3 仪 器
电子分析天平(德国Sartorius公司);倒置荧光显微镜,组织包埋机及石蜡切片机,CM1950冰冻切片机(德国Leica仪器有限公司);ANY-maze动物行为采集分析软件(美国Stoelting公司)。
1.4 动 物
C57BL/6J小鼠,SPF级,8周龄,体重20~25 g,由南京青龙山动物繁殖中心提供,合格证号:SCXK(浙)2019-0002。实验动物饲养于12 h昼夜交替的环境中,室温维持在(24±1)℃,湿度(55±5)%,动物可以自由饮水和摄食,实验开始前先适应性饲养1周。对动物的所有处理均遵循动物伦理委员会标准。
2. 方 法
2.1 小鼠CPP实验模型
实验装置由两个大小相同的正方体(24 cm×24 cm×30 cm)和一个长方体中间室(24 cm×10 cm×30 cm)构成,两个正方体的内壁颜色及底板触感不同,三室所连接隔板取出后小鼠可以在三室自由探索,实验开始时将小鼠从中间室放入,第1天和第2天将隔板取出,让小鼠在装置中自由探索15 min,第1天让小鼠熟悉实验环境,第2天进行前测,记录小鼠在初始偏好侧和初始非偏好侧(药物配对侧)的停留时间,第3~10天将隔板插入,第3,5,7,9天腹腔注射Flub后放入初始非偏好室训练40 min,第4,6,8,10天腹腔注射对照溶液后放入初始偏好室训练40 min。第11天进行测试,隔板取出后将小鼠从中间室放入,让小鼠在实验装置里探索15 min,记录小鼠在各室的停留时间,计算条件性位置偏好评分(CPP评分=测试时小鼠在药物配对侧停留时间–前测时小鼠在药物配对侧停留时间)。在化学遗传学实验中,将腺相关病毒注入目标脑区,病毒表达3~4周,在每次药物配对侧训练前30 min,腹腔注射CNO(2 mg/kg)或套管给予CNO(3 μmol/L,每侧200 nL)。氟马西尼(0.2 nmol/L,每侧200 nL)在每次药物配对侧训练前10 min套管注入RMTg脑区。
2.2 免疫荧光染色
用异氟烷气体吸入麻醉动物,分别用PBS和4%多聚甲醛心脏灌注,分离脑组织,用4%多聚甲醛固定48 h后,包埋、切片,石蜡切片厚度为8 μm,冰冻切片厚度为25 μm。石蜡组织切片在免疫荧光染色前进行抗原修复,脑片在4 ℃条件下孵育TH抗体(1∶500)、c-Fos抗体(1∶300)。4 ℃过夜后,PBS清洗切片3次,每次10 min,室温下避光孵育二抗2 h,用PBS清洗3次,每次10 min,随后孵育DAPI染色液(1∶100),10 min后PBS洗片3次,每次5 min。脑片干燥后滴加防猝灭剂封片,在荧光显微镜下观察。
2.3 脑立体定位注射
用异氟烷气体吸入麻醉动物,用宠物剃毛刀将小鼠头部毛发剔除,放置于定位框架上,碘伏消毒,随后用手术剪刀将小鼠头皮剪开大约1 cm小口,用颅骨钻在合适位置钻孔,脑立体定位注入工具病毒后用可吸收缝合线缝合。病毒注射位点为AP:–3.28 mm,ML:±0.5 mm,DV:–4.4 mm(VTA);AP:–4.04 mm,ML:±0.3 mm,DV:–4.3 mm(RMTg)注射病毒100 nL,表达3~4周后用于后续化学遗传学实验。
2.4 脑立体定位植入套管及经管给药
用异氟烷气体吸入麻醉动物,剔除小鼠头部毛发,放置于定位框架上,碘伏消毒,随后用手术剪刀将小鼠头皮剪开大约1 cm小口,用颅骨钻在目标区域上方钻孔,磨薄颅骨表面,拧上经酒精消毒的螺丝钉,将套管固定于套管夹持器上,待下落到目标区域后用牙科水泥固定,术后恢复1周再进行后续实验。通过注射内管将药物缓慢注入目标脑区,完成注射后将停针5 min,随后缓慢拔出注射内管,旋紧套管帽将小鼠放回笼中,待小鼠在笼内适应10 min后再进行药物配对训练。
2.5 数据分析
采用GraphPad Prism 9统计学软件对研究数据进行统计分析。计量资料以$ \bar{x} $±s表示,两组数据的比较用非配对t检验,两组以上数据组间比较采用单因素方差分析(One-Way ANOVA)检验或双因素方差分析(Two-Way ANOVA)检验。P<0.05表示差异具有统计学意义。
3. 结 果
3.1 Flub诱导小鼠CPP模型的建立
CPP 是一种巴甫洛夫条件反射形式,用于研究与滥用药物相关的奖赏效应。采用隔天训练的CPP范式,其实验流程见图1-A。剂量摸索实验发现,3 mg/kg Flub诱导小鼠CPP评分显著升高(P<0.05),而1、2和4 mg/kg Flub组小鼠CPP评分与对照组小鼠相比无显著性差异(图1-B)。
3.2 抑制VTA中多巴胺能神经元活性降低Flub诱导的CPP评分
VTA多巴胺能神经与药物引起的奖赏效应密切相关。采用免疫荧光检测VTA多巴胺能神经元c-Fos水平。结果显示,Flub诱导CPP小鼠VTA脑区c-Fos阳性细胞数较对照组显著增加(P<0.001)(图2-A ,B),而且c-Fos阳性神经元主要与TH阳性神经元共定位(P<0.01)(图2-A,C)。在VTA中注射携带多巴胺能神经元启动子的化学遗传抑制病毒AAV-TH-hM4Di-mCherry(图2-D,E),此病毒可在VTA DA能神经元上特异性表达带有红色荧光、经过改造的人M4毒蕈碱乙酰胆碱受体(hM4Di)。在药物配对侧训练前30 min腹腔注射CNO,通过hM4Di与特异性配体 CNO结合,特异性抑制VTA中多巴胺能神经元活性。行为学结果显示,化学遗传学抑制VTA中多巴胺能神经元,Flub诱导的小鼠CPP评分显著下降(P<0.05)(图2-F)。结果说明VTA多巴胺能神经元参与且调控Flub诱导的小鼠CPP。
Figure 2. Inhibition of ventral tegmental area (VTA) dopaminergic neuronal activity decreased Flub-induced CPP score A: Representative images showing c-Fos-positive cells and co-localization of c-Fos-positive neurons with tyrosine hydroxylase (TH); B: Statistical plot of number of c-Fos-positive neurons($ \mathit{\mathit{\bar{\mathrm{\mathit{x}}}\mathit{\mathit{\mathit{ }}}}} $±s,n=5); C: Statistical plot of co-localization of c-Fos-positive neurons with TH-positive neurons($ \bar{\mathrm{\mathit{x}}} $±s,n=5); D: Schematic diagram of virus injection; E:Expression of TH-hM4Di-mCherry (red) in the VTA; F: CPP score under chemogenetic inhibition of dopaminergic neurons in VTA of mice treated with Flub ($ \bar{\mathrm{\mathit{x}}} $±s,n=10)*P<0.05, **P<0.01, ***P<0.001,****P<0.00013.3 RMTgGABA→VTADA神经环路调控Flub诱导的小鼠CPP
由于VTA多巴胺能神经元接受VTA尾部RMTg的抑制性神经元投射,在RMTg注射携带GABA能神经元启动子的顺行红色荧光病毒AAV-GAD67-hM3Dq-mCherry(图3-A,B),此病毒可在RMTg GABA能神经元的胞体和轴突特异性表达红色荧光蛋白。病毒表达3周后显微镜观察显示,下游VTA脑区中可见由上游投射的大量红色输入细胞(图3-C)。在VTA注射逆行绿色荧光病毒retro-AAV-GAD67-Cre-EGFP(图3-D,E),此病毒可在上游GABA能神经元轴突和胞体中表达。病毒表达3周,显微镜观察可见RMTg脑区大量绿色病毒荧光(图3-F)。这些实验结果验证了RMTgGABA→VTADA神经环路的存在。
Figure 3. Suppression of rostrum tegmental nucleus (RMTg) inhibitory projections to VTA dopaminergic neurons is necessary for Flub-induced CPP A,D: Schematic diagram of virus injection; B: Expression of GAD67-mCherry (red) in the RMTg; C: mCherry-positive neuronal fibers from VTA-projecting RMTg γ-aminobutyric acid (GABA) neurons; E: Expression of EGFP(green) in the VTA; F:Expression of EGFP in the RMTg; G: Schematic diagram of virus injection; H: The expression of DIO-hM3Dq-mCherry (red) in the RMTg; I: CPP score in chemogenetic activation of RMTgGABA→VTA ($ \mathit{\bar{\mathrm{\mathit{x}}}\mathit{\mathit{\mathit{\mathit{ }}}}} $±s,n=10); J: Schematic diagram of virus injection; K: Representative diagram of cannula track in the VTA; L: CPP score in chemogenetic inhibitions of RMTgGABA→VTA and dopaminergic neurons in VTA($ \mathit{\bar{\mathrm{\mathit{x}}}\mathit{\mathit{\mathit{ }}}} $±s,n=12)**P<0.01为探究RMTgGABA→VTADA环路对Flub诱导的小鼠CPP是否有调控作用,在RMTg注射Cre依赖的红色荧光病毒AAV-hSyn-DIO-hM3Dq-mCherry,在VTA中注射retro-AAV-VGAT1-Cre病毒(图3-G,H),AAV-hSyn-DIO-hM3Dq-mCherry在 Cre 重组酶的作用下可在RMTg GABA 能神经元中特异性表达红色荧光蛋白和经改造的人M3 毒蕈碱受体(hM3Dq),通过给予特异性配体 CNO ,可启动下游 G蛋白信号通路,兴奋 GABA 能神经元。病毒表达3周后进行CPP实验,在药物配对侧训练前30 min腹腔给予CNO激活该环路。实验结果显示,激活环路RMTgGABA→VTADA后Flub诱导的小鼠CPP评分显著下降(P<0.01)(图3-I)。 此外,在RMTg注射AAV-GAD67-hM4Di-mCherry,在VTA注射AAV-TH-hM4Di-mCherry病毒,病毒表达3周后在VTA植入套管(图3-J),1周后进行CPP实验,在药物配对侧训练前30 min通过套管在VTA注射CNO(图3-K),通过hM4Di与特异性配体 CNO 结合,抑制该环路和VTA中多巴胺能神经元。实验结果显示,抑制RMTgGABA→VTADA环路和VTA多巴胺能神经元后Flub诱导的小鼠CPP评分与对照组相比,差异无统计学意义(图3-L)。这说明RMTgGABA→VTADA环路是通过VTA多巴胺能神经元调控Flub诱导的小鼠CPP。
3.4 Flub通过RMTg中的苯二氮䓬受体产生奖赏效应
为了探究Flub是否作用于RMTg脑区苯二氮䓬受体(亦称GABAA受体)产生奖赏效应,在RMTg植入套管(图4-A,B),1周后进行CPP实验,在药物配对侧训练前10 min通过套管在RMTg注入苯二氮䓬受体拮抗剂FMZ。实验结果显示,FMZ阻断RMTg中的苯二氮䓬受体显著降低Flub诱导的小鼠CPP评分(图4-C),这说明RMTg中的苯二氮䓬受体参与Flub诱导的奖赏效应。
Figure 4. Intra-RMTg infusion of flumazenil (FMZ) significantly reduced Flub-induced CPP score A: Schematic diagram of cannula track in the RMTg; B: Representative diagram of cannula track in the RMTg; C: CPP score in intra-RMTg of FMZ 10 min before administration of Flub (ip)($ \bar{\mathrm{\mathit{x}}} $±s,n= 9)**P<0.014. 讨 论
Flub属于未经批准上市的苯二氮䓬类新精神活性物质,其药理作用与阿普唑仑相似。本研究发现,Flub以3 mg/kg剂量腹腔注射4次小鼠CPP评分显著增加,而1 或2 mg/kg给药4次不能诱导小鼠CPP评分显著增加。Flub 4 mg/kg给药使小鼠出现反射减弱、镇静、呼吸抑制等中枢抑制作用,也不能诱导小鼠CPP评分显著增加。说明该药物的奖赏效应与剂量有关,这也从动物实验水平初步解释了Flub服用者描述在服药后感受到欣快感[11]。
精神活性物质所产生的欣快感在成瘾中起正性强化作用,VTA是药物奖赏的重要脑区,VTA多巴胺能神经元投射作用于伏隔核、杏仁核和前额叶皮层等多个脑区,形成中脑边缘奖赏系统,在成瘾药物诱导的奖励驱动行为过程中发挥重要作用[12]。化学遗传学抑制VTA中多巴胺能神经元可以降低Flub诱导的小鼠CPP评分,证实了VTA 多巴胺能神经元参与Flub诱导的奖赏效应。有研究表明苯二氮䓬类药物作用于GABAAα1亚基导致成瘾[13],因此,推测Flub可能通过与VTA上游脑区GABA能神经元GABAA受体结合,进而抑制GABA能神经元的活性,解除对VTA中多巴胺能神经元的抑制作用,从而使VTA多巴胺能神经元兴奋性增加,产生奖赏效应。RMTg是VTA多巴胺神经元抑制性GABA能输入的主要来源[14],越来越多研究表明,RMTg参与调节奖赏、动机、厌恶和行为回避[15−21]。Jalabert等[22]通过在RMTg注入顺行示踪剂或VTA注入逆行示踪剂来探究RMTg-VTA路的联系,发现在VTA中有顺行示踪剂,而在RMTg中检测到逆行示踪剂。本研究通过化学遗传学激活RMTgGABA→VTADA神经环路显著抑制Flub诱导的小鼠CPP,在RMTg经套管给予FMZ,阻断苯二氮䓬受体,也能够抑制Flub诱导的小鼠CPP。这提示Flub分布到RMTg 脑区,通过激动GABA能神经元GABAA受体,减少抑制性神经冲动至VTA多巴胺能神经元,使VTA多巴胺能神经元兴奋,产生奖赏效应。
综上所述,本研究采用评价药物精神依赖性的经典CPP动物模型,从分子、神经核团和神经环路水平揭示了Flub诱导奖赏效应的机制,为进一步研究Flub成瘾机制以及防治方法奠定了实验基础。
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Figure 1. Results of characterization of relevant materialsResults of characterization of relevant materials A:Ninhydrin colorimetry(a. Fe3O4; b. Fe3O4-NH2; c. Fe3O4-CHO; d. Fe3O4@PEI); B:SEM diagram of Fe3O4@PEI, inset is particle size distribution of Fe3O4@PEI; C: VSM diagram for Fe3O4-NH2 and Fe3O4@PEI; D:XRD pattern of Fe3O4@PEI, inset is its physical image
Figure 3. Optimization of sample pretreatment conditions($\bar{x} \pm s,\;n=3 $) A:Effect of adsorption time on extraction efficiencies of NSAIDs; B:Effect of pH on extraction efficiencies of NSAIDs; C:Effect of amount of adsorbent on extraction efficiencies of NSAIDs; D:Effect of various elute agents on extraction efficiencies of NSAIDs; E:Effect of desorption time on extraction efficiencies of NSAIDs
Table 1 Linear ranges, linear equations, correlation coefficients (r2) and limits of quantitation(LOQ) for 4 analytes
Analyte Linear range/ (μg/L) Regression equation r2 LOQ/(μg/L) KPF 1−500 y = 49.26x+30.06 0.9997 0.69 NPX 1−500 y = 48.33x+47.74 0.9989 0.56 DCF 1−500 y = 108.22x+81.74 0.9996 0.29 TOL 1−500 y = 19.31x+117.16 0.9988 0.75 -
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