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中国心理健康调查报告显示国内精神障碍疾病负担较重,抑郁和焦虑症患病率较高[1]. 心理健康受到社会和环境等多种因素影响,引发的炎症、氧化应激和神经递质紊乱都可能是神经系统疾病的致病因素. 长期压力应激状态会诱发焦虑、抑郁等精神类疾病,还具有导致器官功能性病变的风险[2]. 环境污染也可影响疾病的发生发展过程,污染物暴露可通过影响下丘脑-垂体-肾上腺轴(HPA)的功能和应激反应而引发心理疾病[3]. 研究表明心理应激和交通或工业空气污染对健康的不良影响存在明显协同效应[4]. 慢性压力应激状态下,全身易感性增强,环境污染物的毒性作用更为明显. 据报道,慢性压力应激和150 mg·kg−1醋酸铅同时暴露2个月可显著影响大鼠基底皮质酮水平与HPA轴功能[5]. Zhou等[6]发现妊娠期孕妇社会心理压力较大时,铅金属污染物暴露与婴幼儿神经缺陷、认知发育不全等不良健康的关联性增加. Clougherty等[7]研究发现,处于慢性压力下的大鼠对浓缩细颗粒空气污染的呼吸反应更强,并可能存在不同易感性的途径. 现有流行病学数据无法确定差异易感性的生理机制[8],因此,本文基于毒理代谢组学阐明慢性压力应激和污染暴露之间的潜在相互作用.
B[a]P是环境和食品中常见的污染物,主要通过呼吸和饮食途径进入体内,在肝脏蓄积和代谢活化,导致肝功能异常或肝损伤[9]. B[a]P及其代谢物可与体内氨基酸、有机酸、脂质等代谢物相互作用而具有肝毒性效应[10]. 长期慢性心理应激状态下机体生理功能和免疫力显著降低[11],因此可能对B[a]P暴露的应答会产生更复杂影响,但目前未有明确的影响机制研究. 本研究选用慢性不可预知温和刺激(chronic unpredictable mild stimulation,CUMS)作为慢性压力应激模型,采用靶向代谢组学分析方法研究了不同剂量B[a]P和CUMS单独或两者同时暴露对雄性C57BL/6J小鼠肝脏中氨基酸、TCA循环和胆汁酸代谢的影响,并通过统计学分析筛选出了差异代谢物,拟从代谢物差异变化初步探讨肝脏对B[a]P和慢性压力应激的应答和代谢机制.
苯并[a]芘和慢性压力应激暴露对小鼠肝脏代谢的影响
Effects of exposure to benzo[a]pyrene and chronic stress on hepatic metabolism of mice
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摘要: 环境污染和慢性压力是影响人类健康的两大类常见风险因子,本研究通过表征苯[a]并芘(benzo[a]pyrene,B[a]P)与慢性压力应激(chronic unpredictable mild stimulation,CUMS刺激)暴露对小鼠肝脏代谢的影响,并探讨了同时暴露时两大风险因子之间潜在的相互作用. 采用靶向代谢组学结合多元统计学方法分析了两个剂量B[a]P(2.0 mg·kg−1 ·d−1和20.0 mg·kg−1·d−1)与CUMS刺激单独或联合暴露21 d后,雄性C57BL/6J小鼠肝脏中氨基酸代谢、TCA循环和胆汁酸代谢的变化. 研究发现,2.0 mg·kg−1·d−1 B[a]P可使小鼠肝脏中精氨琥珀酸、精氨酸和丙氨酸显著升高,谷氨酰胺显著降低;20.0 mg·kg−1·d−1 B[a]P则主要导致丙氨酸显著上升,谷氨酰胺下降. 慢性压力应激使小鼠肝脏同型半胱氨酸的含量显著下降. B[a]P与慢性压力应激同时暴露时,小鼠肝脏氨基酸和胆汁酸代谢会发生显著变化. 进一步采用代谢扰乱度(metabolic effect level index,MELI)评估了两个风险因子的联合作用效果,发现2.0 mg·kg−1·d−1 B[a]P和慢性压力应激同时暴露对小鼠氨基酸代谢、TCA循环和胆汁酸代谢的影响分别为拮抗、协同和加和作用;而20 mg·kg−1·d−1 B[a]P和慢性压力应激同时暴露的小鼠氨基酸代谢和胆汁酸代谢的影响均为加和作用,TCA循环为拮抗作用. 结果表明,不同剂量的B[a]P和CUMS暴露造成小鼠肝脏氨基酸代谢和胆汁酸代谢紊乱,差异的代谢物与两者单独暴露时明显不同,且代谢的变化与B[a]P暴露剂量密切相关.Abstract: Environmental pollutants and chronic stress are two common risk factors that have great impact on human health. In this study, potential interactions between these two factors were explored by characterizing the effects of benzo[a]pyrene (B[a]P), or chronic stress, or their combination, on liver metabolism of male C57BL/6J mice using targeted metabolomics followed by multivariate statistical analysis. It was found that the hepatic levels of alanine and glutamine were significantly up- and down-regulated respectively after 21 days of exposure to 2.0 mg·kg−1·d−1 or 20.0 mg·kg−1·d−1 of B[a]P. But only in the 2.0 mg·kg−1·d−1 case did we observe the up-regulation of argininosuccinic acid and arginine, suggesting that the B[a]P-induced alterations in amino acid metabolism were dose dependent. Moreover, chronic stress stimulus was found associated with a significant decrease in the hepatic level of homocysteine. Also, we evaluated the effects of combined exposure on the hepatic metabolism based on the metabolic effect level index (MELI). Specifically, the combined exposure to 2.0 mg·kg−1·d−1 B[a]P and chronic stress exhibited antagonistic, synergistic and additive effects on amino acid metabolism, TCA cycle and bile acid metabolism, respectively. In contrast, the combined exposure to 20.0 mg·kg−1·d−1 B[a]P and chronic stress showed additive effects on both amino acid metabolism and bile acid metabolism, but antagonistic effect on TCA cycle. We conclude that the exposure to both B[a]P and chronic stress can trigger significant disorders in amino acid and bile acid metabolism, which, notably, differ from those caused by exposure to either alone and were closely related to the exposure dose of B[a]P.
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Key words:
- benzo[a]pyrene /
- chronic stress /
- exposomics /
- mice liver /
- metabolomics
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图 2 不同剂量B[a]P暴露对小鼠肝脏氨基酸、TCA循环和胆汁酸代谢的影响
Figure 2. Effects of exposure to B[a]P on amino acids, TCA cycle and bile acid metabolism in the liver of mice (a) PLS-DA score plot;(b) Box plots of amino acids with the significant difference in different groups;(c) the relevant metabolic pathways after exposure to B[a]P with low doses ;(d) the relevant metabolic pathways after exposure to B[a]P with high doses
表 1 氨基酸代谢物的质谱参数
Table 1. Mass spectrometry parameters for amino acid metabolites
化合物
Compounds检测离子对
Transitions化合物
Compounds检测离子对
Transitions化合物
Compounds检测离子对
Transitions肾上腺素 183.9→166.1a
183.9→107.2b去甲肾上腺素 170.2→107.1
170.2→152.23-羟基苯甲酸 154.1→136.1
154.1→80.15-羟色胺 177.2→160.2
177.2→115.1褪黑素 233.2→174.2
233.2→159.13-羟基犬尿氨酸 224.9→208.1
224.9→162.1胆碱 104.2→60.2
104.2→58.2肌酸 132.1→90.2
132.1→44.25-氨基戊酸 118.4→55.2
118.4→101.1谷氨酰胺 147.2→84.1
147.2→130.1多巴胺 153.9→91.2
153.9→136.95-羟基吲哚乙酸 192.3→146.1
192.3→91.2甘氨酸 76.1→30.2 肌酐 114.3→44.2 二羟基苯乙酸 166.4→122.9 组胺 112.3→95.2
112.3→41.2犬尿酸 190.1→144.1
190.1→89.1γ-氨基丁酸 104.1→87.1
104.1→69.1多巴 198.1→152.2
198.1→107.2二羟基苯乙醇 152.8→123.0
152.8→95.1犬尿氨酸 209.2→192.2
209.2→94.1丙氨酸 90.1→56.2
90.1→44.2苯丙氨酸 166.1→120.2
166.1→103.1牛磺酸 126.0→107.8
126.0→43.95色氨酸 205.2→188.0
205.2→146.1酪胺 138.2→121.1
138.2→77.1酪氨酸 182.1→91.1
182.1→136.2黄尿酸 206.1→160.1
206.1→132.14-羟基脯氨酸 132.1→86.2
132.1→68.1乙酰胆碱 146.2→97.1
146.2→43.1精氨酸 175.2→70.2
175.2→60.2精氨琥珀酸 291.2→70.1
291.2→116.2天冬精氨 133.1→87.2
133.1→28.2天冬氨酸 134.1→74.2
134.1→88.1肉碱 162.2→60.3
162.2→85.2瓜氨酸 176.2→70.2
176.2→159.2半胱氨酸 122.2→59.2
122.2→76.1胱氨酸 241.3→74.1
241.3→152.1谷氨酸 148.1→84.1
148.1→56.1组氨酸 156.2→110.2
156.2→56.2同型半胱氨酸 136.2→90.1
136.2→56.2异亮氨酸 132.2→86.2
132.2→69.2亮氨酸 132.4→86.2
132.4→30.2赖氨酸 147.4→84.2 甲硫氨酸 150.2→56.1
150.2→104.1烟酰胺 123.1→80.1
123.1→78.1鸟氨酸 133.2→70.2
133.2→116.2丝氨酸 106.1→60.1 脯氨酸 116.1→70.1 苏氨酸 120.1→104.1
120.1→74.3缬氨酸 118.1→72.2
118.1→55.2表 2 有机酸代谢物的质谱参数
Table 2. Mass spectrometry parameters for organic acid metabolites
化合物
Compounds检测离子对
Transitions化合物
Compounds检测离子对
Transitions化合物
Compounds检测离子对
Transitionsα-酮戊二酸 145.0→100.9
145.0→56.8乌头酸 173.0→84.9
173.0→129.0柠檬酸 191.0→111
191.0→86.9富马酸 115.1→71.1
115.1→26.9衣康酸 129.0→60.1
129.0→40.8乳酸 89.1→42.9 苹果酸 133.0→71.1
133.0→73.0丙酮酸 87.1→43.0 琥珀酸 117→73.1 表 3 胆汁酸代谢物的质谱参数
Table 3. Mass spectrometry parameters for bile metabolites
化合物
Compounds检测离子对
Transitions化合物
Compounds检测离子对
Transitions化合物
Compounds检测离子对
Transitions甘氨胆酸 464.0→74.0a
464.0→402.2b甘氨鹅脱氧胆酸 448.1→74.0
448.1→386.0牛磺胆酸 514.2→124.0
514.2→107.0α-鼠胆酸 373.1→355.3
373.1→373.2牛磺鹅脱氧胆酸 498.0→124.0
498.0→80.0β-鼠胆酸 391.1→355.3
391.1→373.2ω-鼠胆酸 373.1→159.2
373.1→337.5鹅去氧胆酸 357.1→105.1
357.1→135.4猪去氧胆酸 357.1→161.2
357.1→135.2石胆酸 359.1→135.2
359.1→95.1去氧胆酸 391.0→345.3
391.0→327.1胆酸 407.3→343.3
407.3→288.9熊去氧胆酸 357.1→161.2
357.1→135.2牛磺熊脱氧胆酸 498.0→124.0
498.0→80.0甘氨熊脱氧胆酸 448.05→74.0
448.05→386.2注:a定量离子对:quantitative ion; b定性离子对:qualitative ion. -
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