Toxicokinetics and in vivo genotoxicity after single dose oral gavage and intravenous administration of N-Nitrosonornicotine in Sprague Dawley rats

IF 3.4 3区医学 Q2 PHARMACOLOGY & PHARMACY

Toxicology and applied pharmacology Pub Date : 2025-09-16 DOI:10.1016/j.taap.2025.117572

Mamata De , Ashley Fields , Guy Lagaud

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引用次数: 0

Abstract

N-Nitrosonornicotine (NNN) is a tobacco specific nitrosamine (TSNA) and a known human carcinogen. NNN is mutagenic in bacterial mutation assay. The dose response and a correlation between its exposure and genotoxic mode of action is not well characterized. In this study, we evaluated the toxicokinetics (TK) of NNN via oral gavage (PO) and intravenous (IV) administration. In addition, genotoxicity assays, such as comet assay and micronucleus assay were conducted using different tissues as a toxicodynamic endpoints. The genotoxicity of NNN in the select target organs of toxicity in vivo was studied in rats following NNN exposure. A single dose of 0.24 μg/kg, 2.4 μg/kg, or 24 μg/kg of NNN (mixture of 70 % R and 30 % S) and 0.9 % saline (vehicle control) was acutely administered in male Sprague-Dawley (SD) rats (9–10 weeks age) via PO and IV administrations. Plasma, urine, and tissue specimens were collected at designated timepoints and analyzed for levels of NNN and its major metabolites, (R, S)-Nornicotine (NN) and N′-nitrosonornicotine-1-N-oxide (NNN-N-Oxide); and DNA from various tissues were evaluated for the genotoxic potential of NNN using in vivo alkaline comet assay. Following IV administration, tail migration increased compared to that of the vehicle control in peripheral blood, bronchoalveolar lavage (BAL), liver, kidney, and bone marrow. These increases were mostly dose dependent. Similar changes were seen for tail moments in peripheral blood lymphocytes (PBLs), BAL, and liver. Similarly to the IV administration, tail migration showed treatment related effects following PO administration. Tail migration in liver, kidney, duodenum, bone marrow, and BAL showed statistically significant increase in length compared to that of the vehicle control. TK data analysis indicated that NNN was rapidly absorbed and metabolized to NNN-N-Oxide after NNN administration via the two routes as shown by the short half-life (T_1/2 = 1.25–2.5 h). While NNN concentration was not quantifiable in plasma at low dose, systemic exposure as indicated by C_max and AUC was found to be increased in a dose proportional manner between the mid and high NNN exposure groups in the plasma samples following the PO and IV administration. Similarly, urinary excretions of NNN showed a dose proportional increase between the mid and high NNN after PO and IV administrations. Overall, the results suggest that the different tissue-specific genotoxic profiles are mainly due to the different effective doses of NNN resulting from the route of administration. First pass metabolism may play a role in enhancing NNN genotoxicity via the PO route as indicated by positive comet assay results from different target organs of toxicity.

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单次灌胃和静脉给药n -亚硝基索烟碱对大鼠的毒性动力学和体内遗传毒性。

n -亚硝基索烟碱（NNN）是一种烟草特有的亚硝胺（TSNA），是一种已知的人类致癌物。在细菌突变试验中，NNN具有致突变性。剂量反应及其暴露与基因毒性作用方式之间的关系尚未很好地表征。在这项研究中，我们通过口服灌胃（PO）和静脉（IV）给药来评估NNN的毒性动力学（TK）。此外，采用不同组织作为毒理学终点进行遗传毒性试验，如彗星试验和微核试验。研究了NNN暴露后大鼠体内毒性靶器官的遗传毒性。将NNN（70 % R和30 % S的混合物）和0.9 %生理盐水（对照）分别以单剂量0.24 μg/kg、2.4 μg/kg或24 μg/kg的剂量急性给予9-10 周龄雄性SD大鼠PO和IV给药。在指定时间点收集血浆、尿液和组织标本，分析NNN及其主要代谢物（R， S）-去甲尼古丁（NN）和N′-亚硝基声尼古丁-1-N-氧化物（NNN-N-氧化物）的水平；并利用体内碱性彗星试验对不同组织的DNA进行遗传毒性评估。静脉给药后，与对照组相比，小鼠在外周血、支气管肺泡灌洗液（BAL）、肝脏、肾脏和骨髓中的尾部迁移增加。这些增加主要是剂量依赖性的。外周血淋巴细胞（PBLs）、BAL和肝脏的尾力矩也出现了类似的变化。与静脉给药类似，PO给药后，尾部迁移显示出与治疗相关的效果。尾巴在肝脏、肾脏、十二指肠、骨髓和BAL中的迁移长度与对照组相比有统计学意义的增加。TK数据分析表明，经两种途径给药后，NNN迅速被吸收并代谢为NNN- n -氧化物，半衰期短（T1/2 = 1.25-2.5 h）。虽然低剂量时血浆中的NNN浓度无法量化，但在PO和IV给药后，血浆样品中高NNN暴露组之间的Cmax和AUC显示的全身暴露量呈剂量比例增加。同样，在PO和IV给药后，尿中NNN的排泄量在中高NNN之间呈剂量比例增加。总的来说，结果表明不同的组织特异性基因毒性谱主要是由于给药途径导致的NNN有效剂量不同。不同毒性靶器官的阳性彗星试验结果表明，首过代谢可能通过PO途径增强NNN遗传毒性。

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来源期刊

Toxicology and applied pharmacology 医学-毒理学

CiteScore

6.80

自引率

2.60%

发文量

309

审稿时长

32 days

期刊介绍： Toxicology and Applied Pharmacology publishes original scientific research of relevance to animals or humans pertaining to the action of chemicals, drugs, or chemically-defined natural products. Regular articles address mechanistic approaches to physiological, pharmacologic, biochemical, cellular, or molecular understanding of toxicologic/pathologic lesions and to methods used to describe these responses. Safety Science articles address outstanding state-of-the-art preclinical and human translational characterization of drug and chemical safety employing cutting-edge science. Highly significant Regulatory Safety Science articles will also be considered in this category. Papers concerned with alternatives to the use of experimental animals are encouraged. Short articles report on high impact studies of broad interest to readers of TAAP that would benefit from rapid publication. These articles should contain no more than a combined total of four figures and tables. Authors should include in their cover letter the justification for consideration of their manuscript as a short article.