Mersch-Sundermann V, Reinhardt A, Emig M
Institut für Medizinische Mikrobiologie und Hygiene, Fakultät für Klinische Medizin Mannheim.
Zentralbl Hyg Umweltmed. 1996 May;198(5):429-42.
In the present study a new in vivo/in vitro animal model was used to study the ability and potency of musk ketone and musk xylene to induce liver specific oxygenases (in vivo) which are necessary of toxify different premutagens, pregenotoxicants and/or precarcinogens to the ultimate DNA damaging agents. Therefore, rats were pretreated with 10, 20 and 40 mg/d nitro musk (NMV) for 5 days by intraperitoneal (i.p.) injection. Then the postmitochondrial fractions of the hepatocytes (S9M) were used to examine the metabolic potency for toxification of the pregenotoxicants benzo[a]pyrene (B[a]P) and 2-aminoanthracene (2-AA) using the SOS chromotest (in vitro). Furthermore, musk xylene, musk ketone, musk ambrette, musk moskene and musk tibetene were examined for their mutagenicity in the Salmonella/microsome assay using S. typhimurium TA97, TA98, TA100 and TA102 and for their genotoxicity in the SOS chromotest using Escherichia coli PQ37 (sfiA::lacZ) in the presence and absence of an exogenous metabolizing system (S9 of PCB induced rats = S9A). Both musk ketone and musk xylene were identified als inducers of toxifying enzymes (oxygenases) in rat liver. Using the in vivo/in vitro model these isoenzyme inductions led to a metabolisation (toxification) of the pregenotoxicants benzo[a]pyrene (B[a]P) and/or 2-aminoanthracene (2-AA) (cogenotoxicity). Using S9M fractions of rats which were i.p.-pretreated with 5 x 40 mg musk ketone the induction factor in the SOS chromotest was IFmax = 4.0 by using 1 nmole B[a]P and IFmax > 4.0 by using 20 nmole 2-AA. Thus, musk ketone seems to be a Cytochrome P450 1A1 and 1A2 isoenzyme inducer in mammals. On the other hand the S9M fractions of musk xylene pretreated rats showed only a toxification of 2-AA (IFmax = 3.0). Therefore, a synergistic effect of enzyme inducers, i.e. musk xylene and musk ketone, and pregenotoxicants, i.e. B[a]P and 2-AA, regarding DNS damaging effects was identified. Musk ambrette showed high mutagenicity in S. typhimurium TA100 (500 His(-)-revertants per mumole, +S9A). Unexpectedly, these DNA damaging effects were not caused by bacterial nitroreductases but by rat S9A metabolisation (!). SOS inducing DNA damages in E. coli PQ37 were not produced (IFmax < 1.5). On the basis of the results presented and under consideration of the concentrations of NMV, other cogenotoxicants and pregenotoxicants such as B[a]P and 2-AA in environmental samples and human tissues, a genotoxic risk for humans has to be assumed.
在本研究中，使用了一种新的体内/体外动物模型来研究麝香酮和二甲苯麝香诱导肝脏特异性加氧酶（体内）的能力和效力，这些酶对于将不同的前诱变剂、前遗传毒性剂和/或前致癌物转化为最终的DNA损伤剂是必需的。因此，通过腹腔注射，用10、20和40mg/d的硝基麝香（NMV）对大鼠进行5天的预处理。然后，使用肝细胞的线粒体后组分（S9M），通过SOS显色试验（体外）检测前遗传毒性剂苯并[a]芘（B[a]P）和2-氨基蒽（2-AA）的代谢毒性。此外，使用鼠伤寒沙门氏菌TA97、TA98、TA100和TA102在沙门氏菌/微粒体试验中检测二甲苯麝香、麝香酮、葵子麝香、西藏麝香和黄葵麝香的诱变性，并在有和没有外源性代谢系统（多氯联苯诱导大鼠的S9 = S9A）的情况下，使用大肠杆菌PQ37（sfiA::lacZ）在SOS显色试验中检测它们的遗传毒性。麝香酮和二甲苯麝香均被鉴定为大鼠肝脏中加毒酶（加氧酶）的诱导剂。使用体内/体外模型，这些同工酶诱导导致前遗传毒性剂苯并[a]芘（B[a]P）和/或2-氨基蒽（2-AA）的代谢（加毒）（共遗传毒性）。使用经腹腔注射5×40mg麝香酮预处理的大鼠的S9M组分，在SOS显色试验中，使用1nmol B[a]P时诱导因子IFmax = 4.0，使用20nmol 2-AA时IFmax > 4.0。因此，麝香酮似乎是哺乳动物中的细胞色素P450 1A1和1A2同工酶诱导剂。另一方面，经二甲苯麝香预处理的大鼠的S9M组分仅显示2-AA的加毒作用（IFmax = 3.0）。因此，确定了酶诱导剂（即二甲苯麝香和麝香酮）和前遗传毒性剂（即B[a]P和2-AA）在DNA损伤作用方面的协同效应。葵子麝香在鼠伤寒沙门氏菌TA100中显示出高诱变性（每微摩尔500个His(-)回复突变体，+S9A）。出乎意料的是，这些DNA损伤作用不是由细菌硝基还原酶引起的，而是由大鼠S9A代谢引起的（！）。在大肠杆菌PQ37中未产生诱导SOS的DNA损伤（IFmax < 1.5）。根据所呈现的结果，并考虑到环境样品和人体组织中NMV、其他共遗传毒性剂和前遗传毒性剂（如B[a]P和2-AA）的浓度，必须假定对人类存在遗传毒性风险。
