title: Detection of micronuclei in hepatocytes isolated from young adult rats repeatedly treated with N-nitrosodi-n-propylamine.
abstract: To assess the effectiveness of the multiple dose liver micronucleus (MN) assay, the induction of micronuclei by N-nitrosodi-n-propylamine (NDPA), a genotoxic rodent carcinogen, was compared in hepatocytes (HEPs) and bone marrow (BM) cells. Young adult male rats were treated orally with NDPA at 6 weeks of age for 14 days using daily doses of 10, 20 and 40mg/kg. Samples of the liver and BM tissues were harvested from each animal one day following the last treatment with NDPA and were evaluated for the frequencies of micronucleated cells. Repeated doses with 40mg/kg/day of NDPA caused systemic and hepatic toxicity, including suppressed body weight gains and histopathological hepatic lesions. The frequencies of micronucleated HEPs were significantly increased in all the NDPA-treated groups in a dose-dependent manner. In contrast, the induction of micronuclei in the BM was undetectable, even at the high dose level of 40mg/kg, for which the inhibition of hematopoiesis was observed. For the detection of micronucleated HEPs induced by NDPA treatment, a 14-day administration period is adequate. The liver MN assay using naive young adult rats may be integrated into general repeated-dose toxicity studies including histopathological examinations. Our results suggest that the liver MN assay using multiple doses is more efficient and sensitive than the BM MN assay in detecting the in vivo genotoxic potential of NDPA.
authors.affiliation: Safety Research Laboratory, R&D, Kissei Pharmaceutical Co., Ltd., 2320-1, Maki, Hotaka, Azumino-shi, Nagano 399-8305, Japan. Electronic address: yukari_terashima@pharm.kissei.co.jp.
authors.forename: Yukari
authors.initials: Y
authors.lastname: Terashima
authors.affiliation: Safety Research Laboratory, R&D, Kissei Pharmaceutical Co., Ltd., 2320-1, Maki, Hotaka, Azumino-shi, Nagano 399-8305, Japan.
authors.forename: Ryohei
authors.initials: R
authors.lastname: Yokoi
authors.affiliation: Safety Research Laboratory, R&D, Kissei Pharmaceutical Co., Ltd., 2320-1, Maki, Hotaka, Azumino-shi, Nagano 399-8305, Japan.
authors.forename: Ikuro
authors.initials: I
authors.lastname: Takakura
authors.affiliation: Safety Research Laboratory, R&D, Kissei Pharmaceutical Co., Ltd., 2320-1, Maki, Hotaka, Azumino-shi, Nagano 399-8305, Japan.
authors.forename: Erika
authors.initials: E
authors.lastname: Saitou
authors.affiliation: LSI Medience Corporation, 14-1 Sunayama, Kamisu-shi, Ibaraki 314-0255, Japan.
authors.forename: Yumi
authors.initials: Y
authors.lastname: Wako
authors.affiliation: LSI Medience Corporation, 14-1 Sunayama, Kamisu-shi, Ibaraki 314-0255, Japan.
authors.forename: Kazufumi
authors.initials: K
authors.lastname: Kawasako
authors.affiliation: Safety Research Laboratory, R&D, Kissei Pharmaceutical Co., Ltd., 2320-1, Maki, Hotaka, Azumino-shi, Nagano 399-8305, Japan.
authors.forename: Shinji
authors.initials: S
authors.lastname: Souma
authors.affiliation: Safety Research Laboratory, R&D, Kissei Pharmaceutical Co., Ltd., 2320-1, Maki, Hotaka, Azumino-shi, Nagano 399-8305, Japan.
authors.forename: Toru
authors.initials: T
authors.lastname: Tamura
mesh_terms: D000284:Administration, Oral; D000367:Age Factors; D000818:Animals; D001835:Body Weight / Q000187:drug effects; D001853:Bone Marrow / Q000187:drug effects; D002273:Carcinogens / Q000633:toxicity*; D002869:Chromosome Aberrations / Q000187:drug effects; D003299:Cooperative Behavior; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D022781:Hepatocytes / Q000187:drug effects* / Q000473:pathology; D006801:Humans; D007564:Japan; D008099:Liver / Q000187:drug effects* / Q000473:pathology; D008297:Male; D015162:Micronucleus Tests; D009602:Nitrosamines / Q000633:toxicity*; D009928:Organ Specificity; D051381:Rats; D017207:Rats, Sprague-Dawley; D012957:Societies, Pharmaceutical
chemical_list: D002273:Carcinogens; D009602:Nitrosamines; C013161:N-nitroso(di-n-propyl)amine
keywords: Bone marrow micronucleus assay; Liver micronucleus assay; N-nitrosodi-n-propylamine; Young adult rat