title: Evaluation of the in vivo mutagenicity of melamine by the RBC Pig-a assay and PIGRET assay.
abstract: The Pig-a assay is a new in vivo genotoxicity test for detecting mutagens in the bodies of animals, using the endogenous Pig-a gene as the target. There are two types of Pig-a assays: the red blood cell (RBC) Pig-a assay, which uses RBCs, and the PIGRET assay, which uses reticulocytes. The Japanese Environmental Mutagen Society-Mammalian Mutagenicity Study Group collaborative study of the Pig-a assay was carried out to investigate the usefulness of the PIGRET assay. The mutagenicity of melamine was evaluated as part of this study. Eight-week-old male Crl:CD (SD) rats were administered a single gavage dose of melamine as a non-genotoxic bladder carcinogen. Blood samples were collected at the first, second and fourth weeks after administration, and the RBC Pig-a assay and PIGRET assays were conducted using these samples. Three dose levels were used in the study: the highest dose was 2000mg/kg, which is generally used as the maximum dose in in vivo genotoxicity testing, and 1000 and 500mg/kg were also used. As a positive control, a group of rats was administered a single dose of N-nitroso-N-ethylurea (ENU) by gavage at 40mg/kg. The Pig-a mutant frequencies (Pig-a MFs) did not increase in any of the melamine groups throughout the experimental period in either the RBC Pig-a assay or the PIGRET assay. Both the RBC Pig-a and PIGRET assays revealed significant increases in the Pig-a MFs in the ENU group, starting at day 7 after a single administration. Therefore, these two assays, when evaluated after a single administration, can be used to determine that melamine is non-mutagenic.
authors.affiliation: Life Science Research Institute, Kumiai Chemical Industry Co., Ltd. 3360 Kamo, Kikugawa-shi, Shizuoka, 439-0031, Japan. Electronic address: t-kyoya@kumiai-chem.co.jp.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Kyoya
authors.affiliation: Life Science Research Institute, Kumiai Chemical Industry Co., Ltd. 3360 Kamo, Kikugawa-shi, Shizuoka, 439-0031, Japan.
authors.forename: Masami
authors.initials: M
authors.lastname: Hori
authors.affiliation: Life Science Research Institute, Kumiai Chemical Industry Co., Ltd. 3360 Kamo, Kikugawa-shi, Shizuoka, 439-0031, Japan.
authors.forename: Megumi
authors.initials: M
authors.lastname: Terada
mesh_terms: D000818:Animals; D004305:Dose-Response Relationship, Drug; D004912:Erythrocytes / Q000187:drug effects*; D008297:Male; D008565:Membrane Proteins / Q000235:genetics*; D009152:Mutagenicity Tests / Q000379:methods*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012156:Reticulocytes / Q000187:drug effects*; D014227:Triazines / Q000633:toxicity*
chemical_list: D008565:Membrane Proteins; D014227:Triazines; C080086:phosphatidylinositol glycan-class A protein; C011907:melamine
keywords: Flow cytometry; In vivo mutagenicity test; Non-genotoxic carcinogen; Pig-a mutation; Reticulocyte Pig-a assay