title: Evaluation of the PIGRET assay in rats by single oral dosing with azidothymidine.
abstract: In vivo phosphatidylinositol glycan, class A (Pig-a) gene mutation assay using peripheral blood is known to be a novel and useful tool to evaluate the mutagenicity of compounds. Recently, the rat PIGRET assay which is an improved method for measuring Pig-a mutant cells in reticulocytes with magnetic enrichment of CD71 positive cells has been developed. Several reports showed that the PIGRET assay could detect the increase of Pig-a mutant frequency earlier than the Pig-a assay in total red blood cells (RBC Pig-a assay). Therefore, as part of a collaborative study by the Mammalian Mutagenicity Study (MMS) Group of the Japanese Environmental Mutagen Society, the usefulness of the PIGRET assay in comparison to the RBC Pig-a assay has been assessed for 24 compounds with various mechanisms of action. In the present study, we performed the PIGRET assay and RBC Pig-a assay with a nucleoside analogue, azidothymidine (AZT), and compared the results in these assays. We administered a single dose of AZT to rats by oral gavage up to 2000mg/kg and examined Pig-a mutant frequencies at days 7, 14 and 28 by PIGRET and RBC Pig-a assays. No significant increases in mutant frequency were observed after administration of AZT in both the RBC Pig-a and PIGRET assays and comparable to the previous results of the International Workshop on Genotoxicity Testing (IWGT) workgroup. AZT has been thought to induce not only DNA chain termination as a pharmacological effect but also a large deletion on the genome DNA. The Pig-a assays may be less sensitive to compounds such as AZT which induce large deletions on the genome DNA.
authors.affiliation: Pharmacokinetics and Safety Department, Drug Research Center, Kaken Pharmaceutical Co., Ltd., 301, Gensuke, Fujieda-shi, Shizuoka 426-8646, Japan. Electronic address: sanada_hisakazu@kaken.co.jp.
authors.forename: Hisakazu
authors.initials: H
authors.lastname: Sanada
authors.affiliation: Pharmacokinetics and Safety Department, Drug Research Center, Kaken Pharmaceutical Co., Ltd., 301, Gensuke, Fujieda-shi, Shizuoka 426-8646, Japan.
authors.forename: Tomoka
authors.initials: T
authors.lastname: Ohsumi
authors.affiliation: Pharmacokinetics and Safety Department, Drug Research Center, Kaken Pharmaceutical Co., Ltd., 301, Gensuke, Fujieda-shi, Shizuoka 426-8646, Japan.
authors.forename: Naomi
authors.initials: N
authors.lastname: Koyama
authors.affiliation: Pharmacokinetics and Safety Department, Drug Research Center, Kaken Pharmaceutical Co., Ltd., 301, Gensuke, Fujieda-shi, Shizuoka 426-8646, Japan.
authors.forename: Taishi
authors.initials: T
authors.lastname: Miyashita
authors.affiliation: Pharmacokinetics and Safety Department, Drug Research Center, Kaken Pharmaceutical Co., Ltd., 301, Gensuke, Fujieda-shi, Shizuoka 426-8646, Japan.
authors.forename: Kazuto
authors.initials: K
authors.lastname: Hashimoto
mesh_terms: D000284:Administration, Oral; D000818:Animals; D019380:Anti-HIV Agents / Q000008:administration & dosage / Q000633:toxicity*; D008565:Membrane Proteins / Q000235:genetics; D009152:Mutagenicity Tests / Q000379:methods*; D009153:Mutagens / Q000008:administration & dosage / Q000633:toxicity*; D051381:Rats; D012156:Reticulocytes / Q000187:drug effects*; D015215:Zidovudine / Q000008:administration & dosage / Q000633:toxicity*
chemical_list: D019380:Anti-HIV Agents; D008565:Membrane Proteins; D009153:Mutagens; C080086:phosphatidylinositol glycan-class A protein; D015215:Zidovudine
keywords: Azidothymidine; PIGRET assay; RBC Pig-a assay