title: The micronucleus test and erythropoiesis: effects of cyclic adenosine monophosphate (cAMP) on micronucleus formation.
abstract: The aim of this study was to determine the mechanism of the rodent bone marrow micronucleus test in relation to erythropoiesis. We have previously reported that an acceleration of erythropoiesis increases the frequency of micronucleated polychromatic erythrocytes (MPCE) induced by mutagens. The blood plasma erythropoietin level increased after the injection of N6-2-O-dibutyladenosine-3',5'-cyclic monophosphate into adenosine 3',5'-cyclic monophosphate (cAMP) at a dose of 500 mg/kg. A peak of erythropoietin induction was observed 3 h after the injection of cAMP. cAMP itself did not induce any micronuclei in erythroblasts of BALB/c mice. So, the frequency of MPCE did not increase after injection of cAMP. The highest frequency of MPCE and the dose-response relationship between the cAMP doses and micronucleus frequency were observed 30 h after injection of mitomycin C (MMC) in mice which had been administered cAMP 24 h previously. The highest effect of cAMP on the increase of MPCE was observed when cAMP was given 24 h before MMC injection, thus indicating that accelerating the multiplication of erythroblasts increases the frequency of MPCE induced by mutagens. The induction of MPCE in the bone marrow by three other chemicals (carboquone, 5-fluorouracil, and vincristine) also increased after pretreatment with cAMP. Our results suggest that the increase of MPCE induced by mutagens can be amplified following the acceleration of erythropoiesis by pretreatment with cAMP.
authors.affiliation: Department of Public Health and Environmental Medicine, The Jikei University School of Medicine, 3-25-8 Nishishinbashi Minato-Ku, Tokyo 105-8461, Japan. suzuki@jikei.ac.jp
authors.forename: Yuji
authors.initials: Y
authors.lastname: Suzuki
authors.forename: Ryo
authors.initials: R
authors.lastname: Takagi
authors.forename: Ichiro
authors.initials: I
authors.lastname: Kawasaki
authors.forename: Toru
authors.initials: T
authors.lastname: Matsudaira
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Yanagisawa
authors.forename: Hidesuke
authors.initials: H
authors.lastname: Shimizu
mesh_terms: D000818:Animals; D001853:Bone Marrow / Q000187:drug effects; D000242:Cyclic AMP / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004912:Erythrocytes / Q000187:drug effects; D004920:Erythropoiesis / Q000187:drug effects*; D004921:Erythropoietin / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D048629:Micronuclei, Chromosome-Defective / Q000187:drug effects*; D015162:Micronucleus Tests; D009153:Mutagens / Q000633:toxicity*; D013997:Time Factors
chemical_list: D009153:Mutagens; D004921:Erythropoietin; D000242:Cyclic AMP