title: Sequence of busulfan-induced neural progenitor cell damage in the fetal rat brain.
abstract: The sequence of neural progenitor cell (NPC) damage induced in fetal rat brain by transplacental exposure to busulfan, an antineoplastic bifunctional-alkylating agent, on gestational day 13 was examined by immunohistochemical and real-time RT-PCR analyses. Following busulfan treatment, pyknotic NPCs first appeared in the medial layer and then extended to the dorsal layer of the ventricular zone (VZ) of the telencephalon. Pyknotic NPCs that were immunohistochemically positive for cleaved caspase-3, i.e. apoptotic NPCs, began to increase at 24 h after treatment, peaked at 48 h, and returned to the control levels at 96 h. On the other hand, the index (%) of phospho-histone H3-positive NPCs, i.e. mitotic NPCs, and that of BrdU-positive NPCs, i.e. S-phase cells, decreased in accordance with the increase in the index of apoptotic NPCs. Prior to the peak time of apoptotic NPCs, the indices of p53- and p21-positive NPCs peaked at 36 h. In addition, the expression levels of p21 and Puma (p53-target genes) mRNAs were elevated in real-time RT-PCR analysis. These findings indicated that busulfan not only induced apoptosis through the p53-mediated intrinsic pathway but also inhibited cell proliferation in NPCs, resulting in a reduction of the width of the telencephalon. On the other hand, in spite of up-regulation of p21 expression, the expression of cyclin D1, part of the cell cycle machinery of the G1/S transition, and the expression levels of Cdc20 and cyclin B1 which are involved in G2/M transition, showed no changes, giving no possible information of busulfan-induced cell cycle arrest in NPCs.
authors.affiliation: Gotemba Laboratories, Biology and Zoology Research Center Inc., 1284, Kamado, Gotemba, Shizuoka 412-0039, Japan.
authors.forename: Toko
authors.initials: T
authors.lastname: Ohira
authors.forename: Ryo
authors.initials: R
authors.lastname: Ando
authors.forename: Yumiko
authors.initials: Y
authors.lastname: Okada
authors.forename: Hodaka
authors.initials: H
authors.lastname: Suzuki
authors.forename: Tsubasa
authors.initials: T
authors.lastname: Saito
authors.forename: Tomomi
authors.initials: T
authors.lastname: Nakazawa
authors.forename: Kaori
authors.initials: K
authors.lastname: Nishihara
authors.forename: Satoshi
authors.initials: S
authors.lastname: Yamamoto
authors.forename: Norihiko
authors.initials: N
authors.lastname: Nakamura
authors.forename: Kazutoshi
authors.initials: K
authors.lastname: Tamura
mesh_terms: D000477:Alkylating Agents / Q000008:administration & dosage / Q000633:toxicity*; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D001921:Brain / Q000187:drug effects* / Q000196:embryology / Q000473:pathology; D002066:Busulfan / Q000008:administration & dosage / Q000633:toxicity*; D049109:Cell Proliferation / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D005260:Female; D005865:Gestational Age; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D018811:Maternal Exposure / Q000009:adverse effects; D055495:Neurogenesis / Q000187:drug effects*; D009474:Neurons / Q000187:drug effects* / Q000473:pathology; D011247:Pregnancy; D051381:Rats; D017207:Rats, Sprague-Dawley; D060888:Real-Time Polymerase Chain Reaction; D013234:Stem Cells / Q000187:drug effects* / Q000473:pathology; D016159:Tumor Suppressor Protein p53 / Q000096:biosynthesis
chemical_list: D000477:Alkylating Agents; D016159:Tumor Suppressor Protein p53; D002066:Busulfan