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Yamaguchi Y, Saito T, Takagi M, Nakazawa T, Tamura K. Changes in 5-Fluorouracil-induced external granular cell damage during the time-course of the developing cerebellum of infant rats. J Toxicol Pathol 2022; 35:299-311. [PMID: 36406170 PMCID: PMC9647215 DOI: 10.1293/tox.2022-0003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Accepted: 05/06/2022] [Indexed: 07/06/2024] Open
Abstract
5-Fluorouracil (5-FU) is widely used as a chemotherapeutic agent that blocks DNA synthesis and replication by inhibiting thymidylate synthetase. This study aimed to elucidate 5-FU-induced changes in the external granular cells (EGCs) in the cerebellum of infant rats and the possible underlying mechanism. Six-day-old infant rats were injected subcutaneously with 40 mg/kg of 5-FU, and their cerebellums were examined at 6, 9, 12, and 24 h after treatment (HAT), and 2, 4, and 10 d after treatment (DAT). The width of the external granular layer (EGL) decreased from 24 HAT to 4 DAT in the 5-FU group compared to that in the control group. However, the width in the 5-FU group was comparable to that of the control group at 10 DAT. The number of apoptotic cells, cleaved caspase 3-labeling index (LI%), p21cip1-LI%, and expression levels of p53, p21cip1, and Fas mRNAs increased at 24 HAT. However, no changes were detected in the expression levels of Puma and Bax mRNAs at any time point. BrdU-LI% increased at 6 and 12 HAT but decreased at 24 HAT. The phospho-histone H3-LI% decreased from 6 HAT to 2 DAT. The width of the molecular layer decreased compared to that of the control group at 10 DAT. No differences were observed in Purkinje cell development. These results indicate that 5-FU inhibited cell proliferation by inducing apoptosis of EGCs via activation of Fas and caspase-3 without the involvement of the mitochondrial pathway and induced p53-dependent G1-S and G2-M phase arrest.
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Affiliation(s)
- Yuko Yamaguchi
- Pathology Division, Gotemba Laboratories, BoZo Research
Center Inc., 1284 Kamado, Gotemba, Shizuoka 412-0039, Japan
| | - Tsubasa Saito
- Pathology Division, Gotemba Laboratories, BoZo Research
Center Inc., 1284 Kamado, Gotemba, Shizuoka 412-0039, Japan
| | - Mizuho Takagi
- Pathology Division, Gotemba Laboratories, BoZo Research
Center Inc., 1284 Kamado, Gotemba, Shizuoka 412-0039, Japan
| | - Tomomi Nakazawa
- Pathology Division, Gotemba Laboratories, BoZo Research
Center Inc., 1284 Kamado, Gotemba, Shizuoka 412-0039, Japan
| | - Kazutoshi Tamura
- Pathology Division, Gotemba Laboratories, BoZo Research
Center Inc., 1284 Kamado, Gotemba, Shizuoka 412-0039, Japan
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NOHARA M, IWASAKI M, NISHIO M, SUGIYAMA A. Histopathologic effect of in ovo exposure to methotrexate at early embryonic stage on optic tectum of Japanese quail (<i>Coturnix japonica</i>). J Toxicol Pathol 2022; 35:269-274. [PMID: 35832899 PMCID: PMC9256001 DOI: 10.1293/tox.2022-0011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Accepted: 04/07/2022] [Indexed: 11/25/2022] Open
Abstract
The optic tectum of Japanese quail embryos with in ovo exposure to methotrexate 100 ng/g
egg on embryonic day 4 was examined from 3 to 24 hour after treatment. At 9 hour after
methotrexate exposure, several apoptotic neuroepithelial cells appeared in the ventricular
zone of the optic tectum; these increased in number and were diffusely distributed
throughout all layers of the ventricular zone of the optic tectum at 12 hour. At 24 hour,
neuroepithelial cells in the ventricular zone of the optic tectum were eliminated and
showed sparse cell density. Throughout the experimental period, proliferation of
neuroepithelial cells in the ventricular zone of the optic tectum of methotrexate-treated
embryos was inhibited. These results suggest that neuroepithelial cells in the ventricular
zone of the optic tectum in Japanese quail embryos can be affected by folic acid
antimetabolites, methotrexate, at an early embryonic stage.
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Affiliation(s)
- Masakatsu NOHARA
- Faculty of Veterinary Medicine, Okayama University of Science, 1-3 Ikoinooka, Imabari, Ehime 794-8555, Japan
| | - Mayo IWASAKI
- Faculty of Veterinary Medicine, Okayama University of Science, 1-3 Ikoinooka, Imabari, Ehime 794-8555, Japan
| | - Mahiro NISHIO
- Faculty of Veterinary Medicine, Okayama University of Science, 1-3 Ikoinooka, Imabari, Ehime 794-8555, Japan
| | - Akihiko SUGIYAMA
- Faculty of Veterinary Medicine, Okayama University of Science, 1-3 Ikoinooka, Imabari, Ehime 794-8555, Japan
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Liu Q, Wang X, Li J, Wang J, Sun G, Zhang N, Ren T, Zhao L, Zhong R. Development and biological evaluation of AzoBGNU: A novel hypoxia-activated DNA crosslinking prodrug with AGT-inhibitory activity. Biomed Pharmacother 2021; 144:112338. [PMID: 34678728 DOI: 10.1016/j.biopha.2021.112338] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Revised: 10/09/2021] [Accepted: 10/11/2021] [Indexed: 11/24/2022] Open
Abstract
Chloroethylnitrosoureas (CENUs) are an important family of chemotherapies in clinical treatment of cancers, which exert antitumor activity by inducing the formation of DNA interstrand crosslinks (dG-dC ICLs). However, the drug resistance mediated by O6-alkylguanine-DNA alkyltransferase (AGT) and absence of tumor-targeting ability largely decrease the antitumor efficacy of CENUs. In this study, we synthesized an azobenzene-based hypoxia-activated combi-nitrosourea prodrug, AzoBGNU, and evaluated its hypoxic selectivity and antitumor activity. The prodrug was composed of a CENU pharmacophore and an O6-benzylguanine (O6-BG) analog moiety masked by a N,N-dimethyl-4-(phenyldiazenyl)aniline segment as a hypoxia-activated trigger, which was designed to be selectively reduced via azo bond break in hypoxic tumor microenvironment, accompanied with releasing of an O6-BG analog to inhibit AGT and a chloroethylating agent to induce dG-dC ICLs. AzoBGNU exhibited significantly increased cytotoxicity and apoptosis-inducing ability toward DU145 cells under hypoxia compared with normoxia, indicating the hypoxia-responsiveness as expected. Predominant higher cytotoxicity was observed in the cells treated by AzoBGNU than those by traditional CENU chemotherapy ACNU and its combination with O6-BG. The levels of dG-dC ICLs in DU145 cells induced by AzoBGNU was remarkably enhanced under hypoxia, which was approximately 6-fold higher than those in the AzoBGNU-treated groups under normoxia and those in the ACNU-treated groups. The results demonstrated that azobenzene-based combi-nitrosourea prodrug possessed desirable tumor-hypoxia targeting ability and eliminated chemoresistance compared with the conventional CENUs.
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Affiliation(s)
- Qi Liu
- Beijing Key Laboratory of Environmental & Viral Oncology, Faculty of Environment & Life, Beijing University of Technology, Beijing 100124, China
| | - Xiaoli Wang
- Beijing Key Laboratory of Environmental & Viral Oncology, Faculty of Environment & Life, Beijing University of Technology, Beijing 100124, China
| | - Jun Li
- Beijing Key Laboratory of Environmental & Viral Oncology, Faculty of Environment & Life, Beijing University of Technology, Beijing 100124, China
| | - Jiaojiao Wang
- Beijing Key Laboratory of Environmental & Viral Oncology, Faculty of Environment & Life, Beijing University of Technology, Beijing 100124, China
| | - Guohui Sun
- Beijing Key Laboratory of Environmental & Viral Oncology, Faculty of Environment & Life, Beijing University of Technology, Beijing 100124, China
| | - Na Zhang
- Beijing Key Laboratory of Environmental & Viral Oncology, Faculty of Environment & Life, Beijing University of Technology, Beijing 100124, China
| | - Ting Ren
- Beijing Key Laboratory of Environmental & Viral Oncology, Faculty of Environment & Life, Beijing University of Technology, Beijing 100124, China
| | - Lijiao Zhao
- Beijing Key Laboratory of Environmental & Viral Oncology, Faculty of Environment & Life, Beijing University of Technology, Beijing 100124, China.
| | - Rugang Zhong
- Beijing Key Laboratory of Environmental & Viral Oncology, Faculty of Environment & Life, Beijing University of Technology, Beijing 100124, China
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Yamaguchi Y, Fukunaga Y, Takagi M, Saito T, Tamura K, Hoshiya T. Time-course changes in 5-fluorouracil-induced neural progenitor cell damages in the developing rat brain. J Toxicol Pathol 2021; 34:299-308. [PMID: 34621107 PMCID: PMC8484929 DOI: 10.1293/tox.2020-0070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2020] [Accepted: 05/11/2021] [Indexed: 11/19/2022] Open
Abstract
5-Fluorouracil (5-Fu) is a DNA-damaging agent and teratogenic in rodents. This study
aimed to investigate its influence on neural progenitor cells (NPCs) in the developing
fetal rat brain. Dams were intraperitoneally injected with 5-Fu (50 mg/kg b.w.) on
gestation day 13 and its effects on fetal NPCs were observed from 3 to 72 hours after
treatment (HAT), via periodic examination at six intervals. In NPCs of the fetal brain,
the p53-labeling index (LI%) was markedly elevated at 3 HAT. Pyknosis and cleaved
caspase-3-LI% also increased at 3 HAT, reaching peak values at 9 and 12 HAT. These
parallel changes suggested the induction of apoptosis through a p53-mediated pathway.
Pyknotic NPCs were distributed across the ventricular zone (VZ) of the telencephalic wall
until 12 HAT, and became localized in the medial and dorsal layers at 12 and 48 HAT.
Significant decreases in the numbers of mitotic NPCs and BrdU-LI% were noted from 3 HAT
and 24 HAT, respectively. BrdU-positive NPCs were located in the ventral and middle layer
at 24 and 48 HAT. p21-positive cells were detected at 12 and 24 HAT. The present results
demonstrated that p53-mediated apoptosis was induced in all phases of the cell cycle of
the NPCs in the early stage after 5-FU treatment. Furthermore, apoptosis of NPCs and
suppression of cell proliferative activity are the events that take place in parallel
leading to prominent reduction in the width of the telencephalic wall.
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Affiliation(s)
- Yuko Yamaguchi
- Pathology Division, Gotemba Laboratories, BoZo Research Center Inc, 1284 Kamado, Gotemba, Shizuoka 412-0039, Japan
| | - Yachiyo Fukunaga
- Pathology Division, Gotemba Laboratories, BoZo Research Center Inc, 1284 Kamado, Gotemba, Shizuoka 412-0039, Japan
| | - Mizuho Takagi
- Pathology Division, Gotemba Laboratories, BoZo Research Center Inc, 1284 Kamado, Gotemba, Shizuoka 412-0039, Japan
| | - Tsubasa Saito
- Pathology Division, Gotemba Laboratories, BoZo Research Center Inc, 1284 Kamado, Gotemba, Shizuoka 412-0039, Japan
| | - Kazutoshi Tamura
- Pathology Division, Gotemba Laboratories, BoZo Research Center Inc, 1284 Kamado, Gotemba, Shizuoka 412-0039, Japan
| | - Toru Hoshiya
- Pathology Division, Gotemba Laboratories, BoZo Research Center Inc, 1284 Kamado, Gotemba, Shizuoka 412-0039, Japan
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Molina V, Rodríguez-Vázquez L, Martí J. Patterns of Apoptosis and Autophagy Activation After Hydroxyurea Exposure in the Rat Cerebellar External Granular Layer: an Immunoperoxidase and Ultrastructural Analysis. Neurotox Res 2019; 37:93-99. [DOI: 10.1007/s12640-019-00094-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Revised: 07/24/2019] [Accepted: 07/30/2019] [Indexed: 12/14/2022]
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Hydroxyurea Exposure and Development of the Cerebellar External Granular Layer: Effects on Granule Cell Precursors, Bergmann Glial and Microglial Cells. Neurotox Res 2018; 35:387-400. [PMID: 30276718 DOI: 10.1007/s12640-018-9964-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Revised: 09/17/2018] [Accepted: 09/21/2018] [Indexed: 12/20/2022]
Abstract
The current paper presents a histological analysis of the cell death in the cerebellar external granular layer (EGL) following the treatment with a single dose (2 mg/g) of hydroxyurea (HU). The rats were examined at postnatal days (P) 5, 10, and 15, and sacrificed at appropriate times ranging from 6 to 48 h after treatment administration. Studies were done in each cortical lobe (anterior, central, posterior, and inferior). The quantification of several parameters, such as density of 5-bromo-2'-deoxyuridine, TUNEL, vimentin, and tomato lectin-stained cells, revealed that HU compromises the viability of EGL cells. Our results indicate that P10 is a time of high vulnerability to injury. We also show here that the anterior and central lobes are the cortical regions most susceptible to the action of the HU. Additionally, our data also indicate that from 6 to 24 h after HU-exposure is a time-window of high sensibility to this agent. On the other hand, our ultrastructural analysis confirmed that HU administration produces the activation of apoptotic cellular events in the EGL, resulting in a substantial number of dying cells. Different stages of apoptosis can be observed in all cortical lobes at all investigated postnatal ages and survival times. Moreover, we observed that dying neuroblasts were covered by laminar processes of Bergmann glia, and that these unipolar astrocytes presented cytological features of phagocytes engulfing apoptotic bodies and cell debris. The electron microscopy study also revealed the participation of ameboid microglial cells in the phagocytosis of apoptotic cells in the regions of the EGL with extensive cell death.
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Rodríguez-Vázquez L, Martí J. Effects of Hydroxyurea Exposure on the Rat Cerebellar Neuroepithelium: an Immunohistochemical and Electron Microscopic Study Along the Anteroposterior and Mediolateral Axes. Neurotox Res 2017; 32:671-682. [PMID: 28744838 DOI: 10.1007/s12640-017-9785-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Revised: 07/11/2017] [Accepted: 07/12/2017] [Indexed: 12/31/2022]
Abstract
We present a histological study of the cell death of cerebellar neuroepithelial neuroblasts following treatment with the cytotoxic agent hydroxyurea (HU) during the embryonic life. Pregnant rats were treated with a single dose of HU (300 mg/kg) at embryonic days 13, 14, or 15 of gestation, and their fetuses were studied from 5 to 35 h after treatment to elucidate the mechanisms of HU-induced fetotoxicity. Quantification of several parameters such as the density of pyknotic, mitotic, and PCNA-immunoreactive cells indicated that HU compromises the survival of the cerebellar neuroepithelium neuroblasts. On the other hand, our light and electron microscopic investigations during the course of prenatal development indicated that HU leads to two types of cell death: apoptosis and cells presenting cytoplasmic vacuolization, altered organelles, and a recognizable cell nucleus. Both modalities of cell death resulted in a substantial loss of cerebellar neuroepithelium cells. Current results suggest that HU exposure during gestation is toxic to the cerebellar neuroepithelium. Moreover, they allow to examine the mechanisms of HU-induced toxicity during the early development of the central nervous system. Our data also suggest that it is essential to avoid underestimating the adverse effects of HU when administered during early prenatal life.
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Affiliation(s)
- Lucía Rodríguez-Vázquez
- Unidad de Citología e Histología, Facultad de Biociencias, Universidad Autónoma de Barcelona, 08193 Bellaterra, Barcelona, Spain
| | - Joaquín Martí
- Unidad de Citología e Histología, Facultad de Biociencias, Universidad Autónoma de Barcelona, 08193 Bellaterra, Barcelona, Spain.
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Wang Y, Hilton BA, Cui K, Zhu MY. Effects of Antidepressants on DSP4/CPT-Induced DNA Damage Response in Neuroblastoma SH-SY5Y Cells. Neurotox Res 2015; 28:154-70. [PMID: 26038195 DOI: 10.1007/s12640-015-9534-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Revised: 05/19/2015] [Accepted: 05/20/2015] [Indexed: 12/16/2022]
Abstract
DNA damage is a form of cell stress and injury. Increased systemic DNA damage is related to the pathogenic development of neurodegenerative diseases. Depression occurs in a relatively high percentage of patients suffering from degenerative diseases, for whom antidepressants are often used to relieve depressive symptoms. However, few studies have attempted to elucidate why different groups of antidepressants have similar effects on relieving symptoms of depression. Previously, we demonstrated that neurotoxins N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP4)- and camptothecin (CPT) induced the DNA damage response in SH-SY5Y cells, and DSP4 caused cell cycle arrest which was predominately in the S-phase. The present study shows that CPT treatment also resulted in similar cell cycle arrest. Some classic antidepressants could reduce the DNA damage response induced by DSP4 or CPT in SH-SY5Y cells. Cell viability examination demonstrated that both DSP4 and CPT caused cell death, which was prevented by spontaneous administration of some tested antidepressants. Flow cytometric analysis demonstrated that a majority of the tested antidepressants protect cells from being arrested in S-phase. These results suggest that blocking the DNA damage response may be an important pharmacologic characteristic of antidepressants. Exploring the underlying mechanisms may allow for advances in the effort to improve therapeutic strategies for depression appearing in degenerative and psychiatric diseases.
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Affiliation(s)
- Yan Wang
- Department of Biomedical Sciences, Quillen College of Medicine, East Tennessee State University, Johnson City, TN, 37604, USA
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Human Stem/Progenitor Cell-Based Assays for Neurodevelopmental Toxicity Testing. METHODS IN PHARMACOLOGY AND TOXICOLOGY 2014. [DOI: 10.1007/978-1-4939-0521-8_16] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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10
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Defects in base excision repair sensitize cells to manganese in S. cerevisiae. BIOMED RESEARCH INTERNATIONAL 2013; 2013:295635. [PMID: 24282812 PMCID: PMC3825218 DOI: 10.1155/2013/295635] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Accepted: 09/10/2013] [Indexed: 11/18/2022]
Abstract
Manganese (Mn) is essential for normal physiologic functioning; therefore, deficiencies and excess intake of manganese can result in disease. In humans, prolonged exposure to manganese causes neurotoxicity characterized by Parkinson-like symptoms. Mn(2+) has been shown to mediate DNA damage possibly through the generation of reactive oxygen species. In a recent publication, we showed that Mn induced oxidative DNA damage and caused lesions in thymines. This study further investigates the mechanisms by which cells process Mn(2+)-mediated DNA damage using the yeast S. cerevisiae. The strains most sensitive to Mn(2+) were those defective in base excision repair, glutathione synthesis, and superoxide dismutase mutants. Mn(2+) caused a dose-dependent increase in the accumulation of mutations using the CAN1 and lys2-10A mutator assays. The spectrum of CAN1 mutants indicates that exposure to Mn results in accumulation of base substitutions and frameshift mutations. The sensitivity of cells to Mn(2+) as well as its mutagenic effect was reduced by N-acetylcysteine, glutathione, and Mg(2+). These data suggest that Mn(2+) causes oxidative DNA damage that requires base excision repair for processing and that Mn interferes with polymerase fidelity. The status of base excision repair may provide a biomarker for the sensitivity of individuals to manganese.
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Sun J, Sugiyama A, Inoue S, Takeuchi T, Furukawa S. Effect of methotrexate on neuroepithelium in the rat fetal brain. J Vet Med Sci 2013; 76:347-54. [PMID: 24200895 PMCID: PMC4013360 DOI: 10.1292/jvms.13-0457] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Pregnant rats were treated with 30 mg/kg of methotrexate (MTX) on gestation day
13, and fetal brains were examined histopathologically from 6 to 48 hr after the
treatment. In the telencephalon of the control group, there were few pyknotic
neuroepithelial cells throughout the experimental period. Six hr after MTX treatment,
several pyknotic neuroepithelial cells scattered throughout the telencephalic wall. At
12–36 hr, pyknotic neuroepithelial cells increased significantly and were diffusely
distributed throughout the telencephalic wall. Neuroepithelial cells were eliminated and
showed sparse cell density at 36 hr in the telencephalon. Almost all fetuses died at 48
hr. Most of the pyknotic neuroepithelial cells were positively stained by the TUNEL method
and positive for cleaved caspase-3. While mitotic and phospho-histone H3-positive
neuroepithelial cells were located along the ventricular layer of telencephalon in the
control group, they were rarely observed in the same region at 6–36 hr in the MTX-treated
group. MTX induced few pyknotic changes to neuroepithelial cells in the metencephalon,
compared to other parts of brain. The distribution of apoptotic neuroepithelial cells and
the time-course changes of the indices of apoptotic and mitotic neuroepithelial cells were
different from those of other DNA-damaging chemicals reported previously. The difference
may reflect the disparity in mechanisms of apoptosis and the inhibition of cell
proliferation in neuroepithelial cells induced by MTX. To our knowledge, this is the first
report demonstrating histopathological findings of fetal brain damage induced by MTX.
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Affiliation(s)
- Jing Sun
- Courses of Veterinary Laboratory Medicine, School of Veterinary Medicine, Faculty of Agriculture, Tottori University, 4-101 Koyama-cho Minami, Tottori, Tottori 680-8553, Japan
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Ohira T, Ando R, Saito T, Yahata M, Oshima Y, Tamura K. Busulfan-induced pathological changes of the cerebellar development in infant rats. ACTA ACUST UNITED AC 2012; 65:789-97. [PMID: 23276622 DOI: 10.1016/j.etp.2012.11.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2012] [Revised: 10/18/2012] [Accepted: 11/22/2012] [Indexed: 11/17/2022]
Abstract
Busulfan, an antineoplastic bifunctional-alkylating agent, is known to induce developmental anomalies and fetal neurotoxicity. We previously reported that busulfan induced p53-dependent neural progenitor cell apoptosis in fetal rat brain (Ohira et al., 2012). The present study was carried out to clarify the characteristics and sequence of busulfan-induced pathological changes in infant rat brain. Six-day-old male infant rats were treated with 10, 20, 30 or 50 mg/kg of busulfan, and their brains were examined at 1, 2, 4, 7, and 14 days after treatment (DAT). As a result, histopathological changes were selectively detected in the external granular layer (EGL), deep cerebellar nuclei (DCN) and cerebellar white matter (CWM) in the cerebellum with dose-dependent severity but not in the cerebrum. In the normal infant rat cerebellum, granular cells in the EGL were proliferating and moving to the internal granular layer during the normal developmental process. In the EGL of the busulfan group, apoptotic granular cells increased at 2 DAT simultaneously with increased numbers of p53- and p21-positive cells while mitotic granular cells decreased, suggesting an occurrence of p53-related apoptosis and depression of proliferative activity in granular cells. In the DCN, apoptotic glial cells increased at 2 DAT and glial cells showing abnormal mitosis increased at 4 DAT. In the CWN, edematous change accompanying a few apoptotic cells was found in the CWN, especially in the parafolliculus (PFL), from 2 to 7 DAT. The present study demonstrated for the first time the characteristics and sequence of busulfan-induced pathological changes in infant rat cerebellum.
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Affiliation(s)
- Toko Ohira
- Gotemba Laboratories, Biology and Zoology Research Center Inc., 1284, Kamado, Gotemba, Shizuoka 412-0039, Japan.
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