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Study of time response of fission neutrons induced apoptosis in murine thymocytes and its molecular mechanism

In English

Författare

  • Bin Yuan
  • Jianmin Sun
  • Chunmei Hou
  • Hongtao Liu
  • Wenchang Xue
  • Liang Li
  • Baoqin Wang

Summary, in English

Objective:To study the time response of fission neutrons induced apoptosis in murine thymocytes with 60 Co γ-rays as the reference radiation and to investigate preliminarily its molecular mechanism. Methods: Apoptosis induction was detected by means of DNA gel electrophoresis, morphologic assay, flow cytometric (FCM) analysis and diphenylamine(DPA) method respectively. p53 and bcl-2 gene expressions were studied by dot hybridization with digoxigenin labeled probes. Results: When mice was exposed to 2.5 Gy of fission neutrons, DNA ladders of thymocytes were detected at different time points during 2-24 hours post-irradiation. Thymocytes with typical morphological characteristics of apoptosis were also observed. Time response curves were obtained with methods of morphologic assay, FCM analysis and DPA method. The percentage of thymocytes undergoing apoptosis steeply increased during the first 6 hours post-irradiation,reached the peak levels at 8-10 hours,began to decrease 12 hours later and significantly decreased by 24 hours as compared with the level at 4-12 hours (P＜0.05)but was still slightly higher than the normal level. Similar curves were obtained by using three different methods. Time response curve after exposure to 5.0 Gy of γ- irradiation was characterized by an initial slow increase in the number of apoptotic thymocytes during the first 6 hours post-irradiation. In addition, DNA ladders were not detected at 24 hours post-irradiation. After exposure to 2.5 Gy of fission neutrons irradiation, p53 gene expression at 2, 4, 12 and 24 hours post-irradiation were obviously higher than in control (P<0.05 or P<0.01),while bcl-2 gene expression at different time points during 2-24 hours post-irradiation decreased obviously (P<0.01)in comparison with non-irradiated control. Conclusions: Apoptosis of murine thymocytes can be induced in mice exposed to 2.5 Gy of fission neutrons. The rules of time response after fission neutrons irradiation for 2.5 Gy is similar to γ-ray irradiation for 5.0 Gy. However,apoptosis induced by fission neutrons irradiation increases were rapidly and lasts longer than that induced by γ-irradiation. These results indicate that damage to murine immune tissues induced by fission neutrons is more severe and difficult for discovery than that induced by γ-rays. The results of examination of gene expression by dot hybridization show that p53 and bcl-2 genes are involved in the regulation of fission neutrons induced apoptosis in thymocytes.

Publiceringsår

2000

Språk

Kinesiska

Sidor

184-184

Publikation/Tidskrift/Serie

Bulletin of Academy of Military Medical Sciences

Volym

24

Dokumenttyp

Artikel i tidskrift

Förlag

Academy of Military Medical Sciences

Ämne

  • Medicinal Chemistry

Nyckelord

  • fission neutron
  • apoptosis
  • thymocyte
  • time response
  • dot hybridization
  • gene expression

Status

Published

ISBN/ISSN/Övrigt

  • ISSN: 1000-5501