[REVIEW ARTICLE]Radiation-Induced Apoptosis in Undifferentiated Cells of the Devleloping Brain as a Biological Defense Mechanism

概要

論文の詳細を見る
Undifferentiated neural cells of the developing mammalian brain are highly sensitive to the lethal effects of ionizing radiation. Nuclear and cytoplasmic condensation, transglutaminase activation, required macromolecular synthesis, and internucleosomal DNA cleavage all reveal radiation-induced cell death in the ventricular zone of the cerebral mantle and external granular layer of the cerebellum to be due to apoptosis. A statistically significant increase of cell mortality can be induced by as low a dose as 0.03 Gy X-irradiation, and the mortality increases linearly with increasing doses. It is not changed by split doses, probably because of the very slow repair of cellular damage and a lack of adaptive response. Although extensive apoptosis in the undifferentiated neural-cell population results in microcephaly and mental retardation, it nevertheless possesses the ability to recover from a considerable cell loss and to form the normal structure of the central nervous system. The number of cell deaths needed to induce tissue adnormalities in the adult murine brain rises in the range of 15-25% of the germinal cell population; with the threshoud doses at about 0.3 Gy for cerebral anomalies and 1 Gy for cerebellar abnormalities. As similar threshold level is suggested in human cases of prenatal exposure to the atomic bombings. The high radiosensitivity of undifferentiated cells is assumed to be a manifestation of the ability of the cell to, as it were, commit suicide when injured (Kondo S. Int J Radiat Biol 1988;53: 95-102). Repeated replication of DNA and extensive gene expression are required of undifferentiated cells in future proliferation and differentiation. Once an abnormality in DNA was induced and fixed in an undifferentiated cell, it would be greatly amplified and prove a danger in producing malformations and tumors. These cells would thus commit suicide for the benefit of the individual in order to eliminate thir acquired genetic abnormalities, rather than make a DNA repair, which is rarely complete, and be replaced by healthy pluripotent cells. Undifferentiated neural cells in the developing brain are highly radiosensitive and readily involved in apoptosis. Paradoxically enough however, this may be to protect individuals against teratogenesis and tumorigenesis.
名古屋大学の論文

[REVIEW ARTICLE]Radiation-Induced Apoptosis in Undifferentiated Cells of the Devleloping Brain as a Biological Defense Mechanism

スポンサーリンク

概要

著者

関連論文

スポンサーリンク