Ionizing radiation and the developing brain

Schull, William J.; Norton, Stata; Jensh, Ronald P.

doi:10.1016/0892-0362(90)90096-u

Cited by 99 publications

(39 citation statements)

References 43 publications

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“…The suggestion of a linear relationship between dose and effect appears consistent with some interpretations of the data for radiation-induced mental retardation in man (Schull et al 1990) and with the results of morphological and behavioural studies with rats and mice . In particular, Konermann (1986Konermann ( , 1987Konermann ( , 1989 has described a linear dose-response relationship for the effects of X-rays on various indices of neuronal development and maturation of the cerebral cortex and hippocampus of the albino inbred mouse, and for reductions in the diameter of the fimbria hippocampi and other structures following irradiation at between 0-05 and 1 .…”

Section: Discussionsupporting

confidence: 70%

Prenatal Irradiation and Spatial Memory in Mice: Investigation of Dose-response Relationship

Sienkiewicz¹,

Haylock²,

Saunders³

1994

International Journal of Radiation Biology

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Pregnant CD1 mice were exposed on gestational day 18 to 250 kV X-rays at 0.1, 0.25, 0.35 and 0.5 Gy. The performances of 10 adult male offspring from each exposure condition were investigated on a spatial discrimination learning task in a radial arm maze. An impairment in the performance of this task was found which showed a correlation with dose. Compared with sham exposed control mice, performance was not significantly affected with irradiation at 0.1 Gy and was slightly but non-significantly reduced at 0.25 Gy. Irradiation at 0.35 Gy caused a significant impairment in performance, and exposure at 0.5 Gy resulted in a still larger impairment. The overall association between dose and behavioural impairment was best described by a linear relationship without a threshold, although at doses lower than about 0.25 Gy any impairment would appear to be too small to be detectable.

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Section: Discussionsupporting

confidence: 70%

Prenatal Irradiation and Spatial Memory in Mice: Investigation of Dose-response Relationship

Sienkiewicz¹,

Haylock²,

Saunders³

1994

International Journal of Radiation Biology

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“…The unique susceptibility of the central nervous system to ionizing radiation exposure has been demonstrated through studies of survivors of the atomic bombing of Hiroshima and Nagasaki and the meltdown of the Chernobyl nuclear power plant in 1986 [Yamazaki and Schull, 1990;Schull et al, 1990;Otake and Schull, 1998;Kolominsky, 1999]. Brain injury resulting in microcephaly and mental retardation occurred in infants born to mothers who were within 2000 meters of the site of the detonation of the bomb.…”

Section: Other Neurotoxicantsmentioning

confidence: 97%

Environmental factors associated with a spectrum of neurodevelopmental deficits

Mendola

Selevan

Gutter

et al. 2002

Ment. Retard. Dev. Disabil. Res. Rev.

247

130

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A number of environmental agents have been shown to demonstrate neurotoxic effects either in human or laboratory animal studies. Critical windows of vulnerability to the effects of these agents occur both pre- and postnatally. The nervous system is relatively unique in that different parts are responsible for different functional domains, and these develop at different times (e.g., motor control, sensory, intelligence and attention). In addition, the many cell types in the brain have different windows of vulnerability with varying sensitivities to environmental agents. This review focuses on two environmental agents, lead and methylmercury, to illustrate the neurobehavioral and cognitive effects that can result from early life exposures. Special attention is paid to distinguishing between the effects detected following episodes of poisoning and those detected following lower dose exposures. Perinatal and childhood exposure to high doses of lead results in encephalopathy and convulsions. Lower-dose lead exposures have been associated with impairment in intellectual function and attention. At high levels of prenatal exposure, methylmercury produces mental retardation, cerebral palsy and visual and auditory deficits in children of exposed mothers. At lower levels of methylmercury exposure, the effects in children have been more subtle. Other environmental neurotoxicants that have been shown to produce developmental neurotoxicity include polychlorinated biphenyls (PCBs), dioxins, pesticides, ionizing radiation, environmental tobacco smoke, and maternal use of alcohol, tobacco, marijuana and cocaine. Exposure to environmental agents with neurotoxic effects can result in a spectrum of adverse outcomes from severe mental retardation and disability to more subtle changes in function depending on the timing and dose of the chemical agent.

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“…Because toxic agents that lead to migration failure are often known to interfere with proliferation as well, it has been difficult to determine whether there are agents that affect migration exclusively, or whether migration failures result when cells are lost, changing the environment of the cells that form later. Ionizing radiation (13) and methylmercury (14,15) provide examples of the dual effect on cell survival and migration. In any case, neurons that are out of position cannot make the proper connections with the neurons that should be their neighbors, so they cannot develop normal function.…”

Section: Cell Migrationmentioning

confidence: 99%

Developing brain as a target of toxicity.

Rodier

1995

Environ Health Perspect

309

147

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The human brain forms over an unusually long period compared to other organs. While most of the basic structure is laid down before birth, neuron proliferation and migration continue in the postnatal period. The blood-brain barrier is not fully developed until the middle of the first year of life. The number of synaptic connections between neurons reaches a peak around age two and is then trimmed back by about half. Similarly, there is great postnatal activity in the development of receptors and transmitter systems as well as in the production of myelin. Many of the toxic agents known to damage the developing brain interfere with one or more of these developmental processes. Those with antimitotic action, such as X-ray and methyl mercury, have distinctly different effects on structure depending on which neurons are forming at the time of exposure. Vulnerability to agents that interfere with cell production decreases rapidly over the early postnatal period. Other toxic substances, such as psychoactive drugs and agents that alter hormone levels, are especially hazardous during synaptogenesis and the development of transmitter systems, and thus continue to be damaging for years after birth. Still other toxic substances such as lead, seem to have their greatest effects during even later stages of brain development, perhaps by interfering with the trimming back of connections. Guidelines designed to protect human populations from developmental neurotoxicity need to take into account the changing sensitivity of the brain as it passes through different developmental stages, as well as the fundamental differences in the effects of toxicants on the mature and the developing brain. -Environ Health Perspect 1 03(Suppl 6): 73-76 (1995)

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Ionizing radiation and the developing brain

Cited by 99 publications

References 43 publications

Prenatal Irradiation and Spatial Memory in Mice: Investigation of Dose-response Relationship

Prenatal Irradiation and Spatial Memory in Mice: Investigation of Dose-response Relationship

Environmental factors associated with a spectrum of neurodevelopmental deficits

Developing brain as a target of toxicity.

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