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Prenatal irradiation: a major concern for the developing brain
1Department of Radiation Oncology, University of Kansas Medical Center, Kansas City 66160-7321, USA.
Insights
Fetal irradiation can cause developmental issues and brain damage, even at low doses. Rodent studies reveal how prenatal radiation exposure impacts brain structure and behavior postnatally.
Area of Science:
- Neuroscience
- Developmental Biology
- Radiation Biology
Background:
- Prenatal irradiation causes congenital abnormalities and developmental deficits in mammals.
- The developing brain is highly susceptible to radiation, leading to decreased size, behavioral changes, and mental retardation.
- Rodent models are crucial for understanding low-dose prenatal irradiation effects on the developing neocortex.
Purpose of the Study:
- Investigate mechanisms of radiation-induced brain damage in developing mammals.
- Determine dose-response relationships and threshold doses for prenatal irradiation effects.
- Extrapolate findings to human risk assessment for fetal radiation exposure.
Main Methods:
- Utilized rodent models to study effects of varying radiation doses and gestational timing.
- Examined physical parameters (dose, LET, dose rate) and biological factors (species, age).
- Correlated acute cellular responses (0-24h post-irradiation) with postnatal structural and functional deficits.
Main Results:
- Low-dose prenatal irradiation can cause significant postnatal brain structural and functional alterations.
- Specific cellular responses in the neocortex correlate with observed behavioral aberrations.
- Thinning of cerebral cortex layers is linked to specific behavioral deficits, enabling predictive correlations.
Conclusions:
- Prenatal radiation exposure can disrupt programmed brain development, leading to postnatal delays and behavioral issues.
- Identified sensitive cellular targets and mechanisms underlying radiation-induced fetal brain damage.
- Established correlations between in utero cellular damage and postnatal neurodevelopmental outcomes.
Abstract:
Irradiation of the mammalian foetus produces a broad spectrum of congenital abnormalities, growth retardations, developmental delays, and functional deficits, depending upon the dose and the specific gestational phase of irradiation. The developing brain is particularly susceptible to production of deleterious effects, with decreased brain size, behavioural alterations, and mental retardation having been documented. Supplementing the limited human data, rodent models have been extensively used to investigate the specific processes by which relatively low doses, with correspondingly minor cellular damage to the developing neocortex, can produce dramatic postnatal consequences in brain structure and function. The effects of a variety of physical (dose, linear energy transfer, dose rate, fractionation) and biological (species, strain, gestational age, time course post-irradiation) parameters have been examined in an attempt to provide much needed information on such critical aspects as dose response, threshold doses for effect, and extrapolation to human risk estimates. Various acute cellular responses (e.g. appearance of pyknotic cells and macrophages) observed in the developing neocortex 0-24 h after in utero irradiation can be associated with postnatal effects. Moreover, it is possible to correlate thinning of specific layers of the cerebral cortex with specific behavioural aberrations, allowing prediction of brain structural changes from functional alterations, and vice versa. Thus, it is possible to speculate as to the mechanisms and targets for extremely sensitive, radiation-induced cellular damage in the developing foetal brain, that will interfere with the orderly and precisely programmed development of the mammalian brain, leading finally to postnatal expression as delays in growth and development, perturbations in behaviour, and alterations in brain structure.