V. V. Talko1, K. M. Loganovsky1, I. P. Drozd2, Ye. V. Tukalenko1,3, T. K. Loganovska1,
S. Yu. Nechayev1, S. V. Masiuk1, Ye. M. Prokhorova1
1State Institution «National Research Center for Radiation Medicine of the National Academy of Medical Sciences of Ukraine», Melnykova str., 53, Kyiv, 04050, Ukraine
2Institute of Nuclear Research, National Academy of Sciences of Ukraine, Nauka ave., 47, Kyiv, 03680, Ukraine
3Taras Shevchenko National University of Kyiv, ESC «Institute of Biology and Medicine», 64/13,
Volodymyrska Street, City of Kyiv, 01601, Ukraine
Cerebral impact of prenatal irradiation by 131I: an experimental model of clinical neuroradioembryological effects
Human brain in prenatal period is a most vulnerable to ionizing radiation body structure. Unlike atomic bombings or radiological interventions in healthcare leading at most to external irradiation the intensive internal exposure may occur upon nuclear reactor accidents followed by substantial release and fallout of radioactive 131I. The latter can lead to specific neuroradioembryological effects.
Objective. To create an experimental model of prenatal cerebral radiation effects of 131I in human and to determine the experimental and clinical neuroradioembryological effects.
Study object. The neuroradioembryological effects in Vistar rats exposed to 131I in prenatal period. Nervous system status and mental status in 104 persons exposed to ionizing radiation in utero due to the ChNPP accident and the same in 78 not exposed subjects.
Methods. Experimental i.e. behavioral techniques, including the spontaneous locomotive, exploratory activity and learning ability assessment, clinical i.e. neuropsychiatric, neuro- and psychometric, neuropsychological, neurophysiological methods, both with dosimetric and statistical methods were applied.
Results. Intrauterine irradiation of Wistar rats by 131I was simulated on a model of one-time oral 27.5 kBq radionuclide administration in the mid-gestation period (0.72±0.14 Gy fetal thyroid dose), which provides extrapolation of neuroradioembryological effects in rats to that in humans exposed to intrauterine radiation as a result of the Chornobyl catastrophe. Abnormalities in behavioral reactions and decreased output of conditioned reflex reactions identified in the 10-month-old rats suggest a deterioration of cerebral cognition in exposed animals. Specific cognitive deficit featuring a disharmonic intellectual development through the relatively decreased verbal intelligence versus relative increase of nonverbal one is remained in prenatally exposed persons. This can indicate to dysfunction of cortical-limbic system with especial involvement of a dominant hemisphere hippocampus. Decreased theta-band spectral power (4–7 Hz range) of cerebral bioelectrical activity in the left frontotemporal area is suggestive of hippocampal dysfunction mainly in dominant hemisphere of prenatally irradiated persons. Disorders of hippocampal neurogenesis due to prenatal exposure by radioactive iodine can be a biologic basis here. Innovative approaches in social adaptation, psychoprophylaxis and psychorehabilitation involve the maximum effective application and development of just the most developed psychological and cognitive abilities in survivors.
Key words: 1131I, cerebral prenatal irradiation, neuroradioembryological effects, Chornobyl catastrophe, hippocampal neurogenesis, cortical-limbic system, social adaptation, innovative approaches.
Problems of radiation medicine and radiobiology. 2017;22:238–269.
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