Later life changes in hippocampal neurogenesis and behavioral functions following low dose prenatal irradiation at early organogenesis stage

Publication date: Available online 7 February 2017
Source:International Journal of Radiation Oncology*Biology*Physics
Author(s): Ramya Ganapathi, Kailash Manda
Low-dose in utero irradiation may occur due to unavoidable radiodiagnosis, accidental or workplace exposure. Moderate to high dose of prenatal irradiation is known to cause cytoarchitectural and behavioral changes in the brain. However, very little is known about the prolonged effect of low-dose prenatal irradiation at early organogenesis stage on hippocampal neurogenesis and behavioral functions. The present study is aimed at investigating delayed neurobehavioral changes following low-dose prenatal irradiation. Pregnant C57BL/6J mice were irradiated (20cGy) at day 5.5 post-coitus. The male and female offspring were subjected to the different behavioral assays for affective, motor and cognitive functions at 3, 6 and 12 months of age. Behavioral functions were further correlated with the population of CA1 and CA3 pyramidal neurons and immature neurons in hippocampal dentate gyrus. Prenatally exposed mice of different age groups showed a gender specific pattern of sustained changes in the behavioral functions. Male mice showed significant changes in anxiety-like phenotypes, learning and long-term memory at the age of 3 months. At 6 months of age, such behavioral functions were recovered to normal level but could not sustain at 12 month age. Female mice showed an appreciable recovery in almost all behavioral functions at 12 months. Pattern of changes in learning and long-term memory were comparable to the population of CA1 and CA3 pyramidal neurons and DCX positive neurons in hippocampus. Our finding suggests that prenatal (early organogenesis stage) irradiation even at lower dose level (20cGy) is sufficient to cause potential changes in the neurobehavioral functions at later stage of life. Male mice showed relatively higher vulnerability to radiation-induced neurobehavioral changes as compared to the female.

Teaser

Low-dose in utero irradiation may occur due to unavoidable radiodiagnosis, accidental or workplace exposure. Moderate to high dose of prenatal irradiation is known to cause cytoarchitectural and behavioral changes in the brain. However, very little is known about the prolonged effect of low-dose prenatal irradiation at early organogenesis stage on hippocampal neurogenesis and behavioral functions. The present study is aimed at investigating delayed neurobehavioral changes following low-dose prenatal irradiation.


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