Cranial irradiation alters dendritic spine density and morphology in the young rat hippocampus / 中华放射医学与防护杂志

ABSTRACT

Objective:To explore the changes of dendritic spine morphology and structure in dentate gyrus(DG) and CA1 areas of hippocampus of young rats, so as to provide a direct morphological basis for studying the molecular mechanism of radiation cognitive impairment.Methods:21-day-old Sprague-Dawley (SD) rats were given a single dose of 10 Gy whole brain irradiation. The changes of cognitive function, dendritic spine density and morphological changes in DG and CA1 areas of hippocampus were observed 1 and 3 months after irradiation, and the expression of postsynaptic density protein (PSD95) was detected by Western blot.Results:The cognitive impairment was observed in young rats 3 months after irradiation. The density of dendritic spines in DG area of hippocampus was decreased significantly by 39.06% and 29.27% at 1 and 3 months after irradiation ( t=14.96, 12.35, P<0.05), respectively. The density of dendritic spines in the basal dendrites of hippocampal CA1 area was decreased by 33.40% ( t=10.39, P<0.05) 1 month after irradiation, but had no significant change at 3 months after irradiation. While the density of dendritic spines in the apical dendrites of CA1 region did not change significantly at 1 and 3 months after irradiation. In addition, the morphology of dendritic spines in DG and CA1 regions of hippocampus was dynamically changed after irradiation. The expression of PSD95 protein was decreased by 24.6% and 50.5% ( t=2.97, 9.27, P<0.05) at 1 and 3 months after irradiation, respectively. Conclusions:This study reported the density and morphological changes of dendritic spines in different brain regions of hippocampus of young rats after ionizing radiation, suggesting that PSD95 may participate in the occurrence of radiation-induced cognitive impairment by affecting the structure and morphology of dendritic spines and reducing synaptic plasticity.