[Effect of cerebral X-ray irradiation on learning and memory function in young SD rats].
To investigate the effect of cerebral X-ray irradiation on learning and memory function in young rats.



Fifty-four SD rats aged 35 d were randomly divided into 3 groups with 18 in each group: rats in 3-d group and 7-d group received X-ray irradiation with a dose of 28.5 mGy/d for 3 d and 7 d, respectively; rats in control group received sham X-ray irradiation. Morris water maze (MWM) was tested when animals at age of 60 d; then the animals were sacrificed and brain samples were taken. The neurodegeneration was observed by Fluro-Jade B staining; the expression of N-methyl-aspartate (NMDA) receptors subunit 2B (NR2B) and postsynaptic density protein-95 (PSD-95) in the hippocampus were analyzed by immunofluorescence and Western blot methods, respectively, and ultrastructure of CA1 region was observed with electron microscopy.



No significant difference in 1-4 d escape latency as shown in MWM test was noted between 3d group and control group (P>0.05); while the escape latency in 7d group was significantly longer than that in control group (P<0.01). No significant differences in lingering in the quadrant and the frequency of passing through the original platform between 3-d group and control group (P>0.05), while those in 7-d group were significantly lower than those in control group (P<0.01). Compared to control group, the number of FJB positive cells in 7-d group was increased (P<0.01); the expressions of NR2B and PSD-95 in hippocampus CA1 region were also increased (P<0.05). The ultrastructure observation in 7-d group showed that the synapse structure of some neurons was impaired.



X-ray irradiation may affect learning and memory function of young rats, which is associated with overexpression of NR2B and PSD-95 in hippocampal regions.
Department of Nuclear Medicine， Dongyang People's Hospital， Dongyang 322100， China.
Zhan-xiong
ZX
Yi
Department of Radiology， Tongji Hospital of Tongji University， Shanghai 200065， China.
Wei
W
Zhang
D000818:Animals; D001921:Brain / Q000528:radiation effects*; D056547:CA1 Region, Hippocampal / Q000378:metabolism / Q000528:radiation effects; D000076122:Disks Large Homolog 4 Protein; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D007858:Learning / Q000528:radiation effects*; D008565:Membrane Proteins / Q000378:metabolism; D008568:Memory / Q000528:radiation effects*; D009474:Neurons; D051381:Rats; D017207:Rats, Sprague-Dawley; D016194:Receptors, N-Methyl-D-Aspartate / Q000378:metabolism; D013569:Synapses; D014965:X-Rays
D000076122:Disks Large Homolog 4 Protein; C501449:Dlg4 protein, rat; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; C121001:NR2B NMDA receptor; D016194:Receptors, N-Methyl-D-Aspartate