核磁共振磁场照射对子代大鼠海马突触形态的影响

研究观察了孕期磁共振磁场照射对子代大鼠海马突触超微结构的影响。SD孕鼠妊娠第12-18d给予0．35T核磁共振(magnetic resonance imaging,MRI)磁场照射。测量1、2和5月龄雌性仔鼠海马CAl区和齿状回的突触结构参数,用立体计量学方法进行定量测定。结果显示,磁场照射可引起2月龄子代大鼠海马CAl区突触间隙增宽．齿状回突触活性区长度变短、突触界面曲率和活性区面密度减小;5月龄子代大鼠CAl区突触间隙增宽,突触后致密物变薄,突触界面曲率减小,齿状回突触间隙增宽。结果提示,妊娠期接受MRI磁场照射可引起海马突触超微结构的改变。对这些结构变化与行为损害之间的关系进行了讨论。

Morphological alteration of the hippocampal synapses in rats prenatally exposed to magnetic resonance imaging magnetic fields

The present study investigated the effects of prenatal exposure to the magnetic resonance imaging ( MRI) magnetic fields on the synaptic ultrastructure of hippocampal formation of rats at different postnatal development stages. Pregnant rats with gestation of 12-18 days were exposed to the magnetic fields used for MRI clinical applications. When the offspring were 1 , 2, or 5-month-old, the synaptic morphologic parameters were measured in female offspring. In the 2-month-old MRI group, the curvature of synaptic interface, the length of active zone and the surface density per unit volume (Sv) of active zone in the dentate gyrus (DG) decreased significantly, and the width of synaptic cleft increased in the CA1 area. In the 5-month-old MRI group, the width of synaptic cleft increased, the thickness of postsynaptic density and the curvature of synaptic interface decreased significantly in the CA1 region, and the width of synaptic cleft increased in the DG. No significant change was observed in the 1-month-old group. These results suggest that prenatal exposure to the medical magnetic fields causes synaptic ultrastructural changes. The relationship of these changes with behavioral impairments was discussed.