Abstract
We investigated the effects of fluid percussion injury (FPI) on the glutamatergic excitatory synaptic transmission of CA1 pyramidal neurons using conventional intracellular recording techniques. A moderate impact (3.8-4.8 atm) was applied to the left hemisphere of the parietal cerebral cortex by using a FPI device (HPD-1700, Dragonfly, Inc.). After a survival period of 7 days, horizontal brain slices containing hippocampus were cut. The slice preparations were devided into three groups (control, FPI-ipsilateral, and FPI-contralateral). The control group includes the data from normal and sham-operated rats. There were no significant differences in resting and acting membrane properties among three groups. However, the EPSPs evoked by stimulations of Schaffer collaterals in the presence of bicuculline showed steeper input-output relationship (I-O) in the FPI-ipsilateral group. The number of spikes evoked by EPSP in the presence of bicuculline was larger in FPI-ipsilateral group although there were no significant differences among three groups in the absence of bicuculline. The paired-pulse facilitation ratio in FPI groups was smaller than that of control group. Frequency of mEPSPs recorded in the presence of tetrodotoxin was higher than that of control while the amplitude of mEPSPs was not different. These results suggest that the post-traumatic facilitation of gultamatergic transmission in pyramidal neurons of rat hippocampal CA1 is mediated by presynaptic origin. [J Physiol Sci. 2006;56 Suppl:S163]
