Cytological mechanism of epileptoid activities of rats hippocampus pyramidal cells induced by low dose of veratrine / 解放军医学杂志

ABSTRACT

Objective To observe the effects of low dose of veratrine on the discharges of rat hippocampus pyramidal neurons,and to elucidate its possible cytological mechanism.Methods The discharge features of hippocampus CA1 pyramidal neurons of 14-day-aged healthy Sprague-Dawley rats induced by low dose(0.3～0.8?mol/L)of veratrine were observed by slice patch-clamp technique.Presynap- tic stimulation was given to Schaffer collaterals.Presynaptic receptor inhibitors such as 6-cyano-7-nitroquinoxaline-2,3-dione(CNQX, 5?mol/L),DL-2-amino-5-phosphonopentanoic acid(AP-5,12.5?mol/L),bicuculline(Bic,10?mol/L)and tetrodotoxin(TTX,40～80nmol/L)were used to investigate the influence on veratrine-induced epilepsy andⅠ-Ⅴcurves were plotted under these conditions.Elec- trophysiological mechanism of veratrine-induced epilepsy was elucidated on the basis of these experiments,Results After a perfusion with low dose of veratrine,the pyramidal neurons were found to discharge relatively fixed-mode slow wave epileptoid bursts accompanied with hyperpolarization of membrane potential.These epileptoid bursts were not blocked by a mixture of CNQX,AP-5 and Bic,but by low dose of TTX.After a perfusion with veratrine,Ⅰ-Ⅴrelationship tended to be nonlinear and the depolarization rectification was enhanced,which were reversed by administration of low dose of TTX.The subthreshold TTX-sensitive persistent sodium current of CA1 pyramidal cells was enhanced by veratrine in a voltage-dependent manner.Conclusion Inducing slow wave epileptoid bursts,the low dose of veratrine can remarkably change the discharge features of CA1 pyramidal neurons.Such epileptoid activities were not influenced by the synaptic receptor inhibitors,and were obviously related to the persistent sodium current.