Taubøll E, Gjerstad L
Department of Neurology, Rikshospitalet, National Hospital, University of Oslo, Norway.
Epilepsia. 1993 Mar-Apr;34(2):228-35. doi: 10.1111/j.1528-1157.1993.tb02403.x.
The effects of 5 alpha-pregnan-3 alpha-ol-20-one (3 alpha-OH-DHP) and phenobarbital (PB) on synaptic excitation and inhibition in rat hippocampal slices in vitro were compared. Stimulations were made orthodromically and antidromically while we recorded extracellularly from the dendritic and the somatic layer of the CA1 region. Perfusion with 5 micrograms/ml of 3 alpha-OH-DHP for 30 min significantly increased the recurrent inhibition evoked by antidromic stimulation. The effect was most pronounced at short interstimulus intervals. The duration of the recurrent inhibition also was prolonged. There was no effect on the conditioned population spike after orthodromic paired-pulse stimulation. Furthermore, no effect was observed on the amplitude of the orthodromic fiber volley, the rate of increase in the field excitatory postsynaptic potential (EPSP) and the latency and amplitude of the CA1 population spike. Qualitative and quantitative similar findings were observed during perfusion with PB 0.1 mg/ml, (i.e., a concentration 20 times higher than that of 3 alpha-OH-DHP). Higher concentrations of PB also affected synaptic excitation. The findings suggest a similar effect of 3 alpha-OH-DHP and PB on recurrent GABA-ergic inhibition; however, 3 alpha-OH-DHP appears to be much more potent.
比较了5α-孕烷-3α-醇-20-酮（3α-OH-DHP）和苯巴比妥（PB）对体外培养的大鼠海马脑片突触兴奋和抑制的影响。在从CA1区树突层和体细胞层进行细胞外记录时，分别进行顺向刺激和逆向刺激。用5微克/毫升的3α-OH-DHP灌注30分钟可显著增强逆向刺激诱发的反复抑制。该效应在短刺激间隔时最为明显。反复抑制的持续时间也延长。顺向配对脉冲刺激后，对条件性群体峰电位无影响。此外，对顺向纤维群峰电位的幅度、场兴奋性突触后电位（EPSP）的增加速率以及CA1群体峰电位的潜伏期和幅度均无影响。在用0.1毫克/毫升的PB灌注期间观察到了定性和定量相似的结果（即浓度比3α-OH-DHP高20倍）。更高浓度的PB也影响突触兴奋。这些发现表明3α-OH-DHP和PB对反复性GABA能抑制有相似的作用；然而，3α-OH-DHP似乎效力更强。
