抄録
We have recently reported that there exist regional differences of benzodiazepine effects in GABA-mediated inhibitory synaptic transmission in vitro studies. In this study, we examined the effects of propofol, one of the most popular intravenous anesthetic agents, on the inhibitory postsynaptic currents (IPSCs) in CA1 pyramidal cells (CA1-PCs) and dentate gyrus granule cells (DG-GCs) in rat hippocampal slices. The monosynaptic IPSCs were evoked by electrical stimulation of GABAergic interneurons and recorded from CA1-PCs and DG-GCs by whole cell patch-clamp technique. The effects of specific concentrations of propofol (0.1, 1, 10 and 100μM) on the IPSCs in CA1-PCs and DG-GCs were examined at varying membrane potentials (20 mV steps, from -120 to +40 mV). In the absence of propofol, at the clamped membrane potential of-120mV and +40mV, IPSC amplitudes and decay time constants in both CA1-PCs and DG-GCs were kept stable for at least 20 minutes. When tested within this stable period, propofol was observed to increase the amplitudes and prolonged the decay time constant of IPSCs in CA1-PCs. However, propofol changed neither the amplitude nor decay time constant of the IPSCs in DG-GCs. These results suggest that propofol possesses differential effects on IPSCs in CA1-PCs and DG-GCs similar to benzodiazepines. The mechanism for these differential effects could be due to the different sensitivity to propofol of the GABAAreceptor subtypes in the CA1-PCs and DG-GCs. [J Physiol Sci. 2006;56 Suppl:S165]
