抄録
Group I metabotropic glutamate receptors (mGluRs) are coupled to phosphoinositide hydrolysis and are thought to modulate neuronal excitability by mobilizing intracellular Ca2+. Difference in Ca2+ mobilization among subclasses of the receptors has been reported and this difference may cause various neuronal modifications. In hippocampal interneurons, several subclasses of mGluRs including type I mGluRs (mGluR1 and mGluR5) have been immunohistochemically identified. The subclass-specific physiological effects of mGluRs on hippocampal synaptic transmission, however, have not been fully determined. In present study, effects of type I mGluR agonist, DHPG on intracellular Ca2+ concentrations ware examined in hippocampal nonprincipal cells. Calcium imaging was performed using acute slices of rat hippocampus. Both transient and oscillatory intracellular calcium elevations were detected after DHPG administration. The calcium elevations were partially inhibited by mGluR1 specific antagonist, CPCCOEt or mGluR5-specific antagonist MPEP. Electrophysiological recording was also performed. GABAA receptor-mediated inhibitory postsynaptic currents (IPSCs) were recorded from CA3 pyramidal neurons, by patch-clamp recording method. Perfusion of DHPG facilitated GABAAergic spontaneous IPSCs. Degree of contribution of mGluR1 and mGluR5 mediated signal transduction to the IPSC suppression was also determined. [J Physiol Sci. 2007;57 Suppl:S145]
