抄録
We have previously reported that a phospholipase A2 (PLA2) activator melittin enhances excitatory and inhibitory synaptic transmission in substantia gelatinosa (SG) neurons of adult rat spinal cord slices. The present study examined a detail of a difference in pharmacology between the melittin-induced enhancements of glycinergic and GABAergic spontaneous inhibitory postsynaptic currents (sIPSCs) recorded at 0 mV by using the whole-cell patch-clamp technique. The enhancements of the frequency and the amplitude of GABAergic but not glycinergic sIPSC produced by melittin (1 μM) superfused for 3 min were largely reduced in extent in the presence of a Na+-channel blocker tetrodotoxin (0.5 μM). The effects of melittin on glycinergic sIPSCs were also resistant to a non-NMDA receptor antagonist CNQX (10 μM) while being depressed to a great extent by a PLA2 inhibitor 4-bromophenacyl bromide (10-50 μM). These effects of melittin on glycinergic sIPSC amplitude and frequency were dose-dependent with EC50 values of about 0.7 μM. These results indicate that PLA2 activation results in enhancing GABAergic and glycinergic transmission in a different manner in such that the former but not latter effect is possibly mediated by the enhancement of excitatory transmission by PLA2 activation which is followed by the release of neuromodulators such as acetylcholine and norepinephrine involved in enhancing GABAergic transmission. [J Physiol Sci. 2007;57 Suppl:S148]
