Abstract
We previously reported the negative interaction between excitatory P2X receptor (P2XR)- and nicotinic ACh receptor-channels in rat area postrema (AP) neurons. We now investigated whether there was also the interaction between excitatory P2XR and inhibitory GABAA- or glycine-receptors (GlyR). At a holding potential of -70mV, the amplitude of the GABA- or Gly-induced current was significantly reduced in the presence of ATP, and there was an inverse correlation between the amplitudes of these responses. On the other hand, the ATP-induced current in the presence of GABA or Gly was only slightly reduced. As the GABA- or Gly-induced current desensitizes faster than the ATP-induced current, the weaker inhibition of the ATP-induced current by GABA or Gly could be due to the reduced amplitude of the GABA- or Gly-induced current at the time of ATP application. In fact, the current caused by the concomitant applications of ATP and GABA or Gly was smaller than the predicted sum of the individual currents.These results suggest that the negative interactions between the different receptors modify the strength of excitatory or inhibitory neurotransmission when plural transmitters are simultaneously released from presynaptic nerve terminals. [J Physiol Sci. 2006;56 Suppl:S155]
