Abstract
The periaqueductal gray matter (PAG) has been identified as the main structure of the supraspinal pain modulation. Accumulating evidence shows that GABAergic and serotoninergic neurons in the PAG have an important role in the pain modulation. The aim of this report is to characterize glutamatergic synaptic transmission in neurons involving serotonin and/or GABA, and plastic changes of this neuronal network by neuropathic pain. We used the control ICR mouse and the mouse with partial ligation of the sciatic nerve. The synaptic current of the ventrolateral PAG (vlPAG) neurons were recorded to find NADA receptor mediated current and AMPA receptor mediated current using the whole cell patch-clamp recording technique, and then the mRNA for neurotransmitter expressed in the recorded neurons were detected using single cell RT-PCR technique. Within neuronal group not containing serotonin in the normal mouse, NMDA receptor mediated currents of GABAergic neurons were significantly larger than those of non-GABAergic neurons. There was a tendency that NMDA receptor mediated currents of neurons in the ligated mouse were larger than those of the normal mouse. These results suggest that NMDA component of the glutamatergic synaptic current is different between neurons with different transmitters and that during neuropathic pain NMDA component of the glutamatergic synaptic current increases in the vlPAG. [J Physiol Sci. 2008;58 Suppl:S131]
