Effects of microinjection of OFQ into PAG on spinal dorsal horn WDR neurons in rats

The aim of the present study was to examine the effect of microinjection of orphanin FQ (OFQ) into periaqueductal gray (PAG) on sensory processing in the wide dynamic range (WDR) neurons of the spinal dorsal horn and to explo re the effect of OFQ on a descending system of pain modulation. The results show that microinjection of OFQ into ipsilateral PAG significantly facilit ated C-fibre evoked response and post-discharge of spinal dorsal horn WDR n eurons. This is consistent with our previous results obtained in behavioral studies. It suggests that the supraspinal effect of OFQ on pain may partly be mediated by PAG neurons. (C) 2001 Elsevier Science B.V. All rights rese rved.