[Effect of 5-HT and somatostatin on SP and chronic pain initiated electrical activity of neurons in spinal dorsal horn].

The effects of SP on the electric activities of neurons of spinal dorsal horn and the influence of 5-HT, somatostatin (SOM) on the effects of SP were observed in anesthetized rats with multimicropipete and iontophoresis techniques. It was found that: (1) The microiontophoretically administrating of SP could increase spinal dorsal horn unit discharge. (2) The noxious electrical activity of neurons induced by formalin could be inhibited by microiontophoretically applied SP. (3) The microiontophoretically administrating of 5-HT and SOM could inhibit the SP and formalin evoked unit discharge of neurons in spinal dorsal horn. It was suggested that SP took a double-effect part in modulation of pain transmission and analgesia in spinal cord, 5-HT and SOM inhibited the effect of SP and participated in pain modulation of SP.