Is there a serotonergic tonic descending inhibition on the responses of dorsal horn convergent neurons to C-fibre inputs?

Abstract

In the anaesthetized rat the intravenous injection of 5-HT antagonists, cinanserin and methysergide, induces in two-thirds of neurones studied, an increase in the responsiveness of dorsal horn convergent neurones to C-fibre stimulation. These results are in favour of the existence of serotonergic tonic descending inhibitory effects on the spinal transmission of noxious messages.