Involvement of solitary tract nucleus in control of nociceptive transmission in cat spinal cord neurons

Abstract

By stimulation of the nucleus tractus solitarius (NTS) at low intensity without any noticeable cardiovascular reaction. As usual, the late response or C-response was found to be preferentially inhibited by NTS stimulation as compared with the early response or A-response. The effective current intensity for NTS stimulation-produced inhibition ranged from 80 μA to 200 μA. Stronger inhibition was induced when the stimulating site was within or in the immediate vicinity of the NTS. There was no significant difference in the efficacy of the NTS stimulation-produced inhibition of nociceptive response between dorsal horn neurons and lamina X neurons. A similar inhibitory effect was elicited by microinjection of monosodium glutamate into the NTS area. The results demonstrate that the NTS may be involved in the control of nociceptive transmission at the spinal cord level. 1Correspondence to: H.-J. Du, Shanghai Brain Research Institute, Academia Sinica, 319 Yue-Yang Road, 200031 Shanghai, People's Rep. of China. Submitted April 19, 1989; revised July 11, 1989; accepted October 2, 1989. © Lippincott-Raven Publishers....