C-FOS EXPRESSION IN SPINAL-CORD AND BRAIN-STEM FOLLOWING NOXIOUS-STIMULATION AND ELECTROACUPUNCTURE PLUS NOXIOUS-STIMULATION

The present study was to trace the neuronal pathway in the spinal cord and brainstem following noxious stimulation and acupuncture plus noxi ous stimulation by using immunohistochemical technique to detect the e xpression of c-fos like protein. The results showed that in both the n oxious stimulation group and acupuncture of Zusanli(St. 36) and Lanwei (Extra 33) points plus noxious stimulation group a lot of Fos-like imm unoreactive (FLI) cell nuclei appeared in the following structures: do rsal horn of lumbar and sacral spinal cord (Laminae I, II, V and X), n . reticularis lateralis, n. reticularis paragigantocellularis laterali s, area Al, n. tractus solitarii, n, raphe magnus, locus coeruleus, n. raphe dorsalis and the periaqueductal grey. In the control group no o bvious c-fos expression was shown in the structures mentioned above. I t was also shown that in the lumbar and sacral spinal cord the number of FLI nuclei in the acupuncture plus noxious stimulation group was mo re than that in the noxious stimulation group, but in locus coeruleus and the ventral part of the periaqueductal grey the number of FLI nucl ei in the acupuncture plus noxious stimulation group was less than tha t of the noxious stimulation group. The results imply that acupuncture and noxious stimulation may activate the intrinsic pain modulating sy stem through the spinal dorsal hem, then suppress the c-fos expression induced by noxious stimulation in the locus coeruleus and ventral par t of the periaqueductal grey.