[Effect of stimulating midbrain periaqueductal gray on the electrical response of somatosensory cortex to C-fiber input in cats].
The electrical responses of the somatosensory cortex (C-CEP) and spinal cord (C-SSP) to C-fiber inputs could be markedly inhibited by stimulating the periaqueductal gray (PAG), and the inhibition on C-CEP was greater than that on C-SSP. After application of cyproheptadine on the dorsal surface of the spinal cord, PAG stimulation could still inhibit C-CEP, but not C-SSP. It was suggested that PAG might inhibit C-CEP through ascending as well as descending pathways. After blocking the descending inhibitory pathway by cyproheptadine i.v. injection, cyproheptadine and naloxone could antagonize the inhibitory effect of PAG stimulation on C-CEP, indicating that endogenous opiate-like substance and serotonin might play an important role in the transmission of the ascending inhibitory pathways from PAG.
Wang
B Q
BQ
Department of Physiology, Sun Yat-Sen University of Medical Sciences, Guangzhou.
Chen
P X
PX
D000344:Afferent Pathways / Q000502:physiology; D000818:Animals; D002415:Cats; D003533:Cyproheptadine / Q000494:pharmacology; D004558:Electric Stimulation; D005073:Evoked Potentials, Somatosensory; D009270:Naloxone / Q000494:pharmacology; D009412:Nerve Fibers / Q000502:physiology*; D010487:Periaqueductal Gray / Q000502:physiology*; D013003:Somatosensory Cortex / Q000502:physiology*
D003533:Cyproheptadine; D009270:Naloxone