Unmyelinated primary afferent fiber stimulation depletes dynorphin A (1-8) immunoreactivity in rat ventral horn

Caroline M. Klein, Linda S. Sorkin, Kyungsoon Chung, Richard E. Coggeshall

Research output: Contribution to journalArticle

8 Scopus citations


The present study demonstrates many dynorphin (DYN)-immunoreactive fibers and presumed presynaptic terminals in rat lumbar ventral horn. The fibers and terminals seem to arise largely from DYN-containing intrinsic neurons in the dorsal horn. The majority of the presumed terminals closely surround a subpopulation of motoneurons that tend to be located in flexor motoneuron columns. Acute C fiber, but not A fiber, primary afferent stimulation depletes the ventral horn DYN immunostaining. We interpret these findings to indicate that the spinal DYN neurons are well positioned to serve both as modulators of nociceptive input and as interneurons in motor reflexes. We further hypothesize that the depletion of DYN-immunoreactivity that follows either acute C fiber stimulation or intense nociceptive stimuli may be the trigger for the upregulation in spinal cord DYN that occurs in models of chronic pain states.

Original languageEnglish (US)
Pages (from-to)70-76
Number of pages7
JournalBrain Research
Issue number1-2
StatePublished - Dec 6 1991



  • Dynorphin A
  • Electrical stimulation
  • Pain
  • Sciatic nerve
  • Unmyelinated sensory fiber
  • Ventral horn

ASJC Scopus subject areas

  • Developmental Biology
  • Molecular Biology
  • Clinical Neurology
  • Neuroscience(all)

Cite this