Further evidence for the existence of long ascending unmyelinated primary afferent fibers within the dorsal funiculus: effects of capsaicin

Joel T. Patterson, Kyungsoon Chung, Richard E. Coggeshall

Research output: Contribution to journalArticle

20 Scopus citations


The present study provides further evidence in support of the hypothesis that there is a fine primary afferent system in the dorsal funiculi by determining the effects of capsaicin (8-methyl-N-vanillyl-6-noneamide) on unmyelinated fibers in the cervical fasciculus gracilis of the rat. The neurolytic effect of this procedure was demonstrated by showing an 89% decrease in the number of unmyelinated fibers in the S2 dorsal roots of the experimental animals. Consequently, we feel that unmyelinated primary afferent fibers are largely removed from these animals. Neonatal administration of capsaicin (50 mg/kg) caused a 54% decrease in the number of unmyelinated fibers in the C3 fasciculus gracilis but no significant change in myelinated fiber numbers. The data provide further evidence for the existence of a significant primary afferent unmyelinated fiber system in the dorsal funiculus and suggest a role for the dorsal funiculi in the transmission of noxious information.

Original languageEnglish (US)
Pages (from-to)117-120
Number of pages4
Issue number1
StatePublished - Apr 1992



  • (Rat)
  • Capsaicin
  • Dorsal columns
  • Fasciculus gracilis
  • Unmyelinated axons

ASJC Scopus subject areas

  • Neurology
  • Clinical Neurology
  • Anesthesiology and Pain Medicine

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