Skip to main content
NCBI home page
The Journal of Physiology logoLink to The Journal of Physiology
. 1984 Dec;357:357–368. doi: 10.1113/jphysiol.1984.sp015504

Dorsal root potentials are unchanged in adult rats treated at birth with capsaicin.

F Cervero, M B Plenderleith
PMCID: PMC1193262  PMID: 6512694

Abstract

The possible contribution of non-myelinated afferent fibres (C fibres) to the mechanisms of primary afferent depolarization (p.a.d.) in the spinal cord of the rat has been investigated. Dorsal root potentials (d.r.p.s.) were recorded in the lumbar cord of normal adult rats, of adult rats which had been injected at birth with a solution of capsaicin (50 mgkg-1 s.c.) and of adult rats which had been injected at birth with the drug vehicle only. D.r.p.s were recorded from the dorsal rootlet that entered the spinal cord in the main area of termination of the tibial nerve. The location of this area was assessed by mapping the spinal cord in the rostro-caudal axis while recording cord dorsum potentials evoked by A-fibre volleys from the tibial nerve. No differences in peak amplitude, area or time to peak amplitude were observed between the d.r.p.s evoked in control and capsaicin-treated rats by stimulation of the tibial, sural or common peroneal nerves. The relation between the size of incoming A volleys to the spinal cord and the size of the d.r.p.s evoked by them was unaffected by the neonatal capsaicin treatment. Rats treated at birth with capsaicin showed a virtual absence of afferent C fibres as assessed from the lack of C waves in the compound action potentials evoked in each of the three nerves studied after antidromic stimulation of the dorsal roots. The presence of p.a.d. in control and in capsaicin-treated animals was also established using the technique of excitability testing of primary afferent fibres (Wall, 1958). No differences were observed between the p.a.d. recorded in control and in capsaicin-treated animals using this technique. D.r.p.s and p.a.d. (assessed by excitability testing of primary afferent fibres) were of similar magnitude in control and in capsaicin-treated rats anaesthetized with either sodium pentobarbitone or urethane. It is concluded that p.a.d. of myelinated afferent fibres produced by incoming volleys in myelinated afferent fibres is not affected by a life-long loss of non-myelinated afferent fibres.

Full text

PDF
357

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Brown A. G. The dorsal horn of the spinal cord. Q J Exp Physiol. 1982 Apr;67(2):193–212. doi: 10.1113/expphysiol.1982.sp002630. [DOI] [PubMed] [Google Scholar]
  2. Cervero F., Iggo A., Molony V. The tract of Lissauer and the dorsal root potential. J Physiol. 1978 Sep;282:295–305. doi: 10.1113/jphysiol.1978.sp012464. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Cervero F., McRitchie H. A. Neonatal capsaicin does not affect unmyelinated efferent fibers of the autonomic nervous system: functional evidence. Brain Res. 1982 May 6;239(1):283–288. doi: 10.1016/0006-8993(82)90853-8. [DOI] [PubMed] [Google Scholar]
  4. Cervero F., Shouenborg J., Sjölund B. H., Waddell P. J. Cutaneous inputs to dorsal horn neurones in adult rats treated at birth with capsaicin. Brain Res. 1984 May 28;301(1):47–57. doi: 10.1016/0006-8993(84)90401-3. [DOI] [PubMed] [Google Scholar]
  5. Fleischer E., Handwerker H. O., Joukhadar S. Unmyelinated nociceptive units in two skin areas of the rat. Brain Res. 1983 May 9;267(1):81–92. doi: 10.1016/0006-8993(83)91041-7. [DOI] [PubMed] [Google Scholar]
  6. Handwerker H. O., Iggo A., Zimmermann M. Segmental and supraspinal actions on dorsal horn neurons responding to noxious and non-noxious skin stimuli. Pain. 1975 Jun;1(2):147–165. doi: 10.1016/0304-3959(75)90099-8. [DOI] [PubMed] [Google Scholar]
  7. Jancsó G., Kiraly E., Jancsó-Gábor A. Pharmacologically induced selective degeneration of chemosensitive primary sensory neurones. Nature. 1977 Dec 22;270(5639):741–743. doi: 10.1038/270741a0. [DOI] [PubMed] [Google Scholar]
  8. Jessell T. M., Iversen L. L., Cuello A. C. Capsaicin-induced depletion of substance P from primary sensory neurones. Brain Res. 1978 Aug 18;152(1):183–188. doi: 10.1016/0006-8993(78)90146-4. [DOI] [PubMed] [Google Scholar]
  9. Jänig W., Schmidt R. F., Zimmermann M. Single unit responses and the total afferent outflow from the cat's foot pad upon mechanical stimulation. Exp Brain Res. 1968;6(2):100–115. doi: 10.1007/BF00239165. [DOI] [PubMed] [Google Scholar]
  10. Jänig W., Schmidt R. F., Zimmermann M. Two specific feedback pathways to the central afferent terminals of phasic and tonic mechanoreceptors. Exp Brain Res. 1968;6(2):116–129. doi: 10.1007/BF00239166. [DOI] [PubMed] [Google Scholar]
  11. Lynn B., Carpenter S. E. Primary afferent units from the hairy skin of the rat hind limb. Brain Res. 1982 Apr 22;238(1):29–43. doi: 10.1016/0006-8993(82)90768-5. [DOI] [PubMed] [Google Scholar]
  12. Nagy J. I., Hunt S. P., Iversen L. L., Emson P. C. Biochemical and anatomical observations on the degeneration of peptide-containing primary afferent neurons after neonatal capsaicin. Neuroscience. 1981;6(10):1923–1934. doi: 10.1016/0306-4522(81)90032-4. [DOI] [PubMed] [Google Scholar]
  13. Nagy J. I., Iversen L. L., Goedert M., Chapman D., Hunt S. P. Dose-dependent effects of capsaicin on primary sensory neurons in the neonatal rat. J Neurosci. 1983 Feb;3(2):399–406. doi: 10.1523/JNEUROSCI.03-02-00399.1983. [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. Nagy J. I., Vincent S. R., Staines W. A., Fibiger H. C., Reisine T. D., Yamamura H. I. Neurotoxic action of capsaicin on spinal substance P neurons. Brain Res. 1980 Mar 31;186(2):435–444. doi: 10.1016/0006-8993(80)90987-7. [DOI] [PubMed] [Google Scholar]
  15. Ribeiro-da-Silva A., Coimbra A. Capsaicin causes selective damage to type I synaptic glomeruli in rat substantia gelatinosa. Brain Res. 1984 Jan 9;290(2):380–383. doi: 10.1016/0006-8993(84)90961-2. [DOI] [PubMed] [Google Scholar]
  16. Salt T. E., Crozier C. S., Hill R. G. The effects of capsaicin pre-treatment on the responses of single neurones to sensory stimuli in the trigeminal nucleus caudalis of the rat: evidence against a role for substance P as the neurotransmitter serving thermal nociception. Neuroscience. 1982 May;7(5):1141–1148. doi: 10.1016/0306-4522(82)91121-6. [DOI] [PubMed] [Google Scholar]
  17. Schmidt R. F. Presynaptic inhibition in the vertebrate central nervous system. Ergeb Physiol. 1971;63:20–101. doi: 10.1007/BFb0047741. [DOI] [PubMed] [Google Scholar]
  18. Schmidt R. F., Senges J., Zimmermann M. Presynaptic depolarization of cutaneous mechanoreceptor afferents after mechanical skin stimulation. Exp Brain Res. 1967;3(3):234–247. doi: 10.1007/BF00235587. [DOI] [PubMed] [Google Scholar]
  19. WALL P. D. Excitability changes in afferent fibre terminations and their relation to slow potentials. J Physiol. 1958 Jun 18;142(1):1–21. doi: 10.1113/jphysiol.1958.sp005997. [DOI] [PMC free article] [PubMed] [Google Scholar]
  20. WALL P. D. The origin of a spinal-cord slow potential. J Physiol. 1962 Dec;164:508–526. doi: 10.1113/jphysiol.1962.sp007034. [DOI] [PMC free article] [PubMed] [Google Scholar]
  21. Wall P. D., Fitzgerald M., Nussbaumer J. C., Van der Loos H., Devor M. Somatotopic maps are disorganized in adult rodents treated neonatally with capsaicin. Nature. 1982 Feb 25;295(5851):691–693. doi: 10.1038/295691a0. [DOI] [PubMed] [Google Scholar]
  22. Wall P. D. The effect of peripheral nerve lesions and of neonatal capsaicin in the rat on primary afferent depolarization. J Physiol. 1982 Aug;329:21–35. doi: 10.1113/jphysiol.1982.sp014288. [DOI] [PMC free article] [PubMed] [Google Scholar]

Articles from The Journal of Physiology are provided here courtesy of The Physiological Society

RESOURCES