Enkephalinergic and Monoaminergic Control of Segmental Pathways from Flexor Reflex Afferents (FRA)

  • E. D. Schomburg


The influence of DOPA, μ- and δ-agonistic enkephalins and naloxone on short- and long latency FRA pathways and spinal rhythm generation was comparatively analyzed in high spinal cats. The results showed that DOPA and the enkephalins are synergistic with respect to a depression of short latency FRA pathways but antagonistic with respect to long latency FRA pathways and spinal rhythm generation which are facilitated by DOPA but depressed by the enkephalins. DOPA and naloxone, on the other hand, are synergistic with respect to a facilitation of long latency FRA pathways and rhythm generation, but antagonistic with respect to the short latency FRA pathways, which are depressed by DOPA but not by naloxone. Without prior DOPA application naloxone may induce high frequency (up to 5.9 cycles/sec) rhythmic activity. The results support the hypothesis that the long latency FRA pathways and their release by DOPA form the basis for a rhythmic motor activity and that spinal motor functions of the enkephalinergic systems go beyond a plain nocifensive engagement. They may subserve a mechanism which blocks the influence of the afferent FRA feed back and its spinal motor actions during the performance of specific movements.


Lumbar Spinal Cord Spinal Motor Muscle Afferents Rhythm Generation Reflex Pathway 
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  1. Andén, N.-E., Jukes, M.G.M., Lundberg, A. and Vyklicky, L. 1966). The effect of DOPA on the spinal cord. 1. Influence on transmission from primary afferents. Acta Physiologica Scandinavica 67, 373-386Google Scholar
  2. Baidissera, F., Hultborn, H. and Illert, M. (1981). Integration in spinal neuronal systems. In V.B. Brooks (Ed.). Handbook of Physiology, Vol. 2, Sect. I, Nervous System, Motor Control, Part 1, American Physiological Society, Bethesda, MD, pp. 509–595Google Scholar
  3. Bras, H., Cavallari, P. and Jankowska, E. (1988). An investigation of local actions of ionophoretically applied DOPA in the spinal cord. Experimental Brain Research 71, 447–449CrossRefGoogle Scholar
  4. Chesselet, M.F., Cheramy, A., Reisine, T.D. and Glowinski, J.(1981). Morphine and delta-opiate agonists locally stimulate in vivo dopamine release in cat caudate nucleus. Nature 291, 320–322PubMedCrossRefGoogle Scholar
  5. Clarke, R.W., Ford, T.W. and Taylor, J.S. (1988). Adrenergic and opioidergic modulation of a spinal reflex in the decerebrated rabbit. Journal of Physiology 404, 407–414PubMedGoogle Scholar
  6. Duggan, A.W. (1985). Pharmacology of descending control systems. Philosophical Transactions of the Royal Society of London B 308, 375–391CrossRefGoogle Scholar
  7. Fields, H.L. and Basbaum A.I. (1978). Brain stem control of spinal pain transmission neurons. Annual Review of Physiology 40, 193–221CrossRefGoogle Scholar
  8. Grillner, S. (1985). Neural control of vertebrate locomotion — central mechanisms and reflex interaction with special reference to the cat. In W.J.P. Barnes and M.H. Gladden (Eds). Feedback and Motor Control in Invertebrates and Vertebrates, Croom Hall, London, pp. 35–56CrossRefGoogle Scholar
  9. Jankowska, E., Jukes, M.G.M., Lund, S. and Lundberg, A. (1967).The effect of DOPA on the spinal cord. 6. Half-centre organization of interneurones transmitting effects from the flexor reflex afferents. Acta Physiologica Scandinavica 70, 389–402Google Scholar
  10. Kniffki, K.-D., Schomburg, E.D. and Steffens, H. (1981).Effects from fine muscle and cutaneous afferents on spinal locomotion in cats. Journal of Physiology 319, 543–554PubMedGoogle Scholar
  11. Koehler, W.J., Schomburg, E.D. and Steffens, H. (1984).Phasic modulation of trunk muscle efferents during fictive spinal locomotion in cats. Journal of Physiology 353, 187–197PubMedGoogle Scholar
  12. Pearson, K.G., Jiang, W. and Ramirez, R.M. (1992). The use of naloxone to facilitate the generation of the locomotor rhythm in spinal cats. Journal of Neuroscience Methods 42, 75–81PubMedCrossRefGoogle Scholar
  13. Schmidt, R..F., Schomburg, E.D. and Steffens, H. (1991). Limitedly selective action of a 8-agonistic leuenkephalin on the transmission in spinal motor reflex pathways in cats. Journal of Physiology 442, 103–126PubMedGoogle Scholar
  14. Schmidt, R..F., Schomburg, E.D., Steffens, H., Strohmeyer, A. and Wada, N. (1987). A nociceptive non-FRA pathway to plantaris in the cat. Journal of Physiology 390, 49PGoogle Scholar
  15. Schomburg, E.D. (1990). Spinal sensorimotor systems and their supraspinal control. Neuroscience Research 7, 265–340PubMedCrossRefGoogle Scholar
  16. Schomburg, E.D. and Steffens, H. (1988). The effect of DOPA and clonidine on reflex pathways from group II muscle afferents to alpha-motoneurones in the cat. Experimental Brain Research 71, 442–446CrossRefGoogle Scholar
  17. Schomburg, E.D. and Steffens, H. (1992). Facilitation of rhythmic motor activity by naloxone in cats. Acta Physiologica Scandinavica 146, Suppl. 608, C 7.3Google Scholar
  18. Yaksh, T.L. (1981). Spinal opiate analgesia: Characteristics and principles of action. Pain 11, 293–346PubMedCrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media New York 1995

Authors and Affiliations

  • E. D. Schomburg
    • 1
  1. 1.Institute of PhysiologyUniversity of GöttingenGöttingenGermany

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