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Actions of Acetylcholine on Spinal Motoneurons

  • Z. G. Jiang
  • N. J. Dun

Abstract

The evidence that acetylcholine (ACh) is a chemical transmitter in the vertebrate peripheral nervous system is unequivocal. A transmitter and/or modulator role of ACh in the vertebrate central nervous system is less well established (cf. Karczmar, 1967; Krnjevic, 1974). The most extensively investigated central cholinergic synapses are those on Renshaw cells of the spinal cord where ACh was shown to be the excitatory transmitter released from collateral branches of spinal motoneurons (Eccles et al., 1954; 1956; Curtis and Eccles, 1958). The effect of ACh on the motoneuron itself is not well understood. Recent studies with antibodies raised against choline acetyltransferase (CAT) revealed in addition to CAT-containing motoneurons, the presence of CAT-containing small diameter neurons as well as fibers in the ventral horn (Kimura et al., 1981; Houser et al., 1983; Borges and Iversen, 1986). In fact, CAT-immunoreactive boutons appeared to abut on motoneurons suggesting that ACh may exert a transmitter and/or modulator role at these neurons (Borges and Iversen, 1986). In an effort to provide a pharmacological basis for a possible transmitter or modulator function of ACh in the ventral horn, the actions of ACh on motoneurons and on spinal synaptic transmission were investigated using thin spinal cord slices as stable intracellular recordings can be maintained for hours in this preparation.

Keywords

Muscarinic Receptor Ventral Horn Membrane Resistance Excitatory Postsynaptic Potential Spinal Cord Slice 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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References

  1. Blight, A.R. and Someya, S., 1985, Depolarizing afterpotentials in myelinated axons of mammalian spinal cord, Neuroscience, 15: 1–12.PubMedCrossRefGoogle Scholar
  2. Borges, L.F. and Iversen, S.D., 1986, Topography of choline acetyltransferase immunoreactive neurons and fibers in the rat spinal cord, Brain Res, 362: 140–148.PubMedCrossRefGoogle Scholar
  3. Brown, D.A. and Adams, P.R., 1980, Muscarinic suppression of a novel voltage-sensitive K+ current in a vertebrate neurone, Nature, 283: 673–676.PubMedCrossRefGoogle Scholar
  4. Bulbring, E. and Burn, J.H., 1941, Observations bearing on synaptic transmission by acetylcholine in the spinal cord, J. Physiol. (Lond.), 100: 337–368.Google Scholar
  5. Calma, I. and Wright, S., 1944, Action of acetylcholine, atropine and eserine on the central nervous system of the decerebrate cat, J. Physiol. (Lond.), 103: 93–102.Google Scholar
  6. Curtis, D.R. and Eccles, R.M., 1958, The excitation of Renshaw cells by pharmacological agents applied electrophoretically, J. Physiol. (Lond.), 141: 435–445.Google Scholar
  7. Curtis, D.R., Ryall, R.W. and Watkins, J.C., 1966, The action of cholinomimetics on spinal interneurones, Expl. Brain Res, 2: 97–106.Google Scholar
  8. Dodd, J., Dingledine, R. and Kelly, J.S., 1981, The excitatory action of acetylcholine on hippocampal neurones of the guinea pig and rat maintained in vitro, Brain Res, 207: 109–127.PubMedCrossRefGoogle Scholar
  9. Eccles, J.C., 1964, “The Physiology of Synapses,” Springer, Berlin.CrossRefGoogle Scholar
  10. Eccles, J.C., Eccles, R.M. and Fatt, P., 1956, Pharmacological investigations on a central synapse operated by acetylcholine, J. Physiol. (Lond.), 131: 154–169.Google Scholar
  11. Eccles, J.C., Fatt, P. and Koketsu, K., 1954, Cholinergic and inhibitory synapses in a pathway from motor axon collaterals to motoneurones, J. Physiol. (Lond.), 126: 524–562.Google Scholar
  12. Fonnum, F., 1984, Glutamate: a neurotransmitter in mammalian brain, J. Neurochem, 42: 1–11.PubMedCrossRefGoogle Scholar
  13. Hashiguchi, T., Kobayashi, H., Tosaka, T. and Libet, B., 1982, Two muscarinic depolarizing mechanisms in mammalian sympathetic neurons, Brain Res, 242: 378–382.PubMedCrossRefGoogle Scholar
  14. Houser, C.R., Crawford, G.D., Barber, R.P., Salvaterra, P.M. and Vaughn, J.E., 1983, Organization and morphological characteristics of cholinergic neurons: an immunocytochemical study with a monoclonal antibody to choline acetyltransferase, Brain Res, 266: 97–119.PubMedCrossRefGoogle Scholar
  15. Jiang, Z.G. and Dun, N.J., 1986, Presynaptic suppression of excitatory postsynaptic potentials in rat ventral horn neurons by muscarinic agonists, submitted.Google Scholar
  16. Karczmar, A.G., 1967, Neuromuscular pharmacology, Ann. Rev. Pharmacol, 7: 241–276.PubMedCrossRefGoogle Scholar
  17. Karczmar, A.G., and Dun, N.J., 1985, Pharmacology of synaptic ganglionic transmission and second messengers, in: “Autonomic and Enteric Ganglia: Transmission and Its Pharmacology,” A.G. Karczmar, K. Koketsu, and S. Nishi, eds., Plenum Press, New York.Google Scholar
  18. Kilbinger, H., 1984, Presynaptic muscarine receptors modulating acetylcholine release, Trends in Pharmacol. Sci, 5: 103–105.CrossRefGoogle Scholar
  19. Kimura, H., McGeer, P.L., Peng, J.H. and McGeer, E.G., 1981, The central cholinergic system studied by choline acetyltransferase immunohistochemistry in the rat, J. Comp. Neurol, 200: 151–201.PubMedCrossRefGoogle Scholar
  20. Koketsu, K., 1969, Cholinergic synaptic potentials and the underlying ionic mechanisms, Federal Proceedings, 28: 101–131.Google Scholar
  21. Koketsu, K. and Yamada, M., 1982, Presynaptic muscarinic receptors inhibiting active acetylcholine release in the bullfrog sympathetic ganglion, Br. J. Pharmacol, 77: 75–82.PubMedGoogle Scholar
  22. Krnjevic, K., 1974, Chemical nature of synaptic transmission in vertebrates, Physiol. Rev, 54: 418–540.Google Scholar
  23. Krnjevic, K., Pumain, R. and Renaud, L., 1971, The mechanism of excitation by acetylcholine in the cerebral cortex, J. Physiol. (Lond.), 215: 247–268.Google Scholar
  24. Kuba, K. and Koketsu, K., 1976, Analysis of the slow excitatory postsynaptic potential in bullfrog sympathetic ganglion cells, Jap. J. Physiol, 26: 647–664.Google Scholar
  25. Ma, R.C. and Dun, N.J., 1985, Vasopressin depolarizes lateral horn cells of the neonatal rat spinal cord in vitro, Brain Res, 348: 36–43.PubMedCrossRefGoogle Scholar
  26. Ma, R.C. and Dun, N.J., 1986, Excitation of lateral horn neurons of the neonatal rat spinal cord by 5-hydroxytryptamine, Develop. Brain. Res, 24: 89–98.CrossRefGoogle Scholar
  27. Nishi, S., 1974, Ganglionic transmission, in: “The Peripheral Nervous System,” J.I. Hubbard, ed., Plenum Press, New York.Google Scholar
  28. Segal, M., 1982, Multiple actions of acetylcholine at a muscarinic receptor studied in the rat hippocampal slice, Brain Res, 246: 77–87.PubMedCrossRefGoogle Scholar
  29. Weight, F.F. and Votava, J., 1970, Slow synaptic excitation in sympathetic ganglion cells: evidence for synaptic inactivation of potassium conductance, Science, 170: 755–758.PubMedCrossRefGoogle Scholar
  30. Weight, F.F. and Salmoiraghi, G.C., 1966, Responses of spinal cord interneurons to acetylcholine norepinephrine and serotonin administered by microelectrophoresis, J.P.E.T, 153: 420–427.Google Scholar

Copyright information

© Plenum Press, New York 1987

Authors and Affiliations

  • Z. G. Jiang
    • 1
  • N. J. Dun
    • 1
  1. 1.Department of PharmacologyLoyola University of Chicago, Stritch School of MedicineMaywoodUSA

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