Abstract
It was found during experiments on isolated frog spinal cord involving extracellular recording from the dorsal roots (sucrose bridging) and intracellular recording from motoneurons by microelectrodes that 10 mM of the M-cholinomimetic arecoline produces motoneuronal depolarization which is matched by depolarizing electronic ventral root potentials and a rise in motoneuronal input resistance. Arecoline changes synaptic transmission by increasing the amplitude of postsynaptic potentials during intracellular recording and that of motoneuronal reflex discharges in the ventral roots but reduces the duration of dorsal root potentials. In the presence of arecoline, L-glutamate-induced motoneuronal response increases. Facilitation of synaptic transmission produced by arecoline in the spinal cord is bound up with cholinergic M2- activation, since it is suppressed by atropine but not by low concentrations of pirenzipine; it is also coupled with a reduction in adenylcyclase activity. When motoneuronal postsynaptic response has been suppressed, as in the case of surplus calcium or theophylline, arecoline produces an inhibitory effect on the amplitude of motoneuronal monosynaptic reflex discharges which is suppressed by pirenzipine at a concentration of 1×10−7 M. This would indicate the presence at the primary afferent terminals of presynaptic cholinergic M1 receptors which mediate its inhibition of impulses of transmitter release. This effect is independent of changes in cyclic nucleotide concentration.
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Literature cited
V. I. Skok, Physiology of the Autonomic Ganglia [in Russian], Nauka, Leningrad (1970).
P. R. Adams, D. A. Brown, and A. Constanti, "M-current and other potassium currents in bullfrog sympathetic neurones," J. Physiol.,330, 537–572 (1982).
L. C. Bernardo and D. A. Prince, "Long-term modulation of intrinsic membrane properties of hippocampal neurons," in: Conditioning, Plenum Press, New York (1982), pp. 13–35.
D. A. Brown, "Slow cholinergic excitation — a mechanism for increasing neuronal excitability," Trends Neurosci.,6, No. 8, 302–307 (1983).
D. A. Brown and P. R. Adams, "Muscarinic suppression of a novel voltage sensitive K+ current in a vertebrate neurone," Nature,283, No. 2536, 673–676 (1980).
D. A. Brown and A. Selyanko, "Muscarinic-sensitive membrane currents in rat sympathetic neurons," J. Physiol.,345, 143P (1983).
A. Constanti and D. A. Brown, "M-current in voltage clamped mammalian sympathetic neurones," Neurosci. Lett.,39, No. 1, 65–70 (1983).
A. Constanti and M. Galvan, "M-current in voltage clamped olfactory cortex neurones," Neurosci. Lett.,24, No. 3, 289–294 (1981).
J. M. H. French-Mullen, N. Hori, H. Nakanishi, et al., "Asymmetric distribution of acetylcholine receptors and M-channels in prepyriform neurons," Cell Mol. Neurobiol.,3, No. 2, 163–181 (1983).
R. Hammer and A. Giachetti, "Muscarinic receptor subtypes: M1 and M2: biochemical and functional characterization," Life Sci.,31, No. 15, 2991–2998 (1982).
T. K. Harden, L. J. Tanner, M. W. Martin, et al., "Characteristics of two biochemical responses to stimulation of muscarinic cholinergic receptors. Subtypes of muscarinic receptors II," Trends Pharmacol. Sci., Suppl. (1986), pp. 14–18.
M. McKinney, S. Steinstrom, and E. Richelson, "Muscarinic responses and binding in murine neuroblastoma clone (N1E-115). Mediation of separate responses by high affinity and low affinity agonist-receptor conformation," Mol. Pharmacol.,27, No. 2, 223–235 (1985).
R. B. Meeker and T. K. Harden, "Muscarinic cholinergic receptor mediated control of cyclic AMP metabolism. Agonist induced changes in nucleotide synthesis and degradation," Mol. Pharmacol.,23, No. 2, 384–392 (1983).
Y. Nishizuka, "Turnover of inositol phospholipids and signal transduction," Science,225, No. 4668, 1365–1370 (1984).
A. Nistri and A. Constanti, "Pharmacological characterization of different types of GABA and glutamate receptors in vertebrates and invertebrates," Prog. Neurobiol.,13, No. 2, 117–235 (1979).
R. A. North, B. E. Slack, and A. Surprenant, "Muscarinic M1 and M2 receptors mediate depolarization and presynaptic inhibition in guinea pig enteric neurons system," J. Physiol.,368, 435–452 (1985).
L. Novak and R. L. Macdonald, "Muscarinic-sensitive voltage dependent potassium current in cultured murine spinal cord neurons," Neurosci. Lett.,35, No. 1, 85–91 (1983).
M. C. Olianas, P. Onali, N. H. Neff, and E. Costa, "Adenylate cyclase activity of synaptic membranes from rat striatum. Inhibition by muscarinic receptor agonists," Mol. Pharmacol.,23, No. 2, 393–398 (1983).
H. Repke and I. Wiss, "Regulatory processes at the muscarinic acetylcholine receptor — an approach to a receptor model," Humboldt Univ. Berlin Naturwiss R.,31, No. 5, 525–527 (1982).
J. K. Wamsley, D. R. Gehlert, W. R. Roeske, and H. I. Yamamura, "Muscarinic antagonists binding site heterogeneity as evidence by autoradiography after labeling with [3H]-qnb and [3H]-pirenzipine," Life Sci.,34, No. 14, 1395–1402 (1984).
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A. M. Gorkii Medical Institute, Donetsk. Translated from Neirofiziologiya, Vol. 19, No. 3, pp. 399–405, May–June, 1987.
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Abramets, I.I., Komissarov, I.V. & Samoilovich, I.M. Cholinergic modulation of the synaptic transmission in the frog spinal cord. Neurophysiology 19, 301–307 (1987). https://doi.org/10.1007/BF01056633
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DOI: https://doi.org/10.1007/BF01056633