Peculiarities of receptor-channel complexes for inhibitory mediators in the membranes of lamprey spinal cord neurones

Safronov, Boris V.; Baev, K. V.; Batueva, I. V.; Rusin, K.I.; Suderevskaya, E. I.

doi:10.1016/0304-3940(89)90311-x

Cited by 14 publications

(7 citation statements)

References 7 publications

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“…It has been reported, using isolated lamprey spinal neurons, that strychnine can reduce neuronal responses to both gamma-aminobutyric acid (GABA) and glycine, and the authors concluded that GABA and glycine share a common receptor-ion channel complex in lamprey (Safronov et al 1989;Baev et al 1992). The possibility thus remains that inhibitory synapses blocked by strychnine may be GABAergic rather than glycinergic.…”

Section: Discussionmentioning

confidence: 83%

Effects of strychnine on fictive swimming in the lamprey: evidence for glycinergic inhibition, discrepancies with model predictions, and novel modulatory rhythms

1994

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1. Inhibitory postsynaptic potentials (ipsps) produced by two classes of interneurons, CC (Contralateral and caudal projecting) and lateral interneurons, were tested for strychnine sensitivity using paired intracellular recordings in the lamprey spinal cord. The ipsps were partially blocked by 0.2-0.5 microM strychnine and were completely blocked by 5 microM strychnine. Thus, the ipsps may be glycinergic. 2. These interneurons are key participants in a proposed circuit model for fictive swimming. A connectionist-type computer simulation of the model demonstrated that the cycle period of the network increased with decreasing ipsp strength. 3. Application of strychnine (0.1-0.5 microM) to the spinal cord during fictive swimming induced by an excitatory amino acid increased cycle period, consistent with previous reports, but at odds with stimulation predictions. 4. Strychnine also produced slow rhythmic modulation of fictive swimming (period = 12 s) which maintained left-right alternation and rostral-caudal coordination. Auto- and cross-correlation analyses revealed that the slow modulation was present in a weaker form in most control preparations during fictive swimming. 5. Since the proposed model for the swimming pattern generator in the lamprey spinal cord does not predict the observed speeding with strychnine, nor the slow modulatory rhythm, it appears to be deficient in its present formulation.

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Section: Discussionmentioning

confidence: 83%

Effects of strychnine on fictive swimming in the lamprey: evidence for glycinergic inhibition, discrepancies with model predictions, and novel modulatory rhythms

1994

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“…Apart from its interaction with the glycine receptor, strychnine has been shown, although less effectively, to interfere with GABA-mediated neuronal inhibition (Curtis et al, 1968;1971;Davidoff et al, 1969;Safronov et al, 1989). In addition, interactions between bicuculline, a specific GABAA receptor antagonist, and specific [3H]-strychnine binding have been observed (Goldinger & Muller, 1980;Marvizon et al, 1986).…”

Section: Discussionmentioning

confidence: 99%

Inhibitory effect of strychnine on acetylcholine receptor activation in bovine adrenal medullary chromaffin cells

Kuijpers

Vergara

Calvo

et al. 1994

British J Pharmacology

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1 Strychnine, which is known as a potent and selective antagonist of the inhibitory glycine receptor in the central nervous system, inhibits the nicotinic stimulation of catecholamine release from bovine cultured adrenal chromaffin cells in a concentration-dependent (1-1100 AM) manner. At 10 JAM nicotine, the IC3o value for strychnine is approximately 30 tiM. Strychnine also inhibits the nicotine-induced membrane depolarization and increase in intracellular Ca2+ concentration. 2 The inhibitory action of strychnine is reversible and is selective for nicotinic stimulation, with no effect observed on secretion elicited by a high external K+ concentration, histamine or angiotensin II. 3 Strychnine competes with nicotine in its effect, but does not modify the apparent positive cooperativity of the nicotine binding sites. In the absence of nicotine, strychnine has no effect on catecholamine release. Glycine does not affect catecholamine release nor the inhibitory action of strychnine on this release. 4 These results suggest that strychnine interacts with the agonist binding site of the nicotinic acetylcholine receptor in chromaffin cells, thus exerting a pharmacological effect independently of the glycine receptor.

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“…1Cii, inset). Strychnine (5 M) was added to the caudal pool to block inhibitory inputs (Safronov et al, 1989). Substance P increased the amplitude of these locomotor-related depolarizations in motor neurons (n ϭ 3) and unidentified gray matter neurons (n ϭ 2).…”

Section: Effects Of Substance P On Synaptic Transmission E Xcitator Ymentioning

confidence: 99%

Cellular and Synaptic Modulation Underlying Substance P-Mediated Plasticity of the Lamprey Locomotor Network

Parker

Grillner

1998

J. Neurosci.

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The tachykinin substance P modulates the lamprey locomotor network by increasing the frequency of NMDA-evoked ventral root bursts and by making the burst activity more regular. These effects can last in excess of 24 hr. In this paper, the effects of substance P on the synaptic and cellular properties of motor neurons and identified network interneurons have been examined. Substance P potentiated the amplitude of monosynaptic glutamatergic inputs from excitatory interneurons and reticulospinal axons. The amplitude and frequency of miniature EPSPs was increased, suggesting that the synaptic modulation was mediated presynaptically and postsynaptically. The postsynaptic modulation was caused by a specific effect of substance P on the NMDA component of the synaptic input, whereas the presynaptic component was calcium-independent. Substance P did not affect monosynaptic glycinergic inputs from lateral interneurons, crossed inhibitory interneurons, or ipsilateral segmental interneurons or postsynaptic GABAA or GABAB responses, suggesting that it has little effect on inhibitory synaptic transmission. At the cellular level, substance P increased synaptic inputs, resulting in membrane potential oscillations in motor neurons, crossed caudal interneurons, lateral interneurons, and excitatory interneurons. The spiking in response to depolarizing current pulses was increased in motor neurons, lateral interneurons, and excitatory interneurons, but usually was reduced in crossed inhibitory interneurons. Substance P reduced the calcium-dependent afterhyperpolarization after an action potential in motor neurons and lateral interneurons, but did not affect this conductance in excitatory or crossed inhibitory interneurons. The relevance of these cellular and synaptic changes to the modulation of the locomotor network is discussed.

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Peculiarities of receptor-channel complexes for inhibitory mediators in the membranes of lamprey spinal cord neurones

Cited by 14 publications

References 7 publications

Effects of strychnine on fictive swimming in the lamprey: evidence for glycinergic inhibition, discrepancies with model predictions, and novel modulatory rhythms

Effects of strychnine on fictive swimming in the lamprey: evidence for glycinergic inhibition, discrepancies with model predictions, and novel modulatory rhythms

Inhibitory effect of strychnine on acetylcholine receptor activation in bovine adrenal medullary chromaffin cells

Cellular and Synaptic Modulation Underlying Substance P-Mediated Plasticity of the Lamprey Locomotor Network

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