Electrical interaction between antidromically stimulated frog motoneurones and dorsal root afferents: enhancement by gallamine and TEA

Grinnell, Alan D.

doi:10.1113/jphysiol.1970.sp009194

Cited by 69 publications

(16 citation statements)

References 23 publications

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“…In agreement with previous studies (Bonnet & Bremer, 1952;Phillis & Tebecis, 1967) the present results indicate that atropine can induce convulsant activity in the spinal cord, but in concentrations greater than 10-3 M, it tends to suppress ongoing activity. It is quite possible that in high concentrations the local anaesthetic action of atropine (Curtis & Phillis, 1961) (Washizu, 1959;Grinnell, 1970) and enhanced transmitter release (Koketsu, 1958;Payton & Shand, 1966). This property could account for some of the observed central excitatory effects of these two compounds.…”

Section: Discussionmentioning

confidence: 99%

“…The fact that a number of agents which antagonize acetylcholine, including curare (Eccles, 1946;Chang, 1953;Feldberg, Malcolm & Darian Smith, 1957; Phillis & Tebecis, 1967;Bhargava & Meldrum, 1969;Banerjee, Feldberg & Georgiev, 1970;Feldberg & Lotti, 1970), gallamine (Salmoiraghi & Steiner, 1963;Curtis, Ryall & Watkins, 1966;Halpern & Black, 1967;Pixner, 1967;Galindo, Krnjevic & Schwartz, 1968;Grinnell, 1970), tetraethylammonium (Furukawa, 1955, Pixner, 1967Grinnell, 1970) and atropine (Bonnet & Bremer, 1952;Phillis & Tebecis, 1967;Bhargava & Meldrum, 1969) that these agents might also interfere with amino acid mediated transmission. Indeed, the observation that curare blocks both cortical inhibition and the action of y-aminobutyric acid (GABA) (Hill, Simmonds & Straughan, 1972) supports this notion.…”

Section: Introductionmentioning

confidence: 99%

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THE ACTION OF ACETYLCHOLINE ANTAGONISTS ON AMINO ACID RESPONSES IN THE FROG SPINAL CORD in vitro

NICOLL

1975

British J Pharmacology

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I The isolated hemisected frog spinal cord has been used to study the action of acetylcholine antagonists on amino acid responses by means of sucrose gap recording. 2 Primary afferents and motoneurones were shown to contain few, if any, cholinoceptors, since acetylcholine and carbachol responses were essentially abolished when synaptic transmission was blocked with magnesium ions or when action potentials were blocked by tetrodotoxin.3 Curare antagonized the y-aminobutyric acid (GABA) and ,B-alanine depolarizations of primary afferents and the hyperpolarizing action of these amino acids on motoneurones. Nicotine also antagonized 3-alanine depolarizations and to a small extent GABA depolarizations of primary afferents. These actions are similar to but weaker than those obtained previously with picrotoxin. 4 Atropine selectively antagonized 3-alanine depolarizations of primary afferents and blocked ,B-alanine and glycine hyperpolarizations of motoneurones. GABA responses were entirely resistant to the action of atropine. These actions are similar to but 50 times weaker than those obtained previously with strychnine. 5 Dihydro-,B-erythroidine, tetraethylammonium, and gallamine were entirely ineffective in antagonizing amino acid responses. Since these agents are known to block the dorsal root potential elicited by ventral root stimulation but have no effect on the amino acid responses of primary afferents, it is evident that a cholinergic step is involved in this pathway.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

THE ACTION OF ACETYLCHOLINE ANTAGONISTS ON AMINO ACID RESPONSES IN THE FROG SPINAL CORD in vitro

NICOLL

1975

British J Pharmacology

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“…A connection equivalent to that found in adult amphibia which leads to depolarization of the dorsal roots following stimulation of motoneurones (e.g. Grinnell, 1970;Shupliakov et al 1990) is unlikely in Xenopu.s embryos where motorneurones lack dorsally projecting axons. The possibility that vertebrate motoneurones could be integral members of a CPG, as is the case in many invertebrate systems (crayfish swimmerets: Heitler, 1978; crab gill chamber ventilation: Simmers & Bush, 1983) clearly requires further study.…”

Section: Discussionmentioning

confidence: 99%

Cholinergic and electrical synapses between synergistic spinal motoneurones in the Xenopus laevis embryo.

Perrins

Roberts

1995

The Journal of Physiology

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connections were found which crossed the cord. The fast PSPs were blocked by 10 /M mecamylamine but not by 1 mm kynurenic acid, so were mediated by nicotinic acetylcholine receptors (nAChRs). These are the first unitary excitatory postsynaptic potentials (EPSPs) mediated by nAChRs recorded intracellularly within the vertebrate central nervous system. 4. Bidirectional electrical synapses were found between five pairs of motoneurones. All these pairs were on the same side of the spinal cord and less than 70 um apart. Each neurone responded in a graded manner to either hyperpolarizing or depolarizing current injected into the other. 5. Since motoneurones are rhythmically active during swimming, both chemical and electrical synapses will add to the fast on-cycle excitation underlying spiking activity in other motoneurones. This may increase the reliability and local synchrony of synergistic motoneurone firing during locomotion.

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“…Of the three types, only chemical synapses are thought to occur widely in the mammalian central nervous system (2,3,6). In contrast, electrical synapses (7), although common in the spinal cords of lower vertebrates and in neonatal mammals (4,(8)(9)(10)(11), are thought to be extremely rare in the spinal cords of adult mammals, having been found only in two small clusters of motor neurons that synchronize the contractions of ejaculatory muscles in adult male rats (12,13). Mixed synapses, however, have not been observed previously in any region of the spinal cords of adult mammals (2,3).…”

mentioning

confidence: 96%

Mixed synapses discovered and mapped throughout mammalian spinal cord.

Rash

Dillman

Bilhartz

et al. 1996

Proc. Natl. Acad. Sci. U.S.A.

145

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Electrical interaction between antidromically stimulated frog motoneurones and dorsal root afferents: enhancement by gallamine and TEA

Cited by 69 publications

References 23 publications

THE ACTION OF ACETYLCHOLINE ANTAGONISTS ON AMINO ACID RESPONSES IN THE FROG SPINAL CORD in vitro

THE ACTION OF ACETYLCHOLINE ANTAGONISTS ON AMINO ACID RESPONSES IN THE FROG SPINAL CORD in vitro

Cholinergic and electrical synapses between synergistic spinal motoneurones in the Xenopus laevis embryo.

Mixed synapses discovered and mapped throughout mammalian spinal cord.

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