The actions of picrotoxin, strychnine, bicuculline and other convulsants and antagonists on the responses to acetylcholine glutamic acid and gamma-aminobutyric acid on Helix neurones

Piggott, Susan M.; Kerkut, G.A.; Walker, Robert

doi:10.1016/0306-4492(77)90054-5

Cited by 11 publications

(5 citation statements)

References 37 publications

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“…7A). Similar effects have been observed for the GABA response of Helix neurones (Piggot, Kerkut & Walker, 1977).…”

Section: Effects Of Antagonists On Gaba and Glycine Currentssupporting

confidence: 84%

GABA and glycine channels in isolated ganglion cells from the goldfish retina.

Cohen¹,

Fain²,

Fain³

1989

The Journal of Physiology

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SUMMARY1. Adult goldfish retinas were enzymatically dissociated and ganglion cells were maintained in culture for periods of 1-5 days. Ganglion cells could be identified by their morphology, and this identification was confirmed by retrograde transport of the fluorescent dye Fast Blue injected into the optic nerve stub.2. All the ganglion cells tested responded to 30 ,tM-GABA or 100 /IM-glycine between 2 and 30 h after enzymatic dissociation of the retina.3. Whole-cell responses to 30 jM-GABA or glycine declined over a period of seconds during sustained applications of the agonists, probably as a result of desensitization. There was an irreversible decline in the peak whole-cell response to repeated applications of 30 /tM-GABA unless the pipette-filling solution contained 2 mM-ATP, 4 mM-Mg2", 10 mM-EGTA and no added Ca2+. Both GABA and glycine responses also showed an irreversible decline in outside-out patches but, in this case, Mg2+, ATP, and very low Ca2+ failed to stabilize the response.4. Whole-cell currents activated by both GABA and glycine were demonstrated to be chloride-selective by investigating the dependence of reversal potential (VT) on internal chloride concentration ([CFi) For GABA responses, the dependence of Vr on [Cl-]i could not be distinguished from that predicted by the Nernst relation. For glycine, deviations from Nernstian dependence were observed, but the permeability to Cl-was at least 20 times greater than to isethionate, S042-, or monovalent cations

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“…7A). Similar effects have been observed for the GABA response of Helix neurones (Piggot, Kerkut & Walker, 1977).…”

Section: Effects Of Antagonists On Gaba and Glycine Currentssupporting

confidence: 84%

GABA and glycine channels in isolated ganglion cells from the goldfish retina.

Cohen¹,

Fain²,

Fain³

1989

The Journal of Physiology

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“…3) Approximately 1.5 X low4 M picrotoxin simultaneously blocked both IPSPs and the delayed excitatory potential following each spike of 301. Picrotoxin has been shown to block GABA, acetylcholine, and glutamate inhibitory connections produced by increases in conductance to both chloride and potassium ions (30,42,72). Only rarely has it been proposed as a blocker of excitatory potentials (3, 23, 3 1, 32).…”

Section: Graded Interactions In the Flight Systemmentioning

confidence: 99%

Neural circuits in the flight system of the locust

Robertson¹,

Pearson²

1985

Journal of Neurophysiology

147

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Circuitry in the flight system of the locust, Locusta migratoria, was investigated by use of intracellular recording and staining techniques. Neuronal connections were established by recording simultaneously from neuropile segments of pairs of identified interneurons. Brief depolarizing current pulses delivered to interneurons 301 and 501 reset the flight rhythm in a phase-dependent manner, thus establishing the importance of these neurons in rhythm generation. Interneuron 301 was found to make a strong delayed excitatory connection with 501 and to receive a short-latency inhibitory connection from 501. The circuit formed by 301 and 501 appears suited for promoting rhythmicity in the flight system. The delayed excitatory potential recorded in 501 following each spike of 301 was reversed by hyperpolarizing 501. This potential and short-latency inhibitory postsynaptic potentials from 301 to other interneurons were blocked with the application of picrotoxin. We conclude that the delayed excitation is produced via a disynaptic pathway from 301 to 501, with 301 inhibiting in a graded manner the tonic release of transmitter from one or more unidentified intercalated neurons. Interconnections between the 301-501 circuit and other identified interneurons were discovered. This circuitry can account for two features of the flight motor pattern recorded in deafferented preparations. These features are the constant-latency relationship between depolarizations in elevator and depressor motoneurons and the relatively constant duration of depressor motoneuron bursts. The locust flight system shares general features with other described rhythm-generating systems. These include the occurrence of graded interactions, the probability of multiple oscillatory mechanisms, and a predominance of inhibitory connections. Its uniqueness lies in the way that components and processes are assembled and operate.

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“…Another difference between invertebrate and mammalian GABAA-receptors is that apart from a few exceptions (Walker et al, 1971;Piggott et al, 1977;Yarowsky & Carpenter, 1978;Waldrop et al, 1987), these receptors are generally only weakly (Smart & Constanti 1986), or not blocked (Scott & Duce 1987;Sattelle et al, 1988;Benson 1988a; by the definitive, competitive GABAA-receptor antagonist, bicuculline. Nevertheless, micromolar concentrations of the noncompetitive antagonist picrotoxin, which acts at the level of the chloride channel in mammalian preparations (Olsen, 1981;Barker, 1985), is sufficient to block GABA-mediated responses in most invertebrates (Piggott et al, 1977;Hori et al, 1978;Constanti, 1978;Walker & Roberts, 1982;Sattelle et al, 1988). In arthropods the interaction of picrotoxin with the receptor channel complex may differ slightly from the interaction in mammalian systems in that the block may not be truly noncompetitive (Constanti, 1978).…”

Section: Introductionmentioning

confidence: 99%

GABA receptors on the somatic muscle cells of the parasitic nematode, Ascaris suum: stereoselectivity indicates similarity to a GABA_A‐type agonist recognition site

Holden‐Dye

Krogsgaard‐Larsen²,

Nielsen³

et al. 1989

British J Pharmacology

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1 The y-aminobutyric acid (GABA) receptors on the somatic muscle cells of Ascaris, which mediate muscle cell hyperpolarization and relaxation, have been characterized by use of intracellular recording techniques. 2 These receptors are like mammalian GABAA-receptors in that the response is mediated by an increase conductance to chloride ions. The GABAA-mimetic, muscimol, has a relative potency of 0.40 + 0.02 (n = 3) compared to GABA. 3 The stereoselectivity of the GABA receptor on Ascaris is identical to that for the mammalian GABAA-receptor, as determined from the relative potency of three pairs of enantiomers of structural analogues of GABA. 4 The most potent agonist is (S)-(+)-dihydromuscimol which is 7.53 + 0.98 (n = 5) times more potent than GABA. 5 The Ascaris GABA receptor is not significantly blocked, at concentrations below OO Mm by the potent, competitive GABAA-receptor antagonist, SR95531. 6 The Ascaris GABA receptor does not recognise agents that are known to block the GABA gated chloride channel in mammalian preparations such as t-butylbicyclophosphorothionate (TBPS, 1OpM, n = 2) or the insecticide dieldrin (100pM, n = 3). 7 GABAergic responses in Ascaris are not potentiated by pentobarbitone (100pM, n = 3) or flurazepam (100pM, n = 3). 8 The potencies of various GABA-mimetics in the Ascaris preparation have been compared with their potency at displacing GABAA-receptor binding in mammalian brain. Excluding the sulphonic acid derivatives of GABA, the correlation coefficient (r) between the potencies of compounds in the two systems is 0.74 (P < 0.01). The significance of this correlation is discussed.9 The pharmacology of the Ascaris GABA receptor is discussed in relation to other invertebrate systems and the mammalian subclassification of GABA receptors.

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The actions of picrotoxin, strychnine, bicuculline and other convulsants and antagonists on the responses to acetylcholine glutamic acid and gamma-aminobutyric acid on Helix neurones

Cited by 11 publications

References 37 publications

GABA and glycine channels in isolated ganglion cells from the goldfish retina.

GABA and glycine channels in isolated ganglion cells from the goldfish retina.

Neural circuits in the flight system of the locust

GABA receptors on the somatic muscle cells of the parasitic nematode, Ascaris suum: stereoselectivity indicates similarity to a GABA_A‐type agonist recognition site

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The actions of picrotoxin, strychnine, bicuculline and other convulsants and antagonists on the responses to acetylcholine glutamic acid and gamma-aminobutyric acid on Helix neurones

Cited by 11 publications

References 37 publications

GABA and glycine channels in isolated ganglion cells from the goldfish retina.

GABA and glycine channels in isolated ganglion cells from the goldfish retina.

Neural circuits in the flight system of the locust

GABA receptors on the somatic muscle cells of the parasitic nematode, Ascaris suum: stereoselectivity indicates similarity to a GABAA‐type agonist recognition site

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GABA receptors on the somatic muscle cells of the parasitic nematode, Ascaris suum: stereoselectivity indicates similarity to a GABA_A‐type agonist recognition site