Pharmacological studies on feline Betz cells

Crawford, Jonathan; Curtis, D. R.

doi:10.1113/jphysiol.1966.sp008024

Cited by 179 publications

(62 citation statements)

References 31 publications

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“…In addition, in the olfactory cortex it has been shown that general anaesthetics, including pentobarbitone, depress both excitatory synaptic transmission and the sensitivity of neurones to ionophoretically-applied glutamate (Richards et al, 1975;Richards & Smaje, 1976). Similar results have been reported for the action of barbiturates on the glutamate sensitivity of neurones in the cat neocortex (Crawford & Curtis, 1966). Since these early studies it has become clear that glutamate acts on two major classes of receptor: ionotropic receptors which are integral parts of ion channels and metabotropic receptors which activate second messenger systems.…”

Section: Introductionsupporting

confidence: 75%

Pentobarbitone modulation of NMDA receptors in neurones isolated from the rat olfactory brain

Charlesworth¹,

Jacobson²,

Richards³

1995

British J Pharmacology

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Section: Introductionsupporting

confidence: 75%

Pentobarbitone modulation of NMDA receptors in neurones isolated from the rat olfactory brain

Charlesworth¹,

Jacobson²,

Richards³

1995

British J Pharmacology

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“…As anaesthetics do not alter the coupling between the population e.p.s.p. and the discharge of the pyramidal cells, this depression is not the result of e a generalized increase in the resting membrane permeability to potassium or chloride such as that seen following the iontophoretic application of 2, 4 dinitrophenol to cortical neurones (Godfraind, Krnjevi6 & Pumain, 1970 In contrast to the other anaesthetics studied, halothane did not depress the glutamate-sensitivity of cortical neurones until relatively high concentrations were reached (> 1%), whereas synaptic transmission became depressed at much lower concentrations (> 0.4%) (Richards, 1973a Crawford & Curtis (1966) and Johnson, Roberts & Straughan (1966) found that systemic administration of barbiturates depressed the sensitivity of cortical neurones to iontophoretically-applied glutamate and DL-homocysteic acid. Crawford (1970), working with the cerveau isole preparation of the cat, found that halothane (< 1.5%) had no effect on the response of cells in the cat pericruciate gyrus but he also reported that methoxyflurane and trichloroethylene were without effect.…”

Section: Discussionmentioning

confidence: 96%

ANAESTHETICS DEPRESS THE SENSITIVITY OF CORTICAL NEURONES TO l‐GLUTAMATE

Richards

Smaje

1976

British J Pharmacology

136

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1The effects of general anaesthetics on the responses of neurones to iontophoretically applied Lglutamate have been examined in slices of the guinea-pig olfactory cortex in vitro. 2 Concentrations of pentobarbitone, ether, methoxyflurane, trichloroethylene and alphaxalone that are known to depress synaptic transmission in the prepiriform cortex also depressed the sensitivity of prepiriform neurones to L-glutamate. 3 Halothane, in concentrations that depress synaptic transmission (< 1%) did not alter the sensitivity of neurones to glutamate. Higher concentrations (> 1%) produced a dose-related depression of the glutamate sensitivity of neurones. 4 All four volatile anaesthetics tested caused some cells to alter their glutamate-evoked firing pattern to one in which the spike discharges were more closely grouped. Pentobarbitone and alphaxalone had no such effect. SIf the sensitivity of the neurones to the endogenous excitatory transmitter is affected by anaesthetics in the same way as the glutamate-sensitivity, these results suggest that halothane depresses synaptic transmission by decreasing the amount of transmitter released from the nerve terminals, whereas the other anaesthetics depress the sensitivity of the post-synaptic membrane to the released transmitter.

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“…In these experiments, the 'control barrel' contained NaCl only as in the bulk of the experiments of Krnjevi6 & Phillis (1963a, b) and Crawford & Curtis (1966). Apparent differences between the 5-HT salts should thus be due to differences between the cation and anion species associated with 5-HT in the salt.…”

Section: Methodsmentioning

confidence: 99%

Excitation and depression of cortical neurones by 5‐hydroxytryptamine

Roberts¹,

Straughan²

1967

The Journal of Physiology

256

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SUMMARY1. 5-Hydroxytryptamine (5-HT) and various 5-HT antagonists have been applied micro-electrophoretically from multibarrelled micropipettes into the environment of single neurones in the post-sigmoid and suprasylvian gyri of the cat cerebral cortex.2. In unanaesthetized animals (encephale isole) a high proportion of neurones (30 %) were excited by 5-HT. This excitation usually had a rapid onset and was seen both in spontaneously active neurones and in otherwise quiescent neurones in which firing was induced by L-glutamate. Some neurones were so sensitive that the uncontrolled diffusion from micropipettes was sufficient to excite them. More cells were excited by 5-HT applied as a cation from solutions of the bimaleate salt than when solutions of the creatinine sulphate salt were used.3. In a high proportion of cells (33 %) spontaneous firing or amino acid excitation was depressed by 5-HT. 4. A mixed effect was seen in a small proportion (6 %) of the cells tested; usually 5-HT caused an excitation initially which was followed by a depression. In other cells, desensitization occurred, and the excitatory effect of 5-HT was diminished or lost. In two cells, however, the depression was reversibly prevented by these antagonists.8. Some cells tested with 5-HT were also tested with ACh or (-noradrenaline. The response of a cell to ACh was not significantly related to its response to 5-HT. The degree of correlation between the responses to noradrenaline and 5-HT was large, but not statistically significant with the small number of cells studied. 9. The effects of 5-HT on cells in animals anaesthetized with oc-chloralose did not differ significantly from its effects in unanaesthetized preparations. It is suggested that the use of this anaesthetic may prove a useful alternative to unanaesthetized preparations.10. The systemic injection of small quantities of thiopentone sodium selectively and reversibly reduced the sensitivity of some units to excitation by 5-HT at a time when the response to glutamate was unaffected. On other occasions, the 5-HT excitation was unaffected, though the response to glutamate was reduced.11. These results are discussed in relation to the possible nature of the 5-HT receptors in the cerebral cortex, and the interfering effects of anaesthesia on the response of brain cells to potential transmitter substances.

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Pharmacological studies on feline Betz cells

Abstract: 4. The significance of these results is discussed in relation to the possible synaptic or non-synaptic action of acetylcholine upon cortical neurones.

Cited by 179 publications

References 31 publications

Pentobarbitone modulation of NMDA receptors in neurones isolated from the rat olfactory brain

Pentobarbitone modulation of NMDA receptors in neurones isolated from the rat olfactory brain

ANAESTHETICS DEPRESS THE SENSITIVITY OF CORTICAL NEURONES TO l‐GLUTAMATE

Excitation and depression of cortical neurones by 5‐hydroxytryptamine

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