Anaesthetics depress the sensitivity of cortical neurones to L-glutamate

Br J Pharmacol. 1976 Nov;58(3):347-57.

Abstract

1 The effects of general anaesthetics on the responses of neurones to iontophoretically applied L-glutamate have been examined in slices of the guinea-pig olfactory cortex in vitro. 2 Concentrations of pentobarbitone, ether, methoxyflurance, 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 (less than 1%) did not alter sensitivity of neurones to glutamate. Higher concentrations (greater than 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. 5 If 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.

MeSH terms

  • Acetylcholine / pharmacology
  • Anesthetics*
  • Animals
  • Cerebral Cortex / cytology*
  • Depression, Chemical
  • Ether / pharmacology
  • Evoked Potentials / drug effects
  • Glutamates / pharmacology*
  • Guinea Pigs
  • Halothane / pharmacology
  • Hydroxysteroids / pharmacology
  • In Vitro Techniques
  • Magnesium / pharmacology
  • Methoxyflurane / pharmacology
  • Neurons / drug effects*
  • Pentobarbital / pharmacology
  • Pregnanediones / pharmacology
  • Trichloroethylene

Substances

  • Anesthetics
  • Glutamates
  • Hydroxysteroids
  • Pregnanediones
  • Ether
  • Trichloroethylene
  • Methoxyflurane
  • alphaxalone
  • Magnesium
  • Pentobarbital
  • Acetylcholine
  • Halothane