Premium
Amino‐acid induced depression of cortical neurones
Author(s) -
JOHNSON E. S.,
ROBERTS M. H. T.,
STRAUGHAN D. W.
Publication year - 1970
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1970.tb09875.x
Subject(s) - strychnine , glycine receptor , glycine , cortical spreading depression , chemistry , iontophoresis , neuroscience , gamma aminobutyric acid , biophysics , pharmacology , medicine , endocrinology , biology , amino acid , biochemistry , receptor , migraine
Summary1 The effects of strychnine on the degree of depression of neuronal firing induced by glycine, γ‐aminobutyric acid (GABA) and 5‐hydroxytryptamine (5‐HT) have been examined quantitatively. All drugs were applied by iontophoresis to spontaneously active cerebral cortical neurones in the anaesthetized cat. The application of these drugs was continued until a plateau or equilibrium depression was reached. The time taken to reach this steady state was noted. Dose‐response curves were then constructed for those currents giving less than complete depression. 2 Glycine was less potent than GABA and about 7‐fold larger currents were needed to achieve comparable depression. 5‐HT was also a weak depressant compared with GABA and had 0·6 the potency of glycine on a current basis. 3 Strychnine in currents up to 25 nA shifted the dose‐response curve of glycine to the right at a time when equilibrium depression in the same cells induced by the control agonists GABA or 5‐HT was unaffected. These currents of strychnine did, however, prolong the time‐course of onset of GABA and 5‐HT depression. 4 In larger currents strychnine reduced GABA equilibrium depression, but the dose‐response curve was not shifted in a parallel fashion. 5 It is concluded that strychnine can specifically and competitively antagonize the effect of glycine on cortical neurones.