Competitive inhibition of the glycine-induced current by pregnenolone sulfate in cultured chick spinal cord neurons.
The effect of the neurosteroid pregnenolone sulfate (PS) on the glycine receptor-mediated response was studied in cultured chick spinal cord neurons using the whole-cell voltage-clamp recording technique. PS rapidly and reversibly inhibits the glycine-induced current in a dose-dependent manner, with an EC50 of 3.7 microM and a maximal inhibition of 100%. The fact that antagonism of the glycine response by PS is neither voltage- nor agonist-dependent indicates that PS does not act as an open-channel blocker. Furthermore, inhibition by PS of the glycine-induced current appears to be of a competitive type since the drug induces a parallel, rightward shift of the glycine dose-response curve.
Wu
F S
FS
Department of Physiology, College of Medicine, National Cheng Kung University, Tainan, Taiwan. fongsen@mail.ncku.edu.tw
Chen
S C
SC
Tsai
J J
JJ
D000818:Animals; D001667:Binding, Competitive; D002478:Cells, Cultured; D002642:Chick Embryo; D005998:Glycine / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D008564:Membrane Potentials / Q000187:drug effects; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D018408:Patch-Clamp Techniques; D011284:Pregnenolone / Q000494:pharmacology*; D013116:Spinal Cord / Q000502:physiology*
C018370:pregnenolone sulfate; D011284:Pregnenolone; D005998:Glycine