Journal of Neuroscience, Vol 10, 2148-2155, Copyright © 1990 by Society for Neuroscience
Glycine-insensitive NMDA-sensitive receptor expressed in Xenopus oocytes by guinea pig cerebellar mRNA
M Sekiguchi, K Okamoto and Y Sakai
Department of Pharmacology, National Defense Medical College, Saitama, Japan.
The electrophysiological and pharmacological properties of N-methyl-D-
aspartate (NMDA)-sensitive receptors expressed in Xenopus oocytes by
injection of total poly(A)+RNAs (mRNAs) from the cerebellum and cerebrum of
guinea pigs were compared. The inward current induced by NMDA under
voltage-clamp in cerebellar mRNA-injected oocytes was depressed in a
voltage-dependent fashion by Mg2+ to show a negative slope conductance and
selectively antagonized by D-2-amino-5- phosphonovalerate (D-APV) and
phencyclidine (PCP). Glycine (0.01-10 microM) did not potentiate
NMDA-induced currents in cerebellar mRNA- injected oocytes, while it
potentiated NMDA-induced currents in cerebral mRNA-injected oocytes in a
dose-dependent fashion. 6-Cyano-7- nitroquinoxaline-2,3-dione and
7-chlorokynure-nate suppressed the NMDA response but significantly less
potently in cerebellar mRNA-injected oocytes than in cerebral mRNA-injected
oocytes. These results suggest that the NMDA-sensitive receptor expressed
in Xenopus oocytes by guinea pig cerebellar mRNA resembles the cerebral
NMDA receptor in its high sensitivities to Mg2+, PCP, and D-APV, but it is
distinct from the cerebral NMDA receptor in responsiveness to glycine.