Glutamate and N-acetyl-aspartyl-glutamate block HVA calcium currents in
frog olfactory bulb interneurons via an mGluR2/3-like receptor.
Bischofberger, Josef and Detlev Schild.
Physiologisches Institut, Universit[umlaut]at G[diaeresis]ottingen,
Humboldtallee 23, D37073 G[diaeresis]ottingen, FRG, T. 49-551-395915, F. 49-
APStracts 3:0108N, 1996.
SUMMARY AND CONCLUSIONS
1. We have investigated the glutamate-mediated modulation of voltage activated
calcium currents in cultured interneurons of the olfactory bulb of Xenopus
laevis using standard patch clamp whole-cell recordings. 2. Glutamate and N-
acetylaspartylglutamate (NAAG) activated DCGIV-sensitive metabotropic
glutamate receptors at olfactory bulb interneurons and thereby inhibited
calcium influx through presynaptic voltage gated calcium channels. 3. The
glutamate- or NAAG-mediated blockage of calcium channels showed
indistinguishable dose-response curves with K1/2 ? = ? 388 and ? 350 nM for
glutamate and NAAG, respectively. At saturating concentrations of glutamate or
NAAG about 40% of the maximum calcium currents was blocked. 4. It is concluded
that glutamate, which excites interneurons at OB reciprocal synapses, also
causes a reduction of GABA-mediated feedback inhibition at these synapses by
activating a mGluR2/3-like receptor.
Received 30 January 1996; accepted in final form 9 May 1996.
APS Manuscript Number J66-6.
Article publication pending J. Neurophysiol.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 5 June 96