GABAA Receptor-Mediated Cl- Currents in Rat Thalamic Reticular and Relay
Neurons.
Shuanglin J. Zhang, John R. Huguenard and David A. Prince.
Department of Neurology and Neurological Sciences, Stanford University
Medical Center, Stanford, CA 94305, USA
APStracts 4:136N, 1997.
ABSTRACT
Spontaneous and evoked inhibitory postsynaptic currents (sIPSCs and eIPSCs)
and responses to exogenously applied ë-aminobutyric acid (GABA), mediated by
GABA type A (GABAA) receptors, were recorded in inhibitory neurons of nucleus
Reticularis thalami (nRt) and their target relay cells in ventrobasal (VB)
nuclei, using patch clamp techniques in rat thalamic slices. The decay of
sIPSCs in both nRt and VB neurons was best-fitted with two exponential
components. The decay time constants of sIPSCs in nRt neurons were much slower
(t1 = 38 ms, t2 = 186 ms) than those previously reported in a variety of
preparations, and 2-3 times slower than those in VB neurons (t1 = 17 ms, t2 =
39 ms). GABAA receptor-mediated Cl- currents directly evoked by local GABA
application also had a much slower decay time constant in nRt (225 ms) than in
VB neurons (115 ms). Slow decay of GABA responses enhances the efficacy of
recurrent intranuclear inhibition in nRt. The results suggest a functional
diversity of GABAA receptors that may relate to the known heterogeneity of
GABAA receptor subunits in these two thalamic nuclei.
Received 28 January 1997; accepted in final form 8 July 1997.
APS Manuscript Number J85-7.
Article publication pending J. Neurophysiol.
ISSN 1080-4757 Copyright 1997 The American Physiological Society.
Published in APStracts on 27 August 1997