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Originally published In Press as doi:10.1074/jbc.M206768200 on August 23, 2002
J. Biol. Chem., Vol. 277, Issue 44, 41369-41378, November 1, 2002
The General Anesthetic Pentobarbital Slows Desensitization and
Deactivation of the Glycine Receptor in the Rat Spinal Dorsal Horn
Neurons*
Hui
Lü and
Tian-Le
Xu
From the Laboratory of Receptor Pharmacology, Department of
Neurobiology and Biophysics, University of Science and Technology
of China, Hefei 230027, People's Republic of China
Although many general anesthetics have been found
to produce anesthetic and analgesic effects by augmenting
GABAA receptor (GABAAR) function, the
role of the glycine receptor (GlyR) in this process is not fully
understood at the neuronal level in the spinal cord. We
investigated the effects of a barbiturate general anesthetic,
pentobarbital (PB), on the glycinergic miniature inhibitory
postsynaptic currents (mIPSCs) and the responses to exogenously applied
glycine, or taurine, a low affinity GlyR agonist, by using the
whole-cell patch-clamp technique in the rat spinal dorsal horn neurons
isolated using a novel mechanical method. Bath application of 30 µM PB significantly prolonged the decay time constant of
the spontaneous glycinergic mIPSC without changing its amplitude and
frequency. Co-application of 0.3 mM PB reduced the peak
amplitude, affected the macroscopic desensitization and deactivation of
the response to externally applied Gly in a
concentration-dependent manner. In addition, the recovery of
Gly response from desensitization was also prolonged by PB. However, PB
did not change the desensitization and deactivation kinetics of the
taurine-induced response. The GABAAR antagonist bicuculline
(10 µM) did not affect the effect of PB on the Gly
response. Thus, PB prolonged the spinal glycinergic mIPSCs by slowing
desensitization and deactivation of GlyR. Two other structurally
different intravenous anesthetics, i.e. propofol (10 µM) and etomidate (3 µM), prolonged the
duration of the glycinergic mIPSC in the rat spinal dorsal horn
neurons. In conclusion, on GlyR-Cl channel
complexes there may exist action site(s) of intravenous general
anesthetics. GlyR and glycinergic neurotransmission may play an
important role in the modulation of general anesthesia in the mammalian
spinal cord.
*
This study was supported in part by the National Natural
Science Foundation of China (Nos. 3970200, 30125015, 30170247), the National Basic Research Program of China (G1999054000), and the Grant
for Outstanding Young Researchers from the Ministry of Education of
China (to T.-L. Xu).The costs of publication of this
article were defrayed in part by the
payment of page charges. The article must therefore be hereby marked
"advertisement" in
accordance with 18 U.S.C. Section
1734 solely to indicate this fact.
To whom correspondence should be addressed: Dept. of Neurobiology
and Biophysics, School of Life Sciences, University of Science and
Technology of China, P.O. Box 4, Hefei 230027, P. R. China. Tel.:
86-551-360-3510; Fax: 86-551-360-7014; E-mail:
xutianle@ustc.edu.cn.
Copyright © 2002 by The American Society for Biochemistry and Molecular Biology, Inc.

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