F. Hamada et al., Comparison of the spinal anti-nociceptive effects of ES-242-1 and MK-801, two different NMDA antagonists, in rats, NEUROSCI RE, 40(1), 2001, pp. 61-66
The purpose of this study was to determine whether ES-242-1, a novel N-meth
yl-D-aspartate (NMDA) receptor antagonist of microbial origin, has anti-noc
iception at the spinal level and to evaluate how its anti-nociceptive effec
t differs from that of MK-801, a non-competitive NMDA receptor antagonist.
Agents were injected intrathecally (0.1, 1.0 and 10 mug) through a previous
ly implanted PE tube in rats. Formalin (2%, 100 mul) was injected subcutane
ously into the left hindpaw 15 min after each antagonist administration. Li
cking time as a nociceptive behavior was measured in three stages after for
malin-injection, such as early phase (0-9 min), late first phase (10-29 min
) and late second phase (30-60 min). In the early phase, the largest dose o
f ES-242-1 significantly decreased total licking time, although MK-801 did
not show any significant reduction. With the treatment of 1.0 and 10 mug MK
-801, total licking time in both late first and second phases was significa
ntly suppressed, although the smallest dose (0.1 mug) of ES-242-1 showed a
significant reduction in the late second phase. These results indicate that
ES-242-1 is highly effective against tonic pain, such as inflammatory pain
. (C) 2001 Elsevier Science Ireland Ltd and the Japan Neuroscience Society.
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