Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
2535250 | European Journal of Pharmacology | 2008 | 6 Pages |
Abstract
Our recent study has shown that the intracerebroventricular administration of d-serine, an endogenous and selective agonist for the glycine site of the N-methyl-d-aspartate receptor, alone or in combination with morphine, leads to the potentiation of antinociception on the tail-flick response. Although there is a variety of information concerning the effects of benzodiazepines on opioid-induced antinociception, little is known about the effect of benzodiazepines on the N-methyl-d-aspartate receptor agonist-induced antinociception. To clarify the analgesic interactions among the benzodiazepine/GABAA, N-methyl-d-aspartate and opioid receptors at the supraspinal level, we investigated the effects of intracerebroventricular administration of midazolam, a benzodiazepine receptor agonist, on the antinociception evoked by the intracerebroventricular application of d-serine or morphine. The intracerebroventricular administration of midazolam alone produced hyperalgesia on the tail-flick response in a benzodiazepine receptor antagonist, flumazenil-reversible manner. The antinociception induced by the intracerebroventricular application of d-serine or morphine was attenuated by the intracerebroventricular administration of midazolam. In addition, this inhibitory effect of midazolam on the antinociception of d-serine or morphine was antagonized by the intracerebroventricular administration of flumazenil. Together with the facts that d-serine and midazolam act as selective agonists for the glycine site of the N-methyl-d-aspartate receptor and benzodiazepine/GABAA receptor, respectively, these observations suggest a functional interaction between the NMDA and benzodiazepine/GABAA receptors in the regulation of antinociception at the supraspinal level.
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Authors
Kenji Ito, Masanobu Yoshikawa, Miho Maeda, Xing Lu Jin, Shigeru Takahashi, Mitsumasa Matsuda, Raita Tamaki, Hiroyuki Kobayashi, Toshiyasu Suzuki, Atsushi Hashimoto,