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Nociceptive behavior induced by poly-L-lysine and other basic compounds involves the spinal NMDA receptors
Koichi Tan-No1, Akihisa Esashi, Osamu Nakagawasai
1Department of Pharmacology, Tohoku Pharmaceutical University, 4-4-1 Komatsushima, Aoba-ku, Sendai 981-8558, Japan. koichi@tohoku-pharm.ac.jp
Brain Research
|April 15, 2004
Summary
Basic polyamines like poly-L-lysine can induce nociceptive behavior in mice. This pain response is mediated by the N-methyl-D-aspartate (NMDA) receptor ion-channel complex.
Area of Science:
- Neuroscience
- Pharmacology
Background:
- Spermine and big dynorphin, basic molecules, induce nociceptive behavior when injected intrathecally (i.t.) in mice.
- This suggests that other basic molecules may elicit similar pain responses.
Purpose of the Study:
- To investigate if poly-L-lysine, another basic molecule, induces nociceptive behavior.
- To explore the underlying receptor mechanisms involved in poly-L-lysine-induced nociception.
Main Methods:
- Intrathecal administration of poly-L-lysine to mice.
- Behavioral observation of nociceptive responses (biting, licking, scratching).
- Pharmacological assessment using antagonists for NMDA receptors, ion-channels, polyamine sites, and other receptor types.
Main Results:
- Poly-L-lysine induced characteristic nociceptive behavior in mice.
- This behavior was dose-dependently inhibited by morphine, an NMDA receptor antagonist (D-APV), an NMDA ion-channel blocker (MK-801), and ifenprodil.
- Antagonists for non-NMDA glutamate receptors, glycine sites, NK1, and NK2 receptors had no effect.
Conclusions:
- Poly-L-lysine administration triggers nociceptive behavior in mice.
- The observed behavior is mediated by the N-methyl-D-aspartate (NMDA) receptor ion-channel complex.
- The NMDA receptor's polyamine recognition site or NR2B subunit is implicated in this response.