Original Articles

Analgesic effect of agmatine and its enhancement on morphine analgesia in mice and rats

Jin Li, Xin Li, Gang Pei, Bo-yi Qin


To study the effect of agmatine on pain and morphine analgesia.
The effect of agmatine on pain was observed in mouse heat radiant tail-flick test, mouse acetic acid writhing test, and rat 4% saline test. Its enhancing effect on analgesia of morphine and clonidine was assessed in rat and mouse heat radiant tail-flick tests.
Agmatine did not significantly prolong tail-flick latency of mice, but reduced the number of acetic acid-induced writhing of mice and inhibited writhing responses to saline completely. It potentiated the analgesic effects of morphine and clonidine in dose-dependent manner and decreased the analgesic ED50 of morphine and clonidine by more than 75% in mouse heat radiant tail-flick test. These effects of agmatine were antagonized by idazoxan.
Agmatine has weak analgesic effects and potentiates morphine and clonidine analgesia by activation of imidazoline receptors.

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