Determination of alpha(2)-adrenoceptor and imidazoline receptor involvement in augmentation of morphine and oxycodone analgesia by agmatine and BMS182874

作者：Bhalla Shaifali^*; Rapolaviciute Vaide; Gulati Anil

来源：European Journal of Pharmacology, 2011, 651(1-3): 109-121.

DOI：10.1016/j.ejphar.2010.10.090

• Agmatine
• Endothelin ETA receptor
• Morphine
• Oxycodone
• alpha(2)-Adrenoceptor
• Imidazoline receptor
• Idazoxan
• Yohimbine
• Naloxone
• Antinociception

Studies have demonstrated that clonidine (alpha(2)-adrenoceptor and imidazoline receptor agonist) and BMS182874 (endothelin ETA receptor antagonist) potentiate morphine and oxycodone analgesia. Agmatine, an endogenous clonidine-like substance, enhances morphine analgesia. However, its effect on oxycodone analgesia and its interaction with endothelin ETA receptor antagonists are not known. The present study was performed to determine the effect of agmatine on morphine and oxycodone analgesia and the involvement of alpha(2)-adrenoceptors, imidazoline receptors, opioid receptors, and endothelin receptors. Antinociception at various time intervals was determined by the tail-flick latency method in mice. Agmatine produced dose-dependent increase in tail-flick latency, while BMS182874 did not produce any change over the 360-min observation period. Agmatine significantly potentiated morphine as well as oxycodone analgesia which was not altered by BMS182874. BMS182874 pretreatment did not increase the analgesic effect produced by agmatine alone. Agmatine-induced potentiation of morphine and oxycodone analgesia was blocked by idazoxan (imidazoline receptor/alpha(2)-adrenoceptor antagonist) and yohimbine (alpha(2)-adrenoceptor antagonist). BMS182874-induced potentiation of morphine or oxycodone analgesia was not affected by yohimbine. However, idazoxan blocked BMS182874-induced potentiation of oxycodone but not morphine analgesia This is the first report demonstrating that agmatine potentiates not only morphine but also oxycodone analgesia in mice. Potentiation of morphine and oxycodone analgesia by agmatine appears to involve alpha(2)-adrenoceptors, imidazoline receptors, and opioid receptors. In addition, imidazoline receptors may be involved in BMS182874-induced potentiation of oxycodone but not morphine analgesia. It is concluded that agmatine may be used as an adjuvant in opiate analgesia.

• 出版日期2011-1-25