Antinociception of omega-conotoxin ω-SO3 in rat formalin test after acute or chronic intrathecal administration
- VernacularTitle:芋螺毒素ω-SO3单次及连续给药对福尔马林致大鼠炎性疼痛的镇痛作用
- Author:
Xiaoli JI
;
Lingdi YAN
;
Peilan ZHOU
;
Huajin DONG
;
Zehui GONG
;
Peitang HUANG
- Publication Type:Journal Article
- Keywords:
ω-SO3;
morphine;
inflammatory pain;
antinociception;
tolerance;
cross tolerance;
locomotor activity]
- From:
Chinese Pharmacological Bulletin
2010;26(4):476-482
- CountryChina
- Language:Chinese
-
Abstract:
Aim To evaluate the antinociception of ω-SO3,a novel Omega-superfamily conotoxin,in rat formalin test.Methods Potency and duration of ω-SO3 antinociception compared with morphine were investigated in rat formalin test after acute intrathecal administration.Development of tolerance or cross tolerance to analgesia of ω-SO3 and morphine was tested in formalin test after chronic intrathecal administration.Locomotor activity of rat after acute intrathecal administration was tested to evaluate possible central side effects.Results In rat formalin test after intrathecal bolus injection,ω-SO3 produced dose-and time-dependent antinociception by suppressing acute(ED_(50),1.79 ng·g~(-1))and tonic phases(ED_(50),0.41 ng·g~(-1)),which was approximately 10-fold potency and twice longer-acting of morphine in blocking tonic phase responses.After repeated intrathecal injections twice daily for 5 consecutive days,ω-SO3 produced analgesia without loss of potency whereas morphine produced analgesia tolerance in rat formalin test;further,ω-SO3 still produced potent analgesia in morphine-tolerant rats.No changes in motor function were seen in rats receiving above antinociceptive doses.Conclusion sNovel ω-SO3 produces potent and long-acting spinal antinociception without observable motor dysfunction and after chronic intrathecal administration.ω-SO3 produces neither tolerance nor cross-tolerance to morphine analgesia.
