Neurotensin injected into periagueductal gray could heighten effect of β-endorphin analgesia in rat

Objective The effect of neurotensin(NT), anti-β-endorphin serum (AEPS) and β-endorphin(β-EP) injected into periaqueductal gray(PAG) on the pain threshold in rats was investigated in this study.Methods The potassium iontophoresis induced tail-flick was used to measure the pain threshold. Results β- EPwhich was injected into PAG produced analgesia effect in the rat. AEPS could weaken the pain threshold in PAG ofrats.The micioinjection of NT in PAG could heighen effect of β-EP analgesia. Conclusion Our results indicatedthat β-EP could enhance the analgesia effect in PAG of rats, and this action of β-EP had closely related with the NTin PAG.