Effect of Morphine on β_2-band of quantitative pharmaco-electroencephalogram in rabbits

OBJECTIVE To study the effect of Morphine on β2-band of quantitative pharmaco-electroencephalogram(QPEEG) in the rabbits and the relation with opiate receptor.METHODS 42 grown rabbits were divided into 7 groups(n = 6) :NS group(normal saline 1 mL·kg-1),LD group(Morphine 0.5 mg·kg-1),MD group(Morphine 1 mg·kg-1),HD group(Morphine 2 mg·kg-1),Na group(Naloxone 200 μg·kg-1),NSM group(normal saline 1 mL·kg-1+ Morphine 2 mg·kg-1) and NAM group(Naloxone 200 μg·kg-1+ Morphine 2 mg·kg-1).QPEEG activity was processed with power spectral analysis in order to analyze the change of β2-band power percentage before and after the rabbits' being administrated drugs.RESULTS Compared with the previous administration,there was no obvious change in β2-band power percentage of NS group,N group and LD group.In MD group and HD group,β2-band power percentage had an increased in several brain regions during 0.5-5 min(P 0.05,P 0.01).The change of β2-band power percentage during 0.5-5 min had a positive correlation with Morphine dose(r = 0.407-0.694,P 0.01).In NAM group,there was no obvious change in β2-band power percentage before and after the rabbits' being administrated Morphine.β2-band power percentage of NAM group were even lower than that of NSM group in some brain regions(P 0.05).CONCLUSION Morphine can increase β2-band power percentage of QPEEG in a dose dependant manner in rabbits,which can be antagonized by Naloxone.It indicates that Morphine affects the sites in cerebral cortex widely.Opiate receptor mediates this effect and β2-band may become an index that reflects analgesia degree.