Abstract
Detail mechanism of the anesthetic effect of Dexmedetomidine (DX) is still unknown. The EEG activity and Fos expression were studied in the rats with different anesthetic levels. Two anesthetic levels were defined as light and deep anesthetic stages from the frequency analysis of the EEG activity during i.v. infusion of sodium pentobarbital (Nembutal), whereas those were defined as the occurrence of body movement during DX infusion. During Nembutal infusion, about 30% of δ and θ waves were observed at the light stage and about 50% of δ and 15% of θ waves were observed at the deep stage. On the other hand, EEG activity was not affected by DX infusion. A large number of Fos protein-LI cells were expressed in the MDH, area postrema, parabrachial nucleus, PAG, raphe, lateral hypothalamus and basolateral Amygdala after noxious heat stimulation of the face during Nembutal infusion, but no Fos protein-LI cells were expressed in the Amygdala during DX infusion. The strong depression of Fos protein-LI cells in the all areas of the CNS was observed at deep stage during Nembutal infusion. On the other hand, significant decrease in Fos expression was observed especially in the PAG and raphe nuclei following large amount of DX infusion. These data suggest that the DX may have a strong antinociceptive function as well as sedative effect. [Jpn J Physiol 55 Suppl:S160 (2005)]
