COMPARISON OF AN ADENOSINE-A1-RECEPTOR AGONIST AND ANTAGONIST ON THE RAT EEG

The effects of the selective adenosine Al receptor agonist N6-cyclopen tyladenosine (CPA; 1 and 0.1 mg/kg, i.p.) and the Al selective antagon ist 8-cyclopentyl-1,3-dipropylxanthine (CPX) have been examined on the electroencephalogram (EEG) of intact rats. From four EEG leads the EE G signal was subjected to Fast Fourier Transform and analysed both in narrow (0.01629638 Hz) and wide frequency bands. CPA tended to increas e EEG power at low frequencies, and in several of the narrow frequency bands significantly shifted peak frequencies to lower values. The ago nist also increased peak power in some frequency bands. The results ar e consistent with the view that Al adenosine receptors mediate a gener ally depressant effect on neuronal activity in most brain regions, but may increase activity in areas with low resting rates of firing. The modest elevation of wave power by CPX indicates a limited control by r esting endogenous adenosine, which is greatest in areas of highest act ivity, consistent with adenosine release being related to neuronal act ivity. (C) 1998 Published by Elsevier Science Ireland Ltd.