[Participation of D1 dopamine and alpha2 adrenoreceptors in formation of the frequency spectrum of the cortical activity in rats].

Intracerebroventricular injections of the alpha 2-adrenoreceptor agonist clonidine (1, 10, and 100 nmole) produced a dose-dependent decrease in the low-frequency (1.5-3.0 Hz) EEG components and increase in the EEG theta-rhythm (4.3-7.2 Hz) in freely moving rats with chronically implanted electrodes in the cortex and a cannule in the lateral ventricle. The beta-frequency EEG components (20.8-26.5 Hz) were stimulated by smaller doses of clonidine and reliably inhibited by the maximum doses. The alpha 2-adrenoreceptor antagonist yohimbine potentiated the effect of clonidine in the theta- and beta-ranges. The D1-dopaminergic receptor agonist SKF-38393 (100 nmole) reduced EEG intensity in the 1.9-2.5 and 9.3-13.8 Hz and increased intensity in the 4.9-5.7 and 20.3-26.5 Hz regions. Preliminary injection of the D1-antagonist SCH-23390 prevented from the agonist effects in the high-frequency part of the spectrum. The possible participation of the pre- and post-synaptic dopaminergic D1- and alpha 2-adrenergic receptors in the EEG profile variation under the action of the above agents is discussed.