Effects of apomorphine in quantified electroencephalography in the frontal cortex: changes with dose and time

The purpose of this study was to investigate the role of four doses of apomorphine (0.01, 0.05, 0.25, 1 mg/kg s.c.) on the cortical activity by a quantified electroencephalography (EEG) method recently developed in our laboratory. The EEG-effects of apomorphine were changed significantly according to the dose and the time. When initial effects were considered an opposition in the apomorphine-induced variations between low (0.01 mg/kg) and higher doses were observed. In the time course with 0.01, 0.25 and 1 mg/kg SC, EEG variations changed the direction in 6-17 Hz and diminished in the other spectral components. Qualitatively, this tardive change with 0.01 mg/kg may show a feed-back response of the dopaminergic system to the initial low dose-induced depressant effects of apomorphine. On the other hand higher doses-induced tardive EEG pattern may show a possible changed balance in the stimulated D1 and D2 receptors.