l-fenfluramine and haloperidol in rats: a qEEG comparison.

EEG effects of l-fenfluramine (l-F) (2.5, 5 and 10 mg/kg) and haloperidol (0.1, 0.25 and 0.5 mg/kg) were studied in 20 adult rats. The EEG signals of two prefrontal (A = +4, L = 2.5) and two sensorimotor (A = -4, L = 4) transcortical electrodes were analyzed in each rat during three 60-min periods, 1, 3 and 5 h after the intraperitoneal (IP) administration of the drugs. In the prefrontal cortex haloperidol induced a decreased power for the 1-3 Hz components and an increase in power for frequencies higher than 8 Hz, with a maximum around 13 Hz. These effects were already observed after 0.1 mg/kg. In this cortical area l-F administration was essentially associated with a decrease of power maximum for 3-8 Hz, an increased power for the 10-19 Hz band being present only after 10 mg/kg. In the sensorimotor cortex haloperidol appeared less potent than in the prefrontal site; a significant power increase for the frequencies higher than 8 Hz was only observed with 0.5 mg/kg. On the contrary, l-F appeared more effective in this area, its action being characterized by a decreased power from 2-8 Hz and a power increase already significant with 2.5 mg/kg for the frequencies higher than 10 Hz, with a maximum lying around 15 Hz. These results suggest that haloperidol induced cortical sedation (increased power) on the two recording sites. l-F also induced a net cortical sedation in sensorimotor cortex but up to 5 mg/kg acted in the opposite direction on the prefrontal cortex.(ABSTRACT TRUNCATED AT 250 WORDS)