Electroencephalographic study with rolipram (ME 3167), a selective inhibitor of adenosine 3', 5'-monophosphate phosphodiesterase, in rabbits.

The electroencephalographic (EEG) effects of rolipram were investigated in rabbits with chronic electrode implants. Intravenous administration of rolipram at 10 to 100 micrograms/kg evoked an increase in the arousal EEG pattern period (low amplitude fast waves) in the cortical EEG and synchronization of the hippocampal theta waves with increased voltages. Rolipram at higher doses caused behavioral excitation in rabbits. Rolipram did not affect EEG arousal responses to both auditory stimulation (2000 Hz, monotone) and electrical stimulation (100 Hz, 0.1 msec, 3-6 V) of the midbrain reticular formation or the posterior hypothalamus. The recruiting response induced by centromedian thalamic stimulation at a low frequency (7 Hz, 0.1 msec, 4-8 V) was not altered by rolipram. Rolipram was without effect on the photic driving response to flash light (2 Hz) in the occipital cortex. Rolipram caused a slight increase in the duration of after discharges induced by electrical stimulation (50 Hz, 0.5 msec, 4-20 V) of the dorsal hippocampus. These results suggest that rolipram is a drug that causes the EEG arousal pattern.