Age-related variation of EEG responses to clonidine, prazosin and yohimbine in rats.

The EEG-effects induced by intraperitoneal administration of clonidine, prazosin and yohimbine to 8 and 22 month old rats were compared. Clonidine (0.01 mg/kg) and prazosin (1 mg/kg) increased spectral powers, yohimbine (0.5 mg/kg) decreased them. In the older rats, EEG variations were smaller for prazosin and yohimbine, but larger for clonidine. These findings show that alpha receptor mediated influences on EEG are changed during aging and show that quantified EEG gives a picture of age related changes in the functional state of the neurotransmitter systems.