BENZODIAZEPINES PROMOTE THE INTERMEDIATE STAGE AT THE EXPENSE OF PARADOXICAL SLEEP IN THE RAT

The effects of diazepam, a long half-life benzodiazepine, midazolam an d triazolam, two with short half-life, on the transitional stage betwe en deep slow wave sleep and paradoxical deep were studied in Wistar an d WAG/Rij rats. This intermediate stage is characterized by the unusua l association of cortical spindles and low frequency hippocampal theta rhythm. The main result was extension of the intermediate stage at th e expense of paradoxical sleep by diazepam and triazolam by influencin g only the duration of the intermediate stage and both the onset and m aintenance of paradoxical sleep. Midazolam increased both intermediate stage and paradoxical sleep. Several differences in the qualitative m odulation of the stage characteristics and between rat strains were fo und. In regard to the possible peculiar physiological significance of the intermediate stage, we conclude that benzodiazepines promote a tra nsient pharmacological cerveau isole-like stage during sleep in rats.