Phasic hippocampal activity during paradoxical sleep in the rat: selective suppression after diazepam administration.

The effects of diazepam on tonic (T theta) and phasic (P theta) components of the paradoxical-sleep hippocampal theta rhythm were studied in the rat. Results show that diazepam, a benzodiazepine analogue known to interfere with the putative neurotransmitter gamma-aminobutyric acid (GABA) in the mammalian central nervous system, selectively abolishes P theta. They confirm previous data according to which sedative/anaesthetic drugs cause an apparent dissociation of T theta and P theta of the paradoxical-sleep hippocampal theta rhythm. Moreover, they suggest a possible involvement of GABA in the neurochemical mechanisms underlying P theta in the rat.