Reversal of desipramine-induced suppression of paradoxical sleep by a long-acting somatostatin analogue (octreotide) in rats.

EEG sleep recordings were performed in rats under intraperitoneal injections of saline, desipramine (DMI, 4 mg/kg) an inhibitor of noradrenaline reuptake, and DMI plus the octapeptide somatostatin analogue (octreotide, 0.2 mg/kg). As already reported, DMI resulted in selective suppression of paradoxical sleep (PS) and increased slow wave sleep (SWS). The administration of the octapeptide somatostatin analogue totally reversed the DMI-induced suppression of PS, but had no effect on SWS. This finding confirms previous results demonstrating a role of somatostatin in the generation of PS. In addition, it suggests that the suppression of PS by DMI may be due to an inhibitory effect on somatostatin release, rather than to an alteration of brain noradrenaline.