Intracerebroventricular infusion of somatostatin selectively increases paradoxical sleep in rats.

Chronic intracerebroventricular (i.c.v.) infusion of somatostatin (SRIF) elicited a specific increase of the daily duration of paradoxical sleep (PS) in rats. I.c.v. administration of cysteamine, a selective SRIF depletor, brought about a dose-dependent reduction of PS. Slow wave sleep (SWS) remained unaffected in both cases. These results suggest that SRIF may be involved in the regulation of PS.