Muramyl dipeptide-elicited production of PGD2 from astrocytes in culture.

We used primary cultures of rat brain astroglial cells in order to investigate the interrelationship between PGD2 and other sleep-promoting substances such as muramyl dipeptide (MDP), lipopolysaccharide (LPS), delta-sleep-inducing peptide (DSIP), uridine, and interleukin 1 (IL-1). A large amount of PGD2 was released into the culture medium by stimulation with MDP, LPS, and IL-1 but DSIP and uridine failed to stimulate such release. These results suggest that PGD2 may be part of the series of biochemical steps involved in induction of sleep by MDP, LPS, and IL-1.