[Prostaglandins and sleep].

Prostaglandin D2 (PGD2) is the endogenous sleep inducing substance in rats, mice, monkeys and probably in humans. PGD synthase (PGDS), the enzyme that produces PGD2 in the brain, is the key enzyme in sleep regulation. When the enzyme activity is inhibited by its specific inhibitor, SeCl4 in vivo, rats can no longer sleep. PGDS is present mainly in the arachnoid membrane and choroid plexus. It is secreted into the cerebrospinal fluid to become beta-trace. PGD2 thus produced is bound to the DP receptor on the surface of the ventro-medial region of the rostral basal forebrain. This signal is probably transmitted into the brain parenchyma by adenosine via adenosine A2a receptors. PGE2 plays a major role in the maintenance of wakefulness.