Molecular mechanism of sleep regulation by prostaglandin D-2

Recent biochemical, molecular biological, and pharmacological experiments revealed that prostaglandin D synthase as well as prostaglandin D-2 circulate in the ventricular system, subarachnoidal space, and extracellular space in the brain. Prostaglandin D-2 then interacts with chemosensors or receptors on the ventro-medial surface of the rostral basal forebrain to initiate the signal to promote sleep. Prostaglandin D-2 is, therefore, not a typical neurotransmitter but rather a 'neurohormone' or an 'informational substance' that circulates through the cerebrospinal fluid and transmits certain chemical messages to promote sleep. The mode of communication through the cerebrospinal fluid in the ventricular system and the extracellular space has advantages for global regulation of the brain to induce sleep.