Plasma prostaglandin D2 synthase levels in sleep and neurological diseases.

Background: Prostaglandin D2 (PGD2) induces sleep and may play a role in sleep and neurological disorders. We investigated PGD synthase (PGDS) levels in various sleep and neurological disorders.

Methods: Sixty-three patients with neurological or sleep disorders (Parkinson's disease with excessive daytime sleepiness (PDS), n = 19; PD without sleepiness (PDWS), n = 14; Alzheimer's disease (AD), n = 10; narcolepsy (NA), n = 10; sleep apnea syndrome (SAS), n = 10) and 21 healthy controls were included in this study. Plasma lipocalin-type PGDS (L-PGDS) and glutathione-dependent hematopoietic PGDS (H-PGDS) levels were assessed using an enzyme-linked immunosorbent assay.

Results: H-PGDS levels were not significantly different among the groups. Compared with healthy controls, the PDWS, PDS and AD groups had higher levels of L-PGDS. Neither H-PGDS nor L-PGDS levels correlated with scores on the Epworth Sleepiness Scale or Pittsburgh Sleep Quality Index in any group.

Conclusion: We found higher levels of L-PGDS in patients with neurodegenerative diseases such as PD and AD. Whether increased L-PGDS levels reflect underlying sleepiness or the pathophysiology of neurodegenerative diseases needs further study.