Effects of prostaglandin D 2, lipoxins and leukotrienes on sleep and brain temperature of rats

Abstract

Prostaglandin (PG) D 2 and four lipoxygenase-derived eicosanoids [lipoxins (LX) A 4 and B 4, and leukotrienes (LT) C 4 and D 4] were examined for their effects on sleep and brain temperature in freely-behaving rats. In the first series of experiments, PGD 2 was infused into the third ventricle at four different locations between 23:00 and 05:00. In a location apposed to the medial preoptic area (MPO), PGD 2 at doses 1, 10 and 100 pmol/min, increased the slow wave sleep (SWS) by 23% (p ≤ 0.01), 35% (p ≤ 0.05) and 44% (p ≤ 0.01), respectively, during the infusion period. In the second series of experiments, LXs and LTs were infused at the location apposed to MPO. Significant increases in SWS were detected with LXA 4 at 100 pmol/min (14%, p ≤ 0.05), LXB 4 at 100 pmol/min (20%, p ≤ 0.05), and LTD 4 at 10 pmol/min (17%, p ≤ 0.05). An increase in paradioxical sleep (PS) was produced by PGD 2 at 1 and 10 pmol/min infusion (p ≤ 0.05), but not by any of the lipoxygenase-derived eicosanoids examined. PGD 2 also elevated the mean brain temperature during infusion by 0.2°C and 0.9°C at infusion doses 10 and 100 pmol/min, respectively. But PGD 2 infusion at 1 pmol/min did not elevate the brain temperature. LXs (excluding LXB 4 at 100 pmol/min) and LTs did not alter the brain temperature significantly at the tested doses. We conclude that PGD 2 is the most effective sleep promoter among the eicosanoids examined so far.