Evidence that activation of nuclear peroxisome proliferator-activated receptor alpha (PPARα) modulates sleep homeostasis in rats

The peroxisome proliferator-activated receptor alpha (PPAR alpha) is a member of the nuclear receptor super family that has been suggested as a modulator of several physiological functions. The PPAR alpha recognizes as an endogenous ligand the anorexic lipid mediator oleoylethanolamide (OEA) which displays wake inducing properties. Despite that recent evidence indicates that activation of PPAR alpha by synthetic agonists such as Wy14643 enhances waking as well as the extracellular contents of wake-related neurotransmitters, the role of PPAR alpha in sleep recovery after prolonged waking has not been fully described. Thus, the aim of this study was to characterize if PPAR alpha regulates sleep rebound after total sleep deprivation (TSD). We report that after 6 h of TSD activation of PPAR alpha by pharmacological systemic administration of OEA (10, 20 or 30 mg/Kg, i.p.) promoted alertness by blocking the sleep rebound after TSD. Besides, wake linked compounds such as dopamine, norepinephrine, serotonin, or adenosine collected from nucleus accumbens were enhanced after TSD in OEA-treated animals. These sleep and neurochemical results were mimicked after injection of PPAR alpha agonist Wy14643 (10, 20, 30 mg/Kg, i.p.). However, similar findings from the sham of vehicle groups were observed if PPAR alpha antagonist MK-886 was administered to rats (10, 20, 30 mg/Kg, i.p.). Our results strengthened the hypothesis that PPAR alpha might modulate sleep and neurochemical homeostasis after sleep deprivation. (C) 2016 Elsevier Inc. All rights reserved.