Tuesday, May 15, 2012

The wake-promoting effects of hypocretin-1 are attenuated in old rats.

The wake-promoting effects of hypocretin-1 are attenuated in old rats.

Neurobiol Aging. 2011 Aug;32(8):1514-27

Authors: Morairty SR, Wisor J, Silveira K, Sinko W, Kilduff TS


Disruption of sleep is a frequent complaint among elderly humans and is also evident in aged laboratory rodents. The neurobiological bases of age-related sleep/wake disruption are unknown. Given the critical role of the hypocretins in sleep/wake regulation, we sought to determine whether the wake-promoting effect of hypocretin changes with age in Wistar rats, a strain in which age-related changes in both sleep and hypocretin signaling have been reported. Intracerebroventricular infusions of hypocretin-1 (10 and 30 μg) significantly increased wake time relative to vehicle in both young (3 mos) and old (25 mos) Wistar rats. However, the magnitude and duration of the wake-promoting effects were attenuated with age. An increase of parameters associated with homeostatic sleep recovery after sleep deprivation, including non-rapid eye movement (NR) sleep time, NR delta power, the ratio of NR to rapid eye movement (REM) sleep, and NR consolidation, occurred subsequent to Hcrt-induced waking in young but not old rats. ICV infusions of hypocretin-2 (10 and 30 μg) produced fewer effects in both young and old rats. These data demonstrate that activation of a major sleep/wake regulatory pathway is attenuated in old rats.

PMID: 19781813 [PubMed - indexed for MEDLINE]

via pubmed: sleep metabolism http://www.ncbi.nlm.nih.gov/sites/entrez