Effects of urocortin, corticotropin-releasing factor (CRF) receptor agonist, and astressin, CRF receptor antagonist, on the sleep-wake pattern: analysis by radiotelemetry in conscious rats.

Stress has been known to release corticotropin-releasing factor (CRF) and have an affect on sleep-wake patterns. However, there is no direct evidence of CRF receptor agonist and antagonist on sleep-wake patterns. Therefore, this study aimed to clarify this point by using radiotelemetry system in conscious rats. Wake, non-rapid eye-moving (NREM) sleep and rapid eye-moving (REM) sleep were analyzed by computer software, simultaneously measuring electroencephalogram and electromyogram. In the light period, urocortin (CRF receptor agonist: i.v.) significantly increased wake duration, and decreased NREM sleep duration. REM sleep was not affected. Astressin (CRF receptor antagonist: i.p.) significantly attenuated the changes induced by urocortin, although astressin itself did not affect the sleep-wake pattern in the light period at this dosage. These findings show that urocortin changes the sleep-wake pattern in the light period. Moreover, urocortin was found to change the sleep-wake pattern by acting on CRF receptor, as astressin significantly attenuated the urocortin-induced changes on sleep-wake patterns.