Restricted feeding-induced sleep, activity, and body temperature changes in normal and preproghrelin-deficient mice

• Published in: American journal of physiology. Regulatory, integrative and comparative physiology integrative and comparative physiology, 2010-02, Vol.298 (2), p.R467-R477
• Main Authors: Szentirmai, Eva, Kapas, Levente, Sun, Yuxiang, Smith, Roy G, Krueger, James M
• Format: Article
• Language: English
• Subjects: Animals; Arousal - physiology; Body Temperature - genetics; Body Temperature - physiology; Body Weight - genetics; Body Weight - physiology; Caloric Restriction; Eating - genetics; Eating - physiology; Electroencephalography; Ghrelin - deficiency; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Motor Activity - genetics; Motor Activity - physiology; Sleep - genetics; Sleep - physiology; Sleep, REM - genetics; Sleep, REM - physiology; Telemetry; Wakefulness - genetics; Wakefulness - physiology
• ISSN: 0363-6119; 1522-1490
• DOI: 10.1152/ajpregu.00557.2009

1 Washington, Wyoming, Alaska, Montana and Idaho (WWAMI) Medical Education Program, Washington State University, Spokane; 2 Sleep and Performance Research Center and 3 Department of Veterinary and Comparative Anatomy, Pharmacology, and Physiology, Washington State University, Pullman, Washington; 4 United States Department of Agriculture, Agricultural Research Service Children's Nutrition Research Center, Huffington Center on Aging, Departments of Pediatrics and Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas; and 5 Department of Metabolism and Aging, The Scripps Research Institute, Scripps Florida, Jupiter, Florida Submitted September 2, 2009 ; accepted in final form November 24, 2009 Behavioral and physiological rhythms can be entrained by daily restricted feeding (RF), indicating the existence of a food-entrainable oscillator (FEO). One manifestation of the presence of FEO is anticipatory activity to regularly scheduled feeding. In the present study, we tested if intact ghrelin signaling is required for FEO function by studying food anticipatory activity (FAA) in preproghrelin knockout (KO) and wild-type (WT) mice. Sleep-wake activity, locomotor activity, body temperature, food intake, and body weight were measured for 12 days in mice on a RF paradigm with food available only for 4 h daily during the light phase. On RF days 1–3 , increases in arousal occurred. This response was significantly attenuated in preproghrelin KO mice. There were progressive changes in sleep architecture and body temperature during the subsequent nine RF days. Sleep increased at night and decreased during the light periods while the total daily amount of sleep remained at baseline levels in both KO and WT mice. Body temperature fell during the dark but was elevated during and after feeding in the light. In the premeal hours, anticipatory increases in body temperature, locomotor activity, and wakefulness were present from RF day 6 in both groups. Results indicate that the preproghrelin gene is not required for the manifestation of FAA but suggest a role for ghrelinergic mechanisms in food deprivation-induced arousal in mice. food-entrainable oscillator; food anticipatory activity; electroencephalographic slow-wave activity; food deprivation; hypothermia Address for reprint requests and other correspondence: É. Szentirmai, WWAMI Medical Education Program, Washington State Univ., Spokane, P.O. Box 1495, Spokane, WA 99210-1495 (e-mail: eszentirmai{at}wsu.