Meeting Abstract

P2.16  Jan. 5  Circadian and ultradian rhythm effects on metabolism BRENNAN, April M*; BULT-ITO, Abel ; University of Alaska Fairbanks; University of Alaska Fairbanks ftamb@uaf.edu

Circadian rhythms are endogenously generated and influence many aspects of an animal�s biology, including behavior, physiology, and reproduction. The suprachiasmatic nucleus (SCN) is the endogenous light-entrainable master circadian clock in mammals and is presumed to drive peripheral circadian, ultradian, and food-entrainable clocks so that all these different clocks are in phase. When circadian rhythmicity is lost, an animal either becomes arrhythmic, i.e., no biological clock expressed, or ultradian, i.e., the ultradian clock is presumed to drive behavioral and physiological traits. In this project, we will elucidate the behavioral and physiological correlates of circadian and ultradian wheel-running activity rhythms and their potential effects on energy metabolism. Our model species is the northern red-backed vole, Clethrionomys rutilus, whose wheel-running activity rhythm is predominantly nocturnal in a 16:8 hour light-dark cycle. We will use constant dark in this study, because about 45% of voles remain circadian in constant darkness, while about 45% become ultradian, which will provided the phenotypes for our experiments. Our aim is to test whether circadian/ultradian wheel-running activity phenotype influences feeding behavior, core body temperature, general activity, glucose metabolism, and daily energy expenditure in C. rutilus. We hypothesize that an ultradian phenotype, through influences on feeding behavior, core body temperature, general activity, and glucose metabolism, confers energy savings over the circadian phenotype.