Body temperature and activity during time-restricted feeding in an herbivorous subterranean rodent (Ctenomys sp.)

FLORES DANILO EFL; ODA GISELE A; VALENTINUZZI VERÓNICA V

Bragança Paulista, Sao Paulo

Simposio; XIII Latin American Symposium on Chronobiology-LASC; 2015

When food is restricted to daytime meals, nocturnal rodents develop daily food anticipatory activity (FAA) regulated by a food entrainable oscillator (FEO). Few studies have explored expression of FAA in herbivorous species, which may have little time limitation for feeding in the wild. We investigated this phenomenon in the herbivorous subterranean rodent tuco-tuco (Ctenomys sp.). Rhythms of running-wheel activity, body temperature and general movement were recorded in 6 animals in LD12:12 (1000 lux) at 23 ± 2ºC. Tuco-tucos were first subjected to ad libitum feeding of carrots and sweet potatoes and, thereafter, food was restricted to 9 hours per day during the light-phase, then to 6 hours per day and finally to 5 hours per day. Three individuals developed stable FAA in running-wheel activity and general movement. In these animals, body temperature was gradually decreased along the days of restricted feeding, eventually presenting hypothermic values prior to the daily meals. A forth individual was mostly arrhythmic in both activity measures, with bouts of general activity around the onset of feeding. Its body temperature was also reduced in the hours prior to feeding time. One animal expressed FAA sporadically in wheel running and the last tuco-tuco did not present FAA in wheel running, but there was occasional FAA in general movement, partially correlated with days of lower body temperature. In summary, herbivorous tuco-tucos present great inter-individual variability in the expression of FAA, and there seems to be a relationship between the development of FAA and body temperature.