Food anticipatory activity in a herbivorous subterranean rodent

FLORES DEFL; DOKKEDAL V; ODA GA; VALENTINUZZI VS

Mendoza

Congreso; XII Latin American Symposium on Chronobiology-LASC; 2013

Tuco-tucos (Ctenomys aff. knighti) are herbivorous subterranean rodents whose foraging involves daily emergences from the underground to the surface. They feed mostly on aerial parts of plants, which are continuously available in the environment on a 24-hour scale. We investigated the effects of time-restricted feeding on the circadian system of tuco-tucos, more specifically, whether feed-fast (FF) daily cycles could induce food anticipatory activity (FAA).  We tested two protocols in LD12:12 (L= 1,000 lux). First, 4 individuals in previous ad libitum food conditions were subjected to an FF cycle with a short (3-hour) feeding window in the photophase, for 6 days. In a second experiment, the same protocol was applied but with a longer window of food availability (9 hours), to two groups of animals: A (n=3, 20-28 days of food restriction) and B (n=7, 76-86 days). The diet consisted of carrots and sweet potatoes.  In addition to wheel-running activity rhythm, we assessed body weight every 3-4 days, daily food ingestion during the FF cycle, as well as food intake every 12 hours in the previous ad libitum.  In the first experiment (short feeding window) 2 animals died and 1 presented body weight decline. In the second (long feeding window) only part of the animals expressed FAA, 2/3 in group A and 3/7 in group B, and some individuals lost body weight.  In conclusion, we observed two main differences between tuco-tucos and the FAA model species, the rat. On the one hand, tuco-tucos present great inter-individual variation in FAA expression. In addition, they may not be able to adjust their daily feeding to short time-windows. These differences are possibly related to disparities in quality and availability of food in the natural environments of the two species.  Funding: CONICET (Argentina), CNPq and FAPESP (Brazil).