Rhythmic 24 h Variation of Core body temperature and Locomotora Activity in a Subterranean Rodent (Ctenomys aff. knighti), the Tuco-Tuco

TACHINARDI P; BICUDO JEW; ODA GA; VALENTINUZZI VS

PLOS ONE

PUBLIC LIBRARY SCIENCE

Lugar: San Francisco; Año: 2014 vol. 9 p. 1 - 8

1932-6203

The tuco-tuco Ctenomys aff. knighti is a subterranean rodent which inhabits a semi-arid area in Northwestern Argentina. Although they live in underground burrows where environmental cycles are attenuated, they display robust, 24h locomotor activity rhythms that are synchronized by light/dark cycles, both in laboratory and field conditions. The underground environment also poses energetic challenges (e.g. high-energy demands of digging, hypoxia, high humidity, low food availability) that have motivated thermoregulation studies in several subterranean rodent species.  By using chronobiological protocols, the present work aims to contribute towards these studies by exploring day-night variations of thermoregulatory functions in tuco-tucos, starting with body temperature and its temporal relationship to locomotor activity.  Animals showed daily, 24h body temperature rhythms that persisted even in constant darkness and temperature, synchronizing to a daily light/dark cycle, with highest values occurring during darkness hours. The range of oscillation of body temperature was consistent with those reported for similar-sized and dark-active rodents. Most rhythmic parameters, such as period and phase, did not change upon removal of the running wheel. Body temperature and locomotor activity rhythms were robustly associated in time. The former persisted even after removal of the acute effects of intense activity on body temperature by a statistical method. Finally, there was a stronger correlation between body temperature and activity in the beginning of the night, suggesting day-night variation in thermal conductance and/or heat production. Consideration of these day-night variations in thermoregulatory processes is beneficial for further studies on thermoregulation and energetic of subterranean rodents.