Synchronization of subterranean rodent’s activity rhythms by light/dark cycles

- TOMOTANI BM; FLÔRES DEFL; TACHINARDI P; VALENTINUZZI VS; ODA GA

Pirenópolis, Brazil

Congreso; 46th Annual Meeting of the Animal Behavior Society; 2009

Animal Behavior Society-ABS

Ctenomys knighti is a solitary species which is active both during the day and night in the field. However, when fully exposed to controlled photoperiods in laboratory, the behavioral activities are strictly nocturnal. The circadian clock which controls 24h rhythms is located in the hypothalamus, in mammals, and is mainly synchronized by the light/dark cycle of the Earth. How can subterranean animals synchronize their activity rhythms to the above ground environmental cycles? Synchronization mechanisms are traditionally analysed by the daily phase sensitivity of the clock to light stimuli. In rodents, this is measured indirectly by the temporal assay of the behavioral locomotor activity rhythm in running wheels. 14 animals in cages were kept in constant darkness, and received 15 minutes light pulses in different phases of their activity/rest rhythm. The Phase Response Curve (PRC), representing the temporal differences between onsets of activity before and after the pulse, is similar to the ones obtained for non-subterranean rodents. These data are the first step towards understanding if and how subterranean rodents synchronize their activity to light/dark cycles.