Temporal expression of clock genes in different regions of suprachiasmatic nuclei of tuco-tucos (Ctenomys famosus) captured in summer and winter

IMPROTA CG; ODA GA; DE LA IGLESIA H; VALENTINUZZI VS

Sao Paulo

Workshop; São Paulo School of Advanced Science on Ecology of Human Sleep and Biological Rhythms; 2022

Faculdade de Saúde Pública da Universidade de São Paulo

In mammals, the suprachiasmatic nuclei (SCN) are the hypothalamic structuresresponsible for generating circadian rhythms, establishing the physiological andbehavioral temporal organization through the rhythmic and self-regulated expression ofclock genes. SCN also play an important part in photoperiod transduction, resulting inthe synchronization of seasonal rhythms with the seasons. Experimental evidenceindicates that SCN neurons are organized into coupled subpopulations and thatdifferent photoperiods cause changes in their internal temporal organization. In thisproject, we aim to investigate the SCN’s circadian clock gene expression in aneotropical subterranean species, the tuco-tucos (Ctenomys famosus). By combiningwild animals live-trapping at summer and winter, and using in situ hybridization (ISH)approach, we will be able to provide spatial and temporal neuroanatomical patterns inparallel for two different natural photoperiods. In Argentina, freshly caught wild animals will be housed for 2 days under constant darkness (DD, food ad lib, T=24 ºC ± 2) whilst running-wheel activity is recorded. Based on activity patterns of each animal, brains will be extracted throughout subjective time every 4-circadian hours. In the USA, the brains will be microtomized into coronal slices and subsequently exposed to radioactive riboprobes targeting Per1, Per2, Bmal1 and Avp. The tuco-tuco is particularly interesting for this study because, despite its unusual exposition to the day/night cycle, it presents seasonal rhythms and evidence of photoperiod processing when exposed to artificial, complete photoperiods in the laboratory, as well as photoperiod-dependent after-effects when captured at different seasons. We expect to observe differences in the expression of these genes in specific areas of the SCN between different seasons, as observed in other rodents housed under artificial photoperiods. This work is a collaboration between “Laboratório de Cronobiologia Binacional Argentina-Brasil” and “de la Iglesia Lab” (University of Washington, USA). This joint effort will be the first characterization of the temporal expression of circadian clock genes in SCN and extra-SCN regions in this species.