Characterizing circadian behaviour in the BTBR mouse model
Circadian rhythms span across species and temporally co-ordinate behaviour and physiological processes to not only maintain a rhythm in the absence of cues but to also effectively coincide with external time giving cycles. A disruption in circadian rhythms causes a variety of psychological and physiological health impacts and can worsen already present disease states. Sleep and circadian issues are also comorbid with many disease and disorder states. Finding ways to alleviate the impact of circadian disruption is thus crucial. We characterized circadian behaviour in BTBR mice, that are used to model aspects of ASD. We found that BTBR mice differ drastically from C57BL/6J mice on many measures of circadian behaviour including, their free running period, their duration of activity, their total activity, their response to dark pulses in LL their entrainment patterns to shifted light dark cycle, their food anticipatory activity to schedules feeding and in the number of VIP and AVP cells in the SCN. Despite their short FRP BTBR mice entrained to ambient light cycles with stability and precision, a property that is not commonly observed. Additionally, they had more drastic changes in constant light conditions when compared to C57 controls. Despite this they maintained normal responses to light pulses, suggesting a conservation light input pathway, instead a possible dysregulation of arousal pathways, which aligns with what is known about BTBR physiology. We also found differences in VIP and AVP expressing cells in the BTBR SCN. Both these peptides have been implicated in the circadian entrainment to light cycle. Therefore, the BTBR mouse model provides not only the novel opportunity to study the mechanisms of circadian rhythms in a mouse with a drastically altered phenotype, but also can be used to study circadian rhythms when they are dysregulated. Finally, their precise entrainment might provide clues of how to better deal with circadian disruption and how to optimize entrainment to changing light cycles.
Circadian, free-running period, entrainment, jet-lag, synchronization, SCN, VIP, AVP, food anticipation, feeding.
Vijaya Shankara, J. (2019). Characterizing circadian behaviour in the BTBR mouse model (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.