Relationships between endogenous circadian period, physiological and cognitive parameters and sex in aged gray mouse lemurs (Microcebus murinus)

ABSTRACT

The biological clock generates circadian rhythms, with an endogenous period tau close to 24 h. The circadian resonance theory proposes that lifespan is reduced when endogenous period goes far from 24 h. It has been suggested that daily resetting of the circadian clock to the 24 h external photoperiod might induce marginal costs that would accumulate over time and forward accelerate aging and affect fitness. In this study, we aimed to evaluate the link between the endogenous period and biomarkers of aging in order to investigate the mechanisms of the circadian resonance theory. We studied 39 middle-aged and aged Microcebus murinus, a nocturnal non-human primate whose endogenous period is about 23.1 h, measuring the endogenous period of locomotor activity, as well as several physiological and behavioral parameters (rhythm fragmentation and amplitude, energetic expenditure, oxidative stress, insulin-like growth factor-1 (IGF-1) concentrations and cognitive performances) in both males and females. We found that aged males with tau far from 24 h displayed increased oxidative stress. We also demonstrated a positive correlation between tau and IGF-1 concentrations, as well as learning performances, in males and females. Together these results suggest that a great deviation of tau from 24 h leads to increased biomarkers of age-related impairments.

KEYWORDS:

• Biological clock
• circadian resonance
• aging
• metabolism
• cognition

Acknowledgements

We are very grateful to Alexxai Kravitz and Bridget Matikainen-Ankney for the development of the infrared sensors system and their availability.

Authors’ contribution

C.H. and F.P. designed the experimental protocol. C.H. made the experiments and wrote the first draft of the manuscript. C.H. and F.P. reviewed the manuscript.

Data availability statement

Data are available for this paper at https://doi.org/10.5061/dryad.44j0zpcfh.

Disclosure statement

No competing interests declared.

Additional information

Funding

This work was supported by the Human Frontier Science Program.