Evidence for age-related changes in the circadian activity rhythm of the diurnal primate Callithrix jacchus: a case report
2016
Gonçalves, Fabiana B. | Borges, Galileu R. | Gonçalves, Bruno S. B. | Cavalcante, Jeferson S. | Menezes, Alexandre A. L. | Azevedo, Carolina V. M.
Many cross-sectional studies have shown that circadian rhythms change with age, but such age-related modifications are gradual and may be insufficiently described by cross-sectional studies. In this case study, circadian activity rhythm (CAR) was evaluated longitudinally, in both LD (12:12) and LL conditions, on two occasions in a single male marmoset: when ‘adult’ (3 y.o.) and when ‘old’ (9 y.o.). When adult, the CAR synchronized with positive phase angles for the onset and offset of activity. In LL, the rhythm free-ran with τ < 24 h. When old, the animal showed a significant phase delay of its activity rhythm with respect to the LD cycle (t -test, p < 0.01) and a reduction on total daily activity (t -test, p < 0.01), with signs of lesser stability, greater fragmentation and some loss of photic synchronization. In LL, the period free-ran with τ > 24 h. We conclude that aging is associated with attenuation of photic synchronization and expression of CAR in LL in the marmoset. Further studies with a larger number of individuals are needed to confirm these findings.
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