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Neuroscience. 2001;106(2):255-61.

Circadian rhythms in firing rate of individual suprachiasmatic nucleus neurons from adult and middle-aged mice.

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Laboratoire d'Ecologie Générale, UMR CNRS 8571, 4 avenue du Petit Château, 91800 Brunoy, France.


The suprachiasmatic nucleus contains a biological clock that drives circadian rhythms in vivo and in vitro. It has been suggested that the suprachiasmatic nucleus is a primary target of the aging process, because age-related changes in behavioral rhythms are mirrored in alterations in circadian pacemaker function. Using long-term, single-cell recording, we assessed the effect of age on firing-rate patterns of individual suprachiasmatic nucleus neurons of young adult (2-4 months) and middle-aged (9-11 months) C3H mice. Individual suprachiasmatic nucleus neurons from adult mice maintained in culture for at least one week exhibited robust circadian rhythms in spontaneous activity that were similar in the free-running period (23.7+/-0.3 h mean+/-S.E.M.) to recordings from neurons dispersed from neonatal tissue, and showed evidence of entrainment to prior light cycles by exhibiting peak activity, in vitro, approximately 4.0+/-0.3 h (mean+/-S.E.M.) after the time of expected light onset. Aging led to a decreased amplitude of impulse activity in dispersed suprachiasmatic nucleus neurons and increased variability in the circadian waveform. From these results we suggest that age-related deterioration in circadian clock function occurs at the level of individual cells, which may account for some of the age-related deficits observed in the expression of behavioral rhythmicity.

[Indexed for MEDLINE]

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