Abstract
In young hamsters, a single injection of the short-acting benzodiazepine, triazolan, can induce permanent phase shift in the circadian clock, while repeated injections of triazolam entrain the circadian clock to the period of the injections. Triazolam appears to act on the circadian clock by inducing an acute increase in the activity of the animals, which in turn phase-shifts the circadian clock. Surprisingly, single injections of benzodiazepines do not phase-shift the activity rhhthm of old hamsters, despite the fact that such treatment induces acute changes in the activity state young and old animals. We compared the entraining effects of repeated injections of triazolam on the circadian clock of young and old hamsters: while six out of seven young hamsters were entrained to the triazolam injections, only one out of seven old animals was entrained by this treatment. Three of the remaining six old hamsters showed a lengthening of the activity rhythm, while no consistent effect on the period of the activity rhythm was observed in the remaining three old animals. These results indicate that the circadian system of old hamsters becomes selectively unresponsive to synchronizing signals mediated by the activity-rest state, and suggest that aging is associated with a weakened coupling between the activity-rest cycle and the circadian clock.
Original language | English (US) |
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Pages (from-to) | 286-292 |
Number of pages | 7 |
Journal | Brain research |
Volume | 607 |
Issue number | 1-2 |
DOIs | |
State | Published - Apr 2 1993 |
Funding
Biological Timing and the Belgian FNRS.O. Van Reeth was the recipient of a NATO Fellowship for Scientific Research. Acknowledgements. This work was supported by NIH Grants HD-09885 and AG-09297, the NSF Science and Technology Center on
Keywords
- Activity
- Aging
- Arousal
- Benzodiazepine
- Circadian
- Clock
- Entrainment
- Rhythm
- Sleep
ASJC Scopus subject areas
- Clinical Neurology
- Molecular Biology
- General Neuroscience
- Developmental Biology