AJP - Regulatory, Integrative and Comparative Physiology, Vol 272, Issue 2 509-R513, Copyright © 1997 by American Physiological Society

ARTICLES

Aging alters the serotonergic modulation of light-induced phase advances in golden hamsters

P. D. Penev, F. W. Turek, E. P. Wallen and P. C. Zee
Department of Neurobiology and Physiology, Center for Circadian Biology and Medicine, Northwestern University, Evanston, Illinois 60208, USA.

Recent findings have raised the possibility that some of the age-related changes in the circadian system and the response of the circadian pacemaker to environmental stimuli may involve central serotonergic mechanisms. The present study compared the effects ofpretreatment with the serotonin agonist 8-hydroxy-2(di-n-propylamino)tetralin (5 mg/kg ip) on the magnitude of light-induced phase advances in young (2-4 mo) and old (18-20 mo) golden hamsters. The ability of this serotonin agonist to attenuate the photic phase resetting of circadian locomotor rhythmicity in young animals was decreased by 46% in old hamsters (P < 0.05). These results suggest that deficits in the mechanisms for serotonergic control of circadian function may interfere with the optimal adaptation of the senescent organism to its temporal environment.

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