AGING ATTENUATES DIURNAL-VARIATION IN HAMSTER LOCOMOTION, ANXIOLYSIS AND GABA TURNOVER

A decrease in amplitude of wheel running circadian rhythms was found i n old (18 month old) Syrian hamsters, as compared with young (3 month old.) animals. In a plus-maze paradigm, amplitude of variation of anxi ety-related variables (2400 vs. 1600 h) was significantly impaired in aged hamsters. Cerebral cortex, hypothalamic and pineal gamma-aminobut yric acid (GABA) turnover was higher at night, amplitude of variation being significantly smaller in aged hamsters. The results further supp ort the existence of impaired amplitude of circadian rhythms in aged S yrian hamsters. (C) 1997 Elsevier Science Ireland Ltd.