Diurnal Monoamine Variation in Young and Old Rats: A Microdialysis Study

Abstract

The levels of striatal extracellular DA, DOPAC, HVA and 5-HIAA significantly decreased in aged rats compared to young adults. The magnitude of age-related reduction was greater in dopaminergic than serotonergic substances. The levels of striatal extracellular monoamines in young adult rats showed significant diurnal variations. On the other hand, these substances of aged rats, except for HVA, did not exhibit significant diurnal variations. Enriched environment housing increased levels of striatal extracellular DOPAC in aged rats, but did not influence on the age-related changes of diurnal variations in the striatal extracellular monoamines.