Behavioral and neurochemical changes induced by aging in dopaminergic systems of male and female rats.

Changes induced by aging in dopaminergic activity of male and female rats were compared by behavioral and neurochemical methods. Young (3 months) and old (23 months) rats were used. Aging decreased animal activity in the open field and increased apomorphine-induced stereotyped behavior. No differences in open field data were observed between males and females. Young and aged female rats had higher striatal DA and HVA levels than males; aging induced a decrease in both striatal DA and HVA levels in males, but not in females. No changes in HVA/DA ratios were observed among the different groups. These results show that aging reduces nigrostriatal activity as well as nigrostriatal DA levels. Furthermore, they indicate that time course events related to aging differ between males and females.