To investigate the influence of age-associated changes in DA uptake on measures of potassium-stimulated DA overflow in the striatum, microdialysis was conducted in anesthetized young (6-month-old) versus aged (24-month-old) F344 rats. Extracellular levels of DA, DOPAC, and HVA were measured under basal and potassium-stimulated (10, 25, 50, & 100 mM) conditions. Basal levels of DA and metabolites did not differ significantly between the two age groups. At the 50 and 100 mM concentrations, potassium stimuli significantly increased DA overflow and decreased DOPAC and HVA - effects that did not differ with age. The addition of the DA uptake inhibitor nomifensine (100 μM) to the perfusion solutions revealed differences between the two age groups. Nomifensine augmented potassium-evoked DA overflow at the 50 mM concentration in both groups, but only amplified the effect of the 100 mM concentration in the young animals. The results demonstrate that decreased DA transporter function in aged rats masks age-related differences in K+-evoked striatal DA release when microdialysis methods are used, resulting in net equalization of K+-evoked striatal DA overflow in young versus aged F344 rats.
|Number of pages||8|
|Journal||Neurobiology of Aging|
|State||Published - 2001|
Bibliographical noteFunding Information:
The authors gratefully acknowledge the expert technical assistance of Peter Huettl with the HPLC-EC system. This work was supported by grants from USPHS AG06434 and MH58414, a level II Research Scientist Award (MH01245) to G. Gerhardt, and a Kentucky Opportunity Fellowship to M. Purdom.
ASJC Scopus subject areas
- Neuroscience (all)
- Developmental Biology
- Clinical Neurology
- Geriatrics and Gerontology