Comparison of DA uptake rate in the striatum and nucleus accumbens of 6-, 12-, 18-, and 24-month-old F344 rats
| Region | DA Uptake Rate/μM Signal Amplitude | Maximal Uptake Rate |
|---|---|---|
| Striatum | μM/s | |
| 6-month | 0.028 ± 0.001 (n = 302) | 0.40 ± 0.02 (n = 55) |
| 12-month | 0.028 ± 0.001 (n = 106) | 0.35 ± 0.02 (n = 22) |
| 18-month | 0.017 ± 0.001*** (n = 158) | 0.18 ± 0.02*** (n = 84) |
| 24-month | 0.017 ± 0.001*** (n = 103) | 0.11 ± 0.02*** (n = 121) |
| Nucleus accumbens | ||
| 6-month | 0.017 ± 0.001 (n = 54) | 0.16 ± 0.01 (n = 38) |
| 12-month | 0.016 ± 0.002 (n = 34) | 0.21 ± 0.03 (n = 18) |
| 18-month | 0.018 ± 0.002 (n = 52) | 0.12 ± 0.01*** (n = 52) |
| 24-month | 0.010 ± 0.001*** (n = 28) | 0.10 ± 0.01*** (n = 28) |
Comparison of uptake parameters for signals recorded in the striatum and the nucleus accumbens of 6-, 12-, 18-, and 24-month-old rats. Data represent the mean ± S.E.M. Age-related differences in the slope of the DA uptake rate/μM signal amplitude (concentration-dependent portion of uptake curve) were found in the striatum of the 18- and 24-month groups and in the nucleus accumbens of 24-month rats (as compared to the 6-month group, ***p< .001). Maximal uptake rates were determined by averaging the clearance rate values for signal amplitudes at which the uptake rate was no longer concentration dependent (dotted lines in Figs. 5 and 6). The maximal DA uptake rates within the striatum and the nucleus accumbens were significantly reduced with age (18- and 24-month group versus 6-month, p < .001).