Effects of Maturation on Striatal Dopamine Transporter Availability in Rats.

Abstract

We investigated the effects of maturation on dopamine transporter (DAT) availability in the rat via longitudinal monitoring with positron emission tomography (PET). Eight 5-week-old male Sprague-Dawley rats (113-186 g) were used. Four 18F-FP-CIT PET scans were taken at 5, 10, 15, and 20 weeks. Baseline PET images were manually fused with the built-in magnetic resonance imaging template; volumes of interest (VOIs) were manually defined by placing a spherical region around the hot spot with the maximum count rate. VOIs were placed on bilateral caudate and putamen (CPu), nucleus accumbens (NAc), and cerebellum. Specific binding ratios (SBRs) were calculated as follows: (mean uptake of bilateral targets-mean uptake of bilateral cerebellum)/(mean uptake of bilateral cerebellum). In CPu, SBRs at 5 weeks (3.25 ± 0.66) were lower than those at 10 weeks (4.59 ± 0.78, p = 0.1151) and at 15 weeks (5.56 ± 0.92, p = 0.0182). In NAc, SBRs at 5 weeks (1.41 ± 0.47) were lower than those at 10 weeks (2.03 ± 0.36, p = 0.1960) and at 15 weeks (2.43 ± 0.50, p = 0.0427). SBRs in CPu and NAc significantly increased with maturation until 15 weeks. However, differences in SBR between 15 and 20 weeks were not significant. Striatal DAT availability increases until 15 weeks postnatally, then remains stable, reflecting maturation of the dopaminergic system in rats.