Brain dopamine transporter in spontaneously hypertensive rats

The brain dopamine system plays an important role in the development of hypertension. Methods: The amounts of the dopamine transporter (DAT) and dopamine D1 and D2 receptors in the brain were assessed by in vitro autoradiography with the ligands [¹²⁵I]β-CIT, [¹²⁵I]SCH23982 and [¹²⁵I]iodospiperone, respectively. Changes in this transporter and the two receptors were evaluated in spontaneously hypertensive (SH) rats and control (Wistar-Kyoto) rats at the prehypertensive (2-wk-old, n = 5) and posthypertensive (15-wk-old, n = 5) stages. Results: The β-CIT binding for the DAT was increased significantly in the caudate-putamen (CPu) of SH rats compared with that of Wistar-Kyoto (WKY) rats at both pre- and posthypertensive stages. In the evaluation of the lateral-to-medial CPu, the β-CIT binding on the lateral side was significantly higher than that on the medial side in SH rats at 2 wk. The SCH23982 binding for D1 receptor was increased significantly in CPu at posthypertensive SH rats. Conclusion: Increased DAT was found before the development of hypertension, and the increased DAT and D1 receptor were found at posthypertensive SH rats. The abnormal dopamine system contributes the development of hypertension, suggesting the possibility of diagnostic imaging for the essential hypertension.