Dopamine D receptor-mediated decreases in mitochondrial reactive oxygen species production are cAMP and autophagy dependent.

Overproduction of reactive oxygen species (ROS) plays an important role in the pathogenesis of hypertension. The dopamine D receptor (DR) is known to decrease ROS production, but the mechanism is not completely understood. In HEK293 cells overexpressing DR, fenoldopam, an agonist of the two D-like receptors, DR and DR, decreased the production of mitochondria-derived ROS (mito-ROS). The fenoldopam-mediated decrease in mito-ROS production was mimicked by Sp-cAMPS but blocked by Rp-cAMPS. In human renal proximal tubule cells with DRD1 gene silencing to eliminate the confounding effect of DR, fenoldopam still decreased mito-ROS production. By contrast, Sch23390, a DR and DR antagonist, increased mito-ROS production in the absence of DR, DR is constitutively active. The fenoldopam-mediated inhibition of mito-ROS production may have been related to autophagy because fenoldopam increased the expression of the autophagy hallmark proteins, autophagy protein 5 (ATG5), and the microtubule-associated protein 1 light chain (LC)3-II. In the presence of chloroquine or spautin-1, inhibitors of autophagy, fenoldopam further increased ATG5 and LC3-II expression, indicating an important role of DR in the positive regulation of autophagy. However, when autophagy was inhibited, fenoldopam was unable to inhibit ROS production. Indeed, the levels of these autophagy hallmark proteins were decreased in the kidney cortices of Drd5 mice. Moreover, ROS production was increased in mitochondria isolated from the kidney cortices of Drd5 mice, relative to Drd5 littermates. In conclusion, DR-mediated activation of autophagy plays a role in the DR-mediated inhibition of mito-ROS production in the kidneys.