Effect of d-aspartate uptake on uncoupling protein-3 and α-tubulin expressions in rat Harderian gland

Although d-aspartate (d-Asp) has been recognized as having an important physiological role within different organs, high concentrations could elicit detrimental effects on those same organs. In this study, we evaluated the oxidative stress response to d-Asp treatment in rat Harderian gland (HG) by measuring total cellular hydroperoxide levels. Further, we examined the effect of d-Asp uptake on the expression of the mitochondrial uncoupling protein-3 (UCP3), β-actin, and α-tubulin. In rat HG, elevated levels of d-Asp significantly increased hydroperoxide production. This phenomenon was probably due to d-Asp uptake as well as lipid and porphyrin increased levels. Higher UCP3 levels and lower α-tubulin expression were also observed after d-Asp treatment. On the contrary, β-actin expression was unchanged. Given the possible role of UCP3 in lipid handling, the higher expression of mitochondria UCP3 protein in d-Asp-treated HG may reflect a major need to export excessive amounts of hydroperoxides deriving from a greater fatty acid flux across these organelles and higher mitochondrial porphyrin levels. Moreover, abundance of hydroperoxides in d-Asp treated rat HG could determine the decrease of α-tubulin expression. Thus, our findings indicate that a high concentration of d-Asp is critical in initiating a cascade of events determined by oxidative stress.