Peripheral Dopamine Suppression and Elevated Cystatin C in Early Diabetic Nephropathy in Spontaneously Diabetic Rats.

ABSTRACT

Intrarenal dopamine plays a protective role against the development of diabetic nephropathy during the early stages of the disease. In streptozotocin-induced diabetic mice with a renal-specific catechol-O-methyl transferase knockout, intrarenal dopamine was found to suppress glomerular hyperfiltration, reduce oxidative stress and inflammation, and inhibit fibrosis. However, while dopamine activation in streptozotocin-induced diabetic models has been shown to provide renal protection, the role of dopamine in models of naturally induced diabetes mellitus is still unclear. In the present study, we administered 10 mg/kg p.o. benserazide, a peripheral decarboxylase inhibitor, to Spontaneously Diabetic Torii rats daily, in order to investigate the activation of the renal dopaminergic system during diabetic nephropathy progression. Our findings show that peripheral dopamine decreased urinary 8-iso-prostaglandin F2a and suppressed increases in plasma cystatin C levels. This study demonstrates that a reduction in peripheral dopamine can exacerbate renal dysfunction, even in the early stages of diabetic nephropathy characterized by glomerular hyperfiltration, thereby clarifying the pivotal role of endogenous peripheral dopamine in modulating oxidative stress and kidney performance.