Impact of oxidative stress on renal dopamine D1 receptor dysfunction in offspring of diabetic rat dams / 中华心血管病杂志

ABSTRACT

Objective@#To explore the effects of oxidative stress on renal dopamine D1 receptor dysfunction in offspring of diabetic rat dams.@*Methods@#The pregnant Sprague Dawley (SD) rats (n=10) were randomly divided into the diabetic group (a single intraperitoneal injection of 35 mg/kg streptozotocin on day 0 of gestation) and control group (injected with the equal volume of 0.9% saline on day 0 of gestation) according to the random number table (n=5 each group). The offspring rats were divided into 4 groups including offspring of control dams treated with vehicle, offspring of control dams treated with antioxidant, offspring of diabetic dams treated with vehicle and offspring of diabetic dams treated with antioxidant (n=10 each group). After birth, the offspring rats were treated with normal drinking water or antioxidant (tempol, 1.0 mmol/L) from the age of 4 weeks until the end of the study (20 weeks). The blood pressure was monitored continuously by non-invasive tail-cuff method. The renal oxidative markers including superoxide dismutase (SOD) and malondialdehyde (MDA) activity and D1 receptor agonist (fenoldopam)-mediated urinary and sodium excretion were detected. Furthermore, the protein expression of renal G protein-coupled receptor kinase 2 (GRK2), GRK4, dopamine D1 receptor and the phosphorylation level of D1 receptor were detected.@*Results@#The mean arterial pressure of offspring from the diabetic dams treated with vehicle was significantly higher than that of offspring from control dams treated with vehicle (P=0.013), while the mean arterial pressure of offspring from diabetic dams treated with antioxidant was significantly lower than that of offspring from the diabetic dams treated with vehicle (P=0.038). The fenoldopam-mediated urinary flow and urinary sodium excretion rate were significantly lower in offspring of diabetic dams treated with vehicle than those in offspring of control dams treated with vehicle (P<0.01), which were significantly higher in offspring of diabetic dams treated with antioxidant as compared to offspring of diabetic dams treated with vehicle (both P<0.01). There was no significant difference in fenoldopam-mediated urinary flow and urinary sodium excretion rate in offspring of control dams treated with antioxidant or vehicle (urinary flow: P=0.772; urinary sodium excretion rate: P=0.716). Compared with offspring of control dams treated with vehicle, the renal MDA activity was significantly increased, while the SOD activity was significantly decreased in offspring of diabetic dams treated with vehicle (MDA: P<0.01; SOD: P=0.013). The renal MDA activity was significantly decreased, while the SOD activity was significantly increased in offspring of diabetic dams treated with antioxidant in comparison with offspring of diabetic dams treated with vehicle (MDA: P<0.01; SOD: P=0.035).The renal GRK2 and GRK4 protein expression in offspring of diabetic dams treated with vehicle were significantly higher than those in offspring of control dams treated with vehicle (P<0.01), while the expression levels of renal GRK2 and GRK4 in offspring of diabetic dams treated with antioxidant were significantly downregulated compared with offspring of diabetic dams treated with vehicle (P<0.01). There was no significant difference in the protein expression of dopamine D1 receptor among 4 groups (P=0.735). The level of dopamine D1 receptor phosphorylation in offspring of diabetic dams treated with vehicle was significantly higher than that in offspring of control dams treated with vehicle (P<0.01), while the dopamine D1 receptor phosphorylation level was significantly lower in offspring of diabetic dams treated with antioxidant compared to that in offspring of diabetic dams treated with vehicle (P<0.01).@*Conclusion@#Oxidative stress is involved in the dopamine D1 receptors dysfunction in the offspring of diabetic dams.