Increased nitration and diminished activity of copper/zinc superoxide dismutase in placentas from diabetic rats

WHITE V, CAPOBIANCO E, HIGA R, MARTÍNEZ N, SOSA M, PUSTOVRH MC AND JAWERBAUM A.

FREE RADICAL RESEARCH

TAYLOR & FRANCIS LTD

Año: 2010 vol. 44 p. 1407 - 1415

1071-5762

Nitration-induced protein damage in the placenta leads to impaired blood flow and deficient feto-placental exchange in diabetic pregnancies. In this work, we studied the effect of nitric oxide and peroxynitrite on Cu/Zn SOD activity in rat placentas and evaluated whether Cu/Zn SOD is nitrated in the placenta from diabetic rats at midgestation. Protein nitration was evaluated by EIA, Cu/Zn SOD activity by inhibition of the epinephrine autoxidation, Cu/Zn SOD expression by western blot and specific nitration by immunoprecipitation. We found higher levels of protein nitration (p<0.001), diminished Cu/Zn SOD activity and enhanced protein expression (p<0.01) in placentas from diabetic rats. Placental Cu/Zn SOD activity was inhibited by peroxynitrite (p<0.01).  Besides, nitration of Cu/Zn SOD was elevated in placentas from diabetic rats (p<0.01). Our results show that rat Cu/Zn SOD can be nitrated, a modification that could lead to the depressed activity of this enzyme found in placentas from diabetic rats.