Supplementation with l-glutathione improves oxidative status and reduces protein nitration in myenteric neurons in the jejunum in diabetic Rattus norvegicus

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Diabetes mellitus is a syndrome with multiple etiologies, characterized by chronic hyperglycemia that increases the production of reactive oxygen species and decreases antioxidant defenses. The present study evaluated oxidative stress parameters and protein nitration in myenteric neurons in the jejunum in diabetic rats supplemented with l-glutathione. Rats (90 days of age) were distributed into four groups (n = 6/group): normoglycemic (N), normoglycemic supplemented with l-glutathione (NGT), diabetic (D), and diabetic supplemented with l-glutathione (DGT). At 210 days of age, the animals were sacrificed, and the jejunum was collected, washed, and subjected to various procedures: tert-butyl hydroperoxide chemiluminescence (CL), determination of total antioxidant capacity (TAC), determination of catalase activity, quantification of nitric oxide (NO), and double-labeling of HuC/D-immunoreactive myenteric neurons and nitrotyrosine (3-NT). Diabetes increased oxidative stress in the jejunum in the D group, reflected by increases in lipid peroxidation, TAC, catalase activity, and NO. The D group exhibited an increase in the percentage of myenteric neurons that were double-labeled with 3-NT. Supplementation with l-glutathione did not cause differences in the average CL curves between the D and DGT groups, but reductions of TAC and catalase activity were observed. Supplementation with l-glutathione promoted a reduction of neurons that contained 3-NT in the DGT group. Diabetes mellitus promoted oxidative stress in the jejunum, and supplementation with l-glutathione improved oxidative status by preventing protein nitration in myenteric neurons in diabetic animals that received supplementation.