Resumo Introdução: Diabetes mellitus (DM) é uma doença crônica caracterizada por hiperglicemia levando à nefropatia diabética (ND). Mostramos que P2X7, um receptor purinérgico, foi altamente expresso na DM; entretanto, quando o estresse oxidativo foi controlado, o NO renal recuperou-se, e a ativação deste receptor permaneceu significativamente reduzida. Este estudo objetivou avaliar a influência do NO no P2X7 e a apoptose em células mesangiais imortalizadas de camundongos (CMiC) cultivadas em meio de glicose elevada (GE). Métodos: CMiCs foram cultivadas em meio DMEM e expostas à glicose normal (GN), manitol (MA), ou GE. A viabilidade celular foi avaliada por contador automático. Sobrenadantes foram coletados para quantificação de NO, e foram extraídas proteínas para análise de NO sintases (iNOS e eNOS), caspase-3, e P2X7. Resultados: A viabilidade celular permaneceu acima de 90% em todos os grupos. Houve aumento significativo na proliferação de células na GE comparado com MA e GN. NO, iNOS, caspase-3 e P2X7 foram significativamente aumentados na GE comparados com GN e MA, sem alterações na eNOS. Observamos que houve correlação forte e significativa entre P2X7 e NO. Discussão: O principal achado foi que a produção de NO pela iNOS foi positivamente correlacionada com aumento de P2X7 em CMs sob condições de GE, mostrando que existe um estímulo comum entre eles e que o NO interage com a via do P2X7, contribuindo para apoptose na DM experimental. Estes achados podem ser relevantes para estudos de alvos terapêuticos para a prevenção e/ou tratamento de danos renais induzidos por hiperglicemia para retardar a progressão da ND.

Abstract Introduction: Diabetes mellitus (DM) is a chronic disease characterized by hyperglycemia that leads to diabetic nephropathy (DN). We showed that P2X7, a purinergic receptor, was highly expressed in DM; however, when oxidative stress was controlled, renal NO recovered, and the activation of this receptor remained significantly reduced. The aim of this study was to assess the influence of NO on the P2X7 and apoptosis in mouse immortalized mesangial cells (MiMC) cultured in high glucose (HG) medium. Methods: MiMCs were cultured with DMEM and exposed to normal glucose (NG), mannitol (MA), or HG. Cell viability was assessed by an automated counter. Supernatants were collected for NO quantification, and proteins were extracted for analysis of NO synthases (iNOS and eNOS), caspase-3, and P2X7. Results: Cell viability remained above 90% in all groups. There was a significant increase in the proliferation of cells in HG compared to MA and NG. NO, iNOS, caspase-3, and P2X7 were significantly increased in HG compared to NG and MA, with no changes in eNOS. We observed that there was a strong and significant correlation between P2X7 and NO. Discussion: The main finding was that the production of NO by iNOS was positively correlated with the increase of P2X7 in MCs under HG conditions, showing that there is a common stimulus between them and that NO interacts with the P2X7 pathway, contributing to apoptosis in experimental DM. These findings could be relevant to studies of therapeutic targets for the prevention and/or treatment of hyperglycemia-induced kidney damage to delay DN progression.

ABSTRACT Objectives: The purpose of this study was to investigate the heterogeneity of the association between glycemic variability and oxidative stress markers in T1DM patients under daily life insulin treatment. Subjects and methods: We studied, in a cross-sectional analysis, 76 T1DM patients without clinical chronic diabetes complications and 22 healthy individuals. Were evaluated the short-term glycemic variability (STGV), long-term glycemic variability (LTGV), oxidative stress markers [8-isoprostaglandin-F2α (Ur-8-iso-PGF2α), nitric oxide (NO), thiobarbituric acid reactive substances (TBARS) and erythrocytes reduced/oxidized glutathione (GSH/GSSG)] and biochemical dosages (glycaemia, HbA1c, lipidogram, albuminuria). Results: Plasmatic NO was positively associated with LTGV (last year average of HbA1c) (8.7 ± 1.6% or 71 ± 18 mmol) (rS: 0.278; p: 0.042). Plasmatic TBARS, erythrocytes GSH/GSSH and Ur-8-iso-PGF-2α didn't show correlation with glycemic variability. GSH/GSSG was inversely correlated with LDL-cholesterol (rS: - 0.417; p: 0.047) and triglycerides (rS: −0.521; p: 0.013). Albuminuria was positive correlated with age (rS: 0.340; p: 0.002), plasmatic NO (rS: 0.267; p 0.049) and TBARS (rS: 0.327; p: 0.015). Conclusion: In daily life insulin treatment, young T1DM patients have higher plasmatic NO than healthy subjects. However, the correlation between glycemic variability and oxidative stress markers is heterogeneous. Lipid profile and albuminuria are associated with different oxidative stress markers. These data collaborate to explain the controversial results in this issue.

INTRODUÇÃO: O ácido ascórbico tem se mostrado como um agente promissor na atenuação da lesão causada pela isquemia/reperfusão (IR). O objetivo deste estudo foi determinar os efeitos protetores do ácido ascórbico na morfologia intestinal durante a IR em ratos. MATERIAL E MÉTODOS: Examinamos alterações morfológicas no intestino delgado de ratos do tipo Wistar. Após 40 minutos de isquemia (I), isquemia seguida de reperfusão (IR), isquemia com tratamento com ácido ascórbico (IA), isquemia seguida por 30 minutos de reperfusão e tratamento com ácido ascórbico (IRA) e do grupo sham (S). Utilizamos a morfometria para avaliar quantitativamente a arquitetura dos vilos da mucosa intestinal, criptas intestinais, necrose, hemorragia, células inflamatórias nas bordas mesentéricas e antimesentéricas do intestino delgado. RESULTADOS: O ácido ascórbico causou uma redução significativa (p<0,05) no infarto hemorrágico dos vilos intestinais da borda antimesentérica do intestino delgado após isquemia seguida por reperfusão, bem como redução da necrose dos vilos em ambas as bordas após a isquemia (p<0.05). As lesões presentes no intestino delgado foram mais proeminentes na borda antimesentérica. CONCLUSÕES: O pré-tratamento com ácido ascórbico atenuou ou reduziu significativamente as alterações morfológicas no intestino delgado induzidas pela isquemia-reperfusão.

BACKGROUND: Ascorbic acid has shown promise in attenuation of intestinal ischemia-reperfusion (I/R) injury. The aim of this study was to determine the protective effects of ascorbic acid on intestinal morphology during IR injury in rats. MATERIALS AND METHODS: We examined morphological changes in the small intestine of Wistar rats after (i) 40 minutes of ischemia (I), (ii) ischemia followed by 30 min of reperfusion (IR), (iii) ischemia with ascorbic acid (IA), (iv) ischemia followed by reperfusion and ascorbic acid (IRA) and (v) in a sham group (S). We used morphometry to evaluate the amount of villous architecture, crypts, necrosis, hemorrhagic infarcts and inflammatory cells at the mesenteric and antimesenteric borders of the small intestine. RESULTS: Ascorbic acid caused a significant reduction of antimesenteric villous hemorrhagic infarction (p<0.05) of the small intestine after ischemia followed by reperfusion as well as villous necrosis reduction at both borders after ischemia (p<0.05). The lesions found in the small intestine were more prominent along the antimesenteric margin. CONCLUSIONS: Ascorbic acid pretreatment has a protective effect against the intestinal morphological lesions induced by ischemia-reperfusion injury in rats.