Naringin and trimetazidine improve baroreflex sensitivity and nucleus tractus solitarius electrical activity in renal ischemia-reperfusion injury / Naringin and trimetazidine improve baroreflex sensitivity and nucleus tractus solitarius electrical activity in renal ischemia-reperfusion injury

Resumo Fundamento: O núcleo do trato solitário (NTS) é uma área do cérebro que desempenha um papel fundamental na regulação renal e cardiovascular através dos impulsos dos barorreceptores. Objetivos: O objetivo deste estudo foi avaliar o efeito da Naringina (NAR) e trimetazidina (TMZ), isoladamente e combinadas, na atividade elétrica do NTS e na sensibilidade barorreflexa (SBR) na lesão de isquemia e reperfusão (I/R) renal. Métodos: Foram utilizados quarenta ratos machos Sprague-Dawley (200-250 g), alocados em 5 grupos com 8 ratos cada. Grupos: 1) Sham; 2) I/R; 3) TMZ 5 mg/kg; 4) NAR 100 mg/kg; e 5) TMZ5 + NAR100. A veia femoral esquerda foi canulada para infundir a solução salina ou droga e avaliar a SBR. A I/R foi induzida por oclusão dos pedículos renais por 45 min, seguida de reperfusão de 4 horas. O eletroencefalograma local do NTS foi registrado antes, durante a isquemia e durante a reperfusão. A fenilefrina foi injetada por via intravenosa para avaliar a SBR ao final do tempo de reperfusão. Os dados foram analisados por ANOVA de duas vias com medidas repetidas seguida pelo teste post hoc de Tukey. Um valor de p<0,05 foi considerado como significativo. Resultados: As ondas elétricas do NTS não se alteraram durante o tempo de isquemia, mas diminuíram significativamente durante todos os tempos de reperfusão. A atividade elétrica do NTS e a SBR foram reduzidas drasticamente em ratos com lesão I/R; no entanto, a administração de NAR e TMZ, isoladamente e combinadas, melhorou significativamente essas alterações em ratos com lesão I/R. Conclusões: Os resultados mostraram que a lesão de I/R leva à redução da atividade elétrica da SBR e do NTS, e pode haver uma ligação entre a I/R e a diminuição da SBR. Além disso, a NAR e a TMZ são agentes promissores para tratar complicações de I/R.

Abstract Background: Nucleus tractus solitarius (NTS) is a brain area that plays a key role in kidney and cardiovascular regulation via baroreceptors impulses. Objectives: The aim of this study was to evaluate the effect of naringin (NAR) and trimetazidine (TMZ) alone and their combination on NTS electrical activity and baroreceptor sensitivity (BRS) in renal ischemia- reperfusion (I/R) injury. Methods: Forty male Sprague-Dawley rats (200- 250 g) were allocated into 5 groups with 8 in each. 1) Sham; 2) I/R; 3) TMZ 5 mg/kg; 4) NAR 100 mg/kg; and 5) TMZ5+ NAR100. The left femoral vein was cannulated to infuse saline solution or drug and the BRS was evaluated. I/R was induced by occlusion of renal pedicles for 45 min, followed by 4 hours of reperfusion. The NTS local electroencephalogram (EEG) was recorded before, during ischemia and throughout the reperfusion. Phenylephrine was injected intravenously to evaluate BRS at the end of reperfusion time. The data were analyzed by two-way repeated measurement ANOVA followed by Tukey's post hoc test. A p-value <0.05 was considered significant. Results: NTS electrical waves did not change during ischemia time, while they significantly decreased during the entire reperfusion time. NTS electrical activity and BRS dramatically reduced in rats with I/R injury; however, administration of NAR, TMZ alone or their combination significantly improved these changes in rats with I/R injury. Conclusions: The results showed that I/R injury leads to reduced BRS and NTS electrical activity and there may be an association between I/R and decreased BRS. In addition, NAR and TMZ are promising agents to treat I/R complications.

Decreased mRNA Expression of Cystathionine Gamma lyase and H2S Concentration in Gastric Mucosal Tissue in Diabetic Rats

ABSTRACT Background and aim: It is well established that the rate of gastric lesions increases in diabetic rats. Recently, the protective effect of hydrogen sulfide (H2S) in gastric mucosa has been proven. This study aimed to determine the release of H2S and mRNA expression of cystathionine gamma lyase (CSE) in gastric mucosa in alloxan-diabetic rats in response to distention-induced gastric acid secretion. Twenty-four rats were randomly assigned to 4 groups (6 in each). They were the normal-control, distention-control, diabetic-control, and distention-diabetic groups. Under anesthesia, animals underwent a tracheotomy and midline laparotomy. To washout the gastric contents, a catheter was inserted in the stomach through the duodenum. To determine the effect of distention-induced gastric acid secretion on H2S release and mRNA expression of CSE, the stomachs were distended by normal saline. At the end of experiments, animals were sacrificed and the gastric mucosa was collected to determine H2S concentration and to quantify mRNA expression of CSE by quantitative real-time PCR. Mucosal release of H2S and mRNA expression of CSE significantly increased in response to stimulated gastric acid secretion in normal rats (P<0.01), while the increases in diabetic rats were not significant. Basal release of H2S and mRNA expression of CSE in gastric mucosa were significantly in diabetic rats lower than normal rats. On the basis of the results, we conclude that the decreased release of H2S in response to basal and stimulated gastric acid output in alloxan-diabetic rats compared to normal rats is largely due to downregulation of mRNA expression of CSE.

The Effect of PM 10 on Ischemia- Reperfusion Induced Arrhythmias in Rats

ABSTRACT Epidemiological studies show that particulate matter (PM) is the principal instigator of some adverse clinical symptoms involving cardiovascular diseases. PM exposure can increase experimental infarct size and potentiate myocardial ischemia and arrhythmias in experimental MI models such as ischemia-reperfusion (I/R) injury.The present study was aimed to evaluate the effects of particulate matter (PM10) on ischemia- reperfusion induced arrhythmias with emphasis on the protective role of VA as an antioxidant on them. Male Wistar rats were divided into 8 groups (n=10): Control, VAc, Sham, VA, PM1 (0.5 mg/kg), PM2 (2.5 mg/kg), PM3 group (5 mg/kg), PM3 + VA group. Within 48 hours, PM10 was instilled into trachea in two stages. Then the hearts were isolated, transferred to a Langendorff apparatus, and subjected to global ischemia (30 minutes) followed by reperfusion (60 minutes). The ischemia- reperfusion induced ventricular arrhythmias were assessed according to the Lambeth conventions.In the present study,the number, incidence and duration of arrhythmiasduring30 minutes ischemia were demonstrated to be more than those in the reperfusion stage. PM exposure increased significantly the number, incidence and duration of arrhythmias in the ischemia and reperfusion duration. Vanillic acid reduced significantly the number, incidence and duration of arrhythmias during the ischemia and reperfusion period.In summary, the results of this study demonstrated that the protective and dysrhythmic effects of VA in the PM exposure rats in I/R model are probably related to its antioxidant properties.

A preliminary study of the anti-inflammatory and anti-apoptotic effects of crocin against gastric ischemia-reperfusion injury in rats

The aim of the present study was to investigate the protective effect of crocin on gastric mucosal lesions caused by ischemia-reperfusion (I/R) injury in rats. Thirty-two male rats were randomly divided into sham, I/R, I/R + crocin pretreatment and crocin alone groups. To induce I/R lesions, the celiac artery was clamped for 30 min, and the clamp was then removed to allow reperfusion for 3 h. Crocin-pretreated rats received crocin (15 mg/kg, i.p.) 30 min prior to the induction of I/R injury. Samples of gastric mucosa were collected to quantify the protein expression of caspase-3, an apoptotic factor, and inducible nitric oxide synthase (iNOS), a pro-inflammatory protein, by Western blot. Pretreatment with crocin decreased the total area of gastric lesions and decreased the protein expression levels of caspase-3 and iNOS induced by I/R injury. Our findings showed a protective effect of crocin in gastric mucosa against I/R injury. This effect of crocin was mainly mediated by reducing the protein expression of iNOS and caspase-3.

O objetivo do presente estudo foi investigar o efeito protetor da crocina em lesões da mucosa gástrica causadas por isquemia-reperfusão (I/R) em ratos. Trinta e dois ratos machos aleatoriamente divididos em grupos de ratos normais, operados como controle, I/R. I/R + pré-tratamento com crocina e crocina sozinha. Para induzir lesões I/R, a artéria celíaca foi grampeada durante 30 minutos e, em seguida, o grampo foi removido para permitir a reperfusão por 3 h. Ratos com pré-tratamento com crocina receberam crocina (15 mg/kg, ip) 30 minutos antes da indução do dano I/R. Amostras de mucosa gástrica foram coletadas para qiuantificar a expressão da proteína da caspase-3, o fator apoptótico, e óxido nítrico sintase induzível (iNOS), uma proteína anti-inflamatória, pela técnica de Western Blot. O pré-tratamento com crocina diminuiu a área total de lesões gástricas e a expressão de níveis de caspase-3 e iNOS induzidas pelo dano I/R. Nossos resultados mostraram o efeito protetor da crocina na mucosa gástrica contra o dano I/R. Este efeito foi mediado, principalmente, por diminuição da expressão das proteínas iNOS e caspase-3.