Myricitrin and Its Solid Lipid Nanoparticle Increase Insulin Secretion and Content of Isolated Islets from the Pancreas of Male Mice

Abstract Glucose exposure induces toxic effects on the function of the pancreatic islets. Moreover, myricitrin as a flavonoid glycoside may have favorable effects on insulin secretion of Langerhans islets. The present study aimed to investigate the effect of Myricitrin and its solid lipid nanoparticles (SLN) on the insulin secretion as well as the content of isolated pancreatic islets from male mice. In this experimental study, Langerhans islets were separated from adult male NMRI mice using the collagenase method. The insulin secretion and content of islets were assessed in glucose-containing medium (2.8, 5.6, and 16.7mM). Further, islets treated were prepared by the administration of Myricitrin and its SLN (1, 3 and 10µM). Myricitrin 3µM, and SLN containing Myricitrin 3 and 10µM increased insulin secretion in medium containing glucose concentration 2.8mM. Accordingly, this variable increased in Myricitrin 3 and 10µM, SLN containing Myricitrin 1, 3, and 10µM utilization as well as glucose concentration 5.6mM. Afterward, the insulin secretion increased in medium containing 16.7mM glucose after the addition of Myricitrin and SLN containing Myricitrin 1, 3, and 10µM. Also, the insulin content increased in Myricitrin and SLN containing Myricitrin 1, 3, and 10µM administered groups in all medium containing glucose concentrations. Myricitrin and its SLN increased islets insulin secretion and content in low, moderate, and high glucose concentration mediums

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.

The Effects of Trimetazidine on QT-interval Prolongation and Cardiac Hypertrophy in Diabetic Rats / Os Efeitos da Trimetazidina no Prolongamento do Intervalo QT e na Hipertrofia Cardíaca em Ratos Diabéticos

Abstract Background: Trimetazidine (TMZ) is an anti-ischemic drug. In spite of its protective effects on cardiovascular system, there is no scientific study on the usefulness of TMZ treatment for prolonged QT interval and cardiac hypertrophy induced by diabetes. Objectives: To evaluate the effects of TMZ on QT interval prolongation and cardiac hypertrophy in the diabetic rats. Methods: Twenty-four male Sprague-Dawley rats (200-250 g) were randomly assigned into three groups (n = 8) by simple random sampling method. Control (C), diabetic (D), and diabetic administrated with TMZ at 10 mg/kg (T10). TMZ was administrated for 8 weeks. The echocardiogram was recorded before isolating the hearts and transfer to a Langendorff apparatus. Hemodynamic parameters, QT and corrected QT interval (QTc) intervals, heart rate and antioxidant enzymes were measured. The hypertrophy index was calculated. The results were evaluated by one-way ANOVA and paired t-test using SPSS (version 16) and p < 0.05 was regarded as significant. Results: The diabetic rats significantly indicated increased hypertrophy, QT and QTc intervals and decreased Left ventricular systolic pressure (LVSP), Left ventricular developed pressure (LVDP), rate pressure product (RPP), Max dp/dt, and min dp/dt (±dp/dt max), heart rate, superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase in the heart. Treatment with TMZ in the diabetic animals was significantly improved these parameters in comparison to the untreated diabetic group. Conclusions: TMZ improves QTc interval prolongation and cardiac hypertrophy in diabetes.

Resumo Fundamento: A trimetazidina (TMZ) é uma droga anti-isquêmica. Apesar de seus efeitos protetores sobre o sistema cardiovascular, não há estudos científicos sobre a utilidade do tratamento com TMZ para o intervalo QT prolongado e a hipertrofia cardíaca induzida pelo diabetes. Objetivo: Avaliar os efeitos da TMZ no prolongamento do intervalo QT e na hipertrofia cardíaca em ratos diabéticos. Métodos: Vinte e quatro ratos machos Sprague-Dawley (200-250 g) foram distribuídos aleatoriamente em três grupos (n = 8) pelo método de amostragem aleatória simples. Controle (C), diabético (D) e diabético administrado com TMZ a 10 mg/kg (T10). A TMZ foi administrada por 8 semanas. O ecocardiograma foi registrado antes de isolar os corações e transferir para um aparelho de Langendorff. Foram medidos os parâmetros hemodinâmicos, intervalo QT e intervalo QT corrigido (QTc), frequência cardíaca e enzimas antioxidantes. O índice de hipertrofia foi calculado. Os resultados foram avaliados pelo one-way ANOVA e pelo teste t pareado pelo SPSS (versão 16) e p < 0,05 foi considerado significativo. Resultados: Os ratos diabéticos indicaram hipertrofia aumentada, intervalos QT e QTc e diminuição da pressão sistólica no ventrículo esquerdo (PSVE), pressão desenvolvida no ventrículo esquerdo (PDVE), duplo produto (DP), Max dp/dt e min dp/dt (± dp/dt max), frequência cardíaca, superóxido dismutase (SOD), glutationa peroxidase (GPx) e catalase no coração. O tratamento com TMZ nos animais diabéticos melhorou significativamente esses parâmetros em comparação com o grupo diabético não tratado. Conclusões: A TMZ melhora o prolongamento do intervalo QTc e a hipertrofia cardíaca no diabetes.

Anti-diabetic effect of betulinic acid on streptozotocin-nicotinamide induced diabetic male mouse model

ABSTRACT Diabetes is a metabolic disease caused by abnormal insulin secretion or action. In the present study, the effects of betulinic acid (BA, a triterpene) are evaluated on glucose, α-amylase and plasma insulin levels, insulin resistance and the histopathology of pancreatic islets in streptozotocin-nicotinamide (STZ-NA) diabetic mice. Seventy adult male NMRI mice were randomly divided into seven groups: control, sham, diabetic, diabetic treated with BA (10, 20 and 40 mg/kg) and diabetic treated with metformin (200 mg/kg). Diabetes was induced in mice by intraperitoneal injection of streptozotocin 50 mg/kg after a dose of nicotinamide 120 mg/kg. Two weeks after treatment with BA, blood samples were collected for measuring glucose, α-amylase and insulin levels, and the pancreas was isolated for histopathology evaluation. Diabetes reduced the number and diameter of pancreatic islets, and increased α-amylase and insulin resistance. BA treatment reduced blood glucose, α-amylase and improved insulin sensitivity as well as pancreas histopathology. In addition, BA showed stronger effects on the pancreatic histology and insulin resistance compared to the metformin group

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.

Effects of Arctium lappa aqueous extract on lipid profile and hepatic enzyme levels of sucrose-induced metabolic syndrome in female rats

ABSTRACT Arctium lappa is known to have antioxidant and antidiabetic effects in traditional medicine. Objectives: The aim of this paper was to study the effects of A. lappa root extract (AE) on lipid profile and hepatic enzyme levels in sucrose-induced metabolic syndrome (MS) in female rats. The study used 40 adult female Wistar rats weighing 150 g-250 g randomly divided into five groups: control, metabolic syndrome (MS), metabolic syndrome+AE at 50,100, 200 mg/kg. MS was induced by administering 50% sucrose in drinking water for 6 weeks. AE was intra-peritoneally administered daily at doses of 50,100, and 200 mg/kg for two sequential weeks at the end of the fourth week in metabolic syndrome rats. Twenty-four hours after the last administration of AE, blood was collected and centrifuged, and then the serum was used for the measurement of lipid profile and hepatic enzyme. Serum glucose, insulin, fasting insulin resistance index, body weight, water intake, lipid profile, and hepatic enzymes were significantly increased although food intake was decreased in MS rats compared to the control rats. The lipids and liver enzymes were reduced by AE extracts in the MS group. This study showed that the A. lappa root aqueous extract exhibits a hypolipidemic activity of hyperlipidemic rats. This activity is practically that of a triple-impact antioxidant, hypolipidemic, and hepatoprotective.

Comparison of therapeutic effects of L-Thyroxin, apelin and a combination of both on antioxidant enzymes in the heart of PTU-induced hypothyroid rats

Atherosclerosis is one of the common disorders among hypothyroidism, which, increased the risk of cardiovascular diseases. Reactive oxygen species are associated with atherosclerosis development. Antioxidant defense systems are the scavenger for free radicals. Apelin is an endogenous ligand for the APJ receptor (apelin receptor) that exists in most tissues, acts as an adiponectin. It has been identified that apelin administration, improve the antioxidant capacity (TAC). Therefore, this study was conducted to assess, therapeutic effects of apelin, T4 (L-Thyroxin) or both on antioxidant capacity in 6-propyl-2-thiouracil (PTU)-induced hypothyroid rats. Forty male Wistar rats were randomly assigned into five groups: C: control group; P group (hypothyroid): PTU (0.05 %) administration for six weeks; P+A, P+T and P+A+T groups: after 4 weeks of PTU administration, animals treated with Apelin (200 μg/kg/day, ip) T4 (0.02 µg/g/day, gavage) and apelin+T4; for two weeks respectively accompanied by PTU administration. Aplein administration in P+A group and P+A+T group had beneficial effect to lowering of malondialdehyde (MDA) content as compared to hypothyroid group (8.52±0.64 and 8.53±1 vs. 13.67±1.64 nmol/g tissue, P<0.05) and also had increasing effect on Superoxide dismutase (SOD) and glutathion peroxidase (GPx) activity and the total antioxidant capacity (TAC) content compared to the hypothyroid group. This study showed that apelin was able to improve the oxidant-antioxidant balance in the heart tissue of the hypothyroid rats by elevating of antioxidant enzyme activity.