Hypolipidemic, hipoglycemiant and antioxidant effects of Myrcia splendens (Sw) DC in an animal type 2 diabetes model induced by streptozotocin / Efectos hipolipemiante, hipoglucemiante y antioxidante de Myrcia splendens (Sw) DC en un modelo animal de diabetes tipo 2 inducido por estreptozotocina

We investigated the effects of dichloromethane extract (DME) from Myrcia splendenson alterations caused by type 2 diabetes in the blood and kidney of rats, in order to reduce side effects caused by synthetic drugs. Rats received streptozotocin (60 mg/kg),15 minutes after nicotinamide (120 mg/kg) or water. After 72 hours, the glycemic levels were evaluated to confirm diabetes and the animals received (15 days) DME (25, 50, 100 or 150 mg/Kg) or water. DME partially reversed hyperglycemia and (100 and 150 mg/kg) reversed hypertriglyceridemia. Histopathological findings elucidated that DME reduced damage to pancreatic islets. DME 150 mg/kgreversed the increases in TBA-RS, the reduction in the sulfhydryl content, 100 and 150 mg/kg increased CAT, reversed the decrease in GSH-Px and increased it activity in the blood. DME 150 mg/kg reversed CAT and GSH-Px reductions in the kidney. We believe that DME effects might be dependent on the presence of phenolic compounds.

Investigamos los efectos del extracto de diclorometano (DME)de Myrcia splendens sobre las alteraciones causadas por la diabetes tipo 2 en la sangre y los riñones de las ratas, para reducir los efectos secundarios causados por las drogas sintéticas. Las ratas recibieron estreptozotocina (60 mg/kg), 15 minutos después de la nicotinamida (120 mg/kg) o agua. Después de 72 horas, se confirmo la diabetes y los animales recibieron (15 días) DME (25, 50, 100 o 150 mg/Kg) o agua. DME revierte parcialmente la hiperglucemia y revierte la hipertrigliceridemia. DME redujo el daño a los islotes pancreáticos. DME revirtió los aumentos en TBA-RS, la reducción en el contenido de sulfhidrilo, aumentó la CAT, revirtió la disminución en GSH-Px y aumentó su actividad en la sangre. Además, DME revirtió las reducciones de CAT y GSH-Px en el riñón. Creemos que los efectos provocados por DME pueden depender de la presencia de compuestos fenólicos.

Efeitos da fração acetato de etila de Tabernaemontana catharinensis sobre respostas glicêmicas e estresse oxidativo de Rattus norvegicus diabéticos / Effects of tabernaemontana catharinensis ethyl acetate fraction on glycemic responses and oxidative stress

OBJECTIVE: To evaluate the Tabernaemontana catharinensis ethyl acetate fraction hypoglycemic and antioxidant activity through the peripheral glycemic dosage and enzymatic tests. Methods: Male rats were divided into 6 groups: control, diabetic control, control extract 50, diabetic extract 50, control extract 80, diabetic extract 80. In diabetic group animals alloxan (150mg/Kg) was administered to induce Diabetes Mellitus. The animals were beheaded following 15 days of treatment with extract or distilled water and the blood was collected in order to perform oxidative stress tests. Results: The diabetic control group showed high levels of glucose, increased levels of thiobarbituric acid and superoxide dismutase activity, and decreased activity of catalase and glutathione peroxidase enzymes. The diabetic animals that received 50mg/Kg and 80mg/Kg of extract showed a decrease in thiobarbituric acid levels and an increase of glutathione peroxidase activity when compared to the diabetic control group. It was observed that only animals treated with 80mg/Kg of extract had positive results regarding superoxide dismutase. Conclusions: The Tabernaemontana catharinensis ethyl acetate fraction when orally administered for 14 consecutive days at doses of 50mg/Kg and 80mg/Kg reduces the oxidative stress induced by alloxan administration

OBJETIVO: Avaliar a ação hipoglicemiante e antioxidante da fração acetato de etila do extrato de Tabernaemontana catharinensis através da dosagem glicêmica periférica e testes enzimáticos. MÉTODOS: Ratos machos foram divididos em seis grupos: controle, controle diabético, controle extrato 50, diabético extrato 50, controle extrato 80, diabético extrato 80. Nos animais dos grupos diabéticos foi induzida Diabetes Mellitus pela administração de 150mg/Kg de aloxana. Após 15 dias de tratamento com a fração acetato de etila de Tabernaemontana catharinensis ou água destilada, os animais foram decapitados e o sangue foi coletado para realização dos testes de estresse oxidativo. RESULTADOS: O grupo controle diabético apresentou níveis elevados de glicose, aumento dos níveis de ácido tiobarbitúrico e atividade da superóxido dismutase, e diminuição da atividade das enzimas catalase e glutationa peroxidase. Os animais dos grupos diabéticos tratados com 50 e 80mg/Kg do extrato apresentaram redução nos níveis de ácido tiobarbitúrico e aumento da atividade de glutationa peroxidase quando comparado ao grupo controle diabético. Apenas os animais que receberam o extrato na dose de 80mg/Kg obtiveram resultados positivos em relação ao superóxido dismutase. CONCLUSÕES: A fração acetato de etila de Tabernaemontana catharinensis, quando administrada por 14 dias consecutivos, via oral, nas doses de 50 e 80mg/Kg, promove redução nos níveis de estresse oxidativo gerado pela administração de aloxana

Hypoxanthine induces oxidative stress in kidney of rats: protective effect of vitamins E plus C and allopurinol.

In the present study, we investigated the in vitro effect of hypoxanthine on the activities of antioxidant enzymes such as catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase, as well as on thiobarbituric-acid-reactive substances (TBA-RS), in the renal cortex and medulla of rats. Results showed that hypoxanthine, at a concentration of 10.0 µM, enhanced the activities of CAT and SOD in the renal cortex of 15-, 30- and 60-day-old rats, enhanced SOD activity in the renal medulla of 60-day-old rats and enhanced TBA-RS levels in the renal medulla of 30-day-old rats, as compared with controls. Furthermore, we also verified the influence of allopurinol (an inhibitor of xanthine oxidase), as well as of the antioxidants, trolox and ascorbic acid on the effects elicited by hypoxanthine on the parameters tested. Allopurinol and/or administration of antioxidants prevented most alterations caused by hypoxanthine in the oxidative stress parameters evaluated. Data suggest that hypoxanthine alters antioxidant defences and induces lipid peroxidation in the kidney of rats; however, in the presence of allopurinol and antioxidants, some of these alterations in oxidative stress were prevented. Our findings lend support to a potential therapeutic strategy for this condition, which may include the use of appropriate antioxidants for ameliorating the damage caused by hypoxanthine.

Adjuvant effects of classical music on simvastatin induced reduction of anxiety but not object recognition memory in rats

Simvastatin is one of many hydroxymethylglutaryl-coenzyme-A reductase inhibitors that are prescribed to lower cholesterol. Some emerging evidence indicates that classical music can serve as an effective adjuvant in rats treated with simvastatin. Moreover, simvastatin and classical music have been shown to influence some cognitive functions. To further understand the mechanisms of action, we exposed rats to classical music for 1 month, and then treated them orally with simvastatin. The behavioral experiments suggested that exposure to subchronic simvastatin (1 or 10 mg/kg/day) reduced anxiety levels in the elevated plus-maze and open-field test in rats exposed to Mozart music. The recognition object test results indicated that simvastatin altered non-spatial working memory only at the 1 mg/kg/day dose and improved both short- and long-term object recognition. No significant differences were found between Mozart music and silence in the object recognition test, suggesting that music did not significant affect learning and memory in adult rats. We hypothesize that the anxiolytic, but not object-recognition memory, effects of simvastatin and classical music occur through similar mechanisms, providing an important foundation for future preclinical and clinical research...

In vitro stimulation of oxidative stress by hypoxanthine in blood of rats: prevention by vitamins e plus C and allopurinol.

We herein investigated the in vitro effect of hypoxanthine on the activities of antioxidant enzymes such as catalase (CAT), glutathione peroxidase (GSH-Px), and superoxide dismutase (SOD) in erythrocytes, as well as on thiobarbituric acid-reactive substances (TBA-RS), in the plasma of rats. Results showed that hypoxanthine, when added to the incubation medium, enhanced CAT (10.0 µM), GSH-Px and SOD (8.5 µM and 10.0 µM) activities in erythrocytes of 15-day-old rats, reduced CAT activity (10.0 µM) and enhanced GSH-Px activity (10.0 µM) in erythrocytes of 30-day-old rats, reduced CAT activity (10.0 µM) and enhanced GSH-Px activity (8.5 µM and 10.0 µM) in erythrocytes of 60-day-old rats, as compared to controls. In addition, hypoxanthine (10.0 µM) enhanced TBA-RS levels in the plasma of 30- and 60-day old rats. Furthermore, we also tested the influence of allopurinol, trolox, and ascorbic acid on the effects elicited by hypoxanthine on the antioxidant enzymes and TBA-RS. Allopurinol and/or administration of antioxidants prevented most alterations caused by hypoxanthine in the oxidative stress parameters evaluated. Findings suggest that hypoxanthine alters antioxidant defenses and induces lipid peroxidation in the blood of rats; however, in the presence of allopurinol and antioxidants, some of these alterations in oxidative stress caused are prevented. Data indicate that, in humans, antioxidant administration might serve as a potential adjuvant therapy for ameliorating the damage caused by hypoxanthine.

The effects of swimming exercise on recognition memory for objects and conditioned fear in rats / Os efeitos do exercício de natação sobre a memória para reconhecimento de objetos e de medo condicionados em ratos

Experiments conducted in animals have repeatedly demonstrated the ability of exercise to enhance cognitive function. This study examines the effects of chronic swimming exercise on non-spatial memory in adult rats after 12 weeks of swimming exercise in object recognition and elevated T-maze tests. In the object recognition test, repeated measures analysis of variance revealed a group effect (F1,42 = 26,093; p < 0.001), control rats had lower discrimination ratios than the exercise group. However, the swimming exercise did not affect the performance of inhibitory avoidance and escapes, when memory was tested in elevated T-maze. Analysis of variance showed a significant reduction in inhibitory avoidance 24h after the first training (F1,42 = 14,552; p < 0.001). Results indicated that regular swimming exercise significantly increased non-spatial memory in object recognition behavior, but did not affect the performance of inhibitory avoidance and escape on elevated T-maze test in adult rats. These findings suggest that the perirhinal cortex plays a role in memory consolidation and storage in addition to that of the amygdala, which could be regarded as the center of a second memory system, separate from those governed by the perirhinal cortex.

As experiências realizadas em animais mostram a capacidade do exercício em melhorar as funções cognitivas. Este estudo analisa os efeitos do exercício crônico de natação sobre a memória não-espacial em ratos adultos após 12 semanas de exercício de natação nos testes de reconhecimento de objetos e labirinto em T elevado. O teste de reconhecimento de objetos, pelas repetidas análises de variância revelaram um efeito de grupo (F1,42 = 26.093; p < 0,001), os ratos controles discriminaram uma razão inferior ao do grupo de exercício. Entretanto, o exercício de natação não afetou o desempenho de esquiva inibitória e escape, quando a memória foi testada no labirinto em T elevado. Análise de variância mostrou redução significativa na esquiva inibitória 24h após o primeiro treino (F1,42 = 14.552; p < 0,001). Os resultados indicam que o exercício regular de natação aumenta significativamente a memória não-espacial no comportamento de reconhecimento de objetos, mas não afeta o medo condicionado no teste do labirinto em T elevado em ratos adultos. Estes resultados sugerem que o córtex peririnal desempenha papel nos processos de consolidação e armazenamento de memória além da amígdala, podendo esta ser encarada como um segundo centro de sistema de memória, separada dos regidos pelo córtex peririnal.

Anxiolytic effects of swimming exercise and ethanol in two behavioral models: beneficial effects and increased sensitivity in mice

Several behavioral mechanisms have been suggested to explain the effects of ethanol or physical exercise on anxiety. The purpose of the current study was to assess the effects of chronic and acute administration of ethanol on swimming exercise in mice, sequentially submitted to the elevated plus-maze and open- tests. In the first experiment, sedentary or physical exercise groups received chronic treatment with ethanol (0.1, 0.2, 0.4, 2 or 4 g ethanol/kg/day by oral gavage) for 14 days before the tests. In the second experiment, groups received a single dose of ethanol (ip: 0.6, 0.8, 1.0 or 1.2 g/kg), ten minutes before the start of behavioral tests. The present study found an anxiolytic-like effect after chronic ethanol treatment or swimming exercise, evidence of beneficial effects. Moreover, we conclude that exercise can increase behavioral sensitivity to ethanol in acute treatment. The experiments described here show that the effects of ethanol on the behavior displayed in the elevated plus-maze and open- are not only dose-dependent but also modified by swimming exercise. These results may provide valuable insights into possible molecular mechanisms governing these adaptations.

Vários mecanismos comportamentais foram propostos para explicar os efeitos do etanol ou do exercício sobre a ansiedade. O objetivo do presente estudo foi avaliar os efeitos da administração crônica e aguda de etanol sobre o exercício de natação em camundongos, seqüencialmente submetidos aos testes do labirinto em cruz elevado e campo aberto. No primeiro experimento, os grupos de sedentários e exercício físico receberam tratamento crônico com etanol (0,1; 0,2; 0,4; 2 e 4 g de etanol/kg/dia através de gavagem oral) durante 14 dias antes dos testes. No segundo experimento, os grupos receberam uma única dose de etanol, i.p. (0,6; 0,8; 1,0 ou 1,2 g de etanol/kg), dez minutos antes do início dos testes comportamentais. O presente estudo encontrou efeitos ansiolíticos após tratamento crônico com etanol ou exercício de natação, provas dos efeitos benéficos. Além disto, concluímos que o exercício pode aumentar a sensibilidade comportamental ao etanol no tratamento agudo. Os experimentos aqui descritos mostram que os efeitos do etanol sobre o comportamento exibido no labirinto em cruz elevado ou campo aberto não são apenas dose-dependente, mas também depende do exercício de natação. Este trabalho pode fornecer ?insights? valiosos sobre os possíveis mecanismos moleculares que regem essas adaptações.