Efeitos preventivos do exercício físico na expressão da miostatina em ratos tratados com Dexametasona

Muscle atrophy is always associated with Dexamethasone (Dexa) treatment, however the mechanisms are not completely understood. This study investigated the effects of Dexa on myostatin and p70S6K protein expression and if previous exercise training (T) can attenuate these effects. Eighty rats were distributed into 4 groups: sedentary control (SC), sedentary treated with Dexa (SD; 0,5 mg/kg per day, i.p., 10 days), trained control (TC) and trained treated with Dexa (TD) and underwent a training period where they were either submitted to a running protocol (60% of physical capacity, 5 days/week for 8 weeks) or kept sedentary. After T period, animals underwent Dexa treatment concomitant with training. Western Blot was performed to identify myostatin and p70S6k protein expression in the tibialis anterior (TA) and soleus (SOL) muscle. Ten days of Dexa treatment increased fasting glucose (SD=+62%), however previous T attenuated this increase (TD=+20%, p<0.05). Dexa determined significant decrease in body weight in TD (-22%) and SD (-25%), followed by TA weight reduction in SD (-23%) and TD (-20%). Previous training could not avoid these decreases. Myostatin protein expression was not altered by dexa treatment or training in TA muscle but in SOL muscle it was significantly modified after T, regardless of treatment (TC=+%23 and TD=+25) compared with their respective controls. The protein p70S6K was not modified neither by dexa nor training in any of the analyzed muscle or condition. The results of this study allowed us to conclude that previous training attenuates the hyperglycemia induced by Dexa, however it did not prevent the body or muscle weight reductions. Even in the presence of muscle atrophy, the expression of myostatin and p70S6K do not justify the mechanisms of muscle loss induced by Dexa, which suggests that other catabolic or anabolic proteins could be involved in the process of muscle atrophy after 10 days of treatment with Dexa

Protocolos de natação em modelos experimentais com ratos

Exercise physiology has attempted to reproduce the experimental exercise in the laboratory using mainly rats. The swimming exercise has emerged as one of the leading research in these type ergometers. Thus, this research consisted of a literature review addressing the key issues which involve the exercise of swimming in the model rats. Training of aerobic and anaerobic swimming, evaluation models and models of periodization were the topics suggested in this research. In several studies, models of aerobic and anaerobic training have been proposed with the aim of studying their effect on normal and abnormal physiological parameters. However, earlier studies lacked methods of analysis aiming to determine the exercise intensity in the animal model. For this reason, in the last decade, assessment models have been adapted for humans to animals, especially rats. The maximal lactate steady state (MLSS) and lactate minimum (LM) are among the various techniques used to measure the amount of effort produced by swimming exercise in rats. Thereafter, based on biochemical parameters such as lactate, swimming exercise in rats has become the highest-rated, ie, using as reference the anaerobic threshold (AT). In another aspect, an entirely new line of research has tried to understand and promising swimming training in a periodized and its effects on some biochemical parameters. But this is an area little researched so far. Thus, the experimental model of swimming has proved an important resource of exercise physiology. From this model, it becomes possible to study the exercise, especially swimming, in more accurate, based on invasive and incisive analysis of the rat

Efeito da coenzima Q10 nos danos oxidativos induzidos pela L-tiroxina no músculo sóleo de ratos

Introduction: skeletal muscles are dynamic tissue that can change their phenotypic characteristics providing a better functional adaptation to different stimuli. L-thyroxine is a hormone produced by the thyroid gland and has been used as an experimental model for stimulation of oxidative stress in skeletal muscle. Coenzyme Q10 (CoQ10) is a fat-soluble provitamin endogenously synthesized and found naturally in foods such red meat, fish, cereals, broccoli and spinach. It has antioxidant properties and potential in the treatment of degenerative and neuromuscular diseases. Objective: to evaluate the protective effect of CoQ10 in the soleus muscle of rats against the oxidative damage caused by L-thyroxine. Methods: the rats were divided in four groups of six animals each: Group 1 (control); Group 2 (coenzyme Q10); Group 3 (L-thyroxine), and Group 4 coenzyme Q10 and L-thyroxine). After euthanasia, blood was collected and serum activity of the enzymes creatine kinase (CK) and aspartate aminotransferase (AST) was analyzed. In the soleus muscle homogenates the factors related to oxidative stress were assessed. Results: CoQ10 protected the soleus muscle against the damage caused by L-thyroxine and favored the maintenance of the antioxidant enzymes glutathione reductase and glutathione peroxidase, the concentration of decreased and oxidized glutathione, and prevented lipid peroxidation. Conclusion: the results indicate that CoQ10 protects rat soleus muscle from oxidative damage caused by L-thyroxine.

Interação entre as vias de sinalização de receptores serotoninérgicos e Β-adrenérgicos em artéria femoral de ratos

Fundamento: A doença coronária tem sido amplamente estudada em pesquisas cardiovasculares. No entanto, pacientes com doença arterial periférica (DAP) têm piores resultados em comparação àqueles com doença arterial coronariana. Portanto, os estudos farmacológicos com artéria femoral são altamente relevantes para a melhor compreensão das respostas clínicas e fisiopatológicas da DAP. Objetivo: Avaliar as propriedades farmacológicas dos agentes contráteis e relaxantes na artéria femoral de ratos. Métodos: As curvas de resposta de concentração à fenilefrina contrátil (FC) e à serotonina (5-HT) e os agentes relaxantes isoproterenol (ISO) e forskolina foram obtidos na artéria femoral de ratos isolada. Para as respostas ao relaxamento, os tecidos foram contraídos com FC ou 5-HT. Resultados: A potência de classificação na artéria femoral foi de 5-HT > FC para as respostas contráteis. Em tecidos contraídos com 5-HT, as respostas de relaxamento ao isoproterenol foram praticamente abolidas em comparação aos tecidos contraídos com FC. A forskolina, um estimulante da adenilil ciclase, restaurou parcialmente a resposta de relaxamento ao ISO em tecidos contraídos com 5-HT. Conclusão: Ocorre uma interação entre as vias de sinalização dos receptores β-adrenérgicos e serotoninérgicos na artéria femoral. Além disso, esta pesquisa fornece um novo modelo para estudar as vias de sinalização serotoninérgicas em condições normais e patológicas que podem ajudar a compreender os resultados clínicos na DAP.

Proteômica como estratégia para estudos dos mecanismos de ativação de mastócitos de ratos causados pelo peptídeo Protopolybia MP-III

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Avaliação da biocompatibilidade de dois adesivos dentinários pelo estudo das reações teciduais em conjuntivo de ratos

The biocompatibility of two dentin adhesives (Scotchbond MultiPurpose- 3M and Optibond Multi-Use - Kerr) was evaluated in rats subcutaneous connective tissue implants. Polyethylene tubes filled with the adhesives were surgically implanted into the dorsal subcutaneous tissues of rats. The tubes were left implanted for periods of 14, 30, 60 and 84 days, following wich the animais were killed and the implants, together with the surrounding tissue, were excised. The specimens were then fixed in 10 per cent formalin, sectioned serially and stained with hematoxylin and eosin and then, examined by light microscopy. After 14 and 30 days the tubes were surrounded by a mild to moderate inflammatory infiltration. After 60 and 84 days microscopic examination revealed the formation of a connective tissue capsule around each tube. The microscopic examination of the biopsy specimens allowed to conclude that: a) both dentin adhesives are considered biologically acceptable when placed in contact with rats subcutaneous connective tissue; b) in the observation period of 30 days there were moderate tissue reaction to the Optibond Multi-Use -light cure- (Kerr); c) after 60 and 84 days the use of both dentine adhesives did not interfere in the healing of the surrounding connective tissue

Efeitos da ciclosporina na lesão renal por isquemia-reperfusão em ratos: estudo em modelo experimental

Pós-graduação em Anestesiologia - FMB

Influência do exercício físico sobre o estresse oxidativo, as MAPK e o NF-kB no músculo sóleo de ratos com insuficiência cardíaca induzida por estenose aórtica

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

O exercício físico é capaz de melhorar expressão de AMPK e GLUT4 em músculo esquelético de ratos alcoolistas e/ou tabagistas

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)