OBJECTIVE: Exercise is a protective factor for cardiovascular morbidity and mortality, with unclear mechanisms. Changing the myocardial metabolism causes harmful consequences for heart function and exercise contributes to metabolic adjustment modulation. Peroxisome proliferator-activated receptors (PPARs) are also myocardium metabolism regulators capable of decreasing the inflammatory response. We hypothesized that PPAR-α is involved in the beneficial effects of previous exercise on myocardial infarction (MI) and cardiac function, changing the expression of metabolic and inflammatory response regulators and reducing myocardial apoptosis, which partially explains the better outcome. METHODS AND RESULTS: Exercised rats engaged in swimming sessions for 60 min/day, 5 days/week, for 8 weeks. Both the exercised rats and sedentary rats were randomized to MI surgery and followed for 1 week (EI1 or SI1) or 4 weeks (EI4 or SI4) of healing or to sham groups. Echocardiography was employed to detect left ventricular function and the infarct size. Additionally, the TUNEL technique was used to assess apoptosis and immunohistochemistry was used to quantitatively analyze the PPAR-α, TNF-α and NF-κB antigens in the infarcted and non-infarcted myocardium. MI-related mortality was higher in SI4 than in EI4 (25% vs 12%), without a difference in MI size. SI4 exhibited a lower shortening fraction than EI4 did (24% vs 35%) and a higher apoptosis/area rate (3.97±0.61 vs 1.90±1.82) in infarcted areas (both p=0.001). Immunohistochemistry also revealed higher TNF-α levels in SI1 than in EI1 (9.59 vs 4.09, p<0.001) in infarcted areas. In non-infarcted areas, EI4 showed higher levels of TNF-α and positive correlations between PPAR-α and NF-κB (r=0.75, p=0.02), in contrast to SI4 (r=0.05, p=0.87). CONCLUSION: Previously exercised animals had better long-term ventricular function post-MI, in addition to lower levels of local inflammatory markers and less myocardial apoptosis, which seemed to be related to the presence of PPAR-α.

OBJETIVO: Realizar um modelo experimental de obstrução do ducto biliar que permita uma observação controlada das fases aguda e subaguda da colestase. MÉTODOS: Submeteram-se camundongos BALB/c, adultos, machos, a ligadura do ducto biliar (22 animais) ou a cirurgia-controle (10 animais). Quinze dias após a cirurgia, ou imediatamente após a morte do animal, foram observados os achados macroscópicos e realizado o estudo histológico do fígado, árvore biliar e pâncreas (haematoxylina-eosina e tricrômico de Masson). RESULTADOS: Vinte e quatro horas após cirurgia, todos os animais do grupo ligadura do ducto biliar apresentaram estado progressivo de mal estar. Todos apresentaram icterícia no peritônio parietal e visceral, fígado aumentado e congesto, dilatação acentuada da vesícula biliar e do ducto biliar comum. Os achados microscópicos incluíram: marcada dilatação e proliferação dos ductos biliares com acentuada deposição de colágeno, áreas freqüentes de necrose isquêmica de hepatócitos, microabcessos hepáticos e colangite purulenta. Animais do grupo cirurgia-controle não apresentaram alterações macro ou microscópicas. CONCLUSÃO: Este estudo conseguiu estabelecer um modelo experimental de indução de colestase, possibilitando a observação das lesões teciduais agudas e subagudas. Nossos resultados apontaram a necrose isquêmica dos hepatócitos como um importante fator contribuinte para o distúrbio hepático na colestase, sugerindo uma participação da isquemia funcional na lesão do tecido. Esse estudo também sugere o quadro infeccioso como causa determinante de morte.

OBJECTIVE: To establish a murine experimental model of bile duct obstruction that would enable controlled observations of the acute and subacute phases of cholestasis. METHODOLOGY: Adult male isogenic BALB/c mice underwent a bile duct ligation (22 animals) or a sham operation (10 animals). Fifteen days after surgery, or immediately after the animal's death, macroscopic findings were noted and histological study of the liver, biliary tree, and pancreas was performed (hematoxylin-eosin and Masson trichromic staining). RESULTS: Beginning 24 hours after surgery, all animals from the bile duct ligation group presented progressive generalized malaise. All animals presented jaundice in the parietal and visceral peritoneum, turgid and enlarged liver, and accentuated dilatation of gallbladder and common bile duct. Microscopic findings included marked dilatation and proliferation of bile ducts with accentuated collagen deposits, frequent areas of ischemic necrosis, hepatic microabscesses, and purulent cholangitis. Animals from the sham operation group presented no alterations. CONCLUSION: We established a murine experimental model of induced cholestasis, which made it possible to study acute and subacute tissue lesions. Our data suggests that in cholestasis, hepatic functional ischemia plays an important role in inducing hepatic lesions, and it also suggests that the infectious process is an important factor in morbidity and mortality.