Avaliação da atividade anti-helmíntica de extratos brutos de plantas da Floresta Amazônica e Mata Atlântica brasileira sobre Haemonchus contortus

No mundo todo, as verminoses são causa de considerável prejuízo econômico na criação de ovinos. As perdas estão relacionadas ao retardo na produção, custos com tratamentos profiláticos e, em casos extremos, à morte dos animais. O objetivo deste trabalho foi verificar a ação anti-helmíntica de extratos vegetais sobre nematoides como alternativa terapêutica no tratamento da verminose em ovinos. Extratos orgânicos e aquosos foram obtidos de plantas nativas da Floresta Amazônica e Mata Atlântica, e foram testados na concentração de 100µg/mL em ensaios de toxicidade in vitro contra ovos de Haemonchus contortus e de 200µg/mL contra suas larvas. Na concentração estabelecida, apresentaram significante atividade relacionada à inibição de eclosão de ovos; em particular, o extrato orgânico de folhas e frutos de Trichilia sp. e o extrato aquoso dos órgãos aéreos de Phyllanthus attenuatus. Os resultados in vitro sugerem que extratos aquosos e orgânicos dessas plantas podem oferecer novas alternativas de controle da verminose em ovinos a partir de produtos naturais

Shock Induction by Arterial Hypoperfusion of the Gut Involves Synergistic Interactions between the Peripheral Enkephalin and Nitric Oxide Systems

To determine whether critical splanchnic artery hypoperfusion can provoke systemic shock and to identify the roles of the peripheral opioid and nitric oxide (NO) systems in this process, various degrees of superior mesenteric artery hypoperfusion (SMA-H) were produced in anesthetized adult rabbits (n=40), and hemodynamic and metabolic indices were measured. Metabolic acidosis and irreversible hypodynamic shock occurred with SMA-H at levels representing 25–20% of mean baseline SMA blood flow. In 112 other rabbits subjected to SMA-H at 20% (SMA-H20%), we studied plasma NO and enkephalin (ENK) levels, cardiovascular reactivity to selected physiological agonists, effects of ENKs on plasma NO levels, and effects of peripheral opioid receptor blockade and inducible NO synthase (iNOS) inhibition. SMA-H20% progressively increased systemic blood levels of NO and ENKs. Exogenous ENK administration accentuated SMA-H20%-induced increases in plasma NO levels, and their cardiovascular depressing effects were significantly greater when they were administered during SMA-H20% (vs. administration under baseline conditions). Selective blockade of cardiovascular δ-opioid receptors improved hemodynamics, prevented shock irreversibility and reduced plasma NO levels; similar effects were obtained by selective iNOS inhibition. These findings demonstrate that critical arterial hypoperfusion of the gut can induce hypodynamic systemic shock through ENK-induced hyperactivation of cardiovascular δ-opioid receptors, which leads to increased plasma levels of NO related in part to increased iNOS activity. Since pronounced splanchnic artery hypoperfusion occurs in all advanced systemic shock states, selective δ-opioid receptor antagonists and/or iNOS inhibitors may prove to be useful in improving shock hemodynamics and metabolic derangements and/or preventing progression toward irreversibility