Macronutrients and essential amino acids on digestive process of the freshwater teleost Matrinxã

The objective of this work was to evaluate the effect of macronutrients and essential amino acids on digestive process of the freshwater teleost Matrinxã (Brycon amazonicus). Juveniles were fed with diets containing starch plus free amino acids or oil plus free amino acids for 15 days. These fish were compared with others fed with diets containing starch or oil without addition of free amino acids. After the experimental span, 12 fish from each treatment were randomly sampled to collect stomach, pyloric cecum, anterior and posterior intestine for assaying digestive enzymes activity. Increase of gastric proteolysis due to dietary amino acids were observed. Amylolytic, proteolytic and lipolytic activities in intestine sections were also positive related to dietary amino acids. However, proteolytic and lipolytic activities in pyloric cecum were not responsive to dietary changes. Moreover, the absence of starch in the diets resulted in decrease of amylolysis, and very low levels of oil did not change the lipolytic activity. In conclusion, activities of amylase, protease and lipase of Matrinxãare selectively responsive to addition of free essential amino acids concerning the gut section

Macronutrients and essential amino acids on the digestive process of the freshwater teleost matrinxã (Brycon amazonicus)

The objective of this work was to evaluate the effect of macronutrients and essential amino acids on digestive process of the freshwater teleost Matrinxã (Brycon amazonicus). Juveniles were fed with diets containing starch plus free amino acids or oil plus free amino acids for 15 days. These fish were compared with others fed with diets containing starch or oil without addition of free amino acids. After the experimental span, 12 fish from each treatment were randomly sampled to collect stomach, pyloric cecum, anterior and posterior intestine for assaying digestive enzymes activity. Increase of gastric proteolysis due to dietary amino acids were observed. Amylolytic, proteolytic and lipolytic activities in intestine sections were also positive related to dietary amino acids. However, proteolytic and lipolytic activities in pyloric cecum were not responsive to dietary changes. Moreover, the absence of starch in the diets resulted in decrease of amylolysis, and very low levels of oil did not change the lipolytic activity. In conclusion, activities of amylase, protease and lipase of Matrinxãare selectively responsive to addition of free essential amino acids concerning the gut section.The objective of this work was to evaluate the effect of macronutrients and essential amino acids on the digestive process of the freshwater teleost matrinxã (Brycon amazonicus). Juveniles were fed with diets containing starch plus free amino acids or oil plus free amino acids for 15 days. These fish were compared with others fed with diets containing starch or oil without addition of free amino acids. After the experimental span, 12 fish from each treatment were randomly sampled to collect stomach, pyloric cecum, anterior and posterior intestine for assaying digestive enzymes activity. Increase of gastric proteolysis due to dietary amino acids were observed. Amylolytic, proteolytic and lipolytic activities in intestine sections were also positive due to dietary amino acids. However, proteolytic and lipolytic activities in pyloric cecum were not responsive to dietary changes. Moreover, the absence of starch in the diets resulted in decrease of amylolysis, and very low levels of oil did not change the lipolytic activity. Based on the results of the present study, the inclusion of essential amino acids in diets for juvenile matrinxã promotes a nutrition strategy to improve digestive function

Metabolismo antioxidativo, biotransformação hepática e alterações histológicas de matrinxã (Brycon amazonicus, SPIX & AGASSIZ, 1829, CHARACIDAE) exposto ao fenol

Pollution is nowadays a problem that affects all environments, including the freshwater and the species living in there. Among them, under the ecotoxicological point of view, fish are a relevant group and the biggest among vertebrates. Phenol is an exogenous chemical usually present in concentrations higher than those allowed by law. Phenol is an organic lipophilic xenobiotic that cause toxic effects even at low concentrations and its presence in freshwater results from discharge of industrial efffluents. The aim of the present study was to determine the phenol effects 1) in the liver and red blood cells antioxidant metabolism, 2) in the liver biotransformation (phase I and II), 3) in the brain acetylcholinesterase plus recovery of 1 and 2 weeks and 4) in gills, liver and kidney, under the histopathological point of view, in matrinxã, Brycon amazonicus, a freshwater teleost from Amazon basin, which is being widely cultivated in Sao Paulo state. For such, three assays were done. Firstly, the phenol LC50 was determined for 96 hours. Second, the exposition to phenol was carried out for 96 h to determine its effects on gills, liver and kidney. At last, an experiment of exposure for 96 h, followed by recovery for one and two weeks, was carried out to determine its antioxidant effects on the liver and on the red blood cell metabolism (vitamin C, SOD, CAT, GPx, GSH and G6PDH); on two liver biotransformation phase I (EROD and ECOD) and phase II activities (UDPGT and GST) and brain acetylcholinesterase activity. The LC50 to phenol was 17, 40 mg/L, showing that matrinxã is a very sensitive species to phenol. From this, the phenol concentration used in all experiments was 2 mg/L. Histopathology observations showed that phenol affected harder the gills than liver and kidney, causing apical and total fusion of the secondary lamella plus blood congestion and sub epithelial edema. In the liver diameter increase of the sinusoidal capillaries and blood stasis was observed. In the kidney, phenol caused an increase of the space between glomerulus and capsule. A hematocrit increase was observed in fish exposed and recovery for one week. These results, associated to gill lesions, suggested that matrinxã endured a reduction in oxygen absorption. Erythrocyte antioxidant metabolism did not suggest that matrinxã exposed to phenol was under oxidative stress. Only G6PDH activity was increased during exposure, while CAT activity was decreased in matrinxã s erythrocytes. Also, oxidative stress was not observed after recovery. The antioxidant metabolism in liver was not affected after exposure, but after recovery, as it is suggested by the increase of GPx activity after first week of recovery followed by its decrease after second week. Hepatic G6PDH also decreases after the second week. These results corroborated the hepatic biotransformation data, which was increasing in the EROD and ECOD activities. The occurrence of oxidative stress only after the recovery may be ascribed to the increase in the hepatic biotransformation enzymes of the phase I, wherein the ERO production occurs. Moreover, phenol might have an inhibitory effect on phase II enzymes after phenol exposure, as suggested by UDPGT and GST activities decreases. Phenol was capable of inhibiting UDPGT activity in vitro, an effect not observed with GST activity. An inhibition of EROD and ECOD activities should be happened after exposition. The brain AChE activity was also inhibited after phenol exposure, regaining the control values after recovery. However, the vitamin C concentration increased after exposure and recovery, while a persistent decrease was observed in the liver after exposure and recovery. These results demonstrated phenol toxicity to matrinxa and the need of limit matrinxã exposure to this xenobiotic.Financiadora de Estudos e ProjetosA poluição é hoje um problema que afeta todos os ambientes inclusive o de água doce, e conseqüentemente, os organismos que vivem nele. Entre estes, os peixes formam um grupo de grande importância sob a perspectiva ecotoxicológica, pois é o maior dentre os vertebrados. O fenol é uma substância química exógena que está usualmente em concentrações acima da permitida por lei. Este xenobiótico é um composto orgânico e lipofílico e sua presença nos corpos de água se deve principalmente aos despejos de origem industrial, podendo causar ações tóxicas mesmo em baixas concentrações. O objetivo deste trabalho foi avaliar os efeitos do fenol, 1) no metabolismo antioxidante eritrocitário e hepático, 2) na biotransformação hepática (fase I e fase II), 3) na atividade da acetilcolinesterase cerebral e na recuperação de 1 e 2 semanas, e 4) nas brânquias, fígado e rim, do ponto de vista histopatológico, em matrinxã, Brycon amazonicus, um teleósteo de água doce originário da bacia Amazônica que vem sendo amplamente cultivado no Estado de São Paulo. Foram realizados 3 ensaios; primeiro, a determinação da CL50 de 96 horas. A partir deste dado, todos os outros experimentos foram feitos utilizando-se 10% da CL50/96h, ou seja, um teste subletal. O segundo ensaio foi a exposição ao fenol por 96 horas para determinar seu efeito nas brânquias, fígado e rim. Por fim, foi feita uma exposição por 96 horas seguida da recuperação por 1 e 2 semanas para se determinar os efeitos do fenol sobre o metabolismo antioxidante (Vit C, SOD, CAT, GPX, GSH, G6PDH) eritrocitário e hepático, e a possível recuperação; a biotransformação hepática (fase I, EROD e ECOD e II, UDPGT e GST), e os efeitos sobre a atividade da acetilcolinesterase cerebral. Os resultados obtidos mostraram que o fenol apresenta uma CL50 de 17,40 mg/L, e que o matrinxã é um organismo bem sensível ao fenol. Com este dado utilizamos uma concentração de fenol de 2 mg/L durante os experimentos de exposição subletal. Os dados observados na avaliação histológica mostraram que o fenol ocasionou alterações mais intensas nas brânquias que no fígado e no rim, causando principalmente fusão apical e total da lamela secundária, com congestão sanguínea e edema subepitelial. No fígado foi possível observar um aumento no diâmetro dos capilares sinusóides e estase sanguínea, e no rim o fenol causou um aumento do espaço entre o glomérulo e a cápsula renal. No experimento de exposição ao fenol em concentração subletal posterior recuperação, verificamos um aumento nos valores de hematócrito no grupo exposto e no grupo recuperado por 1 semana. Estes dados, associados às lesões branquiais, sugerem que o matrinxã sofreu uma diminuição na absorção de oxigênio. O metabolismo antioxidante eritrocitário não sugere estresse oxidativo durante a exposição ao fenol, aumentando somente a atividade da G6PDH, durante a exposição, e queda da atividade da CAT. Também não se observou estresse oxidativo durante a recuperação. Os resultados da análise do metabolismo antioxidante no fígado mostraram que não ocorreu estresse oxidativo após a exposição ao fenol. Todavia, após a recuperação, o aumento da atividade da GPx na primeira semana de recuperação e a redução na segunda semana sugerem estresse oxidativo . Observouse também uma redução na atividade da G6PDH após a segunda semana de recuperação. Estes dados corroboram os de biotransformação hepática que mostraram um aumento da atividade de EROD e ECOD na recuperação. A ocorrência de estresse oxidativo somente na recuperação pode ter sido ocasionada pelo aumento da atividade das enzimas da biotransformação de fase I, onde pode ocorre produção de ERO. Além do mais, o fenol parece exercer um efeito inibidor de algumas enzimas após a exposição, levando à diminuição de UDPGT e GST, as quais aumentaram sua atividade na ausência de fenol. O fenol também mostrou ser um inibidor da atividade da UDPGT in vitro , o que não ocorreu para a GST. Pode ter ocorrido também a inibição de EROD e ECOD durante a exposição. No cérebro a atividade da AChE também apresentou inibição após a exposição ao fenol, retornando aos valores normais após a recuperação. Entretanto, a concentração de vitamina C aumentou durante a exposição e a recuperação no cérebro, enquanto que no fígado observou-se redução. Estes dados mostram o grau de toxicidade do fenol para o matrinxã, mesmo em dose subletal, e a necessidade de redução de seu lançamento nos corpos de água para proteção desta espécie