Efeitos do herbicida clomazone sobre parâmetros metabólicos e antioxidantes em jundiá (Rhamdia quelen)

Abstract

The objective of this study was to evaluate the effect of clomazone herbicide on metabolism of silver catfish (Rhamdia quelen). It was measured levels of lactate, protein and glucose (plasma), glycogen, protein and lactate (liver and muscle), acetylcholinesterase (AChE) activity (brain and muscle), catalase activity (liver), TBARS formation (liver and brain), hematocrit and hemoglobin values, aminotransferases (AST and ALT) activities (liver and plasma) and histological analysis of hepatic tissue. Fishes were exposed to 0.5 and 1.0 mg/L of clomazone for 12, 24, 48, 96 and 192 h. These concentrations are used in rice fields. Some parameters were also assayed after 96 h and 192 h in water without herbicide (recovery periods) after 96 and 192 h of exposure. Levels of muscle glycogen and liver lactate were reduced as well as hematocrit value after experimental period. Hemoglobin content did not changed significantly. Lactate levels diminished in the muscle tissue. Liver glycogen, glucose and lactate in the plasma were enhanced after exposure to herbicide. Protein levels were enhanced in the liver and white muscle, except at last periods of exposure, while plasma protein increased from 48 to 96 h of exposure to the herbicide. Specific AChE activity decreased in brain and muscle after treatments. Catalase activity was reduced in all periods of exposure. Fishes exposed to clomazone increased TBARS production in the liver, while in the brain the fishes showed different responses with exposure period increasing. Aminotransferases activities were elevated in the plasma, while in the liver, ALT increased in the early periods only. Liver AST activity was enhanced after 12 h of exposure, and after 48 h its activity reduced significantly. Hepatic histological analysis presented hepatocyte vacuolation after 192 h of exposure to herbicide concentration of 1.0 mg/L. However, in recovery period of 192 h, hepatocyte vacuolation was observed in both clomazone concentration tested. Most of the metabolic disorders did not persist after recovery period, except to liver AST and ALT activities. The present work shows that clomazone concentrations used in rice fields can cause changes in metabolic state of the fish, which are of moderate intensity and generally reversible.