RESUMO
Aluminium is a major pollutant due to its constant disposal in aquatic environments through anthropogenic activities. The physiological effects of this metal in fish are still scarce in the literature. This study investigated the in vivo and in vitro effects of aluminium sulfate on the activity of enzymes from Nile tilapia (Oreochromis niloticus): brain acetylcholinesterase (AChE), muscle cholinesterases (AChE-like and BChE-like activities), pepsin, trypsin, chymotrypsin and amylase. Fish were in vivo exposed during 14days when the following experimental groups were assayed: control group (CG), exposure to Al2(SO4)3 at 1µg·mL-1 (G1) and 3µg·mL-1 (G3) (concentrations compatible with the use of aluminium sulfate as coagulant in water treatment). In vitro exposure was performed using animals of CG treatment. Both in vivo and in vitro exposure increased cholinesterase activity in relation to controls. The highest cholinesterase activity was observed for muscle BChE-like enzyme in G3. In contrast, the digestive enzymes showed decreased activity in both in vivo and in vitro exposures. The highest inhibitory effect was observed for pepsin activity. The inhibition of serine proteases was also quantitatively analyzed in zymograms using pixel optical densitometry as area under the peaks (AUP) and integrated density (ID). These results suggest that the inhibition of digestive enzymes in combination with activation of cholinesterases in O. niloticus is a set of biochemical effects that evidence the presence of aluminium in the aquatic environment. Moreover, these enzymatic alterations may support further studies on physiological changes in this species with implications for its neurological and digestive metabolisms.
Assuntos
Compostos de Alúmen/toxicidade , Encéfalo/efeitos dos fármacos , Ciclídeos/metabolismo , Proteínas de Peixes/metabolismo , Trato Gastrointestinal/efeitos dos fármacos , Hidrolases/metabolismo , Músculos/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Acetilcolinesterase/metabolismo , Amilases/antagonistas & inibidores , Amilases/metabolismo , Animais , Encéfalo/enzimologia , Butirilcolinesterase/metabolismo , Densitometria , Relação Dose-Resposta a Droga , Eletroforese em Gel de Poliacrilamida , Ativação Enzimática , Ativadores de Enzimas/toxicidade , Proteínas de Peixes/antagonistas & inibidores , Trato Gastrointestinal/enzimologia , Hidrolases/antagonistas & inibidores , Músculos/enzimologia , Peptídeo Hidrolases/metabolismo , Inibidores de Proteases/toxicidade , Fatores de TempoRESUMO
The aim of this study was to investigate the effects of chronically administered aluminum on erythropoiesis in rats. After treatment (i.p. injections of Al(2)(SO(4))(3), 50 micromol/kg body weight, five times a week) for 3 months, the treated (Al) group showed significantly decreased hemoglobin concentration (32%) and hematocrit (24%) compared with the control group. Serum iron decreased significantly in the Al group, whereas total iron binding capacity did not change. Treatment did not alter the activity of hepatic, renal or cerebral delta-ALA-D. Biochemical measurements related to 2-thiobarbituric acid-reactive substance (TBARS) levels from serum and hepatic, renal and cerebral homogenates also did not change after treatment. Hepatic concentrations of aluminum were higher in the Al group than in the control group. Renal and cerebral aluminum concentrations did not vary between groups. The present results indicate that exposure to aluminum sulfate promotes signs of anemia in rats as a consequence of alterations in iron status.