RESUMO
Stingless bees are important pollinators for various plant crops. We investigated the susceptibility of Tetragonisca fiebrigito sublethal concentrations of insecticides fipronil, malathion, and thiamethoxam (administered through contact and ingestion) by determining the LC50values after 24hoursof exposure and analyzing changes in the activity of esterase isoenzymes and the chromatin in brain cells. The LC50values showed that all three insecticides were highly toxic through contact and ingestion. Electrophoretic analysis revealed that the relative EST-4 (carboxylesterase) activity in T. fiebrigi was partially inhibited by malathion and fipronil ingestion. Moreover, the EST-4 band intensity was increased following high-concentration thiamethoxam (contact) exposure, indicating the increased relative activity of this isoenzyme to detoxify the compound. In the cytochemical analysis of brain cells, the critical electrolyte concentration (CEC) points for the control stingless bees and malathion ingestion-exposed and thiamethoxam-exposed (contact and ingestion) stingless bees were in the range of 0.20-0.30 M MgCl2, whereas that for malathion contact-exposed bees was 0.15 M MgCl2, indicating chromatin relaxation and suggesting an increase in gene expression. In conclusion, T. fiebrigistingless bees are susceptible to the insecticides tested, and the parameters analyzed may be used as biomarkers to detect the presence of these compounds.(AU)
Assuntos
Animais , Abelhas , Expressão Gênica , Tiametoxam/toxicidade , Malation/toxicidade , Biomarcadores , Inseticidas/toxicidadeRESUMO
PURPOSE: The incidences of obesity and related diseases have reached epidemic proportions, and new therapeutic approaches are needed. Soy isoflavones have been identified as an important dietary factor for preventing and treating metabolic dysfunction. This study examined the effects of high doses of isoflavone on glucose and fat metabolism in a model of programmed obesity and evaluated its effects on the autonomic nervous system. METHODS: Litters of Wistar rats were standardized at nine pups per dam in normal litters (NL) or reduced to three pups per dam at the third day of life (P3) in small litters (SL) to induce postnatal overfeeding. Gavage with a soy bean isoflavone mixture (1â g/day) diluted in water was started at P60 and continued for 30 days. The control animals received vehicle gavage. At P90, biometric and metabolic parameters as well as direct autonomic nerve activity were measured. RESULTS: Increases in glycaemia and insulinaemia observed in SL rats were reduced by isoflavone treatment, which also caused lower glucose-induced insulin secretion by pancreatic islets. Sympathetic activity in the major splanchnic nerve was increased, while vagus nerve activity was reduced by isoflavone treatment. The dyslipidaemia induced by overfeeding in SL rats was restored by isoflavone treatment. CONCLUSION: The present study shows that treatment with isoflavone reduces adiposity and improves glucose and lipid metabolism. Collectively, these effects may depend on autonomic changes.