RESUMO
The objective of this study was to investigate the effect of ascorbic acid (AA) on the in vitro cytotoxicity of cypermethrin (CM), and on glutathione (GSH) metabolism in rat hepatocytes. In vitro cell viability, lactate dehydrogenase (LDH), alanine aminotransferase (ALT) and aspartate aminotransferase (AST) leakage were measured, as indicators of hepatic damage, at 1, 15 and 30 min of exposure to CM. Glutathione and the activities of glutathione-S-transferase (GST) and gamma glutamyl transpeptidase (gamma-GT) were also measured. CM hepatotoxicity increased in a time and dose-dependent manner. In the presence of 30 microM CM, ALT and AST also increased 49 and 130% (P < 0.05), respectively, indicating metabolic hepatocyte damage. AA (1 mM) was capable to preserve 100% of cell integrity and modulated ALT and AST. Furthermore, CM induced a 27% reduction in the endogenous antioxidant GSH, and increased 203% GST and 283% gamma-GT (P < 0.05), indicating an oxidative insult. The presence of AA showed chemopreventive capacity against CM, recovering 60% of GSH and a 54% decrease in gamma-GT activity. These results suggest that AA in a 1:33 (CM:AA) ratio can modulate up to 90% of the damage caused to the cells by CM. It also demonstrates that AA can act as a primary antioxidant and hepatoprotector in rat hepatocytes.
Assuntos
Ácido Ascórbico/farmacologia , Sobrevivência Celular/efeitos dos fármacos , Piretrinas/efeitos adversos , Alanina Transaminase/antagonistas & inibidores , Alanina Transaminase/metabolismo , Animais , Ácido Ascórbico/fisiologia , Aspartato Aminotransferases/antagonistas & inibidores , Aspartato Aminotransferases/metabolismo , Sobrevivência Celular/fisiologia , Dimetil Sulfóxido/farmacologia , Relação Dose-Resposta a Droga , Quimioterapia Combinada , Glutationa/antagonistas & inibidores , Glutationa/efeitos dos fármacos , Glutationa/fisiologia , Glutationa Transferase/antagonistas & inibidores , Glutationa Transferase/fisiologia , Hepatócitos/efeitos dos fármacos , Hepatócitos/enzimologia , Hepatócitos/metabolismo , L-Lactato Desidrogenase , Fígado/citologia , Fígado/efeitos dos fármacos , Masculino , Perfusão , Piretrinas/antagonistas & inibidores , Piretrinas/farmacocinética , Ratos , Ratos Wistar , Fatores de Tempo , gama-Glutamiltransferase/metabolismoRESUMO
Se estudiaron las tablas de vida en condiciones de laboratorio de 3 cepas de Culex quinquefasciatus: Slab, susceptible de referencia; Habana Vieja, presionada con cipermetrina hasta su cuarta generación; y Cotorro, procedente del terreno. Se encontró que los diferentes niveles de resistencia a insecticidas organofosforados y piretroides presentes en las cepas Cotorro y Habana Vieja no influyeron en la duración del período de desarrollo de los estadios inmaduros ni en la proporción sexual de los adultos emergidos, y ejercieron un efecto favorable y directamente proporcional sobre la supervivencia y longevidad de los adultos. Sin embargo, influyó de manera negativa e inversamente proporcional sobre la reproducción y el crecimiento poblacional de estas cepas. Se proporcionan datos de utilidad para el uso y manejo de insecticidas dentro de las estrategias de control de Culex quinquefasciatus, importante vector de la filariasis linfática.
The life tables of 3 strains of Culex quinquefasciatus were studied under laboratory conditions: Slab, susceptible to reference; Old Havana, treated with cypermethrin until its fourth generation; and Cotorro, from the field. It was found that the different levels of resistance to organophosphate insecticides and pyrethroids present in the Cotorro and Old Havana strains did not influence either on the duration of the period of development of the inmature stages or in the sexual proportion of the emerged adults, but they had a favorable and directly porportional effect on the survival and longevity of the adults. However, they exerted a negative and inversely proportional influence on the reproduction and population growth of these strains. Useful data for the use and management of insecticides within the strategics of control of Culex quinquefasciatus, an important vector of lymphatic filariasis, are provided.
Assuntos
Animais , Feminino , Masculino , Culex , Insetos Vetores , Inseticidas/antagonistas & inibidores , Compostos Organofosforados , Piretrinas/antagonistas & inibidores , Resistência a Inseticidas , Larva , Crescimento Demográfico , ReproduçãoRESUMO
Se seleccionó una cepa de campo de Culex quinquefasciatus resistente al insecticida piretroide lambdacialotrina, con el objetivo de poder utilizarla como cepa de referencia en el laboratorio, en los estudios de bioquímica y genética de la resistencia; evaluar la utilidad de este insectivida para el control de mosquitos en Cuba y determinar la resistencia cruzada a insectividas organofosforados, piretroides y un carbamato. Se obtuvo una alta resistencia a lambdacialotrina después de 6 generaciones de presión de selección. Se observó baja o ninguna resistencia cruzada a otros piretroides (deltametrina y cipermetrina), a un carbamato (propoxur) y a los insecticidas organofosforados (clorpirifos y metil-pirimifos); sin embargo, se observó una alta resistencia cruzada a malatión (organofosforado).
A field strain of Culex quinquefasciatus resistant to pyrethroid lambda-cyhalothrin insecticide was selected to be used as a reference strain in the laboratory for conducting studies of biochemistry and genetics of resistance, to evaluate the utility of this insecticide for the control of mosquitoes in Cuba, and to determine the cross resistance to organophosphate insecticides, pyrethroids and a carbamate. A hig resistance to lambdacyhalothrin was obtained after 6 generations of selective pressure. Lowe or no cross resistance to other pyrethroids (deltamethrin and cyper-methrin), to a carbamate (propoxur) and to the organophosphate insecticides (clorpirifos and methyl-pyrimifos) was observed. A high cross resistance to malathion (organophosphate) was detected.
Assuntos
Animais , Culex , Inseticidas/antagonistas & inibidores , Compostos Organofosforados , Piretrinas/antagonistas & inibidores , Seleção Genética , Bioensaio/métodos , Bioensaio/estatística & dados numéricos , Cuba , Culex/genética , Resistência a Inseticidas/genética , Larva/genética , NitrilasRESUMO
A field strain of Culex quinquefasciatus resistant to pyrethroid lambda-cyhalothrin insecticide was selected to be used as a reference strain in the laboratory for conducting studies of biochemistry and genetics of resistance, to evaluate the utility of this insecticide for the control of mosquitoes in Cuba, and to determine the cross resistance to organophosphate insecticides, pyrethroids and a carbamate. A high resistance to lambdacyhalothrin was obtained after 6 generations of selective pressure. Lowe or no cross resistance to other pyrethroids (deltamethrin and cypermethrin), to a carbamate (propoxur) and to the organophosphate insecticides (clorpirifos and methyl-pyrimifos) was observed. A high cross resistance to malathion (organophosphate) was detected.
Assuntos
Culex , Inseticidas/antagonistas & inibidores , Compostos Organofosforados , Piretrinas/antagonistas & inibidores , Seleção Genética , Animais , Bioensaio/métodos , Bioensaio/estatística & dados numéricos , Cuba , Culex/genética , Resistência a Inseticidas/genética , Larva/genética , NitrilasRESUMO
The life tables of 3 strains of Culex quinquefasciatus were studied under laboratory conditions: Slab, susceptible to reference; Old Havana, treated with cypermethrin until its fourth generation; and Cotorro, from the field. It was found that the different levels of resistance to organophosphate insecticides and pyrethroids present in the Cotorro and Old Havana strains did not influence either on the duration of the period of development of the immature stages or in the sexual proportion of the emerged adults, but they had a favorable and directly proportional effect on the survival and longevity of the adults. However, they exerted a negative and inversely proportional influence on the reproduction and population growth of these strains. Useful data for the use and management of insecticides within the strategies of control of Culex quinquefasciatus, an important vector of lymphatic filariasis, are provided.
Assuntos
Culex , Insetos Vetores , Inseticidas/antagonistas & inibidores , Compostos Organofosforados , Piretrinas/antagonistas & inibidores , Animais , Feminino , Resistência a Inseticidas , Larva , Masculino , Crescimento Demográfico , ReproduçãoRESUMO
The resistance change to different insecticides in Culex quinquesfasciatus strain select at the laboratory with doses of pyrethroid lambdacyhalothrin that would cause a larva mortality of 90% were studied. It was attained an increase of the resistance to this insecticide of 144.5 times compared with the original level, and it was obtained a resistant strain (287x). There was an increase of the levels of resistance to methyl-pyrimifos (2.4 times), propoxur (6 times), DDT (5.2 times), clorpirifos (22 time), cypermethrin (67.5 times), and deltamethrin (20.2 times). The frequencies of the genes that codify for the elevated esterases enzymes and for the modified acetylcholinesterase reached their maximum value. Significant changes were observed in the phenotypes for esterases in the electrophoresis in polyacrylamide gels. It was detected synergism of DEF and PB with lambdacyhalothrin. Therefore, the elevated esterases and the esterases of multiple function may contribute to resistance.
Assuntos
Culex , Inseticidas/antagonistas & inibidores , Piretrinas/antagonistas & inibidores , Seleção Genética , Acetilcolinesterase/genética , Animais , Culex/enzimologia , Culex/genética , Sinergismo Farmacológico , Frequência do Gene , Resistência a Inseticidas/genética , Larva , Dose Letal Mediana , Nitrilas , FenótipoRESUMO
The mechanisms of resistance in Culex quinquefasciatus from 6 municipalities of Havana City were studied in order to determine their genetic frequency. Increased esterases and altered acetylcholinesterase are still being the major resistance mechanisms in Havana City. The mechanisms of esterases is of high frequency, followed by altered acetylcholinestenase. Resistance to cholorpirifos was found for the first time in Culex quinquefasciatus, while resistance of malathion and carbamate propoxur is maintained, and deterioration to pyrethroid susceptibility is being detected. The synergistic effect of S.S.S. trubutyl phosphotritiade (DEF) and piperonil butoxide (PB) was analysed, and it was proven that esterases enzymes and multifunction oxidases are involved in the resistance to pyrethroids. By electrophoresis in polyerylamide gel, it was determined that the combination of esterases that seems to be associated with the resistance to perythroids is B1-A6-B6, which appeared with the greatest percentage. Valves of genetic frequency in the 6 municipalities were found to be high, for both esterase genes and acetylcholinesterase genes (Ache).