AP-1 regulation by exposure to sublethal doses of chlorpyrifos in Bufo arenarum embryos

VERÓNICA SOTOMAYOR; ANDRÉS VENTURINO; ANA FERRARI; ANA M. PECHÉN DE D'ANGELO

Rosario, Santa Fé, Argentina

Congreso; XLII Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB); 2006

SAIB

There is a concern about the effects elicited by some organophosphates (OP) like chlorpyrifos (Cpf) at doses below the recognized anticholinesterase effects. We have beenstudying the adverse effects of several OP at sublethal doses causing oxidative stress in B. arenarum embryos. Here we show the effects of sublethal exposure to Cpf on the expression and function of c-Fos and c-Jun. Western blot analyses of c-Fos showed a decrease when embryos were exposed to 2 mg/L Cpf for 24 h and 48 h, while it increased at 96 h. On the other hand, C-jun showed an increase after 96 h of exposure at the same concentration. Cpf also reduced AP-1 binding (EMSA), at 48 h of exposure. Acetylcholinesterase activity was not affected by 2 mg/L Cpf. Elevation of c-Fos through a non-cholinergic mechanism by Cpf exposure has been reported in other systems, followed by apoptosis. However we could not see any sign of DNA fragmentation by agarose gel electrophoresis in B. arenarum embryos treated with 2 mg/L Cpf. Cpf tended to lower catalase and GSH-S-transferase and increase GSH-reductase activities suggesting a response to oxidative stress. Thus, AP-1 downregulation may be reflecting other mechanisms shared by c-Jun, such as Antioxidant Response Element binding.