Biochemical alterations iduced by azynphosmethyl and carbaryl in Rhinella arenarum larvae

FERRARI A; LASCANO C; VENTURINO A

San Miguel de Tucumán

Congreso; 45 Reunión Anual de la SAIB; 2009

SAIB

Organophosphate (OP) and carbamate pesticides act by inhibiting cholinesterase (ChE). In addition, these compounds are capable to induce oxidative stress and alter antioxidant enzymes. We analyze the effect of  carbaryl (CB) and the OP azinphosmethyl (AM) on reduced glutathione (GSH) levels and enzymatic activities of ChE, carboxylesterases (CarbE), catalase (CAT), GSH peroxidase (GPx), GSH reductase (GR), GSH transferase (GST), PKC and PKA of <i>Rinella arearum</i> larvae. The larvae (stage 25) were exposed 48 h to 3-6mg/L AZ or 10-20 mg/L CB. Enzyme activities and GSH were determined spectrophotometrically. PKC and PKA activities were measured with 32PãATP and histone. ChE and CarbE were significantly inhibited by CB (78%, 64%) and AM (33%, 44%). Both pesticides increased GST (39%) and GR (72%-93%), while GSH levels and GPx were not significantly affected. CAT was significantly inhibited by 10 mg/L Cb (48%); while the other treatments inhibited it 20%. PKC and PKA activities showed a tendency to increase in larvae exposure to pesticides, differing with the response observed in early embryos in our previous works. Beside the strong inhibition of esterases as classical targets, both pesticides affect antioxidant enzymes in a differential way. Larvae show an adaptive response increasing GST and GR enzymes, tuning the antioxidant response to a GSH-dependent pathway, while CAT may be directly downregulated by the reactive Oxygen species.