Glutathione reductase and catalase in toad embryogenesis: pesticide and polyamine interaction

VENTURINO A; ANGUIANO O.L; PECHEN DE D'ANGELO A.M

San Carlos de Bariloche

Congreso; XXXIX Reunión Anual de la SAIB; 2003

SAIB

We have demonstrated the relevance of glutathione (GSH) joined to GSH transferase induction in organophosphate (OP) detoxification for protection and response against ellular damage in aquatic species. Polyamines (PAs) potentiate OP toxicity in toad embryogenesis competing for GSH pool. We evaluate here GSH reductase (GR) and catalase (Cat) profiles in the embryonic development of  Bufo arenarum and their alteration by OP and PA exposures. Cat activity was high and constant through embryogenesis (100 IU mg protein-1). Azinphos methyl elicited a biphasic effect, first inhibiting (20%) and then inducing Cat at last stages (30%), which was also observed for malathion. Larval stages showed up to 50% inhibition by OPs. Spermine inhibited Cat at middle development, while spermidine inhibited it in larvae. GR activity continuously increased along development (7 mIU mg protein -1). Azinphos methyl caused early inhibition of GR (60%), followed by Malathion (45%). Spermine inhibited GR up to 70% in caudal  circulation stages. Effects on exposed larvae were not significant. GR inhibition by spermine and spermidine may contribute to the described redox shift to GSSG during PA degradation and consequently to oxidative stress derived from GSH depletion. Although lipid peroxidation was not enhanced in our experimental system, the early inhibition of Cat might be related to oxygen radical attack, while a compensatory induction would be elicited as response to alleviate oxidative stress.