Impact of desiccation pre-exposure on deltamethrin-induced oxidative stress in Bombina variegata juveniles.

Abstract

Global warming represents a severe threat to existing ecosystems, especially for anuran tadpoles who encounter significant fluctuations in their habitats. Decreasing water levels in permanent and temporary water bodies is a significant risk for larval survival or fitness. On the other hand, the natural environment of amphibians is extremely polluted by various xenobiotics. This study evaluated how pre-exposure of Bombina variegata tadpoles to chronic environmental stress (desiccation) modulates the biochemical response of juvenile individuals to following acute chemical stressor (pesticide deltamethrin). Our results demonstrated that individually applied pesticide changed the thiol and lipid status of the treated juveniles but animals subjected solely to desiccation pressure were more tolerant to free radicals and showed no induction of lipid peroxidation. Comparison of juveniles exposed to deltamethrin revealed that desiccation pretreatment during the larval stage of development modified cellular protection in the juveniles. Higher activities of CAT, GSH-Px and GR were recorded in the pre-exposed group, as well as a lower degree of lipid peroxidation relative to the group that was not pre-exposed to low water stress. Pre-desiccated groups displayed the greatest range of coordination of investigated antioxidant parameters, supported by Pearson's correlations. Activation of the GSH-redox system is a significant marker in juveniles against stress caused by desiccation and a chemical stressor. The stressful environment experienced during tadpole development produced an adaptive reaction to subsequent exposure to another stressor in juveniles. To develop relevant management and conservation strategies, more studies of the interactive effects of environmental and chemical stressors are necessary.