Testing procedures for the determination of several biomarkers in different species, for environmental assessment of pollution.

Antioxidant defences are the primary mechanisms by which organisms compensate oxidative damage caused by contact with several types of substances prone to establish oxidative cycles. Biomarkers are one of the most useful tools to assess effects consequent to environmental exposure to a large number of xenobiotics. However, the use of biomarkers requires previous standardization of enzymatic protocols in order to guarantee accuracy and relevance of obtained results. This article describes standardized conditions for the use of several enzymatic biomarkers (oxidative stress: glutathione peroxidase, lipid peroxidation, glutathione reductase, glutathione-S-transferase and catalase; respiration: lactate dehydrogenase) for the evaluation of responses of specimens of Eisenia andrei, Pelophylax perezi (formerly Rana perezi) and Apodemus sylvaticus. Furthermore, we also present the normal values of activity for the given markers, for non-exposed organisms, that can serve as comparative indexes for subsequent studies. We conclude that these species are thus a suitable target to serve as sentinels in studies of environmental contamination by chemicals, which can lead to oxidative and physiological modifications.