Histopathology of Endocrine Organs of Miranda's White-Lipped Frogs (Leptodactylus macrosternum) from Cultivated and Non-Cultivated Regions in Semi-Arid Northeastern Brazil

Abstract

Endocrine disruption defines the influence of environmental contaminants on the control of behaviour, growth and reproduction of free-living species. Amphibians are considered as bioindicators of environmental balance in aquatic and terrestrial systems and of physiological and immunological sensitivity to environmental stressors. In the Caatinga Domain of northeastern Brazil, the Lower Jaguaribe River (LJR) region is outstanding for the conservation of anurans and has considerable species diversity. However, the use of pesticides and chemical fertilisers is of increasing concern because of consequent risks to environmental, human and animal health. Miranda's white-lipped frogs (Leptodactylus macrosternum) are abundant and well-adapted in this region and, therefore, are considered to be a suitable bioindicator. The objective of this work was to evaluate the morphology of endocrine organs of this species for evidence of potential impacts of agrosystems. We found significantly smaller females and parathyroid cytolysis in frogs collected from cultivated areas, compared with those from non-cultivated regions. Interrenal degeneration was found in both sample populations. Chemical analysis detected pesticides and potentially toxic elements in tissues of Miranda's white-lipped frog tissues from the LJR region (data not shown). These findings suggest that the parathyroid gland acts as a biomarker of environmental toxicity in cultivated areas in the LJR region. In this study, the other examined endocrine organs did not show significant potential for use in biomonitoring the impact of toxic chemicals.