A complex morphofunctional approach for zinc toxicity evaluation in rats

Anthropogenic activity causes the introduction of zinc compounds into the biological cycle in mining and processing sites and its accumulation in organs and tissues, causing systemic toxicity. A cumulative effect of zinc is predominantly neurotoxic and it also affects the respiratory, cardiovascular and digestive systems. This study evaluates the effects of single-dose intragastric administration of 100 mg/kg zinc succinate on the structure and function of organs and tissues in male Wistar rats 1 month after treatment. The presented morphofunctional approach for the toxicity evaluation included the study of behavioral responses using the automated Laboras® complex, fluorescent spectral analysis of the NADH and FAD activity and histological evaluation of animal organs and tissues. The results of the behavioral activity assessment showed a significant decrease in animals' motor activity, whereas the fluorescence spectra analysis demonstrated a decrease in coenzyme NADH without the reduction of FAD levels. We detected toxic and dystrophic changes in the cerebral cortex, heart, lungs and liver tissues. Our original multiparametric approach enables a comprehensive assessment of the long-term toxic effects of the metal salts such as zinc succinate, especially in the cerebral cortex at the doses much lower than the acute LD₅₀ reported for the common zinc salts.