Involvement of striatal lipid peroxidation and inhibition of calcium influx into brain slices in neurobehavioral alterations in a rat model of short-term oral exposure to manganese

Manganese is an essential element for biological systems, nevertheless occupational exposure to high levels of Mn can lead to neurodegenerative disorder, characterized by excessive Mn accumulation, especially in astrocytes of basal ganglia and symptoms closely resembling idiopathic Parkinson's disease (PD). The purpose of this study was to evaluate behavioral and biochemical alterations in adult rats exposed for 30 days to 10 and 25 mg/mL of MnCl₂ in their drinking water. MnCl₂ intoxicated rats showed impaired locomotor activity in comparison to control animals. Furthermore, lipid peroxidation were increased, δ-aminolevulinate dehydratase (δ-ALA-D, an enzyme sensitive to pro-oxidant situations) activity was inhibited and ⁴⁵Ca²⁺ influx into striatal slices was decreased in rats exposed to 25 mg/mL of Mn, indicating that this brain region was markedly affected by short-term Mn exposure. In contrast, Mn exposure was not associated with characteristic extrapyramidal effects and did not modify protein oxidation, suggesting that the striatal damage represents early stages of Mn-induced damage. In addition, treatment with Mn was associated with reduced body weight gain, but there were no discernible alterations in liver and kidney function. In conclusion, Mn caused increased oxidative stress and decreased ⁴⁵Ca²⁺ influx into the striatum, which are likely linked to impaired locomotor activity, but not with the occurrence of orofacial dyskinesia.