Protective actions of quercetin in manganese-induced neurotoxicity; behavioral, neurostructural, and neurochemical evaluations

Abstract

BACKGROUND AND AIM: Excessive exposure to manganese (Mn) alters neuronal structure and functions. This leads to manganism, a neurological syndrome similar but not identical to Parkinson’s disease. Therapeutic interventions for this Parkinsonian syndrome have been largely unsuccessful due to little knowledge on mechanism of manganese induced brain damage. Oxidative stress is implicated as one mechanism of Mn induced neurotoxicity. Here, we investigated the effects of quercetin, a potent antioxidant obtained from fruits and vegetables on Mn induced neurotoxicity.

METHODOLOGY: Adult male rats were exposed to either Mn only or Mn co-administered with 5 or 10 mg/kg of quercetin, while Control rats were treated with normal saline. All treatments were via intraperitoneal injections for 5 weeks. After treatments, behavioral assessments were performed. Following which, rats were sacrificed, brain excised for microanatomical analysis and biochemical quantification of oxidative stress markers.

RESULTS: Cognitive and locomotor associated behaviors were significantly impaired in Mn only treatment, however quercetin co-administration attenuated only cognitive behavior. Mn treatment induced degenerative changes in brain neurons, accompanied by astrogliosis (abnormal increase in astrocyte population). Co-administration with quercetin reduced these microstructural deficits. Additionally, quercetin co-treatment reduced oxidative stress imposed on brain tissues in Mn only treatment.

CONCLUSION: These results suggest that the dietary antioxidant quercetin may attenuate structural and behavioral anomalies associated with Mn overexposure, probably due to its ability to resist oxidative stress.