Gallic and ascorbic acids supplementation alleviate cognitive deficits and neuropathological damage exerted by cadmium chloride in Wistar rats

Abstract

Cadmium is a highly neurotoxic heavy metal that interferes with DNA repair mechanisms via generation of reactive oxygen species. The potentials of polyphenols and antioxidants as effective protective agents following heavy metal-induced neurotoxicity are emerging. We therefore explored the neuroprotective potentials of gallic and ascorbic acids in CdCl2-induced neurotoxicity. Seventy-two Wistar rats were divided into six groups. Group A received distilled water, B: 3 mg/kg CdCl2, C: 3 mg/kg CdCl2 + 20 mg/kg gallic acid (GA), D: 3 mg/kg CdCl2 + 10 mg/kg ascorbic acid (AA), E: 20 mg/kg GA and F: 10 mg/kg AA orally for 21 days. Depression, anxiety, locomotion, learning and memory were assessed using a battery of tests. Neuronal structure and myelin expression were assessed with histological staining and immunofluorescence. The Morris Water Maze test revealed significant increase in escape latency in CdCl2 group relative to rats concurrently treated with GA or AA. Similarly, time spent in the target quadrant was reduced significantly in CdCl2 group relative to other groups. Concomitant administration of gallic acid led to significant reduction in the durations of immobility and freezing that were elevated in CdCl2 group during forced swim and open field tests respectively. Furthermore, GA and AA restored myelin integrity and neuronal loss observed in the CdCl2 group. We conclude that gallic and ascorbic acids enhance learning and memory, decrease anxiety and depressive-like behavior in CdCl2-induced neurotoxicity with accompanying myelin-protective ability.