Neuroprotective effect of quercetin against oxidative damage and neuronal apoptosis caused by cadmium in hippocampus

The purpose of the present investigation was to evaluate cadmium (Cd)-induced neurotoxicity in hippocampal tissues and beneficial effect of quercetin (QE) against neuronal damage. A total of 30 male rats were divided into 3 groups: control, Cd-treated, and Cd + QE-treated groups. After the treatment, the animals were killed and hippocampal tissues were removed for biochemical and histopathological investigation. Cd significantly increased tissue malondialdehyde (MDA) and protein carbonyl (PC) levels and also decreased superoxide dismutase (SOD) and catalase (CAT) enzyme activities in hippocampal tissue compared with the control. Administration of QE with Cd significantly decreased the levels of MDA and PC and significantly elevated the levels of antioxidant enzymes in hippocampal tissue. In the Cd-treated group, the neurons of both tissues became extensively dark and degenerated with pyknotic nuclei. The morphology of neurons in Cd + QE group was well protected, but not as neurons of the control group. The caspase-3 immunopositivity was increased in degenerating neurons of the Cd-treated group. Treatment of QE markedly reduced the immunoreactivity of degenerating neurons. The results of the present study show that QE therapy causes morphologic improvement in neurodegeneration of hippocampus after Cd exposure in rats.