LAUSR

BACKGROUND Lead-induced neurotoxicity was marked with Locomotor and parkinsonian-like changes. Oligodendrocytes and synucleinopathy were signed to in the pathophysiology of some neurodegenerative diseases. Vitamin D3's (D3) role in substantia nigra pars compacta (SNpc) disorders is debated between neuroscientists. The aim of the study was to investigate lead-induced SNpc neurotoxic changes and explore the possible neuroprotective role of D3 and the possible involvement of oligodendrocytes and α synuclein. MATERIAL AND METHODS This study included 40 adult Wistar rats assigned into four equal groups: control, Pb (in drinking water, 1,000 mg/L), Pb + D3 (D3 injection, 1,000 IU/kg IM; 3 days/week), and D3. After eight weeks, the rats were sacrificed, and their midbrain underwent biochemical and immunoblotting analysis. Midbrain paraffin blocks were stained for histological and immunohistochemical assessment. RESULTS Pb had increased significantly (p < 0.05) nigral α-synuclein and caspase-11 by immunoblotting analysis. Histologically, it induced neurodegeneration in SNpc and significantly decreased neuronal cell density by cresyl violet staining. Pb also significantly reduced SNpc tyrosine hydroxylase (TH) immunoreaction, significantly elevated glial fibrillatory acid protein (GFAP) & α-synuclein immunoreaction associated with a mild but significant increase in caspase-3. In the Pb + D3 group, all the previous deleterious changes were significantly alleviated in addition to significant upregulation of anti-oligodendrocytes (Olig- 2) immunoexpression. CONCLUSIONS Pb may induce SNpc neurotoxicity presumably via activation of caspase-11 and α-synuclein. D3 may modulate this neurotoxicity probably through an oligodendrogenic effect.