Locus coeruleus: A brain region exhibiting neuronal alterations in Parkinson’s disease rat model

Toxic insults lead to increased α-synuclein expression in dopaminergic neurons. However, little information is known about α-synuclein alterations in relation to tyrosine hydroxylase (TH) changes in locus coeruleus (LC) of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) rat model for Parkinson’s disease (PD). Four injections (15 mg/kg each) of the neurotoxicant MPTP to rats led to an upregulation of α-synuclein level and increased immunoreactivity with aggregated protein in the MPTP-treated group as revealed by Western blotting and immunohistochemical techniques. Meanwhile, MPTP reduced the level of and caused immunoreactivity toward TH antibody in LC and adjoining noradrenergic neurons. These data indicate that MPTP can induce α-synuclein alterations in other brain regions that have been implicated in the pathogenesis of PD. The findings are also consistent with a pattern that α-synuclein modification influences the TH level.