Inflammatory process as a determinant factor for the degeneration of substantia nigra dopaminergic neurons

The specific degeneration of dopaminergic neurons in the substantia nigra (SN) is a pathological hallmark of Parkinson's disease (PD). Although the cause of chronic nigral cell death in PD and its underlying mechanisms remain elusive, substantial involvement of inflammatory events has been postulated since inflammatory features have been described in parkinsonians CNS tissue. We have developed an animal model of dopaminergic neurons degeneration by the single intranigral injection of lipopolysaccharide (LPS), an inflammatory compound. This single injection produced the induction of inflammatory process with the activation of microglia along with the specific degeneration of dopaminergic neurons in the SN without affecting neither other neurotransmitter systems nor other structures of the CNS. Dexamethasone, a potent anti-inflammatory drug preventing many of the features characterizing pro-inflammatory glial activation, prevented the loss of dopaminergic cells. We also discuss other inductors of inflammatory process in relationship to the dopaminergic degeneration in the SN.