Increase of secondary processes of microglial and astroglial cells after MPTP-induced degeneration in substantia nigra pars compacta of non human primates.

Nigral dopaminergic areas from Parkinsonian patients show an increase of reactive astrocytes and active microglia. The reaction of these two cell types is a clear evidence of inflammatory response associated with dopaminergic cell loss. However, the function of this glial reaction remains unclear. This histological hallmark is also reproduced in induced Parkinsonian animals such as MPTP-treated monkeys. In this work, we analyze with confocal microscopy the number of processes of microglial cells and astrocytes in the SNpc of MPTP-treated monkeys and compare with control animals. We observe that secondary branches from microglia and astrocytes increase in MPTP-treated animals, while the scaffold of primary branches does not change. These results demonstrate that glial reaction in MPTP-treated monkeys is characterized by the emission of new filaments after the dopaminergic degeneration, suggesting that glial cells may increase their scanning progress and modify their microanatomy after dopaminergic injury.