Original Article

Exp Neurobiol 2009; 18(1): 26-31

Published online June 30, 2009

© The Korean Society for Brain and Neural Sciences

Effects of 6-hydroxydopamine on the Adult Neurogenesis of Dopaminergic Neurons in the Mouse Midbrain

Tae Woo Kim, Hyun Kim and Woong Sun*

Department of Anatomy, BK21 Program, Korea University College of Medicine, Seoul 136-705, Korea

Correspondence to: *To whom correspondence should be addressed.
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Recently, restricted progenitor cells have been identified in the substantia nigra (SN) of the rat and mouse, raising a hope that resident stem/progenitor cells may be useful for the therapy of Parkinson's disease. However, it is controversial whether dopamine (DA) neurons can be spontaneously or injury-dependently generated from the endogenous stem cells in the adult brain. Here, we explored the neurogenesis in C57Bl/6 adult mice under the normal and neurotoxin-injured conditions. To monitor adult neurogenesis, we injected 5-bromodeoxyuridine (BrdU) 2 weeks after striatal injection of neurotoxin 6-hydroxydopamine (6-OHDA), and sacrificed the animals 6 weeks after 6-OHDA injection. Whereas the number of BrdU-labeled cells was slightly increased in ipsilateral side than contralateral side of the midbrain, none of BrdU- labeled cells, however, exhibited neuronal markers, NeuN or DCX. Instead, BrdU- labeled cells expressed glial markers such as GFAP (astrocyte), Olig2 (oligodendrocyte) and Iba-1 (microglia). Especially, larger portion of BrdU-labeled cells in the ipsilateral side exhibited microglial marker, indicating that increased cell production in response to the 6-OHDA injection is not related to the adult neurogenesis.

Keywords: Parkinson's disease, 6-OHDA, mice, adult neurogenesis, dopaminergic neurons