[Abstract Title]. - Society for Neuroscience

of the Substantia Nigra (SN) and their projections to the striatum show selective vulnerability,
while neighboring DA neurons of the Ventral Tegmental Area (VTA) are relatively spared from
degeneration. Notably, this selective neurodegeneration is mimicked in humans, non-human
primates and C57BL/6J mice by the neurotoxin MPTP. In this study, we aimed to test the
hypothesis that genes/proteins in the VTA confer neuroprotection against MPP+ mediated
toxicity. We have developed an in vitro cell culture system in which the SN and VTA are grown
separately by utilizing embryonic day 13 midbrains from transgenic C57BL/6J mice carrying the
human TH promoter driving GFP (hTH-GFP) expression. To determine the neuroprotective
potential of VTA derived factors, SN cells grown in VTA-CM were treated with MPP+.
Following treatment, cultures were fixed with 4% paraformaldehyde and GFP postive cells were
counted and quantified. Importantly, we have found that the cells of the SN are susceptible to
MPP+ in the presence of VTA-CM. Our preliminary results show that a concentration of 7.5µM
MPP+ caused approximately 50% cell death in SN cultures plated in 50% VTA-CM. Notably,
there is an inverse relationship between the concentration of VTA-CM and the amount of
protection against MPP+. We found that MPP+ caused approximately 62%-40% SN cell death in
the presence of 25%-75% VTA-CM respectively. Immunocytochemical staining of VTA
cultures at the time conditioned media was drawn (3 days in vitro) demonstrated positive staining
for the neuronal marker β-III tubulin, and negative staining for the astrocytic markers GFAP and
s100β. This suggests that the factors conferring protection against MPP+ toxicity have a
neuronal origin. Importantly, the origin of these factors is specific to the VTA, as media
conditioned by cortical neurons do not appear to offer protection against MPP+ toxicity. In order
to isolate specific VTA-derived factors as potential neuroprotectants, we are currently using
microarray analysis to create gene expression profiles of the SN and VTA during the progression
of DA neuron death in an MPTP mouse model of PD.
Disclosures: S. Phani , None; L. Iacovitti, The Parkinson Council, B. Research Grant (principal
investigator, collaborator or consultant and pending grants as well as grants already received).
Poster
253. Parkinson's Disease Models: Neuroprotective Mechanisms I
Time: Sunday, November 16, 2008, 1:00 pm - 5:00 pm
Program#/Poster#: 253.16/X17
Topic: C.11.j. Neuroprotective mechanisms: Parkinson‟s disease models
Support: NSERC Grant
OMHF Grant