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Transgenic Murine Dopaminergic Neurons Expressing Human Cu/Zn Superoxide Dismutase Exhibit Increased Density in Culture, but No Resistance to Methylphenylpyridinium‐Induced Degeneration
Author(s) -
SanchezRamos Juan R.,
Song Shije,
Facca Alicia,
Basit Abdul,
Epstein Charles J.
Publication year - 1997
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1046/j.1471-4159.1997.68010058.x
Subject(s) - superoxide dismutase , dopaminergic , dopamine , tyrosine hydroxylase , microbiology and biotechnology , biology , superoxide , medicine , endocrinology , biochemistry , enzyme
Primary dopaminergic neuronal cultures with increased superoxide dismutase (SOD) activity were established for studying the role of superoxide anion (O 2 − ) in 1‐methyl‐4‐phenylpyridinium (MPP + )‐induced degeneration of dopamine (DA) neurons. Mean SOD activity in cultures prepared from transgenic (human) Cu/Zn SOD (hSOD1) mice was 2.46–2.60 times greater than in cultures prepared from nontransgenic control mice. After 1 and 2 weeks in culture, the mean density of DA neurons [number of tyrosine hydroxylase‐immunoreactive (TH‐ir) cells per visual field] was significantly higher in cultures prepared from transgenic mice compared with those prepared from nontransgenic control mice (4.55–5.63 TH‐ir neurons per field in hSOD1 cultures vs. 2.66–2.8 TH‐ir neurons per field in control cultures). However, uptake of [ 3 H]DA relative to uptake of [ 3 H]GABA was only slightly greater in hSOD1 cultures than in normal cultures (14.1 nmol of DA/100 nmol of GABA vs. 12.1 nmol of DA/100 nmol of GABA). Resistance to MPP + toxicity was not significantly different from that in normal cultures when based on density of surviving TH‐ir cell bodies (EC 50 = 0.54 µ M in hSOD1 and EC 50 = 0.37 µ M in normal cultures). A more sensitive measure of DA neuron integrity and function ([ 3 H]DA uptake) also failed to demonstrate increased resistance of hSOD1 cultures to the toxin (EC 50 = 73.7 n M in hSOD1 and EC 50 = 86.2 n M in controls). These results do not support the hypothesis that neurotoxicity of the active metabolite of MPTP, MPP + , is mediated by generation of O 2 − in the cytoplasm. Nevertheless, mesencephalic cultures with increased hSOD1 activity appear to survive better than normal control cultures in the oxidatively stressful environment of cell culture incubators, and such mesencephalic cells may be useful for cell grafting studies in animal models of Parkinson's disease.