Lipopolysaccharide preconditioning induces protection against lipopolysaccharide-induced neurotoxicity in organotypic midbrain slice culture.
OBJECTIVE
To identify the protective effect of lipopolysaccharide (LPS) preconditioning against LPS-induced inflammatory damage in dopaminergic neurons of midbrain slice culture and the possible mechanisms.


METHODS
After cultured in vitro for 14 d, the rat organotypic midbrain slices were pretreated with different concentrations (0, 1, 3, 6 or 10 ng/mL) of LPS for 24 h followed by treatment with 100 ng/mL LPS for 72 h. The whole slice viability was determined by measurement of the activity of lactic acid dehydrogenase (LDH). Tyrosine hydroxylase-immunoreactive (TH-IR) neurons and CD11b/c equivalent-immunoreactive (OX-42-IR) microglia in the slices were observed by immunohistochemical method, and tumor necrosis factor-alpha (TNF-alpha) levels in the culture media were detected by enzyme-linked immunosorbent assays (ELISA).


RESULTS
In the slices treated with 100 ng/mL LPS for 72 h, the number of TH-IR neurons reduced from 191+/-12 in the control slices to 46+/-4, and the LDH activity elevated obviously (P < 0.01), along with remarkably increased number of OX-42-IR cells and production of TNF-alpha (P < 0.01). Preconditioning with 3 or 6 ng/mL LPS attenuated neuron loss (the number of TH-IR neurons increased to 126+/-12 and 180+/-13, respectively) and markedly reduced LDH levels (P < 0.05), accompanied by significant decreases of OX-42-IR microglia activation and TNF-alpha production (P < 0.05).


CONCLUSIONS
Low-dose LPS preconditioning could protect dopaminergic neurons against inflammatory damage in rat midbrain slice culture, and inhibition of microglial activation and reduction of the proinflammatory factor TNF-alpha production may contribute to this protective effect. Further understanding the underlying mechanism of LPS preconditioning may open a new window for treatment of Parkinson's disease.
Ding
Ye
Y
Department of Pathology, Capital Medical University, Beijing, China.
Li
Liang
L
D000818:Animals; D018845:CD11 Antigens / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D007150:Immunohistochemistry; D007249:Inflammation / Q000139:chemically induced / Q000473:pathology*; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008070:Lipopolysaccharides / Q000008:administration & dosage* / Q000633:toxicity*; D008636:Mesencephalon / Q000187:drug effects / Q000276:immunology / Q000473:pathology; D017628:Microglia / Q000187:drug effects / Q000276:immunology / Q000473:pathology; D009410:Nerve Degeneration / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control*; D009474:Neurons / Q000187:drug effects / Q000276:immunology / Q000473:pathology*; D009924:Organ Culture Techniques; D051381:Rats; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism
D018845:CD11 Antigens; D008070:Lipopolysaccharides; D014409:Tumor Necrosis Factor-alpha; D007770:L-Lactate Dehydrogenase; D014446:Tyrosine 3-Monooxygenase