Mechanisms of Neurotoxicity and Neurodegeneration. We are taking a combination of pharmacological and genetic inactivation approaches to investigate whether TNF signaling plays a critical role in dopaminergic neurodegeneration and thus, whether inhibition of the TNF pathway could provide neuroprotection in models of Parkinson’s Disease. We have proposed a dual-site of action model to investigate the relative roles that direct TNF neurotoxicity and TNF-dependent neuroinflammation (i.e. microglia activation) play in hastening death of dopamine-producing neurons in culture and in vivo. By combining newly engineered dominant negative TNF inhibitors (Steed et al., 2003), TNF receptor-selective agonists, and mice deficient in TNF pathway genes, we are testing our model in vitro and in vivo. These studies will provide new and critical information on the cellular and molecular details of TNF-dependent events that are required to elicit dopaminergic neurodegeneration; with the long-term goal of establishing the role of TNF in etiology or progression of Parkinson’s Disease and perhaps other neurodegenerative diseases in which neuroinflammation plays a pathophysiological role.

Figure 1. Activated microglia visualized with a monoclonal antibody against complement receptor 3 (CR3) and Alexa-488-anti-mouse secondary antibody.

Figure 2. Immunofluorescence detection of tyrosine hydroxylase-positive dopaminergic neurons (red) in primary neuron-glia cultures from rat ventral midbrain.

Figure 3. Brightfield immunohistological detection of tyrosine hydroxylase-positive dopaminergic neurons (dark purple) and NeuN-positive total neurons (brown) in brain cryosections from rat ventral midbrain.

Figure 4. Immunofluorescence detection of GFAP-positive mouse astrocytes (red) transduced with a lentivirus encoding dominant negative TNF (green).

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Last reviewed: September 10, 2008