Extensive production of acrylamide and gamma-diketones for diverse industrial, agricultural and commercial use creates the potential for occupational and environmental neurotoxicity. Additionally, these agents act as prototypes for other toxicants as well as models for neuropathologies. While research has identified characteristics of the neurotoxicity, pathogenetic mechanisms remain unresolved. This proposal logically extends our previous studies by evaluating inhibition of the motor protein kinesin, compromise of fast anterograde axonal transport (faAXT) and reduced delivery of distal axonal/terminal proteins with subsequent development of dysfunctional axons and/or terminals as a significant contributant to behavioral deficits (neurotoxicity). 1) The significance of faAXT reductions will be tested by challenging the association of reduced transport with neurotoxicity over a range of dosing rates using video-enhanced DIC microscopy of isolated axons. 2) Changes in quantity of fast-transported proteins, specific for axolemmal, synaptic vesicle and synaptic plasma membrane compartments and possessing neurophysiological relevance, will be determined with immunofluorescence, Western blots and/or immunoprecipitation. Different dosing rate paradigms as well as quantitation in PNS and CNS axons and terminals are planned. 3) Electrophysiological testing of axonal conduction and neurotransmission efficacy will challenge the association of protein deficits with functional outcomes and may identify specific molecular mechanisms related to behavioral deficits. 4) Specific and quantitative alterations in neuronal kinesin content using antisense and overexpression techniques are integrated with determination of sensitivity of faAXT, morphological changes and/or distal axonal protein content to toxicant challenges. The integrative design permits quantitative comparison of key elements of the hypothesized pathogenic cascade while simultaneously challenging the relationship of these outcomes to neurotoxicity. These studies will improve our understanding of compromised fast axonal transport with these toxicants and in neurodegenerative disorders, in general. These studies will enhance the evaluation of the emerging concept of motor protein defects producing specific peripheral neuropathies.
| Gearhart, Debra A; Sickles, Dale W; Buccafusco, Jerry J et al. (2007) Chlorpyrifos, chlorpyrifos-oxon, and diisopropylfluorophosphate inhibit kinesin-dependent microtubule motility. Toxicol Appl Pharmacol 218:20-9 |
| Sickles, Dale W; Sperry, Ann O; Testino, Angie et al. (2007) Acrylamide effects on kinesin-related proteins of the mitotic/meiotic spindle. Toxicol Appl Pharmacol 222:111-21 |
