Previous studies in both human and animals have demonstrated the presence of serum autoantibodies to neurotypic [e.g., neurofilament triplet (NF)] and gliotypic proteins [myelin basic protein (MBP) and glial fibrillary acidic protein (GFAP)] following exposure to some heavy metals, solvents, or pesticides. TMT has been used as a denervation tool to validate the enhanced expression of GFAP as a biomarker of astrogliosis resulting from neuronal damage and cell death. In particular, TMT targets hippocampal pyramidal neurons in CA3 and CA1. In the present study TMT was used to assess the detection of the serum polyclonal IgG responses against NFs, measured by ELISA, as a peripheral marker of neurotoxicity. Western-blots, using purified NF proteins, or hippocampal homogenates, were used to confirm ELISA. Male Long-Evans rats (45 days of age) were administered either TMT (8mg/kg; sc; n=16) or an equal volume of sterile 0.9% saline (n=16). At 3 weeks post-administration, serum was collected, and rats were sacrificed for the collection of brains. The polyclonal IgG response to NF68, NF160, and NF200, using ELISA, showed detectable titers of IgG autoantibodies to NFs in sera from TMT-exposed rats, only. Anti-NF68 titers were highest compared to NF160, or NF200. Immunostaining of Western-blots using HRP-conjugated anti-rat IgG confirmed the presence of antibodies, against purified proteins or hippocampal homogenates, in sera of rats exposed to TMT. This corresponded to the molecular weights of NF 68, NF160, and NF200. Immunoblot confirmed the use of the ELISA as a means of detecting the autoantibody response. This study suggests that the detection of autoantibodies to neurotypic proteins, using ELISA, may be used to indicate chemical neurotoxicity.
The Toxicologist. Society of Toxicology 41st Annual Meeting and ToxExpo, March 17-21, 2002, Nashville, Tennessee
Pharmacology and Toxicology Laboratory, Mercy College, Dobbs Ferry, NY; Environmental Medicine, NYU Medical Center, Tuxedo NY