3 Immunohistochemical Correlation of Novel Biomarkers with Neurodegeneration in Rat Models of Brain Injury Shyam Gajavelli, Amade Bregy, Markus Spurlock, Daniel Diaz, Stephen Burks, Christine Bomberger, Carlos J. Bidot, Shoji Yokobori, Julio Diaz, Jose Sanchez-Chavez and Ross Bullock Lois Pope LIFE Center, University of Miami Miller School of Medicine, Miami, FL USA 1. Introduction Immunohistochemistry is an important technique used to visualize specific changes in tissues as part of both normal development and pathological conditions. Immunohistochemistry (IHC) combines antibody specificity with high resolution imaging techniques which, together, can provide reliable visual evidence of presumed physiological processes. The technique is amenable to rigorous experimental design. In controlled settings, with the appropriate constraints, and image acquisition settings, data obtained becomes reliable, quantifiable and reproducible. Through the numerous past and current explorations of IHC, novel, antibody-based, ‘point of care’ diagnostics as well as antibody- based therapeutics will and are becoming a valuable tool for clinicians and researchers. A field that really craves such new diagnostic and therapeutic technologies is that of traumatic brain injury. Brain injury, especially traumatic brain injury, or TBI, initiates a complex series of neurochemical signalling events. These pathological changes are mediated, at lease in part, by glutamate excitotoxity, inflammation and increased blood-brain barrier (BBB) permeability leading to numerous sequale which include neuronal hyperactivity, increased cellular vulnerability, edematous states, cellular dysfunction and consequent apoptotic and necrotic cell death. Many of these changes produce subtle and slight global manifestations and hence are invisible to current diagnostic imaging techniques such as magnetic resonance imaging or computer aided tomography scans. Recently though, the decades-long efforts of a few pioneering groups has established novel protein biomarkers for TBI (Mondello, Muller et al. 2011). Unlike many traditional biomarkers, these novel protein biomarkers can be investigated using IHC. As their discovery remains recent, the relationship between their presence in the extracellular environment and their intracellular source has not been explored. Our group investigated one such biomarker, namely ubiquitin carboxy-terminal hydrolase-1 (UCH-L1), and found that it could provide powerful information regarding the