Low back pain is the second most common symptom necessitating a visit to a physician. Complex biological, biochemical, and biomechanical phenomena pervade both diagnostic and treatment of low back pain. Despite recent advances in bioengineering capabilities to delineate key factors influencing clinical outcomes, current clinical decision making still rests mostly on subjective empirical experience due to the lack of appropriate model for studying this significant problem. We propose a 2-year interdisciplinary pilot study to develope an animal model required for addressing long lasting controversy, i.e., degenerative disc disease (DDD) and aberrant mechanics as a source of back pain. We designed a comprehensive interdisciplinary projects to test the following hypotheses: 1) The application of abnormal shear force induces accelerated degeneration of the intervertebral disc and its surrounding structures of endplates and subchondral bones. 2) These degenerative changes alone, however, may induce no or little inflammation, not severe enough to cause peripheral and consequent central sensitization for generating pain. 3) An additional shear force application on the already degenerated disc either enhances already existing inflammation or generates the severe inflammation enough to generate pain-like behaviors. These hypotheses will be tested using an in vivo rat model. We will determined the degree of disc degeneration using histology. The pain sensation will be identified through the pain behavior test and immunostaining of an immediate early gene in the superficial laminar of the dorsal horn in the spinal cord. Intradiscal inflammation will be found by immunostaining of inflammatory cytokines while the ingrowth of nociceptic nerve endings into the disc will be located by immunostaining techniques. ? ? ?
