Immunocytochemical studies of plasticity candidate proteins in the cat primary visual cortex during postnatal development

The developing visual cortex has served as a model system for understanding activity-dependent neural development, learning and memory, and the treatment and prognosis of some diseases. The anatomy, physiology, development, and plasticity of the visual cortex have been well characterized at the systems level. However, current knowledge of molecular mechanisms underlying visual cortical development remains limited. The purpose of this thesis is to investigate the cellular and laminar distributions of two proteins (OBCAM and IL-11) in the visual cortex during postnatal development, as there is evidence suggesting that these proteins may play important roles in visual cortical development and plasticity. The expressions of OBCAM and IL-11 were characterized in the primary visual cortices of normal cats at various postnatal ages as well as in 4-month-old dark-reared cats. The relative immunopositive cell density was determined across visual cortical layers. OBCAM and IL-11 expressions are regulated by age and rearing condition. OBCAM immunoreactivity is highest between 2 and 4 weeks of age and then rapidly reduced afterwards until 6 weeks of age, when it is then similar to adult levels. IL-11 immunoreactivity is highest between 1 and 2 weeks of age and then rapidly reduced after 2 weeks of age until 4 weeks of age, when it is similar to adult levels. Dark rearing slowed the decrease of both proteins. Our data indicated the expression levels of these two proteins were well correlated with the level of ocular dominance plasticity, and suggested that OBCAM and IL-11 might be involved in visual cortical plasticity. Unfortunately, the results from western blot and immunocytochemical analysis of AC-7 and Rap1B demonstrated that the antibodies were not specific to AC-7 and Rap1B in cat tissue. Therefore, the developmental studies of AC-7 and Rap1B were not performed.Medicine, Faculty ofGraduat