Annemie Cuyvers, Melissa Paulussen, Katrien Smolders, Tjing-Tjing Hu and Lutgarde Arckens

Laboratory of Neuroplasticity and Neuroproteomics, K.U. Leuven, Naamsestraat 59, Leuven, Belgium.  

Abstract

In this study we used incorporation of the DNA synthesis marker 5-bromo-2’-deoxyuridine or BrdU to visualize cell proliferation in the visual system of the adult mouse as a response to monocular enucleation. We detected new BrdU-labeled cells in different subcortical retinal target regions and we established a specific time frame in which this cell proliferation occurred. By performing immunofluorescent double stainings for BrdU and different vascular (glucose transporter type 1, collagen type IV), glial (thymosin β₄, glial fibrillary acidic protein) and neuronal (Neuronal Nuclei, doublecortin) markers, we identified these proliferating cells as activated microglia. Additional immunohistochemical stainings for thymosin β₄ and glial fibrillary acidic protein also revealed reactive astrocytes in the different retinorecipient nuclei and allowed us to delineate a time frame for microglial and astroglial activation.
A PCR array experiment further showed increased levels of cytokines, chemokines, growth factors and enzymes that play an important role in microglial-astroglial communication during the glial activation process in response to the deafferentation.