Nucleolin in Neurons of the Human Substantia Nigra

Abstract

Using immunocytochemistry and confocal laser microscopy, the distribution of nucleolin (protein C23) in neurons of the human substantia nigra was investigated. Fragments of the human midbrain (n = 8) with the verified lack of neurodegeneration were used in the study. The material was fixed in zinc ethanol formaldehyde, a special fixative that provides high preservation of antigenic determinants. New morphological data on the distribution of nucleolin in neurons of the human substantia nigra were obtained. Nucleolin was found in the nucleolus and nucleoplasm of dopaminergic neurons but not in the cytoplasm or cell surface. In the nucleolus and nucleoplasm, protein C23 is distributed irregularly in the form of some accumulations (clumps) with fuzzy borders. Moreover, nucleolin distribution varied in structurally similar neurons containing cytoplasmic neuromelanin. The Marinesco bodies typically not exhibiting nucleolin expression were identified in the nucleus, in addition to nucleoli, by confocal laser microscopy with simultaneous use of transmitted light detector. The findings can contribute to elucidation of the role of nucleolin in the specific functions of normal dopaminergic neurons in the human substantia nigra and assessment of probable involvement of C23 in the development of nucleolar stress and neurodegeneration.