Administration of Dexamethasone to Neonatal Rats Induces Hypomyelination and Changes in the Morphology of Oligodendrocyte Precursors
Abstract:To examine whether hypomyelination in neonatal rats might be related to apoptosis of oligodendrocyte progenitors, we administered dexamethasone (0.5 mg/kg SC) to neonatal rats on postnatal (P) days 1 through 5. Immunofluorescent staining and Western blotting for myelin basic protein (MBP) were performed on P14. Morphologic changes associated with apoptotic death of oligodendrocyte progenitors were assessed by using immunofluorescent staining on P5 of surface markers present at different developmental stages of oligodendrocyte progenitors (O4 and O1) and by double-staining with terminal deoxynucleotidyl transferase-mediated digoxigenin–dUTP nick end-labeling (TUNEL) and O4 or O1. Administration of dexamethasone to neonatal rats reduced the expression of MBP in the white matter by P14. In addition, dexamethasone reduced the expression of O4-positive cells, presumably preoligodendrocytes, in the corpus callosum and induced degenerative changes, such as cytoplasmic condensation and fragmented, tortuous processes, in oligodendrocyte progenitors, and increased the number of TUNEL-positive pyknotic nuclei of oligodendrocyte progenitors. These findings suggest that the dexamethasone-induced decreased expression of MBP in the cerebral hemispheres of the neonatal rats is due to apoptotic degeneration of oligodendrocyte progenitors. Administration of dexamethasone during the critical period of brain development may increase the risk of apoptosis in oligodendrocyte progenitors, subsequently resulting in hypomyelination.
Document Type: Research Article
Affiliations: 1: Department of Nanobiomedical Science, WCU Research Center of Nanobiomedical Science, Institute of Tissue Regeneration Engineering (ITREN), Dankook University, Cheonan, South Korea 2: Department of Pediatrics, Dankook University, Cheonan, South Korea 3: Department of Pediatrics, Dankook University, Cheonan, South Korea. firstname.lastname@example.org
Publication date: February 1, 2013
Comparative Medicine (CM), an international journal of comparative and experimental medicine, is the leading English-language publication in the field and is ranked by the Science Citation Index in the upper third of all scientific journals. The mission of CM is to disseminate high-quality, peer-reviewed information that expands biomedical knowledge and promotes human and animal health through the study of laboratory animal disease, animal models of disease, and basic biologic mechanisms related to disease in people and animals.
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