Originally published as JHC exPRESS on September 28, 2009. doi:10.1369/jhc.2009.954610 Journal of Histochemistry and Cytochemistry Volume 58 (1): 53-60, 2010 Copyright © 2010 Horton et al.
Localization of Angiopoietin-1 and Tie2 Immunoreactivity in Rodent Ependyma and Adjacent Blood Vessels Suggests Functional Relationships
Department of Neurology, University of Alabama at Birmingham, Birmingham, Alabama (BNH); Department of Neurology, University of Chicago, Chicago, Illinois (RBS,AAA); Department of Neurosurgery, University of California, Irvine, California (KFR); and Department of Pathology, Northwestern University, Chicago, Illinois (PK) Correspondence to: Agnieszka A. Ardelt, MD, PhD, 5841 S. Maryland Ave., MC2030, Chicago, IL. E-mail: aardelt{at}neurology.bsd.uchicago.edu Angiopoietin-1 (Angpt1; previously Ang-1) participates in vascular maintenance and remodeling. In the current study, we investigated the distribution of Angpt1 protein in rat brain. We detected Angpt1 immunoreactivity (IR) in cerebral blood vessels, cuboidal ependyma, and tanycytes, which are specialized hypothalamic bipolar ependymal cells. We also evaluated patterns of IR of endothelium-specific receptor tyrosine kinase 2 (Tie2, the receptor for Angpt1). Tie2 IR was present in Angpt1-immunoreactive cuboidal ependyma in a membranous pattern, suggesting an autocrine or paracrine role for Angpt1–Tie2. Tie2 IR was also associated with peri-ependymal blood vessels, some of which were contacted by tips of Angpt1-immunoreactive tanycyte processes, implying a potential functional ligand–receptor interaction mediating communication between the cerebrospinal fluid and vascular compartments. Because we previously found that cerebral Angpt1 expression was modulated by 17β-estradiol (E2), and because some tanycyte functions are modulated by E2, we tested the hypothesis that E2 affects ependymal and tanycyte Angpt1 expression in vivo. No gross E2 effect on the ependymal pattern of Angpt1 IR or cerebral Angpt1 protein content was observed. (J Histochem Cytochem 58:53–60, 2010)
Key Words: tanycyte ependyma angiopoietin Ang-1 estradiol Tie2
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