title: Distribution of the regulatory peptide alarin in the eye of various species.
abstract: Alarin is a recently discovered regulatory peptide with vasoconstrictive properties in murine skin. Control of vasoconstriction/-relaxation is essential for ocular blood flow and hence the eye's homeostasis, and regulatory peptides are involved in regulation of ocular blood flow. Here we describe the existence and distribution of alarin in the eye of human and potential experimental animals (rat, mouse). Eyes of rat, mouse, and human were prepared for immunohistochemistry against murine and human alarin, respectively. Additionally, double staining experiments for alarin and CD31 were performed in human choroidal flat-mount preparations. For documentation, confocal laser scanning microscopy was used while quantitative real-time-PCR was applied to confirm immunohistochemical data and to detect alarin mRNA expression in human retina and choroid. Alarin-like immunoreactivity (alarin-LI) was detected in corneal epi- and endothelium of human, mouse, and rat, as well as in the conjunctiva of mouse and rat. Alarin-LI was found in the iris of all the species investigated and, in humans, was concentrated around blood vessels. All three species showed distinctive alarin-LI in the non-pigmented epithelium of the ciliary body. In the retina of mouse and rat, maximum signals were detected in the outer nuclear and ganglion cell layer, whereas in humans a strong alarin-LI was found around retinal blood vessels and in intrinsic choroidal neurons (ICN). Quantitative RT-PCR in human confirmed alarin mRNA expression retina and choroid. The existence of alarin in cornea and conjunctiva might indicate a role in immune defense, while its presence in the non-pigmented ciliary epithelium favors an involvement in aqueous humor production. Alarin around blood vessels/in ICN might indicate an involvement in ocular blood flow regulation. Since alarin is found widely distributed in the eyes of species investigated, we were able to establish the basis for further functional experiments.
authors.affiliation: Dept. of Ophthalmology, Paracelsus Medical University, SALK, Muellner Hauptstrasse 48, 5020 Salzburg, Austria; Dept. of Anatomy, Paracelsus Medical University, Strubergasse 21, 5020 Salzburg, Austria. falk.schroedl@pmu.ac.at
authors.forename: Falk
authors.initials: F
authors.lastname: Schrödl
authors.forename: Andrea
authors.initials: A
authors.lastname: Trost
authors.forename: Clemens
authors.initials: C
authors.lastname: Strohmaier
authors.forename: Barbara
authors.initials: B
authors.lastname: Bogner
authors.forename: Christian
authors.initials: C
authors.lastname: Runge
authors.forename: Alexandra
authors.initials: A
authors.lastname: Kaser-Eichberger
authors.forename: Nicole
authors.initials: N
authors.lastname: Eberhard
authors.forename: Radmila
authors.initials: R
authors.lastname: Santic
authors.forename: Barbara
authors.initials: B
authors.lastname: Kofler
authors.forename: Herbert A
authors.initials: HA
authors.lastname: Reitsamer
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D001483:Base Sequence; D001808:Blood Vessels / Q000378:metabolism; D004847:Epithelial Cells / Q000378:metabolism; D005123:Eye / Q000378:metabolism*; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect; D044089:Galanin-Like Peptide / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018613:Microscopy, Confocal; D008875:Middle Aged; D008969:Molecular Sequence Data; D009474:Neurons / Q000378:metabolism; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D011914:Rats, Inbred BN; D060888:Real-Time Polymerase Chain Reaction
chemical_list: D044089:Galanin-Like Peptide; D019408:Platelet Endothelial Cell Adhesion Molecule-1; D012333:RNA, Messenger