title: Distribution of galanin receptors in the human eye.
abstract: The neuropeptide galanin (GAL) is widely distributed within intrinsic and extrinsic sources supplying the eye. It is involved in regulation of the vascular tone, thus important for ocular homeostasis. Since the presence/distribution of its receptors is unknown, we here screen for the presence of the various GAL receptors in the human eye. Meeting the Helsinki-Declaration, human eyes (n = 6; 45-83 years of age, of both sex, post mortem time 10-19 h) were obtained from the cornea bank and prepared for immunohistochemistry against GAL receptors 1-3 (GALR1-GALR3). Over-expressing cell assays served as positive controls and confocal laser-scanning microscopy was used for documentation. Cell assays reliably detected immunoreactivity for GALR1-3 and cross-reactions between antibodies used were not observed. In the cornea, GALR1-3 were detected in basal layers of the epithelium, stroma, endothelium, as well as in adjacent conjunctiva. In the iris, GALR1-3 were detected in iris sphincter and dilator, while iris vessels displayed immunoreactivity for GALR1 and GALR3. In the ciliary body, GALR1 was exclusively found in the non-pigmented epithelium while GALR3 was detected in the ciliary muscle and vessels. In the retina, GALR1 was present in fibers of the IPL, OPL, NFL, many cells of the INL and few cells of the ONL. GALR2 and GALR3 were present in few neurons of the INL, while GALR2 was also found surrounding retinal vessels. RPE displayed weak immunoreactivity for GALR2 but intense immunoreactivity for GALR3. In the choroid, GALR1-3 were detectable in intrinsic choroidal neurons and nerve fibers of the choroidal stroma, and all three receptors were detected surrounding choroidal blood vessels, while the choriocapillaris was immunoreactive for GALR3 only. This is the first report of the various GALRs in the human eye. While the presence of GALRs in cornea and conjunctiva might be relevant for wound healing or inflammatory processes, the detection in iris vessels (GALR1, 2) and choroidal vessels (GALR1-3) highlights the role of GAL in vessel dynamics. Presence of GALR1 in ciliary body epithelium and GALR3 in ciliary vessels indicates involvement in aqueous humor production, whereas retinal GALR distribution might contribute to signal transduction.
authors.affiliation: University Clinic of Ophthalmology and Optometry, Research Program for Ophthalmology and Glaucoma Research, Paracelsus Medical University, Muellner Hauptstrasse 48, 5020 Salzburg, Austria; Department of Anatomy, Paracelsus Medical University, Strubergasse 21, 5020 Salzburg, Austria. Electronic address: falk.schroedl@pmu.ac.at.
authors.forename: Falk
authors.initials: F
authors.lastname: Schrödl
authors.affiliation: University Clinic of Ophthalmology and Optometry, Research Program for Ophthalmology and Glaucoma Research, Paracelsus Medical University, Muellner Hauptstrasse 48, 5020 Salzburg, Austria.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Kaser-Eichberger
authors.affiliation: University Clinic of Ophthalmology and Optometry, Research Program for Ophthalmology and Glaucoma Research, Paracelsus Medical University, Muellner Hauptstrasse 48, 5020 Salzburg, Austria.
authors.forename: Andrea
authors.initials: A
authors.lastname: Trost
authors.affiliation: University Clinic of Ophthalmology and Optometry, Research Program for Ophthalmology and Glaucoma Research, Paracelsus Medical University, Muellner Hauptstrasse 48, 5020 Salzburg, Austria.
authors.forename: Clemens
authors.initials: C
authors.lastname: Strohmaier
authors.affiliation: University Clinic of Ophthalmology and Optometry, Research Program for Ophthalmology and Glaucoma Research, Paracelsus Medical University, Muellner Hauptstrasse 48, 5020 Salzburg, Austria.
authors.forename: Barbara
authors.initials: B
authors.lastname: Bogner
authors.affiliation: University Clinic of Ophthalmology and Optometry, Research Program for Ophthalmology and Glaucoma Research, Paracelsus Medical University, Muellner Hauptstrasse 48, 5020 Salzburg, Austria.
authors.forename: Christian
authors.initials: C
authors.lastname: Runge
authors.affiliation: University Clinic of Ophthalmology and Optometry, Research Program for Ophthalmology and Glaucoma Research, Paracelsus Medical University, Muellner Hauptstrasse 48, 5020 Salzburg, Austria.
authors.forename: Daniela
authors.initials: D
authors.lastname: Bruckner
authors.affiliation: University Clinic of Ophthalmology and Optometry, Research Program for Ophthalmology and Glaucoma Research, Paracelsus Medical University, Muellner Hauptstrasse 48, 5020 Salzburg, Austria.
authors.forename: Karolina
authors.initials: K
authors.lastname: Motloch
authors.affiliation: Laura-Bassi Centre of Expertise, THERAPEP, Department of Pediatrics, Paracelsus Medical University, Muellner Hauptstrasse 48, 5020 Salzburg, Austria.
authors.forename: Barbara
authors.initials: B
authors.lastname: Holub
authors.affiliation: Laura-Bassi Centre of Expertise, THERAPEP, Department of Pediatrics, Paracelsus Medical University, Muellner Hauptstrasse 48, 5020 Salzburg, Austria.
authors.forename: Barbara
authors.initials: B
authors.lastname: Kofler
authors.affiliation: University Clinic of Ophthalmology and Optometry, Research Program for Ophthalmology and Glaucoma Research, Paracelsus Medical University, Muellner Hauptstrasse 48, 5020 Salzburg, Austria.
authors.forename: Herbert A
authors.initials: HA
authors.lastname: Reitsamer
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001808:Blood Vessels / Q000378:metabolism*; D002460:Cell Line; D002829:Choroid / Q000098:blood supply*; D002924:Ciliary Body / Q000378:metabolism; D003228:Conjunctiva / Q000378:metabolism; D003315:Cornea / Q000378:metabolism; D005123:Eye / Q000378:metabolism*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007498:Iris / Q000098:blood supply*; D008297:Male; D008875:Middle Aged; D009130:Muscle, Smooth / Q000378:metabolism; D044088:Receptors, Galanin / Q000378:metabolism*; D012160:Retina / Q000378:metabolism
chemical_list: D044088:Receptors, Galanin
keywords: Autonomic nervous system; Blood flow regulation; G-protein coupled receptor; Galanin; Neuropeptide