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Falk Schroedl, Alexandra Kaser-Eichberger, Andrea Trost, Barbara Bogner, Christian Runge, Daniela Bruckner, Clemens Strohmaier, Herwig Brandtner, Miriam Barnerssoi, Anja Horn-Bochtler, Herbert Reitsamer; Urocortin in human choroid and eye-related cranial ganglia. Preliminary results. Invest. Ophthalmol. Vis. Sci. 201657(12):.
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© 2017 Association for Research in Vision and Ophthalmology.
Neuropeptides are important for all aspects of ocular homeostasis. Since recent studies demonstrated vasodilator effects of the neuropeptide urocortin-1 (Ucn) in arterioles of different highly vascularized tissues, we here ask whether Ucn is also present in the human choroid. We further investigated various cranial ganglia supplying the eye, i.e., the pterygopalatine (PPG), ciliary (CIL), superior cervical (SCG) and trigeminal ganglion (TRI) for the presence of Ucn-expressing neurons as potential sources for an Ucn input to the choroid.
Meeting the Declaration of Helsinki, human choroids and cranial ganglia supplying the eye (n=5) were obtained and prepared for immunohistochemistry against Ucn, substance P (SP), tyrosine hydroxylase (TH) and vesicular acetylcholine transporter (VAChT). For documentation, light- and confocal laser-scanning microscopy was applied.
In the choroidal stroma, dispersed Ucn+ nerve fibers were detected forming boutons. Some Ucn+ nerve fibers co-expressed VAChT or SP, but all Ucn+ nerve fibers lacked TH-immunoreactivity. Further, small ovoid cells (cell diameters ~10 µm) with smooth contoured outline displayed Ucn-immunoreactivity, a subpopulation of which was also SP+. In addition, few intrinsic choroidal neurons (ICN) displayed faint Ucn-immunoreactivity, but these and also all small ovoid cells were VAChT-. In cranial ganglia, Ucn-immunoreactivity was absent in the PPG and SCG whereas in the CIL few small neurons displayed strong Ucn-immunoreactivity. Similarly, few small neurons in the TRI were Ucn+ and all of them coexpressed SP-immunoreactivity.
The human choroid contains Ucn+ nerve fibers with different co-expression patterns, which may indicate the sources of choroidal Ucn innervation: the Ucn+/VACht- fibers could derive from ICN, while the Ucn+/VACht+ population could derive from the CIL, if indeed projecting to the choroid. Ucn+/VAChT-/SP+ nerve fibers may derive from the TRI, or the small cells of the choroidal stroma, or from a subpopulation of ICN. The origin of the Ucn+/VAChT-/SP+ fibers as well as the functional significance of the observed Ucn-innervation for ocular homeostasis has to be clarified in upcoming studies.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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