Alarin in cranial autonomic ganglia of human and rat

Falk Schrödl; Alexandra Kaser-Eichberger; Andrea Trost; Clemens Strohmaier; Barbara Bogner; Christian Runge; Daniela Bruckner; Karolina Krefft; Barbara Kofler; Herwig Brandtner; Herbert A Reitsamer

doi:10.1016/j.exer.2014.12.007

Alarin in cranial autonomic ganglia of human and rat

Exp Eye Res. 2015 Feb:131:63-8. doi: 10.1016/j.exer.2014.12.007. Epub 2014 Dec 9.

Affiliations

¹ Department of Ophthalmology and Optometry, Paracelsus Medical University, Muellner Hauptstrasse 48, 5020, Salzburg, Austria; Department of Anatomy, Paracelsus Medical University, Strubergasase 21, 5020, Salzburg, Austria. Electronic address: falk.schroedl@pmu.ac.at.
² Department of Ophthalmology and Optometry, Paracelsus Medical University, Muellner Hauptstrasse 48, 5020, Salzburg, Austria.
³ Laura-Bassi Centre of Expertise, THERAPEP, Department of Pediatrics, Paracelsus Medical University, Muellner Hauptstrasse 48, 5020, Salzburg, Austria.
⁴ Department of Legal Medicine, Paracelsus Medical University, Ignaz-Harrer-Straße 79, 5020, Salzburg, Austria.

PMID: 25497346
DOI: 10.1016/j.exer.2014.12.007

Abstract

Extrinsic and intrinsic sources of the autonomic nervous system contribute to choroidal innervation, thus being responsible for the control of choroidal blood flow, aqueous humor production or intraocular pressure. Neuropeptides are involved in this autonomic control, and amongst those, alarin has been recently introduced. While alarin is present in intrinsic choroidal neurons, it is not clear if these are the only source of neuronal alarin in the choroid. Therefore, we here screened for the presence of alarin in human cranial autonomic ganglia, and also in rat, a species lacking intrinsic choroidal innervation. Cranial autonomic ganglia (i.e., ciliary, CIL; pterygopalatine, PPG; superior cervical, SCG; trigeminal ganglion, TRI) of human and rat were prepared for immunohistochemistry against murine and human alarin, respectively. Additionally, double staining experiments for alarin and choline acetyltransferase (ChAT), tyrosine hydroxilase (TH), substance P (SP) were performed in human and rat ganglia for unequivocal identification of ganglia. For documentation, confocal laser scanning microscopy was used, while quantitative RT-PCR was applied to confirm immunohistochemical data and to detect alarin mRNA expression. In humans, alarin-like immunoreactivity (alarin-LI) was detected in intrinsic neurons and nerve fibers of the choroidal stroma, but was lacking in CIL, PPG, SCG and TRI. In rat, alarin-LI was detected in only a minority of cranial autonomic ganglia (CIL: 3.5%; PPG: 0.4%; SCG: 1.9%; TRI: 1%). qRT-PCR confirmed the low expression level of alarin mRNA in rat ganglia. Since alarin-LI was absent in human cranial autonomic ganglia, and only present in few neurons of rat cranial autonomic ganglia, we consider it of low impact in extrinsic ocular innervation in those species. Nevertheless, it seems important for intrinsic choroidal innervation in humans, where it could serve as intrinsic choroidal marker.

Keywords: Autonomic nervous system; Blood flow regulation; Neuropeptide.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Aged
Animals
Choroid / injuries*
Female
Galanin-Like Peptide / analysis*
Galanin-Like Peptide / genetics
Ganglia, Autonomic / chemistry*
Ganglia, Autonomic / cytology
Humans
Immunohistochemistry
Male
Microscopy, Confocal
RNA, Messenger / analysis*
Rats
Real-Time Polymerase Chain Reaction

Substances

Galanin-Like Peptide
RNA, Messenger
alarin