PE-11, a peptide derived from chromogranin B, in the rat eye
Katrin Lorenz1, Josef Troger, Oliver Gramlich
1Experimental Ophthalmology, Department of Ophthalmology, University Medical Center, Johannes Gutenberg-University Mainz, Langenbeckstraße 1, 55131 Mainz, Germany.
Insights
This study found PE-11 peptide in all rat eye tissues, with capsaicin reducing its levels. PE-11 is present in sensory neurons innervating the eye, with a unique distribution in the retina.
Area of Science:
- Neuroscience
- Ophthalmology
- Peptide Research
Background:
- Chromogranin B is a precursor to various bioactive peptides.
- PE-11 is a peptide derived from chromogranin B with unknown functions in the eye.
- Sensory innervation of the eye plays a crucial role in ocular physiology and pathology.
Purpose of the Study:
- To investigate the presence and distribution of PE-11 in the rat eye.
- To determine if PE-11 is associated with capsaicin-sensitive sensory neurons.
- To characterize the localization of PE-11 within ocular tissues and the trigeminal ganglion.
Main Methods:
- Radioimmunoassay to quantify PE-11-like immunoreactivity in rat eye tissues.
- Reversed-phase High-Performance Liquid Chromatography (HPLC) to characterize PE-11.
- Immunofluorescence to map the distribution of PE-11 in the rat eye and trigeminal ganglion.
- Capsaicin pretreatment to assess the role of sensory neurons.
Main Results:
- PE-11 was detected in all examined rat eye tissues.
- Capsaicin pretreatment significantly reduced PE-11 levels in the cornea and choroid/sclera, and abolished it in the iris/ciliary body.
- PE-11-immunoreactive nerve fibers were observed in the cornea, uveal stroma, around blood vessels, and in the ciliary body and choroid.
- PE-11 was also found in corneal endothelium, retinal glia, optic nerve glia, and small/medium trigeminal ganglion cells.
Conclusions:
- PE-11 is a component of capsaicin-sensitive sensory neurons innervating the rat eye.
- The distribution pattern of PE-11 in peripheral ocular innervation is typically peptidergic.
- PE-11 exhibits an atypical and unique distribution within the retina, distinct from other neuropeptides.
Abstract:
The aim of the study was to investigate the presence and distribution of PE-11, a peptide derived from chromogranin B, in the rat eye. For this purpose, newborn rats were injected with a single dosage of 50mg/kg capsaicin subcutaneously under the neck fold and after three months, particular eye tissues were dissected and the concentration of PE-11-like immunoreactivity was determined by radioimmunoassay. Furthermore, PE-11-like immunoreactivities were characterized in an extract of the rat eye by reversed phase HPLC. Then, the distribution pattern of PE-11 was investigated in the rat eye and rat trigeminal ganglion by immunofluorescence. As a result, PE-11 was present in each tissue of the rat eye and capsaicin pretreatment led to a 88.05% (±7.07) and a 64.26% (±14.17) decrease of the levels of PE-11 in the cornea and choroid/sclera, respectively, and to a complete loss in the iris/ciliary body complex. Approximately 70% of immunoreactivities detected by the PE-11 antiserum have been found to represent authentic PE-11. Sparse nerve fibers were visualized in the corneal and uveal stroma, surrounding blood vessels at the limbus, ciliary body and choroid and in association with the dilator and sphincter muscle. Furthermore, immunoreactivity was present in the corneal endothelium. In the retina and optic nerve, glia was labeled. In the rat trigeminal ganglion, PE-11-immunoreactivity was visualized in small and medium sized ganglion cells with a diameter of up to 30μm. In conclusion, there is unequivocal evidence that PE-11 is a constituent of capsaicin-sensitive sensory neurons innervating the rat eye and the distribution pattern is typically peptidergic in the peripheral innervation but in the retina completely atypical for neuropeptides and unique.
