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Ocular effects of adrenomedullin
T Taniguchi1, K Kawase, Z B Gu
1Department of Ophthalmology, Gifu University School of Medicine, Gifu, Japan.
Experimental Eye Research
|November 5, 1999
Summary
Adrenomedullin (AM), a vasodilator peptide, is expressed in the eye and lowers intraocular pressure (IOP) through specific AM receptors. This suggests AM plays a role in regulating ocular pressure.
Area of Science:
- Ophthalmology
- Endocrinology
- Pharmacology
Background:
- Adrenomedullin (AM) is a novel vasodilator peptide with potential physiological roles.
- The presence and function of AM within the ocular system were previously uncharacterized.
Purpose of the Study:
- To investigate the expression of adrenomedullin (AM) in the eye.
- To determine the effects of AM on intraocular pressure (IOP) and related parameters.
Main Methods:
- AM mRNA expression was analyzed in rat iris-ciliary body via RT-PCR.
- Intraocular pressure (IOP) was measured in rabbits following intravitreal injections of AM.
- Receptor antagonist studies were conducted using AM-(22-52) and CGRP-(8-37) to elucidate AM's mechanism of action.
Main Results:
- AM mRNA was detected in the rat iris-ciliary body.
- Intravitreal AM administration dose-dependently reduced IOP in rabbits, with effects observed 4-8 hours post-injection.
- The ocular hypotensive effect of AM was primarily mediated by specific AM receptors, as evidenced by blockade with AM-(22-52).
Conclusions:
- Adrenomedullin is expressed in the iris-ciliary body and exerts a significant ocular hypotensive effect.
- AM lowers IOP mainly through interaction with specific AM receptors.
- These findings suggest a potential role for AM in the physiological regulation of intraocular pressure.