Ghrelin’s expression in the eye and its implication in the reduction of intraocular pressure

Abstract

AbstractPurpose To investigate ghrelin’s and GHSR‐1 distribution in the rat’s ocular tissue and ghrelin’s role in the modulation of IOP in animal models of acute glaucoma.Methods Immunolocalization of ghrelin and GHSR‐1 was performed in male Wistar rats (200–300g). Acute glaucoma was induced in male New Zealand white rabbits (2,0‐3,0Kg) and male Wistar rats (200–300g) through an intravitreous injection of 20% NaCl. Afterwards either ghrelin or des‐acyl ghrelin was subconjunctivaly injected. In the rabbit, ghrelin’s effect in the presence of L‐NAME or ketorolac.Results Ghrelin and GHSR‐1 were detected in the rat’s eye, being ghrelin expressed in the ciliary processes, having co‐localization with lectin, an endothelial cell marker, been also verified. GHSR‐1 expression was detected in the base of the ciliary body and in the choroid, presenting focal co‐localization with α‐smooth muscle actin. Ghrelin, but not des‐acyl ghrelin, decreased the IOP in rabbit’s and rat’s glaucomatous eyes (maximal percentual decrease relative to peak versus control in rabbit: 65,9±12,4%; maximal percentual decrease relative to peak versus control in rat:27,45±4,8%). In the rabbit, this effect was blunted in the presence of L‐NAME and ketorolac.Conclusion Ghrelin and GHSR‐1 are expressed in the rat’s eye. Ghrelin promoted a decrease in the IOP of rat’s and rabbit’s glaucomatous eyes. These data suggest a role for ghrelin in the pathophysiology of glaucoma. Commercial interest