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Ghrelin and obestatin decreases the IOP in a acute glaucoma model
Author(s) -
ROCHA DE SOUSA AA,
TAVARESSILVA M,
PEREIRASILVA P,
AZEVEDO PINTO S,
RODRIGUESARAUJO J,
LEITEMOREIRA AF
Publication year - 2011
Publication title -
acta ophthalmologica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.534
H-Index - 87
eISSN - 1755-3768
pISSN - 1755-375X
DOI - 10.1111/j.1755-3768.2011.3326.x
Subject(s) - ghrelin , obestatin , glaucoma , intraocular pressure , endocrinology , medicine , chemistry , hormone , ophthalmology
Purpose The aim of this study is to evaluate the effect of the pro‐ghrelin derived peptides in the intra‐ocular pressure in animal models of acute glaucoma. Methods The first part of the experimental protocol was the calibration of the Tonovet® used to measure the IOP. In the second part of the protocol we studied, in a rabbit model of acute glaucoma, the effects of ghrelin (10‐4M, n=6), des‐acyl‐ghrelin (10‐4M, n=7) and obestatin (10‐4M, n=7), as well as the subcellular pathways involved. This model was achieved with an intra‐vitreal injection of 20% NaCl. Then, one of the three peptides was sub‐conjunctivally injected. Concerning the subcellular pathways, keterolac (a COX inhibitor; 30mg/ml; 500microl; n=7) and L‐NAME (a NO synthase inhibitor; 150mg/Kg; 500 microl; n=11) were sub‐conjunctivally injected previously to both NaCl and ghrelin injection. All the results were compared to a control group which did not receive ghrelin, des‐acyl‐ghrelin or obestatin. Results There is a linear correlation between the IOP measured by the Tonovet (Y) and its real value (X), being that underestimated (Y= ‐0,331 + 0,750X). Our results show that the NaCl injection increases the IOP from 9.9 ± 1.9 to 44.9 ± 4.1. After that ghrelin promotes a decrease of 20,8 ± 5,0 mmHg (decrease of 47,9 ± 11,6%); obestatin promotes a maximal decrease of 15,8 ± 3,9 mmHg (decrease of 37,5 ± 9,4%), while des‐acyl‐ghrelin does not significantly change IOP. When keterolac or L‐NAME are added, ghrelin’s effect is completely blunted. Conclusion Ghrelin showed to promote a decrease of the intra‐ocular pressure, independently from GHSR‐1a and dependently on NO and prostaglandins. Obestatin also promotes a decrease in the IOP.