The Effect of 5HT(3) Receptor Agonist on Intraocular Pressure and Pupil Diameter in Rabbits

ABSTRACT

PURPOSE: The effects of 5HT3 receptor agonist and antagonist on rabbit intraocular pressure (IOP) and pupil size were evaluated. METHODS: A 5HT3 receptor agonist, I-Phenylbiguanide (PBG, 1%) and a 5HT3 receptor antagonist, 3-Tropanyl-indole-carboxylate methiodide (ICS-205,930) were applied topically to the rabbit eye, and intraocular pressure and pupil diameter were checked with a Tono-PenTM XL and a ruler. RESULTS: Topical application of 1% PBG significantly increased IOP by 4.6+/-1.2 mmHg (p<0.001) over a period of up to 2 hours, the IOP maximum reached at 1 hour and caused pupil dilatation by 3.3+/-0.3mm (p<0.001) over a period of up to 5 hours, the dilation maximum reached at 2 hour. Topical preadministration of 1% ICS-205,930 prevented a rise in IOP but did not counteract on the pupil dilatation brought about by 5HT3 receptor agonist. CONCLUSIONS: These findings indicate that topically applied 5HT3 receptor agonist could raise IOP and dilate pupil.