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Aqueous humor dynamics in monkeys after topical R-DOI
B'Ann T Gabelt1, Mehmet Okka, Tom R Dean
1Ophthalmology and Visual Sciences, University of Wisconsin, Madison, Wisconsin 53792-3220, USA. btgabelt@wisc.edu
Investigative Ophthalmology & Visual Science
|November 24, 2005
Summary
R-DOI, a selective 5-HT2 agonist, significantly lowered intraocular pressure (IOP) in monkeys by increasing uveoscleral outflow (Fu) and aqueous humor formation (AHF). This study investigated R-DOI
Area of Science:
- Ophthalmology
- Pharmacology
- Physiology
Background:
- Intraocular pressure (IOP) regulation is crucial for ocular health.
- Serotonin receptors, particularly 5-HT2, are implicated in various physiological processes, including ocular dynamics.
Purpose of the Study:
- To investigate the effects of R-DOI, a selective 5-HT2 agonist, on intraocular pressure (IOP) and aqueous humor dynamics in normotensive monkeys.
Main Methods:
- Topical administration of R-DOI or vehicle to cynomolgus monkeys.
- Measurement of IOP using Goldmann applanation tonometry.
- Quantification of aqueous humor formation (AHF) via fluorophotometry and isotope dilution.
- Assessment of uveoscleral outflow (Fu) and trabecular outflow facility.
Main Results:
- R-DOI treatment led to a significant reduction in IOP (1.4-4.7 mm Hg).
- Aqueous humor formation (AHF) increased by 13% (fluorophotometry) and 30% (isotope dilution).
- Uveoscleral outflow (Fu) increased significantly by 241%, while flow to blood decreased by 28%.
Conclusions:
- R-DOI effectively lowers IOP in normotensive monkeys.
- The primary mechanism involves a significant increase in uveoscleral outflow (Fu).
- A modest increase in aqueous humor formation (AHF) also contributes to the IOP reduction.