Dopamine- 3 receptor modulates intraocular pressure: Implications for glaucoma

Abstract

The aim of the present study was to investigate the role of D 3 receptor on intraocular pressure regulation using WT and KO D 3R −/− mice. Both mice were used with normal eye pressure or steroid-induced ocular hypertension. As measured by tonometry, the topical application of 7-OH-DPAT, a dopamine D 3-preferring receptor agonist, significantly decreased, in a dose-dependent manner, the intraocular pressure in WT mice both in an ocular normotensive group and an ocular hypertensive group. Pretreatment with U-99194A, a D 3 receptor antagonist, reverted 7-OH-DPAT induced ocular hypotension in WT mice. No change of intraocular pressure was observed after topical application of 7-OH-DPAT in KO D 3R −/− mice. PCR analysis demonstrated the presence of all dopamine receptor genes in eye tissues obtained from WT mice, and the lack of D 3R mRNAs in KO mice. The present study identified the D 3R subtype as the most important receptor of the dopaminergic system to modulate intraocular pressure with relevant implications for glaucoma that represents one of the most crippling optic neuropathies.