title: Effects of dopamine D-1 and D-2 receptors on intraocular pressure in conscious rabbits.
abstract: This investigation was designed as a randomized, placebo-controlled, double-masked, crossover study in NZW rabbits with normal intraocular pressure (IOP) to investigate dopaminergic effects on IOP. SKF 38393, a selective D1-receptor agonist, increased, and SDZ PSD-958, a selective D1-receptor antagonist, decreased IOP, respectively. The selective D2-receptor agonist quinpirole decreased IOP, whereas the selective D2 receptor antagonist metoclopramide had no significant effect. Combinations of quinpirole with SDZ PSD-958 decreased IOP in an additive manner. SDZ GLC-756, a mixed D1-receptor antagonist/D2-receptor agonist, decreased IOP in a dose-dependent manner with a maximum effect greater than the maximum effects produced either by the D1-receptor antagonist SDZ PSD-958 and the D2-receptor agonist quinpirole. The effect of SDZ GLC-756 could only be partially blocked by the selective D2-receptor antagonist metoclopramide suggesting that both D1-receptor blockade and D2-receptor stimulation participate in its IOP-lowering effect. Tonography suggests that SDZ GLC-756 has no significant effect on outflow facility. Furthermore, the results suggest that both D1 and D2 receptors each play an independent role in the regulation of IOP in rabbits. Thus, simultaneous blockade of D1 receptors and stimulation of D2 receptors may provide a new pharmacological approach for the treatment of ocular hypertension frequently associated with glaucoma.
authors.affiliation: University Eye Clinic, Basel, Switzerland.
authors.forename: C
authors.initials: C
authors.lastname: Prünte
authors.forename: I
authors.initials: I
authors.lastname: Nuttli
authors.forename: R
authors.initials: R
authors.lastname: Markstein
authors.forename: C
authors.initials: C
authors.lastname: Kohler
mesh_terms: D015647:2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine / Q000494:pharmacology; D000818:Animals; D001082:Aqueous Humor / Q000187:drug effects; D018491:Dopamine Agonists / Q000494:pharmacology; D018492:Dopamine Antagonists / Q000494:pharmacology; D065127:Dopamine D2 Receptor Antagonists; D004305:Dose-Response Relationship, Drug; D005260:Female; D015590:Fluorophotometry; D007429:Intraocular Pressure / Q000187:drug effects*; D011680:Pupil / Q000187:drug effects; D011804:Quinolines / Q000494:pharmacology; D011810:Quinoxalines / Q000494:pharmacology; D011817:Rabbits; D017447:Receptors, Dopamine D1 / Q000819:agonists* / Q000037:antagonists & inhibitors*; D017448:Receptors, Dopamine D2 / Q000819:agonists*
chemical_list: D018491:Dopamine Agonists; D018492:Dopamine Antagonists; D065127:Dopamine D2 Receptor Antagonists; D011804:Quinolines; D011810:Quinoxalines; D017447:Receptors, Dopamine D1; D017448:Receptors, Dopamine D2; C102871:SDZ GLC 756; C104716:SDZ PSD 958; D015647:2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine