Dopaminergic Modulation of Choroidal Blood Flow Changes During Dark/Light Transitions

Condition(s) targeted: Regional Blood Flow; Ocular Physiology

Intervention: Quetiapine (drug) (Drug); Sulpiride (drug) (Drug)

Phase: Phase 4

Status: Recruiting

Sponsored by: Medical University of Vienna

Official(s) and/or principal investigator(s):
Gabriele Fuchsjaeger-Mayrl, MD, Principal Investigator, Affiliation: Department of Clinical Pharmacology

Overall contact:
Gerhard Garhöfer, M.D., Phone: +43 1 40400 2981, Email: gerhard.garhoefer@meduniwien.ac.at

There is evidence from a variety of animal studies that choroidal blood flow is under neural control. By contrast, only little information is available from human studies. Recent results indicate that a light/dark transition is associated with a reduction in choroidal blood flow due to an unknown mechanism. We have shown that during unilateral dark/light transitions both eyes react with choroidal vasoconstriction strongly indicating a neural mechanism responsible for the blood flow changes.

Dopamine has been discussed as a chemical messenger for light adaptation. However, dopaminergic effects in the eye are not restricted to synaptic sites of release, but dopamine also diffuses to the outer retinal layers and pigment epithelium. Accordingly, dopaminergic effects also include a modulatory role on retinal vessel diameter and animal studies provide evidence for vasodilatory effects in the choroid. There is evidence that during darkness retinal and choroidal dopamine levels decrease. Accordingly, dopamine could provide a modulatory input to the light/dark transition induced changes of choroidal circulation. The aim of the present study is to test this hypothesis.

Official title: Dopaminergic Modulation of Choroidal Blood Flow Changes During Dark/Light Transitions

Study design: Treatment, Randomized, Double-Blind, Placebo Control, Crossover Assignment, Safety/Efficacy Study

Primary outcome:

choroidal blood flow

fundus pulsation amplitude

Minimum age: 18 Years. Maximum age: 35 Years. Gender(s): Male.

Criteria:

Inclusion Criteria:

Men aged between 18 and 35 years, nonsmokers

Body mass index between 15th and 85th percentile

Normal findings in the medical history and physical examination unless the investigator considers an abnormality to be clinically irrelevant

Normal laboratory values unless the investigator considers an abnormality to be clinically irrelevant

Normal ophthalmic findings, ametropy < 3 Dpt.

Exclusion Criteria:

Regular use of medication, abuse of alcoholic beverages, participation in a clinical trial in the 3 weeks preceding the study

Treatment in the previous 3 weeks with any drug

Symptoms of a clinically relevant illness in the 3 weeks before the first study day

History of hypersensitivity to the trial drug or to drugs with a similar chemical structure

History or presence of gastrointestinal, liver or kidney disease, or other conditions known to interfere with, distribution, metabolism or excretion of study drugs

Blood donation during the previous 3 weeks

Gerhard Garhöfer, M.D., Phone: +43 1 40400 2981, Email: gerhard.garhoefer@meduniwien.ac.at

Department of Clinical Pharmacology, Vienna 1090, Austria; Recruiting

Starting date: July 2005
Last updated: January 19, 2006