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

Medical University of Vienna

Status: Completed

Conditions: Regional Blood Flow; Ocular Physiology

Treatments: Drug: Quetiapine (drug); Drug: Sulpiride (drug); Drug: Placebo

Study type: Interventional

Funder types: Other

Identifiers

NCT00280501

OPHT-160905

Details and patient eligibility

About

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.

Enrollment: 21 patients

Sex: Male

Ages: 18 to 35 years old

Volunteers: Accepts Healthy Volunteers

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, ametropia < 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

Trial design

Primary purpose: Treatment

Allocation: Randomized

Interventional model: Crossover Assignment

Masking: Double Blind

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21 participants in 3 patient groups, including a placebo group

1

Active Comparator group

Description:

Quetiapine

Treatment:

Drug: Placebo

Drug: Sulpiride (drug)

Drug: Quetiapine (drug)

2

Active Comparator group

Description:

Sulpiride

Treatment:

Drug: Placebo

Drug: Sulpiride (drug)

Drug: Quetiapine (drug)

3

Placebo Comparator group

Description:

Placebo

Treatment:

Drug: Placebo

Drug: Sulpiride (drug)

Drug: Quetiapine (drug)