Dopamine is an intermediate in tyrosine metabolism and precursor of norepinephrine and epinephrine; it accounts for 90 percent of the catecholamines; its presence in the central nervous system and localization in the basal ganglia (caudate and lentiform nuclei) suggest that dopamine may have other functions. Now a new research study reveals that the body's dopaminergic system plays a role in the regulation of retinal blood flow in the body. In addition, their data presents evidence for the diminishing effect of dopamine on the pathways coupling sensory input to vascular response.
Dopaminergic functions in the eye are complex and affect several ocular tissues. These include transmitter effects and impacts on intraocular (within the eyeball) pressure (IOP) and ocular blood flow. It is known from several tissues that vascular effects of dopamine are not only mediated via specific dopamine receptors but also by influencing other effector pathways like catecholamine receptors, a major responder to stress.
Vascular dopaminergic effects in the eye in past studies have revealed that dopamine antagonists (domperidone and haloperidol) increase ocular blood flow in rabbits. Other dopamine antagonists had similar effects, whereas dopamine agonists did not affect beating ocular blood flow. Dopamine has been investigated extensively in glaucoma research. One previous effort found that D1 agonists (when combined with receptors initiate drug action) increase pressure within the eye, where D1 antagon
Contact: Donna Krupa
American Physiological Society