Bethesda, MD -- The primary function of the retina is to capture light and initiate neural signals. The retina contains the photoreceptors, which are the site of sensory transduction in the visual pathway. Major landmarks in the retina are the fovea and macula, where light has a direct pathway to the receptors. An interruption of the blood supply to these landmarks can lead to age-related macular degeneration and diabetes, the cause of severe visual problems.

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
djkrupa1@aol.com
703-527-7357
American Physiological Society
12-Feb-2003

Page: 1 2 3 4
Related biology news :

1. Research suggests new avenue for stopping, preventing colon cancer
2. Data show investigational antibiotic safe, effective in preventing travelers diarrhea
3. NIH told regular and moderate exposure to sunlight is the key to preventing chronic disease
4. Study points to new gene therapy tool in preventing epileptic seizures
5. Brain reserve capacity and its role in preventing clinical signs of Alzheimers disease studied
6. Vitamin D may be crucial in preventing colon cancer
7. Conference focuses on practical strategies for preventing and treating obesity
8. Cancer-preventing gene protects against stress and extends life span in worms
9. New protein may play role in preventing malignant change in cells
10. Researchers develop new method for preventing hip dysplasia in dogs
11. Vitamin K intake may be helpful in preventing hip fracture