Featured Research

from universities, journals, and other organizations

Protein Transports Nutrients Believed To Protect Against Eye Disease

Date:
July 18, 2008
Source:
Ohio State University
Summary:
Scientists have identified the protein responsible for transporting nutrients to the eye that are believed to protect against the development of age-related macular degeneration, a leading cause of vision loss in elderly Americans. The research sought to illuminate the process by which compounds called lutein and zeaxanthin move from the bloodstream to the eye.

Scientists have identified the protein responsible for transporting nutrients to the eye that are believed to protect against the development of age-related macular degeneration, a leading cause of vision loss in elderly Americans.

The research sought to illuminate the process by which compounds called lutein and zeaxanthin move from the bloodstream to the eye. Various studies have suggested that high concentrations of these two dietary compounds in particular, known as xanthophylls, have properties that can prevent macular degeneration.

These two nutrients are not made by the body and must be obtained through the diet. They are commonly found in green, leafy vegetables, such as kale, spinach, broccoli, zucchini and peas, and in yellow or orange fruits and vegetables, such as carrots, papaya, squash and peaches.

According to the study, the protein SR-B1, or scavenger receptor class B, type 1, plays a central role in transporting these nutrients from the bloodstream to cells in the eye.

“Our research to understand this mechanism might provide a greater appreciation for how one could intervene to possibly slow macular degeneration,” said senior study author Earl Harrison, Dean’s Distinguished Professor and chair of human nutrition at Ohio State University.

An estimated 10 million Americans have age-related macular degeneration, which gradually destroys sharp, central vision. The macula is located in the center of the retina, the light-sensitive tissue at the back of the eye that sends nerve signals to the brain. Deterioration of the macula blurs the central field of vision needed to drive and read. Treatment can slow vision loss, but does not restore vision, according to the National Eye Institute.

The research appears in the August issue of the Journal of Lipid Research.

Xanthophylls are a class of carotenoids, naturally occurring pigments that absorb blue light and sometimes function as antioxidants. Several studies have suggested that the ability of lutein and zeaxanthin to filter out damaging blue light, combined with their antioxidant properties, might protect against macular degeneration. The xanthophylls are known to accumulate in the macula region of the retina to form a yellow spot, and are referred to as macular pigment.

Though this xanthophyll concentration in the retina has been observed and associated with a lower risk for the disease, the cause of macular degeneration and the precise role these compounds play in protecting against vision loss remain a mystery.

But Harrison and colleagues had observed in their previous work that SR-B1 was involved when intestinal cells absorb these nutrients from the diet, and believed that the same transporter would be needed to help the nutrients travel to cells in the eye as well.

Lutein and zeaxanthin typically represent about 80 percent of the total carotenoid content of the retina, while beta-carotene, a major dietary carotenoid, is found in only trace amounts. That high concentration of one type of carotenoid over another also suggested that a specific binding protein would be involved in the absorption process, Harrison said.

The scientists worked with a line of human retinal pigment epithelial cells from the lining of the retina, which served as a model for how macula cells function. The researchers introduced to these cells three types of carotenoids typically found in eye cells – the xanthophylls lutein and zeaxanthin, as well as beta carotene.

As expected, the retinal pigment epithelial cells absorbed much more of the xanthophylls than the beta carotene. To test the role of the SR-B1 transporter, the researchers used two different methods to block the protein’s action. Under both experimental circumstances, blocking the SR-B1 protein also blocked the cells’ absorption of the two xanthophylls by between 41 percent and 87 percent compared to absorption when SR-B1 activity was not inhibited.

“It’s fairly safe to say that if you inhibit this transporter, you inhibit the uptake of xanthophylls. So that certainly suggests that this transporter is involved in that process,” Harrison said.

Harrison conducted the work with postdoctoral fellow Alexandrine During, now at the Universitι Catholique de Louvain in Belgium, and Sundari Doraiswamy, a support scientist in Harrison’s laboratory when he was at the U.S. Department of Agriculture’s Human Nutrition Research Center in Beltsville, Md.

The research was supported by grants from the National Institutes of Health.


Story Source:

The above story is based on materials provided by Ohio State University. Note: Materials may be edited for content and length.


Cite This Page:

Ohio State University. "Protein Transports Nutrients Believed To Protect Against Eye Disease." ScienceDaily. ScienceDaily, 18 July 2008. <www.sciencedaily.com/releases/2008/07/080717092037.htm>.
Ohio State University. (2008, July 18). Protein Transports Nutrients Believed To Protect Against Eye Disease. ScienceDaily. Retrieved September 2, 2014 from www.sciencedaily.com/releases/2008/07/080717092037.htm
Ohio State University. "Protein Transports Nutrients Believed To Protect Against Eye Disease." ScienceDaily. www.sciencedaily.com/releases/2008/07/080717092037.htm (accessed September 2, 2014).

Share This




More Health & Medicine News

Tuesday, September 2, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Snack Attack: Study Says Action Movies Make You Snack More

Snack Attack: Study Says Action Movies Make You Snack More

Newsy (Sep. 2, 2014) — You're more likely to gain weight while watching action flicks than you are watching other types of programming, says a new study published in JAMA. Video provided by Newsy
Powered by NewsLook.com
U.N. Says Ebola Travel Restrictions Will Cause Food Shortage

U.N. Says Ebola Travel Restrictions Will Cause Food Shortage

Newsy (Sep. 2, 2014) — The U.N. says the problem is two-fold — quarantine zones and travel restrictions are limiting the movement of both people and food. Video provided by Newsy
Powered by NewsLook.com
Doctors Fear They're Losing Battle Against Ebola

Doctors Fear They're Losing Battle Against Ebola

AP (Sep. 2, 2014) — As a third American missionary is confirmed to have contracted Ebola in Liberia, doctors on the ground in West Africa fear they're losing the battle against the outbreak. (Sept. 2) Video provided by AP
Powered by NewsLook.com
Tech Giants Bet on 3D Headsets for Gaming, Healthcare

Tech Giants Bet on 3D Headsets for Gaming, Healthcare

AFP (Sep. 2, 2014) — When Facebook acquired the virtual reality hardware developer Oculus VR in March for $2 billion, CEO Mark Zuckerberg hailed the firm's technology as "a new communication platform." Duration: 02:24 Video provided by AFP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins