INDIANAPOLIS --Indiana University School of Medicine researchers have shown that optic lens cells may be added to the growing list of parts of the body found to be sensitive to the hormone estrogen.
Lens cells have receptors for estrogen, adding further evidence to epidemiological research showing that estrogen may play a role in preventing cataracts in aging women. The new work was published in the August 3 issue of Proceedings of the National Academy of Science. Robert M. Bigsby, Ph.D., associate professor of obstetrics and gynecology is the lead author.
In the study, researchers removed the ovaries of rats before treating them with methylnitrosourea, a carcinogenic compound that causes breast cancer in laboratory animals.
The rats were divided into groups that received no estrogen, estradiol (the predominant natural estrogen in pre-menopausal women) or estrone (the predominant natural estrogen in post-menopausal women).
Within six to eight months, 74 percent of the rats receiving no estrogen developed a type of cataract similar to age-related cataracts seen in humans. Only 12 percent of the rats treated with estradiol and 25 percent of those treated with estrone developed cataracts.
"This experimental model gives credence to the epidemiological studies that estrogens are protective against cataracts," said Dr. Bigsby.
Seventy-five percent of people over the age of 75 exhibit some degree of cataracts. It is estimated that more than 50 percent of cases of blindness are caused by cataracts. Age-related cataracts affect more women than men, and one study of women with early onset of menopause showed a 2.9-fold risk of developing cataracts.
"We now have an animal model system that will allow us to determine if the different types of estrogens used in post-menopausal hormone replacement therapy will also prove protective against cataracts," Dr. Bigsby said.
Journal
Proceedings of the National Academy of Sciences