We may live in the 21st century, but it appears that the traditional or ancient medicines of Asia may be key preventing the ravaging effects of retinal degenerations that can ultimately cause blindness.
Researchers at Emory Eye Center have found that a synthetic version of bear bile, which has been used in Asia for more than 3,000 years to treat visual disorders, has the potential to treat age-related macular degeneration (AMD), retinitis pigmentosa (RP), and glaucoma. The results of their recent study were published Dec. 29, 2006 in Molecular Vision (http://www.molvis.org/molvis).
Principal Investigator Jeffrey Boatright, PhD and others at Emory University, the Atlanta VA Medical Center, the University Minnesota, and the University of Lisbon found that systemic injection of synthetic tauroursodeoxycholic acid (TUDCA), a primary component of bear bile, prevents programmed cell death (apoptosis) and preserves function and structure of retinal photoreceptor cells in two different mouse models of human retinal degeneration.
In ancient Asian medicine, the bile liquid within bear gall bladders was called a bitter, "cold" medicine and was used for detoxifying the liver, dissolving kidney stones and gallstones, relieving convulsions and improving vision. Today, this medicine is still used in eye drops in traditional Asian medicine.
Western scientific evidence now indicates that synthetic formulations of bear bile are medically efficacious. The researchers at Emory state that this is the first controlled, experimental proof of the ophthalmic efficacy of a component of bear bile. They underscore that the compounds tested are synthetic, relatively inexpensive, and do not come from bears.
The importance of the findings to ophthalmologists is underscored because many forms of intractable blindness result from apoptotic neurodegeneration. In addition, the synthetic bile acids are inexpensive and well-tolerated at high doses in humans. Currently, the bile acid is approved for use by the U.S. Food and Drug Administration (FDA) and the MHRA (Medicines and Healthcare products Regulatory Agency, UK), as well as regulatory agencies in many other countries.
Dr. Boatright and his co-authors are hopeful that their results in these two very different animal models will lead to clinical trials and eventual use in treatment of AMD, RP, glaucoma, and other diseases involving apoptosis that lead to blindness.
Background AMD: The disease, which typically strikes those over 65, is the leading cause of blindness in the United States. It leads to loss of central vision in those affected and can lead to complete loss of vision.
RP: The disease, which strikes 1 in 3,700, is comprised of hereditary and progressive conditions that begin with loss of night vision, progresses to a loss of peripheral vision and then to "tunnel vision," finally resulting in blindness.
Glaucoma: a group of diseases that result in damage to the optic nerve and often blindness. About 1 in 136 or 2 million people in USA are afflicted with some form of glaucoma.
Photoreceptor cells: The cells of the retina that capture light and convert it into electrochemical signals that are interpreted by the brain as "vision". There are two types: rods and the cones. Rod photoreceptors are sensitive in dim lighting. Cone photoreceptors detect color and work in brighter light. Photoreceptor cells die by apoptosis in diseases such as AMD and RP.
Apoptosis: Also known as "programmed cell death". A normal mechanism the body uses to control cell number. However, in disease states such as AMD or RP, useful cells die via this mechanism. A recognized strategy to slow or stop disease progression is to inhibit apoptosis.