Pain medicine helps preserve vision in model of inherited retinal degeneration

A pain medicine that potently activates a receptor vital to a healthy retina appears to help preserve vision in a model of severe retinal degeneration, scientists report.
Potentially blinding diseases such as retinitis pigmentosa and macular degeneration result in the loss of photoreceptor cells in the retina that enable us to convert light into images.
The study, in the journal Proceedings of the National Academy of Sciences, shows that in an animal model of severe, inherited retinal degeneration, the drug (+)-pentazocine enables the survival of cone cells, a type of photoreceptor cell that gives us detailed, color vision, said Dr. Sylvia Smith, chair of the Department of Cellular Biology and Anatomy at the Medical College of Georgia at Augusta University.
There was a “striking” preservation of cone function in affected mice treated with (+)- pentazocine, said Smith, retinal cell biologist and the study’s corresponding author. In fact, cone function was essentially the same as in normal mice, while vision loss progressed as expected in untreated mutant mice.
By day 42, when vision should have been lost, several layers of photoreceptor cells were still clearly visible in the treated mice and the vast majority of those cells were cones. Mice lacking sigma receptor 1 did not benefit from (+)- pentazocine treatment, more evidence of the receptor’s essential role in retinal protection, Smith said. Treated mice also had evidence of reduced oxidative stress.
While it might not be the drug of choice for patients with these problems, the scientists knew that (+)- pentazocine, a proven pain reliever that appears to have potential as well for improving a failing memory, was a potent activator of the sigma 1 receptor.
While work remains on exactly what it does, overactivating the sigma receptor with the drug likely increases activity of the natural anti-oxidative protein Nrf2, and potentially other mechanisms to better protect cells, said Smith.
They also have evidence that treatment decreases inflammation, which often accompanies oxidative stress, as well as stress on the endoplasmic reticulum, an important organelle that helps the body make, fold and transport proteins including eliminating badly folded ones that don’t function as they should………
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source: Medical Xpress