Nerve cells and blood vessels engage in a chemical discussion to keep healthy and avoid disease, according to a new study.
The findings could lead to ways to prevent eyesight loss in diabetes and macular degeneration - and could even provide a ‘window to the brain' and its complex biochemistry, the Scripps Research Institute scientists said.
"This is fascinating," said Peter Westenskow, one of the authors of the new report. "The signals from these cells are fine-tuning this layer of the vasculature."
The target area of the study was the second of four layers in the retina of the eye. In that layer, a transcription factor called hypoxia-inducible factor, of HIF, responds at times of low oxygen and blood flow to trigger the production of a chemical known as VEGF. VEGF, in turn, jump-starts the growth of new blood vessels, the Scripps researchers said.
Unfortunately, that process can lead to overgrowth in the blood vessels, causing leaking blood and other fluids - and for some patients, macular degeneration and diabetes-related vision loss, said Martin Friedlander, senior author of the study. Diabetic retinopathy alone affects some 7.7 million Americans, experts say.
Other studies dating back to the 1990s investigated this interaction between HFI and VEGF. But for the first time, the researchers pinpointed the neurons that were transmitting the electrical signals to the brain causing the two entities to "talk" to one another, they said. Those neurons were the amacrine cells and horizontal cells, the researchers found. Taken together, the experiments outlined how the cells communicated to strike a balance - providing enough blood to the eye, while avoiding overgrowth of blood vessels, they found. Using lab mice and genetic manipulation, they proved that tipping the balance either way would adversely affect the animals' vision, they said.
"The retina has a very sophisticated architecture," said Friedlander. "If you have a little extra fluid, some swelling or a few dead cells, light isn't going to come through correctly and vision can be impaired."
The complex interaction could provide a "window into the brain" and its complicated chemistry - particularly when it comes to diseases such as Alzheimer's, Parkinson's, and amyotrophic lateral sclerosis, or ALS.
"For example, patients with Alzheimer's get protein deposits in the brain, and we can see similar deposits in the backs of the eyes of patients who have macular degenerations," said Friedlander. "If we can better understand what leads to accumulations of these abnormal proteins in the eye, that will hopefully also give us insight into how the brain works."
Source: Drug Discovery & Development