Katrin Andreasson, M.D., an assistant professor in the neurology and neuroscience departments at Hopkins, and lead author of the study, explains that the recent discoveries of cardiovascular complications with long-term use of some COX-2 inhibitors are thought to be due to blocking effects of "good" prostaglandins, which are the downstream products of COX activity, potentially leading to heart attacks and strokes. "Defining which prostaglandin pathways are good and which promote disease would help to design more specific therapeutics," she says.
In their latest laboratory studies, the Hopkins scientists discovered that the prostaglandin PGD2 has a protective or harmful effect in the brain depending on where it docks on a brain cell's surface. After brain cells experience the laboratory equivalent of a stroke, PDG2 can protect them from being killed if it binds to one docking point, or receptor, on the cells' surface, but causes them to die in greater numbers if it binds to a second receptor instead, the researchers report. Prostaglandins are involved in a wide variety of bodily activities including relaxation and contraction of muscles and blood vessels, control of blood pressure and inflammation.
"PGD2 is the most-produced prostaglandin in the brain," says Andreasson. "It trumps all of the rest. So we theorized that high levels are protective. But it was a surprise that it was so effective at protecting neurons."
Because the Hopkins team found that PGD2's positive effects generally outweigh its negative ones, the group speculates that PGD2 may provide a potential target
Contact: Joanna Downer or Katherine Unger
Johns Hopkins Medical Institutions