Researchers have developed a new imaging agent that could help guide and assess treatments for people with various neurological diseases, including Alzheimer’s, Parkinson’s, and multiple sclerosis. The agent, which is used in positron emission tomography (PET) scans, targets receptors in nerve cells in the brain that are involved in learning and memory. The study is featured in the April issue of The Journal of Nuclear Medicine.
Swiss and German scientists developed the new PET radioligand, 11C-Me-NB1, for imaging GluN1/GluN2B-containing N-methyl-D-aspartate (NMDA) receptors (a class of glutamate receptor) in nerve cells. When NMDA receptors are activated, there is an increase of calcium (Ca2+) in the cells, but Ca2+ levels that are too high can cause cell death. Medications that block NMDA receptors are therefore used for the treatment of a wide range of neurological conditions from depression, neuropathic pain and schizophrenia to ischemic stroke and diseases causing dementia.
“The significance of the work lies in the fact that we have for the first time developed a useful PET radioligand that can be applied to image the GluN2B receptor subunit of the NMDA receptor complex in humans,” explains Simon M. Ametamey, PhD, of the Institute of Pharmaceutical Sciences, ETH Zurich, in Switzerland. “The availability of such a PET radioligand would not only help to better understand the role of NMDA receptors in the pathophysiology of the many brain diseases in which the NMDA receptor is implicated, but it would also help to select appropriate doses of clinically relevant GluN2B receptor candidate drugs. Administering the right dose of the drugs to patients will help minimize side-effects and lead to improvement in the efficacy of the drugs.”
Neuropathic pain — which affects more than 1 million Americans — could be reduced or even eliminated by targeting brain cells that are supposed to provide immunity but, in some instances, do the opposite, causing chronic pain that could last a lifetime.
“The general thought has been that these cells are supposed to be beneficial in the nervous system under normal conditions” said Long-Jun Wu, a professor of cell biology and neuroscience at Rutgers University. “But, in fact, in those with this neuropathic pain these cells known as microglia, have proliferated and instead become toxic.”
In new research, published in both Nature Communications and Cell Reports, Wu and his team discovered that chronic neuropathic pain — caused by nerve damage as a result of an injury, surgery or a debilitating disease like diabetes or cancer — could be greatly reduced in animals if the injury was treated targeting microglia within a few days.
Opioids such as morphine, codeine and Tylenol 3 can be effective for treating pain, however, a new University of Alberta study finds that patients with neuropathic pain taking opioids report no improvements in physical functioning compared to those who were not prescribed opioids.
“We studied patients with neuropathic pain from nerve injuries such as diabetic neuropathy and pinched nerves, and the ones who weren’t prescribed any opioids had statistically lower disability and higher physical functioning scores,” says Geoff Bostick, associate professor of physical therapy at the Faculty of Rehabilitation Medicine and lead author of the study published in Pain Medicine.
The study looked at 789 patients across Canada who provided baseline measures of self-reported function, and again at six and 12 months after treatment. Adjusting for severity of the symptoms, the research showed physical functioning and disability did not improve in patients with neuropathic pain who were prescribed opioids compared with those who were not prescribed.