New PET imaging agent may help assess, treat brain diseases

By Allen Cone
These rat brain PET images, using the 11C‐Me‐NB1 imaging agent, are superimposed on an MRI template. Photo courtesy of ETH Zurich
These rat brain PET images, using the 11C‐Me‐NB1 imaging agent, are superimposed on an MRI template. Photo courtesy of ETH Zurich

April 2 (UPI) -- A new imaging agent for positron emission tomography, or PET, scans could help assess and treat people with various neurological diseases, including Alzheimer's and Parkinson's diseases and multiple sclerosis, according to new research.

Researchers in Switzerland and Germany found the drug agent targets receptors in nerve cells in the brain linked to learning and memory. The study was published Monday in the Society of Nuclear Medicine and Molecular Medicine's The Journal of Nuclear Medicine.


Using live rats, scientists developed the radioligand, 11C‐Me‐NB1, for imaging containing N-methyl-D-aspartate receptors, which are a class of glutamate receptors in nerve cells.

When NMDA receptors are activated, calcium increases in the cells -- and they can cause cell death when too high.

Medications are used to block NMDA receptors for the treatment of a wide range of neurological conditions, including depression, neuropathic pain, schizophrenia, ischemic stroke and diseases causing dementia.

The finding, researchers say, could be a boon to research on brain disorders.

"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," Dr. Simon M. Ametamey, a researcher at the Institute of Pharmaceutical Sciences at ETH Xurich university in Zurich, Switzerland, said in a press release. "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."


The scientists tested C-Me-NB1 to check the dosage and effectiveness of the drug eliprodil in rats in the study. The drug, an NMDA antagonist, has been used in clinical trials for the treatment of Parkinson's disease and other movement disorders.

They found PET scans with the new radioligand successfully showed that the receptors are fully occupied at acceptable doses, according to the National Institutes of Health.

The tool joins the list of existing PET radiopharmaceuticals used in imaging studies.

"These results mean that a new radiopharmaceutical tool is now available for studying brain disorders such as Alzheimer`s disease, Parkinson`s disease and multiple sclerosis, among others," Ametamey said. "Furthermore, future imaging studies using this new radioligand would throw more light on the involvement of NMDA receptors, specifically the GluN2B receptors, in normal physiological processes such as learning and memory, as well as accelerate the development of GluN2B candidate drugs currently under development."

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