Existing methods of spotting the presence of specific molecules in the brain requires using chemical or radioactive markers. These can have side effects for patients, at times be difficult to acquire and use, and they’re limited in their spatial and temporal resolutions. Now scientists at MIT have come up with an entirely new method of imaging molecules that uses targeted proteins and MRI to get a quality picture of activity inside the brain.
The proteins were designed to hold onto a peptide called calcitonin gene-related peptide (CGRP). CGRP is involved in migraines and inflammation, dilating blood vessels as it passes through. The protein/peptide packages are designed to open up when in the presence of proteases, the target molecules the researchers were looking for, and release the CGRP. Since the peptide is released wherever the proteases are present, nearby vessels begin to dilate. This change in blood flow can be spotted using MRI, revealing the location of the target protease molecules.
The same technique is now being translated to target neurotransmitters like dopamine and serotonin. This will require engineering new protein structures that hold onto CGRP and break down when a specific neurotransmitter is present.
From the study abstract in Nature Communications:
Variants of the calcitonin gene-related peptide artificially activate vasodilation pathways in rat brain and induce contrast changes that are readily measured by optical and magnetic resonance imaging. CGRP-based agents induce effects at nanomolar concentrations in deep tissue and can be engineered into switchable analyte-dependent forms and genetically encoded reporters suitable for molecular imaging or cell tracking. Such artificially engineered physiological changes, therefore, provide a highly versatile means for sensitive analysis of molecular events in living organisms.
Open access study in Nature Communications: Molecular imaging with engineered physiology…