Zwitterionic neurotransmitter-sensitive gadolinium complex as a potential MRI contrast agent for Alzheimer's disease diagnosis

An imbalance in neurotransmitters (NTs) is associated with the progression of Alzheimer's disease (AD). Glutamate (Glu), a zwitterionic NT, is strongly associated with AD and is highly concentrated in the brain. Therefore, Glu is a good target for the diagnosis of AD using magnetic resonance imaging (MRI). In the current study, we synthesized a gadolinium-based MR contrast agent (Gd-crown) that could detect Glu. Relaxivity measurements showed that Gd-crown has selectivity for zwitterionic NTs including Glu. Furthermore, Gd-crown was successfully used to monitor MRI signal differences between APP/PS1 transgenic AD mice and normal mice according to the concentrations of Glu in MRI experiments in vivo.