Age and gender effects of 11 C-ITMM binding to metabotropic glutamate receptor type 1 in healthy human participants.

We examined possible age- and gender-related changes in binding of the selective antagonist N-[4-[6-(isopropylamino)pyrimidin-4-yl]-1,3-thiazol-2-yl]-4-11 C-methoxy-N-methylbenzamide (11 C-ITMM) to metabotropic glutamate receptor type 1 in healthy human brains. Dynamic 11 C-ITMM positron emission tomography scans (90 min) with serial arterial blood sampling were performed in 15 young and 24 older healthy adult volunteers. The total distribution volume (VT ) of several brain regions was estimated with 2-tissue compartment model analysis. The VT s of the cerebellar cortex, parietal cortex, putamen, amygdala, and hippocampus in older adult participants were significantly higher than in young participants. The age-related VT increase was only observed in male participants. Our data suggest that an age-dependent increase in metabotropic glutamate receptor type 1 availability in several brain regions may exist predominantly in males.