Sex differences in [ 11 C]ABP688 binding: a positron emission tomography study of mGlu5 receptors

Purpose The purpose of this study was to assess, in a large sample of healthy young adults, sex differences in the binding potential of [ 11 C]ABP688, a positron emission tomography (PET) tracer selective for the metabotropic glutamate type 5 (mGlu5) receptor. Methods High resolution [ 11 C]ABP688 PET scans were acquired in 74 healthy volunteers (25 male, 49 female, mean age 20 ± 3.0). Mean binding potential (BP ND = f ND * (B avail / K D )) values were calculated in the prefrontal cortex, striatum, and limbic regions using the simplified reference tissue model with cerebellar grey matter as the reference region. Results [ 11 C]ABP688 BP ND was significantly higher in men compared to women in the prefrontal cortex ( p < 0.01), striatum ( p < 0.001), and hippocampus ( p < 0.05). Whole-brain BP ND was 17% higher in men. BP ND was not related to menstrual phase in women. Conclusions Binding availability of mGlu5 receptors as measured by PET [ 11 C]ABP688 is higher in healthy men than women. This likely represents a source of variability in [ 11 C]ABP688 studies and could have relevance for sex differences in cognitive-behavioral functions and neuropsychiatric disorders.