[11C]PS13 PET shows that age is positively correlated with constitutively expressed cyclooxygenase-1 in the brain

Cyclooxygenase-1 (COX-1), an essential enzyme in the synthesis of pro-inflammatory prostanoids from arachidonic acid, is widely expressed in the brain, primarily in microglia. Previous studies from our laboratory found that the novel positron emission tomography (PET) radioligand [11C]PS13 has excellent in vivo selectivity for constitutively expressed COX-1 in human brain. This study sought to further evaluate the effects of age and sex on levels of constitutive COX-1 expression in the brains of 56 healthy volunteers. COX-1 density in the brain measured by [11C]PS13 PET showed a significant positive correlation with age in the whole brain, as well as in regions with the highest COX-1 expression, such as the hippocampus, lateral occipital cortex, and pericentral cortex. No significant sex differences were observed in any regions. The physiological roles of COX-1 in these regions and its potential contributions to the aging process remain largely unknown, and further investigation is warranted.