11C-verapamil to Assess P-gp Function in Human Brain During Aging,Depression and Neurodegenerative Disease

P-glycoprotein (P-gp) at the blood-brain barrier (BBB) functions as an active efflux pump by extruding a wide range of substrates from the brain. This is important for maintaining loco-regional homeostasis and for protecting the brain against blood-borne toxic substances. Altered P-gp function seems to be involved in the pathophysiology of neurodegenerative disease and various neurological and psychiatric disorders. Positron emission tomography (PET) with the radiotracer 11C-verapamil (VPM-PET) is a validated technique allowing measurement of P-gp function at the human BBB. In this review, we highlight changes of P-gp function, as measured with VPM-PET, in aging and in the pathogenesis and progression of neurodegenerative disease, as well as their role in depressive disorders.