 This is a subject blind, investigator and sponsor open, randomized study consisting of 2 parts. Up to 15 healthy subjects will be included in the study. In the first part of the study the test retest reliability of the radiotracer 11C PF 04767135 binding in man will be assessed. In the second part of this study, using 11C PF 04767135, kappa opioid receptor occupancy RO will be assessed in up to three cohorts of subjects. 