Beyond Monoamines: The Role of the Nociceptin/Orphanin FQ Receptor in Major Depression

Electrotactile stimulation will be used as the aversive stimulus. The aversive stimulus is delivered in the form of a mild half-second stimulation to the ankle, calibrated to a subjective threshold that is uncomfortable but not painful. This stimulation is delivered by Digitimer DS8R Constant Current Stimulator (Digitimer North America, LLC. Ft. Lauderdale, FL). Its previous model DS71 has been safely implemented in studies with previously MGH-approved IRB's (Milad et al., 2013).

"A Nociceptin/Orphanin FQ (N/OFQ) peptide tracer (\[11C\] NOP-1A) will be used as the PET radiotracer. Approximately 10 mCi of this tracer will be delivered intravenously as a slow bolus over 60 seconds with beginning of the PET imaging acquisition. Approximately 60 ml of blood will be drawn from an artery throughout the dynamic PET acquisition in order to measure the blood N/OFQ levels."