RADIOPHARMACOLOGY 

The Quarterly Journal of Nuclear Medicine 2001 June;45(2):124-38

Copyright © 2009 EDIZIONI MINERVA MEDICA

language: English

Vulnerability of Positron Emission Tomography radiotracers to endogeneous competition. New insights

Laruelle M., Huang Y.

From the Departments of Psychiatry and Radiology, Columbia University College of Physicians and Surgeons, and New York State Psychiatric Institute, New York, NY, USA

PET and ­SPECT neu­ro­re­ceptor ­imaging tech­niques com­bined ­with phar­mac­o­log­ical chal­lenges ­have ­been intro­duced to ­measure ­acute fluc­tu­a­tions of syn­aptic dop­a­mine (DA) con­cen­tra­tions in the ­living ­human ­brain. ­Changes in the in ­vivo ­binding of radio­lig­ands fol­lowing manip­u­la­tion of trans­mitter ­levels are gen­er­ally ­believed to be ­driven by ­binding com­pe­ti­tion ­between the radio­ligand and neu­ro­trans­mitter. ­This ­imaging ­modality has ­been ­very suc­cessful in the ­study of DA trans­mis­sion at D2 recep­tors. Yet, the exten­sion of ­this tech­nique to the ­study of ­other neu­ro­trans­mitter ­systems has ­proven dif­fi­cult. ­This ­paper ­reviews ­recent evi­dence sug­gesting ­that ­simple ­binding com­pe­ti­tion ­might not be the ­only phe­nom­enon reg­u­lating trans­mitter-radio­ligand inter­ac­tions in ­vivo, and exam­ines ­emerging ­data indi­cating ­that ­receptor traf­ficking ­might ­also be ­involved. A ­better under­standing of the mech­a­nisms under­lying ­these inter­ac­tions ­should facil­i­tate the devel­op­ment of PET and ­SPECT radio­tracers suit­able for the ­reporting of syn­aptic trans­mitter ­levels.