http://www.nitrc.org/forum/forum.php?forum_id=5567 <table border="0" width="100%"><tr><td align="left"/></tr></table> <p><b>Imaging Agonist-Induced D2/D3 Receptor Desensitization and Internalization in vivo with PET/fMRI.</b></p> <p>Neuropsychopharmacology. 2015 Sep 21;</p> <p>Authors: Sander CY, Hooker JM, Catana C, Rosen BR, Mandeville JB</p> <p>Abstract<br/> This study investigated the dynamics of dopamine receptor desensitization and internalization, thereby proposing a new technique for non-invasive, in vivo measurements of receptor adaptations. The D2/D3 agonist quinpirole, which induces receptor internalization in vitro, was administered at graded doses in a non-human primate model while imaging with simultaneous PET and fMRI. A pronounced temporal divergence between receptor occupancy and fMRI signal was observed: Occupancy remained elevated while fMRI responded transiently. Analogous experiments with an antagonist (prochlorperazine) and a lower-affinity agonist (ropinirole) exhibited reduced temporal dissociation between occupancy and function, consistent with a mechanism of desensitization and internalization that depends upon drug efficacy and affinity. To describe the data, we postulate a model that incorporates internalization into the neurovascular-coupling relationship. This model yielded in vivo desensitization/internalization rates (0.2 min(-1) for quinpirole) consistent with published in vitro measurements. Overall, these results suggest that simultaneous PET/fMRI enables characterization of dynamic neuroreceptor adaptations in vivo, and may offer a first non-invasive method for assessing receptor desensitization and internalization.Neuropsychopharmacology accepted article preview online, 21 September 2015. doi:10.1038/npp.2015.296.<br/> </p><p>PMID: 26388148 [PubMed - as supplied by publisher]</p> en-us Copyright 2000-2026 NITRC OSI Sun, 03 May 2026 16:25:16 GMT http://blogs.law.harvard.edu/tech/rss NITRC RSS generator