{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,5,23]],"date-time":"2025-05-23T16:05:31Z","timestamp":1748016331693},"reference-count":43,"publisher":"Wiley","issue":"4","license":[{"start":{"date-parts":[[2007,1,17]],"date-time":"2007-01-17T00:00:00Z","timestamp":1168992000000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Synapse"],"published-print":{"date-parts":[[2007,4]]},"abstract":"<jats:title>Abstract<\/jats:title><jats:p>In positron emission tomography and single photon emission computed tomography studies using D2 dopamine (DA) receptor radiotracers, a decrease in radiotracer binding potential (BP) is usually interpreted in terms of increased competition with synaptic DA. However, some data suggest that this signal may also reflect agonist (DA)\u2010induced increases in D2 receptor (D2R) internalization, a process which would presumably also decrease the population of receptors available for binding to hydrophilic radioligands. To advance interpretation of alterations in D2 radiotracer BP, direct methods of assessment of D2R internalization are required. Here, we describe a confocal microscopy\u2010based approach for the quantification of agonist\u2010dependent receptor internalization. The method relies upon double\u2010labeling of the receptors with antibodies directed against intracellular as well as extracellular epitopes. Following agonist stimulation, DA D2R internalization was quantified by differentiating, in optical cell sections, the signal due to the staining of the extracellular from intracellular epitopes of D2Rs. Receptor internalization was increased in the presence of the D2 agonists DA and bromocriptine, but not the D1 agonist SKF38393. Pretreatment with either the D2 antagonist sulpiride, or inhibitors of internalization (phenylarsine oxide and high molarity sucrose), blocked D2\u2010agonist induced receptor internalization, thus validating this method in vitro. This approach therefore provides a direct and streamlined methodology for investigating the pharmacological and mechanistic aspects of D2R internalization, and should inform the interpretation of results from in vivo receptor imaging studies. Synapse 61:231\u2013241, 2007. \u00a9 2007 Wiley\u2010Liss, Inc.<\/jats:p>","DOI":"10.1002\/syn.20360","type":"journal-article","created":{"date-parts":[[2007,1,18]],"date-time":"2007-01-18T01:18:03Z","timestamp":1169083083000},"page":"231-241","source":"Crossref","is-referenced-by-count":23,"title":["Agonist\u2010dependent internalization of D2 receptors: Imaging quantification by confocal microscopy"],"prefix":"10.1002","volume":"61","author":[{"given":"Julian L.","family":"Goggi","sequence":"first","affiliation":[]},{"given":"Alessandro","family":"Sardini","sequence":"additional","affiliation":[]},{"given":"Alice","family":"Egerton","sequence":"additional","affiliation":[]},{"given":"Philip G.","family":"Strange","sequence":"additional","affiliation":[]},{"given":"Paul M.","family":"Grasby","sequence":"additional","affiliation":[]}],"member":"311","published-online":{"date-parts":[[2007,1,17]]},"reference":[{"key":"e_1_2_1_2_1","doi-asserted-by":"publisher","DOI":"10.1176\/ajp.155.11.1550"},{"key":"e_1_2_1_3_1","first-page":"650","article-title":"Agonist\u2010induced desensitization of D2 dopamine receptors in human Y\u201079 retinoblastoma cells","volume":"39","author":"Barton AC","year":"1991","journal-title":"Mol Pharmacol"},{"key":"e_1_2_1_4_1","doi-asserted-by":"publisher","DOI":"10.3109\/10799899109066397"},{"key":"e_1_2_1_5_1","first-page":"956","article-title":"Agonists and antagonists differentially regulate the high affinity state of the D2L receptor in human embryonic kidney 293 cells","volume":"48","author":"Boundy VA","year":"1995","journal-title":"Mol Pharmacol"},{"key":"e_1_2_1_6_1","doi-asserted-by":"publisher","DOI":"10.1073\/pnas.94.6.2569"},{"key":"e_1_2_1_7_1","unstructured":"2001 Academic Press San Diego RE Carson MA Channing B Vuong H Watabe P Herscovitch MC Eckelman Amphetamine\u2010induced dopamine release: Duration of action assessed with [ 11 C]\u2010raclopride in anesthetised monkeys. 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