BEHAVIORAL, INTEGRATIVE AND CLINICAL NEUROSCIENCESensitization by ventral pallidal DAMGO: lack of cross-sensitization to morphineRokosik, Sandra L.a,b; Persons, Amanda L.b*; Napier, T. CelestebAuthor Information aNeuroscience Program, Stritch School of Medicine, Loyola University Chicago, Maywood bDepartment of Pharmacology, Center for Compulsive Behavior and Addiction, Rush University Medical Center, Chicago, Illinois, USA *Amanda L. Persons previously published as A.L. Mickiewicz. Correspondence to T. Celeste Napier, PhD, Department of Pharmacology, Center for Compulsive Behavior and Addiction, Rush University Medical Center, 1735 W. Harrison Street, Cohn Research Bldg, Suite # 422, Chicago, IL 60612, USA Tel: +1 312 563 2428; fax: +1 312 563 2403; e-mail: email@example.com Received October 23, 2012 Accepted December 15, 2012 NeuroReport: February 13th, 2013 - Volume 24 - Issue 3 - p 152-158 doi: 10.1097/WNR.0b013e32835e11a2 Buy Metrics Abstract Repeated injections of morphine into the ventral pallidum of laboratory rats results in the development and expression of motor sensitization. Although morphine and [D-Ala2, N-MePhe4, Gly(ol)5]-enkephalin (DAMGO) both activate μ-opioid receptors, their influence on receptor-mediated signaling differs; therefore, we determined if they differentially influenced ventral pallidal-mediated motor sensitization. Repeated intraventral pallidal injections of DAMGO led to the development of motor sensitization and this behavior persisted for at least 18 days. When DAMGO-sensitized rats were challenged with a morphine treatment (either in the ventral pallidum or systemically), the resulting motor response was similar to that seen in rats with a history of intrapallidal saline, that is, cross-sensitization did not occur. As DAMGO and morphine likely activate different arms of the heterologous signal transduction system associated with μ-opioid receptors, these observations may reflect behavioral consequences of biased agonism at these receptors. © 2013 Lippincott Williams & Wilkins, Inc.