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----- Original Message ----- From: "WE MOVE" <[log in to unmask]> To: <[log in to unmask]> Sent: Thursday, June 22, 2000 1:50 PM Subject: Opioid Receptors in Dyskinesias (MovDis Congress 2000) > E-MOVE reports from the 6th International Congress of Parkinson's Disease > and Movement Disorders, held in Barcelona, Spain, 11-15 June 2000. > Citation numbers refer to abstract numbers published in Movement Disorders > 2000;15 (Supplement 3). > > 1. The effects of administration of an opioid receptor antagonist in the > 6-OHDA-lesioned rat model of L-dopa-induced dyskinesia > P Ravenscroft, JM Brotchie > P301 > > Coadministration of naltrexone with levodopa reduces development of > dyskinesia-like movements in 6-OHDA-treated rats, according to this study. > > Unilaterally lesioned rats received twice-daily injections of vehicle, > levodopa, or naltrexone/levodopa for 21 days. Counts of contraversive > rotational behavior indicated naltrexone-treated rats displayed > approximately one third the number of rotations as rats receiving levodopa > alone. In situ hybridization with RNA probes for pre-proenkephalin A or B > revealed increased PPE-A levels on the lesioned side, with further > elevations following levodopa administration. Naltrexone coadministration > significantly reduced PPE-A levels in both the rostral and caudal > striatum. The authors conclude, "Enhanced opioid peptide transmission may > contribute to the neural mechanisms underlying L-dopa-induced dyskinesia. > Therefore, the de novo coadministration of L-dopa with opioid receptor > antagonists may be beneficial in treating Parkinson's disease without > eliciting dyskinesias." > > > 2. Enhanced mu-opioid receptor stimulation in the medial pallidal segment > and substantia nigra pars reticulata may underlie L-dopa-induced > dyskinesias in Parkinson's disease > S Begum, AR Crossman, JM Brotchie > P312 > > Autoradiography of opioid receptors in MPTP-treated primates indicates > that mu-opioid receptors are down-regulated in the output regions of the > basal ganglia in dyskinetic animals. Receptor number was decreased by > approximately 50% in the globus pallidus medial segment and substantia > nigra pars reticulata, with no change in receptor affinity. The authors > conclude, "Down regulation of mu-opioid receptors...may reflect enhanced > mu-opioid receptor stimulation in these regions in dyskinesias," and > suggest that blockade of this enhanced transmission "may underlie the > anti-dyskinetic actions of mu-opioid receptor antagonists." > > > 3. Alterations in cortical and basal ganglia levels of opioid receptor > binding in a rat model of L- dopa-induced dyskinesia > MA Cenci, M Andersson, PA Johansson > P250 > > Autoradiography of opioid receptors in rats unilaterally lesioned with > 6-OHDA showed widespread reduction of opioid receptors in the basal > ganglia, but not the cortex. Animals with levodopa-induced dyskinesias > showed further reduction in kappa-opioid receptors in the caudate, > putamen, and substantia nigra on the lesioned side, and an unexpected > increase in mu-opioid receptors on the non-lesioned side. Additional > changes in receptor densities were seen in other sites as well. > > Copyright 2000 WE MOVE > Editor: Richard Robinson ([log in to unmask]) > > This service is provided free of charge to the Internet community, > courtesy of WEMOVE.org. This document may be freely redistributed by > email only in its unedited form. We encourage you to share it with your > colleagues. > > E-MOVE archives, plus information on subscribing, are > available at http://www.wemove.org/emove. > To unsubscribe, send an e-mail to [log in to unmask], > with "unsubscribe e-move" in the message body. > > E-MOVE is a service of WE MOVE (Worldwide Education and Awareness for > Movement Disorders) > 204 West 84th Street > New York, NY 10024 > > TEL 800-437-MOV2 > TEL 212-875-8312 > FAX 212-875-8389 > http://www.wemove.org