Article date: March 2018
By: Ludovico Arcuri, Salvatore Novello, Martina Frassineti, Daniela Mercatelli, Clarissa Anna Pisanò, Ilaria Morella, Stefania Fasano, Blair V Journigan, Michael E Meyer, Willma E Polgar, Riccardo Brambilla, Nurulain T Zaveri, Michele Morari in Volume 175, Issue 5, pages 782-796
Background and Purpose
We previously showed that nociceptin/orphanin FQ opioid peptide (NOP) receptor agonists attenuate the expression of levodopa‐induced dyskinesia in animal models of Parkinson's disease. We now investigate the efficacy of two novel, potent and chemically distinct NOP receptor agonists, AT‐390 and AT‐403, to improve Parkinsonian disabilities and attenuate dyskinesia development and expression.
Experimental Approach
Binding affinity and functional efficacy of AT‐390 and AT‐403 at the opioid receptors were determined in radioligand displacement assays and in GTPγS binding assays respectively, conducted in CHO cells. Their anti‐Parkinsonian activity was evaluated in 6‐hydroxydopamine hemi‐lesioned rats whereas the anti‐dyskinetic properties were assessed in 6‐hydroxydopamine hemi‐lesioned rats chronically treated with levodopa. The ability of AT‐403 to inhibit the D1 receptor‐induced phosphorylation of striatal ERK was investigated.
Key Results
AT‐390 and AT‐403 selectively improved akinesia at low doses and disrupted global motor activity at higher doses. AT‐403 palliated dyskinesia expression without causing sedation in a narrow therapeutic window, whereas AT‐390 delayed the appearance of abnormal involuntary movements and increased their duration at doses causing sedation. AT‐403 did not prevent the priming to levodopa, although it significantly inhibited dyskinesia on the first day of administration. AT‐403 reduced the ERK phosphorylation induced by SKF38393 in vitro and by levodopa in vivo.
Conclusions and Implications
NOP receptor stimulation can provide significant albeit mild anti‐dyskinetic effect at doses not causing sedation. The therapeutic window, however, varies across compounds. AT‐403 could be a potent and selective tool to investigate the role of NOP receptors in vivo.
DOI: 10.1111/bph.14123
View this article