A novel mechanism for pergolide-induced neuroprotection: inhibition of NF-kB nuclear translocation D. Uberti a , T. Carsana a , S. Francisconi a , G. Ferrari Toninelli a , P.L. Canonico b , M. Memo a,* a Department of Biomedical Sciences and Biotechnologies, School of Medicine, University of Brescia, Viale Europa 11, 25123 Brescia, Italy b DiSCAFF Department, University of Piemonte Orientale, Novara, Italy (P.L.C.) Received 4 November 2003; accepted 16 January 2004 Abstract We previously demonstrated that the dopaminergic agonist pergolide, independently from its DA agonist activity, can exert neuroprotective effects against cell death induced in SH-SY5Y neural cells by H 2 O 2 treatment. Since oxidative stress in SH-SY5Y neural cells is known to activate the NF-kB pathway we tested the hypothesis that pergolide may interfere with NF-kB activity. Based on Western blot analysis and immunocytochemistry, pergolide was found to prevent H 2 O 2 -induced apoptosis by inhibiting NF-kB nuclear translocation and activation of p53 signalling pathway. Similarly, the cell-permeable SN50 peptide, which is known to block NF-kB nuclear translocation, prevented both H 2 O 2 -induced p53 expression and apoptosis. The mechanism of action of pergolide responsible for neuroprotection differed from that of antioxidants. In fact, Vitamin E, contrary to pergolide and SN50, rescued neuronal cells from H 2 O 2 -induced apoptosis acting upstream NF-kB activation, as demonstrated by the prevention of H 2 O 2 -induced IkB degradation. These data suggest a novel site of action of pergolide that may account for additional pharmacological properties of this drug. # 2004 Elsevier Inc. All rights reserved. Keywords: Parkinson’s disease; Oxidative stress; Dopamine agonists; Human neuroblastoma cell line; Tumour suppressor protein p53 1. Introduction Pergolide mesylate, a synthetic ergoline derivative endowed with dopamine (DA) agonist activity [1,2], is one of the drugs successfully used in clinical therapy of Parkinson’s disease (PD), a chronic and progressive neu- rological disease characterized by selective degeneration of DA neurons in the substantia nigra. Several double- blind, controlled studies have demonstrated the efficacy of pergolide as adjunctive therapy in the treatment of PD [3], and recent studies have indicated pergolide monotherapy as an efficacious and well-tolerated first-line treatment in patients with early-stage PD [4]. Although, it is generally believed that treatment of PD with drugs acting as agonists at the DA receptor level, such as pergolide, is symptomatic rather than curative, increasing evidence indicates that these drugs may elicit neuroprotective properties, in experi- mental models [5–11] and in patients [12]. Thus, it is very important to address this claim because, at present, no effective treatments are available for slowing the progres- sion of the disease. Among factors involved in idiopathic PD, oxidative stress, as the result of inefficacious antioxidant defense mechanism as well as an excessive production of reactive oxygen species (ROS), is considered an important cause/ factor in the pathogenesis of the disease (see [13,14] as reviews). Experimental studies demonstrated that enhanced dopamine turnover, occurring to compensate for dopamine depletion in PD, is associated with increased formation of oxidized glutathione, and is prevented by inhibitors of DA metabolism [15]. Postmortem studies show increased lipid hydroperoxide and reactive carbonyl levels in the substantia nigra of PD compared with normal subjects [16,17]. Further insight on the oxidative stress hypothesis in PD has been achieved experimentally using the neurotoxin MPTP, which produces irreversible clin- ical, biochemical and neuropathological effects similar to those found in PD. MPTP, through the formation of MPP þ , causes an impairment in the function of the mito- chondrial respiratory chain with generation of ROS in nigral DA-containing neurons [18]. Biochemical Pharmacology 67 (2004) 1743–1750 0006-2952/$ – see front matter # 2004 Elsevier Inc. All rights reserved. doi:10.1016/j.bcp.2004.01.012 Abbreviations: DA, dopamine; NF-kB, nuclear factor kappaB; PD, Parkinson’s disease; ROS, reactive oxygen species * Corresponding author. Tel.: þ39-030-3717516; fax: þ39-030-3717407. E-mail address: memo@med.unibs.it (M. Memo).