Abstract
Dopamine receptor agonists are playing an increasingly important role in the treatment of not only patients with advanced Parkinson’s disease and those with levodopa-induced motor fluctuations, but also in the early treatment of the disease. This shift has been largely due to the demonstrated levodopa-sparing effect of dopamine agonists and their putative neuroprotective effect, with evidence for the latter being based largely on experimental in vitro and in vivo studies. In this article we review the evidence for neuroprotection by the dopamine agonists pramipexole, ropinirole, pergolide, bromocriptine and apomorphine in cell cultures and animal models of injury to the substantia nigra.
Most of the studies suggest that dopamine agonists may have neuroprotective effects via direct scavenging of free radicals or increasing the activities of radical-scavenging enzymes, and enhancing neurotrophic activity. However, the finding that pramipexole can normalise mitochondrial membrane potential and inhibit activity of caspase-3 in cytoplasmic hybrid cells derived from mitochondrial DNA of patients with nonfamilial Alzheimer’s disease suggests an even broader implication for the neuroprotective role of dopamine agonists. Although the clinical evidence for neuroprotection by dopamine agonists is still limited, the preliminary results from several ongoing clinical trials are promising. Several longitudinal studies are currently in progress designed to demonstrate a delay or slowing of progression of Parkinson’s disease using various surrogate markers of neuronal degeneration such as 18F-levodopa positron emission tomography and 123I β-CIT (carbomethoxy-β-4-iodophenyl-nortropane) single positron emission computed tomography. The results of these experimental and clinical studies will improve our understanding of the action of dopamine agonists and provide critical information needed for planning future therapeutic strategies for Parkinson’s disease and related neurodegenerative disorders.
Access this article
We’re sorry, something doesn't seem to be working properly.
Please try refreshing the page. If that doesn't work, please contact support so we can address the problem.
Similar content being viewed by others
References
Fearnley J, Lees A. Neurodegenerative diseases. In: Calne DB, editor. Pathology of Parkinson’s disease. Philadelphia: W.B. Saunders Company, 1994: 545–54
Jenner P, Olanow CW. Understanding cell death in Parkinson’s disease. Ann Neurol 1998; 44Suppl. 1: S72–S84
Fahn SA, Cohen G. The oxidant stress hypothesis in Parkinson’s disease: evidence supporting it. Ann Neurol 1992; 32: 804–12
Burns RS, Chiueh CC, Markey SP, et al. A primate model of parkinsonism: selective destruction of dopaminergic neurons in the pars compacta of the substantia nigra by N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine. Proc Natl Acad U S A 1983; 80: 4546–50
Langston JW, Irwin I, Langston EB, et al. 1-Methyl-4-phenylpyridinium ion (MPP+): identification of a metabolite of MPP+, a toxin selective to the substantia nigra. Neurosci Lett 1984; 48: 87–92
Montine TJ, Underhill TM, Linney E, et al. Covalent crosslinking of neurofilament proteins by oxidized catechols as a potential mechanism of Lewy body formation. J Neuropathol Exp Neurol 1995; 54: 311–9
Ebadi M, Srinivasan SK, Baxi MD. Oxidative stress and antioxidant therapy in Parkinson’s disease. Prog Neurobiol 1996; 48: 1–19
Hastings TG, Lewis DA, Zigmond MJ. Role of oxidation in the neurotoxic effects of intrastriatal dopamine injections. Proc Natl Acad Sci U S A 1996; 93: 1956–61
Li H, Dryhurst G. Irreversible inhibition of mitochondrial complex I by 7-(2-aminoethyl)-3,4-dihydro-5-hydroxy-2H-1,4-benzothiazine-3-carboxylic acid (DHBT-1): a putative nigral endotoxin of relevance to Parkinson’s disease. J Neurochem 1997; 69: 1530–41
Hyman C, Hofer M, Barde YA. BDNF is a neurotrophic factor for dopaminergic neurons of the substantia nigra. Nature 1991; 350: 230–2
Jankovic J, Marsden CD. Therapeutic strategies in Parkinson’s disease. In: Jankovic J, Tolosa E, editors. Parkinson’s disease and movement disorders. 3rd ed. Baltimore (MD): Williams and Wilkins, 1998: 67–104
Jankovic J. New and emerging therapies for Parkinson disease. Arch Neurol 1999; 56: 785–790
Feiten DL, Feiten SY, Fuller RW, et al. Chronic dietary pergolide preserves nigrostriatal neuronal integrity in aged Fischer-344 rats. Neurobiol Aging 1992; 13: 339–51
Carvey PM, Pieri S, Ling ZD. Attenuation of levodopa-induced toxicity in mesencephalic cultures by pramipexole. J Neurol Transm 1997; 104: 209–28
Olanow CW, Jenner P, Brooks D. Dopamine agonists and neuroprotection in Parkinson’s disease. Ann Neurol 1998; 44Suppl. 1: S167–74
Sawada H, Ibi M, Kihara T, et al. Dopamine D2-type agonists protect mesencephalic neurons from glutamate neurotoxicity: mechanisms of neuroprotective treatment against oxidative stress. Ann Neurol 1998; 44: 110–19
Zou LL, Jankovic J, Rowe D, et al. Neuroprotection by pramipexole against dopamine- and levodopa-induced cytotoxicity. Life Sci 1999; 64: 1275–85
Ogawa N, Tanaka K, Asanuma M, et al. Bromocriptine protects mice against 6-hydroxydopamine and scavenges hydroxyl free radicals in vitro. Brain Res 1994; 657: 207–13
Gassen M, Glinka Y, Pinchasi B, et al. Apomorphine is a highly free radical scavenger in rat brain mitochondrial fraction. Eur J Pharmacol 1996; 308: 219–25
Grünblatt E, Mandel S, Berkuzki T, et al. Apomorphine protects against MPTP-induced neurotoxicity in mice. Mov Disord 1999; 14: 612–8
Cassarino DS, Fall CP, Smith TS, et al. Pramipexole reduces reactive oxygen species production in vivo and in vitro and inhibits the mitochondrial permeability transition produced by the parkinsonian neurotoxin methylpyridinium ion. J Neurochem 1998; 71: 295–301
Ling ZD, Robie HC, Tong CW, et al. Both the antioxidant and D3 agonist actions of pramipexole mediate its neuroprotective actions in mesencephalic cultures. J Pharmacol Exp Ther 1999; 289: 202–10
Takashima H, Tsujihata M, Kishikawa M, et al. Bromocriptine protects dopaminergic neurons from levodopa-induced toxicity by stimulating D2 receptors. Exp Neurol 1999; 159: 98–104
Le WD, Zou LL, Xu J, et al. Antioxidant property of pramipexole in neuroprotection [abstract]. Parkinsonism Related Dis 1999; 5 Suppl.: 78
Liu XH, Kato H, Chen T, et al. Bromocriptine protects against delayed neuronal death of hippocampal neurons following cerebral ischemia in the gerbil. J Neurol Sci 1995; 129: 9–14
Hall ED, Andrus PK, Oostveen JA, et al. Neuroprotective effects of the dopamine D2/D3 agonist pramipexole against postischemic or methamphetamine-induced degeneration of nigrostriatal neurons. Brain Res 1996; 742: 80–8
Sethy VH, Wu H, Oostveen JA, et al. Neuroprotective effects of the dopamine agonists pramipexole and bromocriptine in 3-acetylpyridine-treated rats. Brain Res 1997; 754: 181–6
Muralikrishnan D, Mohanakumar KP. Neuroprotection by bromocriptine against 1-methy-4-phenyl-1,2,3,6-tetrahydropyridine-induced neurotoxicity in mice. FASEB J 1998; 12: 905–12
O’Neill MJ, Hicks CA, Ward MA, et al. Dopamine D2 receptor agonists protect against ischemia-induced hippocampal neurodegeneration in global cerebral ischaemia. Eur J Pharmacol 1998; 352: 37–46
Vu TQ, Ling ZD, Ma SY, et al. Pramipexole attenuates the dopaminergic cell loss induced by intraventricular 6-hydroxy-dopamine. J Neural Transm 2000; 107: 159–176
Zou LL, Xu J, Jankovic J, et al. Pramipexole inhibits lipid peroxidation and reduces injury in the substantia nigra induced by the dopaminergic neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine in C57BL/6 mice. Neurosci Lett 2000; 281: 167–70
Iida M, Miyazaki I, Tanaka K, et al. Dopamine D2 receptor-mediated antioxidant and neuroprotective effects of ropinirole, a dopamine agonist. Brain Res 1999; 838: 51–9
Noh JS, Gwag BJ. Attenuation of oxidative neuronal necrosis by a dopamine D1 agonist in mouse cortical cell cultures. Exp Neurol 1997; 146: 604–8
Gassen M, Gross A, Youdim MB. Apomorphine enantiomers protect cultured pheochromocy toma (PC 12) cells from oxidative stress induced by H2O2 and 6-hydroxydopamine. Mov Dis 1998; 13: 242–8
Yoshikawa T, Minamiyama Y, Naito Y, et al. Antioxidant properties of bromocriptine, a dopamine agonist. J Neurochem 1994; 62: 1034–8
Kondo T, Ito T, Sugita Y. Bromocriptine scavenges metham-phetamine-induced hydroxyl radicals and attenuates dopamine depletion in mouse striatum. Ann NY Acad Sci 1994; 738: 222–9
Nishibayashi S, Asanuma M, Kohno M, et al. Scavenging effects of dopamine agonists on nitric oxide radicals. J Neurochem 1996; 67: 2208–11
Le WD, Xie W, Jankovic J, et al. Antioxidant property of pramipexole independent of dopamine receptor activation in neuroprotection. J Neural Transm 2000; 107: 1165–73
Asanuma M, Ogawa N, Nishibayashi S, et al. Protective effects of pergolide on dopamine levels in the 6-hydroxydopamine-lesioned mouse brain. Arch Int Pharmacodyn 1995; 329: 221–30
Gomez-Vargas M, Nishibayashi-Asanuma S, Asanuma M, et al. Pergolide scavenges both hydroxyl and nitric oxide free radicals in vitro and inhibits lipid peroxidation in different regions of the rat brain. Brain Res 1998; 790: 202–8
Kitamura Y, Kohno Y, Nakazawa M, et al. Inhibitory effects of talipexole and pramipexole on MPTP-induced dopamine reduction in the striatum of C57BL/6N mice. Jpn J Pharmacol 1997; 74: 51–7
Ling ZD, Tong CW, Carvey PM. Partial purification of a pramipexole-induced trophic activity directed at dopamine neurons in ventral mesencephalic cultures. Brain Res 1998; 791: 137–45
Takata K, Kitamura Y, Kakimura J, et al., Increase of protein in neuronal dendritic processes of cerebral cortex and hippocampus by the antiparkinsonian drugs, talipexole and pramipexole. Brain Res 2000; 872: 236–41
Khan SM, Cassarino DS, Abramova NN, et al. Alzheimer’s disease cybrids replicate β-amyloid abnormalities through cell death pathways. Ann Neurol 2000; 48: 148–55
Piercey MF, Camacho-Ochoa M, Smith MW. Functional roles for dopamine-receptor subtypes. Clin Neuropharmacol 1995; 18: 34–42
Carter AJ, Muller RE. Pramipexole, a dopamine D2 autoreceptor agonist, decreases the extracellular concentration of dopamine in vivo. Eur J Pharmacol 1991; 200: 65–72
Masserano JM, Gong L, Kulaga H, et al. Dopamine induces apoptotic cell death of a catecholaminergic cell line derived from the central nervous system. Mol Pharmacol 1996; 50: 1309–15
Camp DM, Loeffler DA, Le Witt PA. L-DOPA does not enhance hydroxyl radical formation in the nigrostriatal dopamine system of rats with a unilateral 6-hydroxydopamine lesion. J Neurochem 2000; 74: 1229–40
Murer MG, Dziewczapolski G, Menalled LB, et al. Chronic levodopa is not toxic for remaining dopamine neurons, but instead promotes their recovery, in rats with moderate nigrostriatal lesions. Ann Neurol 1998; 43: 561–75
Rajput AH, Fenton ME, Birdi S, et al. Is levodopa toxic to human substantia nigra? Mov Disord 1997; 12: 634–8
Steece-Collier K, Collier TJ, Sladek CD, et al. Chronic levodopa impairs morphological development of grafted embryonic dopamine neurons. Exp Neurol 1990; 110: 201–8
Jenner PG, Brin MF. Levodopa neurotoxicity: experimental studies versus clinical relevance. Neurology 1998; 50Suppl. 6: S39–43
Carvey PM, Ling Z. Pramipexole enhances Bcl-xl expression in mesencephalic cultures [abstract]. Mov Dis 2000; 15Suppl. 3: 17
Offen D, Ziv I, Panet H, et al. Dopamine-induced apoptosis is inhibited in PC 12 cells expressing Bcl-2. Cell Mol Neurobiol 1997; 17: 289–304
Kitamura Y, Kodaka T, Kakimura JI, et al. Protective effects of the antiparkinsonian drugs talipexole and pramipexole against 1-methyl-4-phenylpyridinium-induced apoptotic death in human neuroblastoma SH-SY5Y cells. Mol Pharmacol 1998; 54: 1046–54
Dennis J, Khan SM, Cassarino DS, et al. Inhibition of cell death pathways by S(-) and R(+) pramipexole in pharmacological models of Parkinson’s and Alzheimer’s disease [abstract]. Soc Neurosci Abstr 1999; 29: 539
Parkinson Study Group. Pramipexole vs levodopa as initial treatment for Parkinson’s disease: a randomized controlled trial. JAMA 2000; 284: 1931–8
Rascol O, Brooks DJ, Korczyn AD, et al. A five-year study of the incidence of dyskinesia in patients with early Parkinson’s disease who were treated with ropinirole or levodopa. 056 Study Group. N Engl J Med 2000; 18: 1484–91
Yamanoto M. Do dopamine agonists provide neuroprotection? Neurology 1998; 51Suppl. 2: S10–S12
Le WD, Conneely OM, He Y, et al. Reduced Nurrl expression increases the vulnerability of mesencephalic dopamine neurons to MPTP-induced injury. J Neurochem 1999; 73: 2218–21
Masliah E, Rockenstein E, Veinbergs I, et al. Dopaminergic loss and inclusion body formation in alpha-synuclein mice: implications for neurodegenerative disorders. Science 2000; 287: 1265–9
Kitada T, Asakawa S, Hattori N, et al. Mutations in the parkin gene causes autosomal recessive juvenile parkinsonism. Nature 1998; 392: 544–5
Betarbet R, Sherer TB, MacKenzie G, et al. Chronic systemic pesticide exposure produces features of Parkinson’s disease. Nat Neurosci 2000; 3: 1301–6
Acknowledgements
This work was supported by a research grant from Parkinson’s Disease Foundation (Dr Le) and the Center of Excellence, National Parkinson Foundation (Dr Jankovic).
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Le, WD., Jankovic, J. Are Dopamine Receptor Agonists Neuroprotective in Parkinson’s Disease?. Drugs & Aging 18, 389–396 (2001). https://doi.org/10.2165/00002512-200118060-00001
Published:
Issue Date:
DOI: https://doi.org/10.2165/00002512-200118060-00001