Parkinson Disease: Brotchie J

Brotchie J, Fitzer-Attas C. · Toronto Western Research Institute, University Health Network, Toronto, Canada. · Neurology. · Pubmed #19221312 No free full text.

Abstract: Parkinson disease (PD) is a disorder with a substantive period before the emergence of motor symptoms, during which significant dopaminergic neuronal loss is counterbalanced by endogenous compensatory mechanisms. Many potential compensatory mechanisms have now been proposed; these are both dopaminergic, focused on enhancing effects or exposure to existing dopamine, and nondopaminergic, being focused on reducing activity of the indirect striatal output pathway. Compensatory mechanisms can potentially postpone and reduce the severity of parkinsonian symptoms, and contribute to the benefit provided by a symptomatic therapy, thus offering targets for novel therapeutics. However, enhancement of certain compensatory mechanisms may produce problems when subsequent therapies are initiated, e.g., the development of motor complications with levodopa. Supporting endogenous compensatory mechanisms, to delay or reverse apparent disease progression, is a novel and attractive "disease-modifying" approach to PD. Such actions may contribute to the apparent disease-modifying benefit of initiating early treatment with levodopa or rasagiline, as suggested by the ELLDOPA and TEMPO studies.

Schapira AH, Bezard E, Brotchie J, Calon F, Collingridge GL, Ferger B, Hengerer B, Hirsch E, Jenner P, Le Novère N, Obeso JA, Schwarzschild MA, Spampinato U, Davidai G. · University Department of Clinical Neurosciences, Royal Free and University College Medical School, University College London, Rowland Hill Street, London NW3 2PF, UK. · Nat Rev Drug Discov. · Pubmed #17016425 No free full text.

Abstract: Dopamine deficiency, caused by the degeneration of nigrostriatal dopaminergic neurons, is the cause of the major clinical motor symptoms of Parkinson's disease. These symptoms can be treated successfully with a range of drugs that include levodopa, inhibitors of the enzymatic breakdown of levodopa and dopamine agonists delivered by oral, subcutaneous, transcutaneous, intravenous or intra-duodenal routes. However, Parkinson's disease involves degeneration of non-dopaminergic neurons and the treatment of the resulting predominantly non-motor features remains a challenge. This review describes the important recent advances that underlie the development of novel dopaminergic and non-dopaminergic drugs for Parkinson's disease, and also for the motor complications that arise from the use of existing therapies.

Ravenscroft P, Brotchie J. · Manchester Movement Disorders Laboratory, University of Manchester, UK. · J Anat. · Pubmed #10923988 links to  free full text

Abstract: The basal ganglia consist of several interconnected nuclei located in the telecephalon, diencephalon and mesencephalon that are involved in a variety of motor and non-motor behavioural functions. Glutamate receptors play a major role in neurotransmission within the basal ganglia and are present in all nuclei of the basal ganglia. This review focuses on the contribution of the NMDA class of glutamatergic receptors to various movement disorders whose primary pathology lies within the basal ganglia and discusses how pharmacological manipulation of such receptors may be therapeutically useful.

Fox S, Silverdale M, Kellett M, Davies R, Steiger M, Fletcher N, Crossman A, Brotchie J. · The Walton Centre for Neurology and Neurosurgery, Liverpool, United Kingdom. · Mov Disord. · Pubmed #15133820 No free full text.

Abstract: Opioid peptide transmission is enhanced in the striatum of animal models and Parkinson's disease (PD) patients with levodopa-induced motor complications. Opioid receptor antagonists reduce levodopa-induced dyskinesia in primate models of PD; however, clinical trials to date have been inconclusive. A double-blind, placebo controlled, crossover design study in 14 patients with PD experiencing motor fluctuations was carried out, using the non-subtype-selective opioid receptor antagonist naloxone. Naloxone did not reduce levodopa-induced dyskinesia. The duration of action of levodopa was increased significantly by 17.5%. Non-subtype-selective opioid receptor antagonism may prove useful in the treatment of levodopa-related wearing-off in PD but not in dyskinesia.