Synaptic dysfunction in Parkinson's disease

Biochem Soc Trans. 2010 Apr;38(2):493-7. doi: 10.1042/BST0380493.

Abstract

In neuronal circuits, memory storage depends on activity-dependent modifications in synaptic efficacy, such as LTD (long-term depression) and LTP (long-term potentiation), the two main forms of synaptic plasticity in the brain. In the nucleus striatum, LTD and LTP represent key cellular substrates for adaptive motor control and procedural memory. It has been suggested that their impairment could account for the onset and progression of motor symptoms of PD (Parkinson's disease), a neurodegenerative disorder characterized by the massive degeneration of dopaminergic neurons projecting to the striatum. In fact, a peculiar aspect of striatal plasticity is the modulation exerted by DA (dopamine) on LTP and LTD. Our understanding of these maladaptive forms of plasticity has mostly come from the electrophysiological, molecular and behavioural analyses of experimental animal models of PD. In PD, a host of cellular and synaptic changes occur in the striatum in response to the massive loss of DA innervation. Chronic L-dopa therapy restores physiological synaptic plasticity and behaviour in treated PD animals, but most of them, similarly to patients, exhibit a reduction in the efficacy of the drug and disabling AIMs (abnormal involuntary movements) defined, as a whole, as L-dopa-induced dyskinesia. In those animals experiencing AIMs, synaptic plasticity is altered and is paralleled by modifications in the postsynaptic compartment. In particular, dysfunctions in trafficking and subunit composition of NMDARs [NMDA (N-methyl-D-aspartate) receptors] on striatal efferent neurons result from chronic non-physiological dopaminergic stimulation and contribute to the pathogenesis of dyskinesias. According to these pathophysiological concepts, therapeutic strategies targeting signalling proteins coupled to NMDARs within striatal spiny neurons could represent new pharmaceutical interventions for PD and L-dopa-induced dyskinesia.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Animals
  • Antiparkinson Agents / adverse effects
  • Antiparkinson Agents / therapeutic use
  • Basal Ganglia / pathology
  • Basal Ganglia / physiology
  • Basal Ganglia / physiopathology
  • Carrier Proteins / metabolism
  • Carrier Proteins / physiology
  • Dyskinesias / etiology
  • Humans
  • Levodopa / adverse effects
  • Levodopa / therapeutic use
  • Nerve Tissue Proteins / metabolism
  • Nerve Tissue Proteins / physiology
  • Neuronal Plasticity / physiology
  • Parkinson Disease / drug therapy
  • Parkinson Disease / pathology
  • Parkinson Disease / physiopathology*
  • Receptors, N-Methyl-D-Aspartate / metabolism
  • Receptors, N-Methyl-D-Aspartate / physiology
  • Synapses / pathology
  • Synapses / physiology*
  • Synaptic Transmission / physiology

Substances

  • Antiparkinson Agents
  • Carrier Proteins
  • GRIN1 protein, human
  • Nerve Tissue Proteins
  • Receptors, N-Methyl-D-Aspartate
  • Levodopa