Unaltered striatal dopamine release levels in young Parkin knockout, Pink1 knockout, DJ-1 knockout and LRRK2 R1441G transgenic mice

PLoS One. 2014 Apr 14;9(4):e94826. doi: 10.1371/journal.pone.0094826. eCollection 2014.

Abstract

Parkinson's disease (PD) is one of the most prevalent neurodegenerative brain diseases; it is accompanied by extensive loss of dopamine (DA) neurons of the substantia nigra that project to the putamen, leading to impaired motor functions. Several genes have been associated with hereditary forms of the disease and transgenic mice have been developed by a number of groups to produce animal models of PD and to explore the basic functions of these genes. Surprisingly, most of the various mouse lines generated such as Parkin KO, Pink1 KO, DJ-1 KO and LRRK2 transgenic have been reported to lack degeneration of nigral DA neuron, one of the hallmarks of PD. However, modest impairments of motor behavior have been reported, suggesting the possibility that the models recapitulate at least some of the early stages of PD, including early dysfunction of DA axon terminals. To further evaluate this possibility, here we provide for the first time a systematic comparison of DA release in four different mouse lines, examined at a young age range, prior to potential age-dependent compensations. Using fast scan cyclic voltammetry in striatal sections prepared from young, 6-8 weeks old mice, we examined sub-second DA overflow evoked by single pulses and action potential trains. Unexpectedly, none of the models displayed any dysfunction of DA overflow or reuptake. These results, compatible with the lack of DA neuron loss in these models, suggest that molecular dysfunctions caused by the absence or mutation of these individual genes are not sufficient to perturb the function and survival of mouse DA neurons.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Dopamine / metabolism*
  • Electrochemical Techniques
  • Leucine-Rich Repeat Serine-Threonine Protein Kinase-2
  • Male
  • Mice, Knockout
  • Mutation / genetics*
  • Neostriatum
  • Oncogene Proteins / deficiency*
  • Oncogene Proteins / metabolism
  • Peroxiredoxins / deficiency*
  • Peroxiredoxins / metabolism
  • Protein Deglycase DJ-1
  • Protein Kinases / deficiency*
  • Protein Kinases / metabolism
  • Protein Serine-Threonine Kinases / genetics*
  • Synaptic Transmission
  • Ubiquitin-Protein Ligases / deficiency*
  • Ubiquitin-Protein Ligases / metabolism

Substances

  • Oncogene Proteins
  • Peroxiredoxins
  • Ubiquitin-Protein Ligases
  • parkin protein
  • Protein Kinases
  • Leucine-Rich Repeat Serine-Threonine Protein Kinase-2
  • Lrrk2 protein, mouse
  • PTEN-induced putative kinase
  • Protein Serine-Threonine Kinases
  • PARK7 protein, mouse
  • Protein Deglycase DJ-1
  • Dopamine

Grants and funding

This work was funded by a Rapid Response award from the Michael J. Fox Foundation for Parkinson's Research to L.-E.T. as well as by a grant to L.-E.T. and D.S.P. from the Brain Canada Foundation and the Krembil Foundation. R.K.V. was supported by a Science without Borders fellowship from the Conselho Nacional de Pesquisa e Desenvolvimento (CNPq), Brazil. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.