Sustained chemogenetic activation of locus coeruleus norepinephrine neurons promotes dopaminergic neuron survival in synucleinopathy

PLoS One. 2022 Mar 22;17(3):e0263074. doi: 10.1371/journal.pone.0263074. eCollection 2022.

Abstract

Dopaminergic neuron degeneration in the midbrain plays a pivotal role in motor symptoms associated with Parkinson's disease. However, non-motor symptoms of Parkinson's disease and post-mortem histopathology confirm dysfunction in other brain areas, including the locus coeruleus and its associated neurotransmitter norepinephrine. Here, we investigate the role of central norepinephrine-producing neurons in Parkinson's disease by chronically stimulating catecholaminergic neurons in the locus coeruleus using chemogenetic manipulation. We show that norepinephrine neurons send complex axonal projections to the dopaminergic neurons in the substantia nigra, confirming physical communication between these regions. Furthermore, we demonstrate that increased activity of norepinephrine neurons is protective against dopaminergic neuronal depletion in human α-syn A53T missense mutation over-expressing mice and prevents motor dysfunction in these mice. Remarkably, elevated norepinephrine neurons action fails to alleviate α-synuclein aggregation and microgliosis in the substantia nigra suggesting the presence of an alternate neuroprotective mechanism. The beneficial effects of high norepinephrine neuron activity might be attributed to the action of norepinephrine on dopaminergic neurons, as recombinant norepinephrine treatment increased primary dopaminergic neuron cultures survival and neurite sprouting. Collectively, our results suggest a neuroprotective mechanism where noradrenergic neurons activity preserves the integrity of dopaminergic neurons, which prevents synucleinopathy-dependent loss of these cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Disease Models, Animal
  • Dopaminergic Neurons / metabolism
  • Humans
  • Locus Coeruleus / metabolism
  • Mice
  • Mice, Transgenic
  • Norepinephrine / pharmacology
  • Norepinephrine / physiology
  • Parkinson Disease* / pathology
  • Substantia Nigra / metabolism
  • Synucleinopathies*
  • alpha-Synuclein / genetics
  • alpha-Synuclein / metabolism

Substances

  • alpha-Synuclein
  • Norepinephrine

Grants and funding

This study was funded by the Leon Fine Award in Translational Science (Cedars Sinai Medical Center). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.