Down-regulation of ghrelin receptors on dopaminergic neurons in the substantia nigra contributes to Parkinson's disease-like motor dysfunction

Mol Brain. 2018 Feb 20;11(1):6. doi: 10.1186/s13041-018-0349-8.


Ghrelin exerts a wide range of physiological actions throughout the body and appears to be a promising target for disease therapy. Endogenous ghrelin receptors (GHSRs) are present in extrahypothalamic sites including the substantia nigra pars compacta (SNc), which is related to phenotypic dysregulation or frank degeneration in Parkinson's disease (PD). Here we found a dramatic decrease in the expression of GHSR in PD-specific induced pluripotent stem cell (iPSC)-derived dopaminergic (DAnergic) neurons generated from patients carrying parkin gene (PARK2) mutations compared to those from healthy controls. Consistently, a significant decrease in the expression of GHSR was found in DAnergic neurons of isogenic PARK2-iPSC lines that mimicked loss of function of the PARK2 gene through CRISPR Cas9 technology. Furthermore, either intracerebroventricular injection or microinjection into the SNc of the selective GHSR1a antagonist [D-Lys3]-GHRP6 in normal mice produced cataleptic behaviors related to dysfunction of motor coordination. These findings suggest that the down-regulation of GHSRs in SNc-DA neurons induced the initial dysfunction of DA neurons, leading to extrapyramidal disorder under PD.

Keywords: Dopamine neuron; GHSR; Ghrelin; Parkinson’s disease; iPS.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Differentiation / drug effects
  • Cell Line
  • Dopaminergic Neurons / drug effects
  • Dopaminergic Neurons / metabolism*
  • Down-Regulation* / drug effects
  • Gene Knock-In Techniques
  • Gene Knockout Techniques
  • Humans
  • Induced Pluripotent Stem Cells / drug effects
  • Induced Pluripotent Stem Cells / metabolism
  • Injections, Intraventricular
  • Male
  • Mice, Inbred C57BL
  • Motor Activity* / drug effects
  • Oligopeptides / pharmacology
  • Parkinson Disease / metabolism
  • Parkinson Disease / pathology*
  • Parkinson Disease / physiopathology*
  • Receptors, Ghrelin / antagonists & inhibitors
  • Receptors, Ghrelin / genetics*
  • Receptors, Ghrelin / metabolism
  • Substantia Nigra / metabolism*
  • Substantia Nigra / pathology*
  • Ubiquitin-Protein Ligases / metabolism


  • GHRP-6, Lys(3)-
  • Oligopeptides
  • Receptors, Ghrelin
  • Ubiquitin-Protein Ligases
  • parkin protein