Endogenous galanin protects mouse hippocampal neurons against amyloid toxicity in vitro via activation of galanin receptor-2

J Alzheimers Dis. 2011;25(3):455-62. doi: 10.3233/JAD-2011-110011.

Abstract

Expression of the neuropeptide galanin is known to be upregulated in the brain of patients with Alzheimer's disease (AD). We and others have shown that galanin plays a neuroprotective role in a number of excitotoxic injury paradigms, mediated by activation of the second galanin receptor subtype (GAL2). In the present study, we investigated whether galanin/GAL2 plays a similar protective role against amyloid-β(Aβ) toxicity. Here we report that galanin or the GAL2/3-specific peptide agonist Gal2-11, both equally protect primary dispersed mouse wildtype (WT) neonatal hippocampal neurons from 250 nM Aβ1-42 toxicity in a dose dependent manner. The amount of Aβ1-42 induced cell death was significantly greater in mice with loss-of-function mutations in galanin (Gal-KO) or GAL2 (GAL2-MUT) compared to strain-matched WT controls. Conversely, cell death was significantly reduced in galanin over-expressing (Gal-OE) transgenic mice compared to strain-matched WT controls. Exogenous galanin or Gal2-11 rescued the deficits in the Gal-KO but not the GAL2-MUT cultures, confirming that the protective effects of endogenous or exogenous galanin are mediated by activation of GAL2. Despite the high levels of endogenous galanin in the Gal-OE cultures, the addition of exogenous 100 nM or 50 nM galanin or 100 nM Gal2-11 further significantly reduced cell death, implying that GAL2-mediated neuroprotection is not at maximum in the Gal-OE mice. These data further support the hypothesis that galanin over-expression in AD is a neuroprotective response and imply that the development of a drug-like GAL2 agonist might reduce the progression of symptoms in patients with AD.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amyloid beta-Peptides / toxicity*
  • Analysis of Variance
  • Animals
  • Animals, Newborn
  • Cell Death / drug effects
  • Cell Death / genetics
  • Cells, Cultured
  • Dose-Response Relationship, Drug
  • Galanin / genetics
  • Galanin / metabolism*
  • Galanin / pharmacology
  • Glutamic Acid / toxicity
  • Hippocampus / cytology*
  • Mice
  • Mice, Transgenic
  • Neurons / drug effects*
  • Neurons / metabolism*
  • Peptide Fragments / pharmacology
  • Peptide Fragments / toxicity*
  • Receptor, Galanin, Type 2 / deficiency
  • Receptor, Galanin, Type 2 / metabolism*

Substances

  • Amyloid beta-Peptides
  • Peptide Fragments
  • Receptor, Galanin, Type 2
  • amyloid beta-protein (1-42)
  • galanin (2-11)-amide
  • Glutamic Acid
  • Galanin