Neurotoxicity induced by okadaic acid in the human neuroblastoma SH-SY5Y line can be differentially prevented by α7 and β2* nicotinic stimulation

Toxicol Sci. 2011 Sep;123(1):193-205. doi: 10.1093/toxsci/kfr163. Epub 2011 Jun 29.

Abstract

A good model of neuronal death that reproduces the characteristic tau (τ) hyperphosphorylation of Alzheimeŕs disease is the use of okadaic acid (OA). The aim of this study was to determine the contribution of α7 and β2* nicotinic acetylcholine receptor (nAChR) subtypes to neuroprotection against OA in the SH-SY5Y cell line by using the selective α7 and β2* nAChR agonists PNU 282987 and 5-Iodo-A85380, respectively. The results of this study show that both α7 and β2* nAChR can afford neuroprotection against OA-induced neurotoxicity. Protection mediated by α7 nAChRs was independent of Ca(2+) and involved the intracellular signaling pathway Janus Kinase-2/Phosphatidylinositol-3-kinase/Akt. When Ca(2+) entry was promoted through the α7 nAChR by using the α7-selective positive allosteric modulator PNU 120596, protection was lost. By contrast, protection mediated by β2* nAChRs was Ca(2+) dependent and implicated the signaling pathways PI3K/Akt and extracellular regulated kinase 1/2. Both α7 and β2* nAChR activation converged on downregulation of GSK-3β and reduction of τ phosphorylation in cells undergoing cell death induced by OA. Therefore, targeting nAChR could offer a strategy for reducing neurodegeneration secondary to hyperphosphorylation of protein τ.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Azetidines / pharmacology*
  • Benzamides / pharmacology*
  • Bridged Bicyclo Compounds / pharmacology*
  • Calcium / metabolism
  • Cell Line, Tumor
  • Humans
  • Ionophores / antagonists & inhibitors
  • Ionophores / toxicity*
  • Isoxazoles / pharmacology
  • Janus Kinase 2 / metabolism
  • Neuroblastoma
  • Neurons / drug effects*
  • Neurons / metabolism
  • Nicotinic Agonists / pharmacology*
  • Okadaic Acid / antagonists & inhibitors
  • Okadaic Acid / toxicity*
  • Phenylurea Compounds / pharmacology
  • Pyridines / pharmacology*
  • Receptors, Nicotinic / drug effects
  • Receptors, Nicotinic / metabolism
  • Signal Transduction / drug effects
  • Signal Transduction / physiology
  • alpha7 Nicotinic Acetylcholine Receptor

Substances

  • 1-(5-chloro-2,4-dimethoxyphenyl)-3-(5-methylisoxazol-3-yl)urea
  • 5-iodo-3-(2-azetidinylmethoxy)pyridine
  • Azetidines
  • Benzamides
  • Bridged Bicyclo Compounds
  • Chrna7 protein, human
  • Ionophores
  • Isoxazoles
  • Nicotinic Agonists
  • PNU-282987
  • Phenylurea Compounds
  • Pyridines
  • Receptors, Nicotinic
  • alpha7 Nicotinic Acetylcholine Receptor
  • nicotinic receptor beta2
  • Okadaic Acid
  • JAK2 protein, human
  • Janus Kinase 2
  • Calcium