Alpha-tocopherol-mediated long-lasting protection against oxidative damage involves an attenuation of calcium entry through TRP-like channels in cultured hippocampal neurons

Free Radic Biol Med. 2007 May 1;42(9):1326-37. doi: 10.1016/j.freeradbiomed.2007.01.032. Epub 2007 Jan 23.

Abstract

We have reported that a transient treatment of hippocampal neurons with alpha-tocopherol induced a long-lasting protection against oxidative damage mediated by Fe(2+) ions. This protection required protein synthesis. Here, we have studied whether this "hyposensitivity" to oxidative stress could be linked to an altered Ca(2+) homeostasis. Fe(2+) ions triggered a Ca(2+) entry which was required for Fe(2+) ion-induced toxicity. This influx was sensitive to blockers of TRP-like nonspecific Ca(2+) channels, including Ruthenium Red, La(3+), and Gd(3+) ions which also prevented the Fe(2+) ion-induced toxicity and oxidative stress as revealed by protein carbonylation status. The pretreatment with alpha-tocopherol resulted in a reduction of the Ca(2+) increase induced by Fe(2+) ions and masked the blocking effect of La(3+) ions. Moreover, such a pretreatment reduced the capacitive Ca(2+) entries (CCE) observed after metabotropic glutamate receptor stimulation, which are known to involve TRP-like channels. By contrast, in a model of "hypersensitivity" to oxidative stress obtained by chronic stimulation of glucocorticoid receptors, we observed an exacerbation of the various effects of Fe(2+) ions, i.e., cellular toxicity and Ca(2+) increase, and the glutamate-stimulated CCE. Therefore, we conclude that the long-lasting neuroprotection induced by alpha-tocopherol pretreatment likely results from an attenuation of Ca(2+) entries via TRP-like channels.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Biological Transport
  • Calcium / metabolism
  • Calcium Channels / drug effects
  • Calcium Channels / physiology*
  • Cells, Cultured
  • DNA Damage / drug effects*
  • Hippocampus / cytology*
  • Neurons / drug effects
  • Neurons / physiology*
  • Oxidative Stress / drug effects*
  • Rats
  • Rats, Sprague-Dawley
  • TRPC Cation Channels / drug effects
  • TRPC Cation Channels / physiology*
  • alpha-Tocopherol / pharmacology*

Substances

  • Calcium Channels
  • TRPC Cation Channels
  • alpha-Tocopherol
  • Calcium