Glutamate-induced internalization of Ca(v)1.3 L-type Ca(2+) channels protects retinal neurons against excitotoxicity

J Physiol. 2010 Mar 15;588(Pt 6):953-66. doi: 10.1113/jphysiol.2009.181305. Epub 2010 Feb 1.

Abstract

Glutamate-induced rise in the intracellular Ca(2+) level is thought to be a major cause of excitotoxic cell death, but the mechanisms that control the Ca(2+) overload are poorly understood. Using immunocytochemistry, electrophysiology and Ca(2+) imaging, we show that activation of ionotropic glutamate receptors induces a selective internalization of Ca(v)1.3 L-type Ca(2+) channels in salamander retinal neurons. The effect of glutamate on Ca(v)1.3 internalization was blocked in Ca(2+)-free external solution, or by strong buffering of internal Ca(2+) with BAPTA. Downregulation of L-type Ca(2+) channel activity in retinal ganglion cells by glutamate was suppressed by inhibitors of dynamin-dependent endocytosis. Stabilization of F-actin by jasplakinolide significantly reduced the ability of glutamate to induce internalization suggesting it is mediated by Ca(2+)-dependent reorganization of actin cytoskeleton. We showed that the Ca(v)1.3 is the primary L-type Ca(2+) channel contributing to kainate-induced excitotoxic death of amacrine and ganglion cells. Block of Ca(v)1.3 internalization by either dynamin inhibition or F-actin stabilization increased vulnerability of retinal amacrine and ganglion cells to kainate-induced excitotoxicity. Our data show for the first time that Ca(v)1.3 L-type Ca(2+) channels are subject to rapid glutamate-induced internalization, which may serve as a negative feedback mechanism protecting retinal neurons against glutamate-induced excitotoxicity.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Calcium Channels, L-Type / metabolism*
  • Cytoskeleton / physiology
  • Dynamins / metabolism
  • Electrophysiological Phenomena / physiology
  • Feedback, Physiological / physiology*
  • Glutamic Acid / adverse effects
  • Glutamic Acid / pharmacology*
  • Patch-Clamp Techniques
  • Receptors, Glutamate / drug effects
  • Receptors, Glutamate / metabolism
  • Retinal Neurons / cytology
  • Retinal Neurons / drug effects
  • Retinal Neurons / metabolism*
  • Urodela

Substances

  • Calcium Channels, L-Type
  • Receptors, Glutamate
  • Glutamic Acid
  • Dynamins