Up-regulation of Striatal Adenosine A(2A) Receptors With Iron Deficiency in Rats: Effects on Locomotion and Cortico-Striatal Neurotransmission

Exp Neurol. 2010 Jul;224(1):292-8. doi: 10.1016/j.expneurol.2010.04.004. Epub 2010 Apr 10.

Abstract

Brain iron deficiency leads to altered dopaminergic function in experimental animals, which can provide a mechanistic explanation for iron deficiency-related human sensory-motor disorders, such as Restless Legs Syndrome (RLS). However, mechanisms linking both conditions have not been determined. Considering the strong modulation exerted by adenosine on dopamine signaling, one connection could involve changes in adenosine receptor expression or function. In the striatum, presynaptic A(2A) receptors are localized in glutamatergic terminals contacting GABAergic dynorphinergic neurons and their function can be analyzed by the ability of A(2A) receptor antagonists to block the motor output induced by cortical electrical stimulation. Postsynaptic A(2A) receptors are localized in the dendritic field of GABAergic enkephalinergic neurons and their function can be analyzed by studying the ability of A(2A) receptor antagonists to produce locomotor activity and to counteract striatal ERK1/2 phosphorylation induced by cortical electrical stimulation. Increased density of striatal A(2A) receptors was found in rats fed during 3 weeks with an iron-deficient diet during the post-weaning period. In iron-deficient rats, the selective A(2A) receptor antagonist MSX-3, at doses of 1 and 3 mg/kg, was more effective at blocking motor output induced by cortical electrical stimulation (presynaptic A(2A) receptor-mediated effect) and at enhancing locomotor activation and blocking striatal ERK phosphorylation induced by cortical electrical stimulation (postsynaptic A(2A) receptor-mediated effects). These results indicate that brain iron deficiency induces a functional up-regulation of both striatal pre- and postsynaptic A(2A) receptor, which could be involved in sensory-motor disorders associated with iron deficiency such as RLS.

Publication types

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

MeSH terms

  • Adenosine A2 Receptor Antagonists
  • Animals
  • Blotting, Western
  • Cerebral Cortex / drug effects
  • Cerebral Cortex / physiology*
  • Corpus Striatum / drug effects
  • Corpus Striatum / metabolism*
  • Electric Stimulation
  • Electromyography
  • Exploratory Behavior / drug effects
  • Exploratory Behavior / physiology
  • Iron / deficiency*
  • Male
  • Motor Activity / drug effects
  • Motor Activity / physiology*
  • Neural Pathways / drug effects
  • Neural Pathways / physiology
  • Phosphorylation / drug effects
  • Phosphorylation / physiology
  • Rats
  • Rats, Sprague-Dawley
  • Receptor, Adenosine A2A / metabolism*
  • Receptors, Transferrin / metabolism
  • Synaptic Transmission / drug effects
  • Synaptic Transmission / physiology
  • Up-Regulation / drug effects
  • Up-Regulation / physiology
  • Xanthines / pharmacology

Substances

  • Adenosine A2 Receptor Antagonists
  • MSX 3 compound
  • Receptor, Adenosine A2A
  • Receptors, Transferrin
  • Xanthines
  • Iron