Fimbria-fornix transections selectively down-regulate subtypes of glutamate transporter and glutamate receptor proteins in septum and hippocampus

J Neurochem. 1996 Sep;67(3):1208-16. doi: 10.1046/j.1471-4159.1996.67031208.x.

Abstract

The effects of CNS axotomy on glutamate transporter and glutamate receptor expression were evaluated in adult rats following unilateral fimbria-fornix transections. The septum and hippocampus were collected at 3, 7, 14, and 30 days postlesion. Homogenates were immunoblotted by using antibodies directed against glutamate transporters (GLT-1, GLAST, and EAAC1) and glutamate receptors (GluR1, GluR2/3, GluR6/7, and NMDAR1), and they were assayed for glutamate transport by D-[3H]aspartate binding. GLT-1 was decreased at 7 and 14 days postlesion within the ipsilateral septum and at 7 days postlesion in the hippocampus. GLAST was decreased within the ipsilateral septum and hippocampus at 7 and 14 days postlesion. No postlesion alterations in EAAC1 immunoreactivity were observed. D-[3H]Aspartate binding was decreased at 7, 14, and 30 days postlesion within the ipsilateral septum and 14 days postlesion in the hippocampus. GluR2/3 expression was down-regulated at 30 days postlesion within the ipsilateral septum, whereas GluR1, GluR6/7, and NMDAR1 immunoreactivity was unchanged. In addition, no alterations in glutamate receptor expression were detected within hippocampal homogenates. This study demonstrates a selective down-regulation of primarily glial, and not neuronal, glutamate transporters and a delayed, subtype-specific down-regulation of septal GluR2/3 receptor expression after regional deafferentation within the CNS.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • ATP-Binding Cassette Transporters / analysis
  • ATP-Binding Cassette Transporters / biosynthesis
  • ATP-Binding Cassette Transporters / metabolism*
  • Amino Acid Transport System X-AG
  • Animals
  • Aspartic Acid / metabolism
  • Axons / physiology
  • Biological Transport / physiology
  • Blotting, Western
  • Densitometry
  • Down-Regulation / physiology
  • Hippocampus / chemistry*
  • Hippocampus / surgery
  • Male
  • Rats
  • Rats, Sprague-Dawley
  • Receptors, Glutamate / analysis
  • Receptors, Glutamate / biosynthesis
  • Receptors, Glutamate / metabolism*
  • Septal Nuclei / chemistry*
  • Septal Nuclei / surgery
  • Tritium

Substances

  • ATP-Binding Cassette Transporters
  • Amino Acid Transport System X-AG
  • Receptors, Glutamate
  • Tritium
  • Aspartic Acid