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AMPA-receptor mediated plasticity within the rat spinal cord

Previous research from our laboratory has demonstrated that the spinal cord is
capable of a simple form of instrumental learning. In this instrumental learning
paradigm, rats typically receive a complete spinal transection at the second thoracic
vertebra, and are tested 24 hours after surgery. Subjects that receive shock to a hind leg
quickly learn to maintain the leg in a flexed position, reducing net shock exposure
whenever that leg is extended (controllable shock). Subjects that receive shock that is
independent of leg position do not exhibit an increase in flexion duration (uncontrollable
shock). This behavioral deficit can be induced with shock to the leg or tail and as little
as 6 minutes of uncontrollable shock impairs learning for up to 48 hours.
The present thesis explores how the related α-amino-3-hydroxy-5-methyl-4-
isoxazole propionic acid-receptor (AMPAR) ionotropic glutamate receptor affects spinal
instrumental learning. Experiment 1 showed that inactivation of the AMPAR by
administration of an antagonist blocks the acquisition of instrumental learning in a dose
dependant fashion. Experiment 2 demonstrated that blocking the AMPAR after the
acquisition of the instrumental response subsequently blocked the maintenance of that response. Experiment 3 revealed that antagonizing the AMPAR during uncontrollable
shock blocked the acquisition of the learning deficit. Experiments 4-6 demonstrated that
the activation of the AMPAR at high levels could acutely block the acquisition spinal
instrumental learning. Understanding how the AMPAR influences learning in the spinal
cord will lead us to develop therapeutic strategies for recovery of function after spinal
cord injury.

Identiferoai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/ETD-TAMU-3056
Date15 May 2009
CreatorsHoy, Kevin Corcoran
ContributorsGrau, James, W.
Source SetsTexas A and M University
Languageen_US
Detected LanguageEnglish
TypeBook, Thesis, Electronic Thesis, text
Formatelectronic, application/pdf, born digital

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