Effects of anisomycin, a protein synthesis inhibitor, on disrupting a fear memory in a predator stress situation

Strasser, Kirby J. (2005) Effects of anisomycin, a protein synthesis inhibitor, on disrupting a fear memory in a predator stress situation. Masters thesis, Memorial University of Newfoundland.

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Abstract

Posttraumatic stress disorder (PTSD) is an incurable psychological condition that develops as a result of being exposed to an extraordinary traumatic event. Many aspects of this affective disorder have been successfully initiated in animals through experimental shock, classical conditioning, pharmacological and predator stress procedures. This has led to the tentative hypothesis that all aspects of PTSD may be reduced to functional alterations in specific pre-existing neural nuclei or circuitry. The theory is that these presumed alterations follow the induction of long-term potentiation (LTP), a model of long-term memory, within the amygdala and related circuitry. This is based upon evidence that implicates the phosphorylation of CREB within the amygdala following predator stress. The hypothesized result of the phosphorylation of CREB is ultimately the synthesis of new protein. If protein synthesis is necessary in order to consolidate a predator stress (cat exposure) memory, then subcutaneous administration of anisomycin, a protein synthesis inhibitor, just after predator stress should prevent the memory from being formed. The effects of treatments were tested using board, elevated plus-maze, light/dark box and social interaction tests; and, acoustic startle) 7-8 days post-exposure. Protein synthesis-dependent consolidation was demonstrated for open-arm exploration in the elevated plus-maze. A reconsolidation condition was added in order to probe whether or not a consolidated memory, once reactivated (i.e. exposed to a cat twice), was again susceptible to protein synthesis various behavioural measures of rodent affect (i.e. hole- inhibition. In this instance, anisomycin was given just after the second cat exposure. For some tests (elevated plus-maze) there was no evidence for protein synthesis-dependent reconsolidation. The results were less clear for the other tests. Due to the effects of vehicle injection, i.c.v. administration of anisomycin in future work may clarify the role of protein synthesis in reconsolidation.

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