Effect of sex on fear conditioning is similar for context and discrete CS in Wistar, Lewis and Fischer rat strains

Christopher R. Pryce*, Julia Lehmann, Joram Feldon

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Enhanced fear in males relative to females, both innate and conditioned, is a well-described characteristic of behavior in the laboratory rat. In the case of aversive conditioning to foot shock in Long-Evans rats, it has been described that conditioning to general (nondiscrete) contextual cues is greater in male rats relative to female rats, whereas conditioning to a discrete, predictive stimulis (CS) is not. These findings have been combined with evidence for greater levels of hippocampal LTP in males in Sprague- Dawley rats to derive a model of hippocampal-LTP-mediated contextual and not CS, fear conditioning. The present study reports on an analysis of the effect of sex in contextual and discrete CS conditioning to foot shock, assessed via measurement of freezing behavior in a novel automated paradigm, in three rat strains: Wistar, Fischer, and Lewis. In Wistar rats, there was a consistent but nonsignificant tendency for males to demonstrate both more contextual and more CS conditioning than females; in Fischer rats, males demonstrated both more contextual and more CS conditioning than females; in Lewis rats, a markedly enhanced acquisition of freezing in males did not translate into a sex difference in either context or CS conditioning at expression. Therefore, within each strain the effect of sex was consistent between context and CS conditioning. These findings, taken together with the hippocampal LTP evidence, suggest that the latter mediates both contextual and discrete CS aversive conditioning, and contributes to sex differences in both these forms of conditioning, in those strains where these sex differences exist.

Original languageEnglish
Pages (from-to)753-759
Number of pages7
JournalPharmacology Biochemistry and Behavior
Volume64
Issue number4
DOIs
StatePublished - Dec 1999
Externally publishedYes

Funding

FundersFunder number
Swiss Federal Institute of Technology
Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung

    Keywords

    • CS
    • Conditioning
    • Context
    • Fear
    • Freezing
    • Hippocampus
    • LTP
    • Sex
    • Strain

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