ArticlesEffect of Sex on Fear Conditioning is Similar for Context and Discrete CS in Wistar, Lewis and Fischer Rat Strains
Section snippets
Subjects
Six groups of animals are reported on in this study; namely, Wistar males (n = 8), Wistar females (n = 8), Fischer males (n = 6), Fischer females (n = 6), Lewis males (n = 6), and Lewis females (n = 6). The Wistar rats were studied in one experiment, and the Fischer and Lewis rats were studied together in a second experiment. The Wistar subjects were bred in-house (Zur: WIST [HanIbm], Animal Services, Swiss Federal Institute of Technology, Schwerzenbach), and were weaned at age 21 days and
Wistar Males vs. Females
In terms of activity in the shock chamber without the auditory CS on day 1, there was a consistent decline in activity as confirmed by a significant main effect of the repeated measure of time, F(9, 126) = 44.40, p < 0.001. Males were more active than females overall, F(1, 14) = 5.13, p < 0.04, and a significant sex × time interaction confirmed that males demonstrated a more rapid attenuation in activity across time, F(9, 126) = 2.77, p < 0.006. The day 2 development of conditioned freezing,
Discussion
This comparative study of sex differences in aversive conditioning to context and discrete tone CS in Wistar, Fischer, and Lewis rats, carried out using a novel, fully automated apparatus, has revealed some interesting effects, both between males and females and between strains. In the outbred Wistar strain there was no sex difference in the development of conditioning, either in terms of its rate or asymptotic level. Although not statistically significant in either case, there was a marked
Acknowledgements
This study was carried out under experimental permit in accordance with the Swiss Animal Protection Act (1978). Financial support was provided by the Swiss Federal Institute of Technology and the Swiss National Science Foundation in grants to Prof. J. Feldon. P. Schmid and B. Pouzet provided expert advice on the running of the automated freezing system, and Dr. I. Allmann and T. Karich were responsible for animal husbandry and care. We are extremely grateful to all of the above for their
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