Research ArticleSusceptibility and Resilience to PTSD-Like Symptoms in Mice Are Associated with Opposite Dendritic Changes in the Prelimbic and Infralimbic Cortices Following Trauma
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INTRODUCTION
Post-traumatic stress disorder (PTSD) is a debilitating disorder that occurs after being exposed to one or multiple traumatic events. Clinical studies have highlighted that only a minority of trauma-exposed individuals develop PTSD (Kessler et al., 1995, Chilcoat and Breslau, 1998, Breslau and Kessler, 2001). Like humans, laboratory mice (Lebow et al., 2012, Sillivan et al., 2017) and rats (Elharrar et al., 2013, Toledano and Gisquet-Verrier, 2014) also display a great heterogeneity in their
Animals
The experiments were performed on 47 young male Swiss mice obtained from the animal care facility of the faculty of Science Semlalia, Marrakech, Morocco. Animals were group housed (3–6 per cage) and maintained under constant conditions of ambient temperature (22 ± 2 °C), under a 12 h light/12 h dark cycle with food and water available Ad libitum. The behavioral experiments were conducted between 8 AM and 3 PM in conformity with approved institutional protocols. All animal procedures were in
Labeling of mice as stress-susceptible or stress-resilient
All trauma-exposed mice acquired avoidance behavior, which was characterized by increases of step-through latency (Fig. 2A: Shocked group). Unpaired t-test revealed a significant difference between the Control and Shocked groups (t = 2.70, P = .009). After examining the frequency distribution of step-through latency time of mice (Fig. 2B), we found that the Control group showed a unimodal distribution while trauma-exposed mice showed a high variability with bimodal distribution (bimodal
DISCUSSION
In this study, we examined whether trauma exposure would cause opposite changes in the mPFC of mice that develop at least 3 PTSD-like symptoms (stress-susceptible group) and those developing less symptoms (stress-resilient group). To this end, a reliable evaluation method was used to allow the differentiation of trauma-exposed mice into susceptible and resilient groups. The Golgi-Cox method revealed significant decreases and increases in the total number of dendrites in the PrL and IL,
Authors' contributions
A.L., Y.B., M.B., S.B.M., and R.G. conceived and designed the study.
A.L. and Y.B. acquired the data.
A.L. analyzed the data.
A.L., S.B.M. and R.G. drafted the article.
All authors interpreted the data, discussed the results, and commented on the article.
Funding
This work was supported by a Marie Curie International Research Staff Exchange Scheme Fellowship within the 7th European Community Framework Programme (PIRSES-GA-2012-318997).
Notes
We acknowledge the support of the Centre National de la Recherche Scientifique et Technique (CNRST) of Morocco and the Université Cadi Ayyad in Marrakech.
Declaration of competing interest
None declared.
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