Effects on sociability after predator scent exposure in early‐life stressed mice
Authors: Cruz Kevin Osvaldo , Afroz Kazi‐Farhana , Shoemaker Danton , Alviña Karina 
Published: June 2021

Early life stress (ELS) has been shown to affect a variety of brain functions with potential negative consequences in later stages of life. If adverse events occur early in life, the developing brain can be more susceptible to permanent changes. Human and animal studies have shown for example, an increased susceptibility to anxiety, sociability disorders and mood disorders in adults that experienced ELS. However, the mechanisms that underlie these pathological conditions are not fully established.

In our study we hypothesized that mice exposed to ELS would have an abnormal response to a threatening experience in adulthood. We used the predator scent test (PST) as a well‐accepted model of fear‐inducing paradigm. The smell of a predator can be perceived by a mouse through their olfactory epithelium in the nose, and this can trigger a stress response by increasing blood corticosterone (stress hormone in mice). 24 hours after PST we performed several tests to probe social behavior in the PST exposed mice. Preliminary data in control mice showed that female mice were significantly more social than males and thus we focused on females for the rest of this project. We probed social behavior in three different experiments, one per day. First, we conducted a social interaction test and observed how much time the subject mouse interacted with either a cage‐mate or an unknown mouse. After that, we proceeded with a 3‐chamber social approach test. The experiment consisted on dividing an open field arena in three compartments, making the subject mouse choose between a non‐social compartment and a social compartment with an unknown female mouse. Decreased time spent in the social compartment compared to the non‐social compartment indicated social avoidance. Finally, we conducted the modified T‐maze for social approach. The arena consisted T‐shaped maze with three arms. We observed the time spent by the target mouse on the social and non‐social arm to identify social avoidance. Two weeks after these behavioral tests, we proceeded to repeat the same behavioral experiments to test for long‐term effects. Our results showed that ELS caused a small short‐term decrease in social interaction with cage mate 24 hours after PST, no differences in 3‐chambers test between control mice and ELS, and a significant change in T‐maze after 2 weeks of PST.

Overall our results show an important sex‐dependent difference in sociability and short‐ and long‐term effects of ELS in social behavior in adult female mice.

Support or Funding Information

I want to thank Dr. Karina Alvina for giving me the opportunity to work in her laboratory at Texas Tech University Department of Biology in Lubbock, TX. Kazi‐Farhana Afroz for teaching me the techniques required for the experiments. To all members of the Alvina lab for all the support and to the UPR‐PRISE PROGRAM (R25GM082406).

This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.