Variability in Behavioral Phenotypes after Forced Swimming-Induced Stress in Rats Is Associated with Expression of the Glucocorticoid Receptor, Nurr1, and IL-1β in the Hippocampus.

Elizabeth Ruiz-Sánchez,Aldo A Reséndiz-Albor,Patricia Rojas,Minerva Calvillo,Arely M López-Ramírez,Brenda Anguiano,Ángel Ruiz-Chow

doi:10.3390/ijms222312700

Abstract

Individual differences in coping with stress may determine either a vulnerable or resilient phenotype. Therefore, it is important to better understand the biology underlying the behavioral phenotype. We assessed whether individual behavioral phenotype to acute stress is related with the hippocampal expression of glucocorticoid receptor (GR), Nurr1, interleukin-1 beta (IL-1β) or brain-derived neurotrophic factor (BDNF). Wistar male rats were exposed to forced swimming for 15 min and sacrificed at different times. Behavioral response was analyzed, and it was compared with the gene and protein expression of GR, Nurr1, IL-1β and BDNF in the hippocampus for each time point. Behavioral phenotyping showed a group with high immobility (vulnerable) while another had low immobility (resilient). No significant differences were found in the Nurr1, IL-1β and BDNF mRNA levels between resilient and vulnerable rats at different recovery times except for Nr3c1 (gene for GR). However, exposure to stress caused significantly higher levels of GR, Nurr1 and IL-1β proteins of vulnerable compared to resilient rats. This variability of behavioral phenotypes is associated with a differential molecular response to stress that involves GR, Nurr1, and IL-1β as mediators in coping with stress. This contributes to identifying biomarkers of susceptibility to stress.

Highlights

In the current study we identified two different behavioral phenotypes in response In the current study we identified two different behavioral phenotypes in response to a single forced swim session in animals exposed for first time to this novel challenge
The diverse behavioral responses due to individual differences in coping with stress is consistent with other studies [34,35,36,37,38]
Rats were exposed to a single forced swim test of 15 min to identify individual behavioral vulnerability to develop behavioral despair according to immobility scores

Summary

Introduction

Stress is a potential risk factor related to the development of psychiatric disorders such as depression and post-traumatic stress disorder that alter the quality of life [1]. Psychological stress due to a traumatic event has long-lasting effects on behavior that leads to the development of adaptive or coping mechanisms in individuals, which are associated with memories linked to strong emotions [3]. The majority of the population can adapt successfully, between 7% to 15% of people can develop a stressrelated disorder [4]. It is accepted that an individual’s genetic predisposition may contribute either resilience or vulnerability to developing stress-induced mental disorders [2,5]

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Results

Conclusion