Research articleDevelopment and optimization of psychological stress model in mice using 2 level full factorial design

IntroductionPsychological stress has long been a silent killer, impairing normal physiological functions and leading to a variety of diseased conditions. However, the existing animal models for studying psychological stress have been marred by their inherent limitations warranting further research in their development and optimization.MethodsIn this study 25 full factorial design was utilized for the development and optimization of psychological stress model in mice by applying different stressors viz., slanted cage(X1), restraint(X2), no bedding(X3), dirty bedding(X4) and isolation(X5) at two time duration levels of 30 and 60 min. The development of behavioral changes like depression, anxiety and anhedonia was taken as criteria for development of stress. These responses were analyzed using Design Expert 7.1.6. (Stat-Ease, Inc., USA). The maximum effective responses obtained were taken as a criterion for optimization. The optimized model was applied to measure the change in serum cortisol level to confirm the stress development.ResultsThe statistical data showed that a quadratic model was fitted to the data obtained. All the factors were found to have a significant role in the development of stress among which restraint, slanted cage and dirty bedding were found to be more causal (p < 0.05). Serum cortisol level was increased significantly in the stressed mice of optimized model (p < 0.05).DiscussionUtilizing the magnitude of responses from the quadratic equations, it can be concluded that slanted cage, restraint and dirty bedding stressors should be applied for longer duration than other stressors for psychological stress development in mice. The study could lay a strong platform for the use of quality by design approach in the development of robust, efficient and resourceful animal models.