Helplessness, LearnedEscape ReactionElectroshockAvoidance LearningDominance-SubordinationBehavior, AnimalStress, PsychologicalDepressionFluoxetineAntidepressive Agents, Second-GenerationCorticosteroneFearMotor ActivityAnalysis of VarianceIllness BehaviorDisease Models, AnimalRats, Sprague-DawleyHippocampusCatastrophizationAdaptation, PsychologicalEmotionsExploratory Behavior