Conditioned fear and analgesia to conspecific odors: Benzodiazepine and 5-HT1A agonists

Abstract

When male albino rats experience one session of attack and defeat by an alpha conspecific, conditioned fear and analgesia are observed during later testing only when alpha-colony odors are present. In Experiment 1, subjects experienced a nondefeat (ND) or a defeat (D) session 24 h prior to testing of fear using the shock-prod burying paradigm. Thirty min before ND and D sessions, subjects were injected with saline (SAL), diazepam (DZP; 2.5 mg/kg), or buspirone (BUS; 5 mg/kg). The results indicated that defeated subjects that had been injected with DZP or BUS failed to show the typical decrease in burying and the increase in freezing indicative of the conditioning of fear to the odor context. In Experiment 2 we utilized the same defeat and drug administration procedure but used the formalin paw-lick test of analgesia. The administration of DZP or BUS prevented the conditioning of fear and analgesia to the alpha-colony odors. These are the first experiments to demonstrate that both diazepam and buspirone can block the conditioning of fear and analgesia resulting from the naturalistic Stressor of defeat.