Dexamethasone impairs encoding and expression of aversive conditioning promoted by pentylenetetrazole

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Behavioral and neuroendocrine responses following threatening situations promote the release of corticosterone, which is known to modulate trauma-related learning and memory process. However, it remains unknown whether the aversive learning generated by interoceptive fear conditioning is affected by glucocorticoid modulation. Therefore, the present study aimed to investigate the role of dexamethasone suppression in encoding and expression of pentylenetetrazole-induced olfactory fear conditioning (OFC) and in contextual second-order conditioning promoted by the conditioned odor. Adult male Long-Evans rats were treated with dexamethasone 60 min before the encoding or the expression in both OFC and contextual second-order conditioning. Dexamethasone treatment impaired encoding and expression of the OFC, but failed to impair encoding and expression of the contextual second-order conditioning. Altogether, our results show that although OFC and thereafter contextual second-order conditioning may allow the study of traumatic memories, each order of conditioning seems to present specific features related to their pharmacological modulation. These findings highlight the importance of addressing the role of neuromodulatory systems in first-order and second-order conditioning to gain a better understanding of these phenomena and support future therapies related to traumatic memories.

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