Lidocaine Reversible Inactivation of the Central Nucleus of Amygdala Impairs Acquisition, Consolidation, and Retrieval of Morphine State-Dependent Learning in Rat

Abstract

Background/Aims: Morphine causes state-dependent learning that its mechanism and brain-related structures are not fully understood. This study aimed to determine whether lidocaine reversible inactivation of the central nucleus of the amygdala (CeA) could affect acquisition, consolidation, and retrieval of morphine state-dependent learning. Methods: One hundred twenty male Wistar rats were allocated into 15 experimental groups. Subcutaneous administration of morphine (5 mg/kg) induced morphine state-dependent learning. Intra-CeA injection of Lidocaine hydrochloride was performed 5 min before each morphine session for transient inactivation of the CeA. The step-through latency and the time spent in the dark compartment were measured using passive avoidance learning task. Results: Our results showed that pretraining, posttraining, and pretest inhibition of the CeA severely impaired acquisition, consolidation, and retrieval of morphine state-dependent learning. Conclusion: These data revealed the involvement of the CeA in different stages of memory and morphine state-dependent learning.