[Interaction of intrahippocampal injection of naltheroxone and corticosterone on consolidation and retreival memory processes in passive avoidance task in rat]

ABSTRACT

Previous studies suggested that the role of corticosterone on memory process probably is mediated by opiate system in Dorsal Hippocampus [DH]. The aim of this study was to test whether there is any interaction between glucocorticoids and opiate system on memory consolidation and retrieval in passive avoidance learning task. In this experimental study 120 male Wistar rats [250-300 gr] surgically implanted bilaterally with cannulae aimed at the DH were trained in passive anoidnace learning [PAL] task. Two days after training, retention test was done. Naltoroxe [10 or 20 micro g/ul/ preside] were injected bilaterally into DH following immediately after training by IP injection of corticostrone [1mg/kg] or 30 min before IP injection of corticostrone [1mg/kg] in retrieval test. The data indicated that injection of corticostrone immediately after training of injected 30 min before of retrieval test enhanced and impaired memory consolidation and retrieval respectively [p<0.01] and these effects were blocked by injection of nalthroxone on DH [p<0.01]. The findings showed that the opioid receptors in hippocampus play an important role in mediating the enhancing or impairing effects of corticosterone on memory consolidation and retrieval in passive avoidance task