Memory consolidation impairment induced by Interleukin-1 beta is associated with changes in hippocampal structural plasticity

摘要

Pro-inflammatory cytokines, particularly Interleukin-1 beta (IL-1 beta), can affect cognitive processes such as learning and memory. The aim of this study was to establish whether the effect of IL-1 beta on contextual fear memory is associated with changes in hippocampal structural plasticity. We also studied the effect of alpha-melanocyte-stimulating hormone (alpha-MSH), a potent anti-inflammatory and neuro-protective peptide. Different groups of animals were implanted bilaterally in dorsal hippocampus (DH). After recovery they were conditioned for contextual fear memory and received the different treatments (vehicle, IL-1 beta, alpha-MSH or IL-1 beta + alpha-MSH). Memory was assessed 24 hs after conditioning and immediately after rats were perfused for dendritic spine analysis. Our results show that local hippocampal administration of IL-1 beta just after memory encoding induced impairment in contextual memory and a reduction in the total density of CA1 hippocampal dendritic spines, particularly the mature ones. alpha-MSH administration reversed the IL-1 beta induced changes. The results suggest that neuro-inflammation induced by IL-1 beta interferes with experience-dependent structural plasticity in DH whereas alpha-MSH has a beneficial modulatory role in preventing this effect.