Curcumin Rescues Aging-Related Loss of Hippocampal Synapse Input Specificity of Long Term Potentiation in Mice

Curcumin has neuroprotective effect and could enhance memory. However, the mechanisms underlying the protection of curcumin on aging-related memory decline are not well understood. In this study, high frequency stimulation (HFS)-induced long term potentiation (LTP) was evaluated by a cellular model of memory formation. A two-input stimulation paradigm was used to record the potentiation as well as synapse input specificity. The data suggested that an N-Methyl-d-aspartate receptors (NMDAR) -dependent LTP was inducible in adult hippocampal slices with a characteristic of synapse input specificity. It also indicated that aging resulted in a reduction in LTP but more importantly a loss of synaptic input specificity. The reason behind the above conclusions is that LTP induction is more dependent on the calcium channel. This is due to a switch of the dependence of LTP induction to voltage-dependent calcium channel (VDCC) compared to NMDA receptors. Curcumin administration recovers input specificity by re-establishing NMDA receptor dependence of induction. In addition, curcumin administration ameliorated aging-related increase of brain thiobarbituric acid-reactive substances and elevated aging-related decrease of glutathione in hippocampus. It is then concluded that curcumin modulates hippocampal redox status and restores aging-related loss of synapse input specificity of HFS-induced LTP by switching VDCC calcium source into NMDA receptor-dependent one.