Synapse-specific effects of IL-1β on long-term potentiation in the mouse hippocampus

Interleukin-1 beta (IL-1 beta) is a key molecule in the inflammatory responses elicited during infection and injury. It exerts local effects on synaptic plasticity by binding to IL-1 receptors that are expressed at high levels in the hippocampus. We examined the effects of IL-1 beta on synaptic plasticity in different hippocampal regions in acute mouse brain slices by measuring long-term potentiation (LTP). IL-1 beta (1 ng/mL) was applied for 30 min before LTP was induced with high-frequency stimulation (HFS). LTP was significantly impaired by either IL-1 beta application to the Schaffer collateral- CA1 synapses or the associational/commissural (A/C) fiber-CA3 synapses, which are both dependent on N-methyl-D-aspartate (NMDA) receptor activation. However, mossy fiber-CA3 LTP, which is expressed presynaptically in an NMDA-independent manner, was not impaired by IL-1 beta. Our results demonstrate that IL-1 beta exerts variable effects on LTP at different kinds of synapses, indicating that IL-1 beta has synapse-specific effects on hippocampal synaptic plasticity.