Copper enhances cellular and network excitabilities, and improves temporal processing in the rat hippocampus

Area of Science:

• Neuroscience
• Neurochemistry

Background:

• Copper is an essential ion with known metabolic functions.
• Its role in neuronal function and neuromodulation is proposed but not fully understood at the network level.
• Previous studies observed copper's effects at micromolar concentrations, differing from the current study's findings.

Purpose of the Study:

• To investigate the neuromodulatory mechanisms of copper in a functional neuronal network.
• To determine copper's effects on intrinsic, synaptic, and network properties of the CA1 hippocampal region.
• To explore copper's role at lower, nanomolar concentrations.

Main Methods:

• Utilized rat hippocampus slices as a model neuronal network.
• Tested copper effects in the 10-100 nm concentration range.
• Assessed intrinsic, synaptic, and network properties, including action potential (AP) conductances and synaptic event frequency.
• Investigated the impact of copper chelation using bathocuproine.

Main Results:

• Copper (10-100 nm) acts as a multifaceted neuromodulator.
• Observed activity enhancement: hyperpolarized AP firing threshold, increased neuronal and network excitability, modified CA3-CA1 pathway gain, and increased spontaneous synaptic event frequency.
• Demonstrated temporal processing improvements: decreased inhibitory network activity and enhanced AP timing reliability.
• Copper chelation reduced spontaneous network spiking activity.

Conclusions:

• Copper exerts significant neuromodulatory effects at nanomolar concentrations within hippocampal circuitry.
• These effects encompass both activity enhancement and improved temporal processing.
• Copper influences network activity from cellular to circuit levels, acting as a crucial functional component.