Heterogeneity in Kv2 Channel Expression Shapes Action Potential Characteristics and Firing Patterns in CA1 versus CA2...

Area of Science:

• Neuroscience
• Molecular Biology

Background:

• The CA1 hippocampus region is key for spatial memory, while CA2 is vital for social memory.
• CA2 pyramidal neurons (PNs) lack CA1-like plasticity and are less studied.
• The role of voltage-gated potassium (Kv) channels in CA1 vs. CA2 PN differences is largely unknown.

Purpose of the Study:

• To investigate the region-specific expression of Kv2 family Kv channels in CA1 and CA2 PNs.
• To determine the contribution of Kv2 channels to the distinct intrinsic excitability and firing properties of CA1 and CA2 PNs.

Main Methods:

• Multiplex fluorescence immunolabeling of mouse brain sections.
• Whole-cell recordings in acute mouse brain slices.
• Analysis of Kv2.1, Kv2.2, and AMIGO-1 expression and function.

Main Results:

• Kv2.1, Kv2.2, and AMIGO-1 expression is highest in CA1 PNs, decreases sharply at the CA1-CA2 boundary, and is significantly reduced in CA2 PNs.
• CA1 PNs show a substantial Kv2-based delayed rectifier current affecting action potential (AP) shape and after-hyperpolarization potential (AHP).
• CA2 PNs exhibit less contribution from Kv2 channels to AP shape and AHP.

Conclusions:

• Heterogeneous Kv2 channel expression creates distinct intrinsic excitability patterns in CA1 and CA2 PNs.
• These Kv2-driven differences may underlie the distinct roles of CA1 and CA2 in hippocampal network function and memory.
• Kv2 channels are critical regulators of hippocampal pyramidal neuron excitability.