Precise dynamic control of tissue oxygenation during brain slice electrophysiology

Area of Science:

• Neuroscience
• Physiology
• Biomedical Engineering

Background:

• Precise oxygen regulation is critical for neuronal integrity in ex vivo brain slice electrophysiology.
• Conventional chambers offer poorly defined oxygenation, limiting studies of neurological disorders involving hypoxia.
• Modeling transient or intermittent hypoxia (IH) is challenging with existing electrophysiology setups.

Purpose of the Study:

• To develop a versatile Oxyslice Recording Chamber (ORC) for real-time neural activity monitoring.
• To enable rapid and precise oxygen modulation during standard electrophysiological recordings.
• To accurately model continuous hypoxia (CH) and IH in ex vivo brain slices.

Main Methods:

• A polydimethylsiloxane (PDMS)-based ORC with a gas-permeable membrane was designed for uniform oxygen exchange.
• The ORC integrates into standard electrophysiological setups and operates at low perfusion rates.
• Hippocampal slices were subjected to CH (3% or 1% O2) and IH (6-1% O2 cycles) while recording field excitatory postsynaptic potentials (fEPSPs).

Main Results:

• The ORC achieved precise and reproducible cellular-level oxygen control.
• Both CH and IH caused hypoxia severity-dependent reductions in fEPSP slopes, which reversed upon reoxygenation.
• Severe CH (1% O2) reduced fEPSP slope by ~60%, while IH reduced it by ~40%, suggesting partial mitigation during reoxygenation.

Conclusions:

• The novel ORC offers a robust and adaptable method for real-time oxygen modulation in ex vivo neuronal recordings.
• This device effectively models CH and IH at physiological oxygen tensions, addressing a gap in current methodologies.
• The ORC facilitates mechanistic studies of hypoxia-driven neuronal dysfunction and supports therapeutic discovery.