Effect of hydrogen peroxide on electrical coupling between identified Lymnaea neurons

Area of Science:

• Neuroscience
• Cellular Biology
• Biochemistry

Background:

• Gap junctions mediate direct electrical and chemical communication between neurons.
• Hydrogen peroxide (H₂O₂) is a reactive oxygen species with known signaling roles in biological systems.
• Understanding H₂O₂'s impact on neuronal communication is crucial for deciphering cellular responses to oxidative stress.

Purpose of the Study:

• To investigate the effect of hydrogen peroxide (H₂O₂) on gap-junction coupling between VD1 and RPaD2 neurons in Lymnaea stagnalis.
• To elucidate the mechanisms underlying H₂O₂-induced modulation of neuronal excitability and intercellular communication.

Main Methods:

• Intracellular microelectrode recordings were used to monitor the electrical activity of VD1/RPaD2 neurons.
• Application of H₂O₂ (1 × 10⁻⁴ M) and nifedipine (a Ca²⁺ channel blocker) to assess their effects on neuronal firing and coupling.
• Measurement of gap-junction coupling ratio and network input resistance.

Main Results:

• H₂O₂ application (1 × 10⁻⁴ M) caused a rapid 1.3-fold increase in neuronal spiking frequency and a reduction in action potential amplitude.
• A significant 1.8-1.9 fold reduction in the bidirectional coupling ratio between VD1 and RPaD2 neurons was observed after H₂O₂ exposure.
• The effects of H₂O₂ were abolished by nifedipine and were fully reversible upon washing, with no change in network input resistance.

Conclusions:

• Hydrogen peroxide dynamically modulates gap-junction properties between Lymnaea stagnalis neurons.
• H₂O₂-induced changes in neuronal excitability and coupling are likely mediated by voltage-gated calcium channels.
• These findings highlight a novel role for H₂O₂ in regulating intercellular communication within the central nervous system.