Development of a Hypersensitivity Evaluation Method for Cultured Sensory Neurons Using Electrical Activity Recording

Area of Science:

• Neuroscience
• Pain Research
• Biomedical Engineering

Background:

• Peripheral sensitization is crucial for understanding pain hypersensitivity and developing new pain treatments.
• Current methods struggle to capture the long-term neuronal activity changes associated with plastic alterations over days.
• High-density microelectrode arrays (HD-MEAs) offer potential for long-term neuronal recording.

Purpose of the Study:

• To establish an efficient method for evaluating neuronal activity alterations in dorsal root ganglion (DRG) neurons during peripheral sensitization.
• To utilize HD-MEAs for long-term monitoring of neuronal activity in cultured DRG neurons.
• To investigate the role of substance P and specific receptor co-expression in peripheral sensitization.

Main Methods:

• Rat embryonic DRG neurons were cultured on HD-MEAs.
• Neurons were labeled with the live staining dye NeuO for detection and electrode selection via fluorescence imaging.
• Pharmacological stimulation (substance P, capsaicin) and immunofluorescence staining were employed to assess neuronal activity and receptor expression.
• Neuronal activity was recorded using HD-MEAs.

Main Results:

• The fluorescence-based method identified five times more DRG neurons than activity-based detection.
• Substance P induced peripheral sensitization and increased capsaicin sensitivity.
• Immunofluorescence revealed that peripheral sensitization predominantly occurred in neurons co-expressing transient receptor potential vanilloid 1 (TRPV1) and neurokinin 1 receptor (NK1R).

Conclusions:

• An efficient method was established for assessing peripheral sensitization effects on DRG neurons cultured on HD-MEAs.
• This method facilitates the study of neuronal plasticity in pain sensitization.
• Findings highlight the involvement of TRPV1 and NK1R co-expressing neurons in substance P-induced sensitization.