Central neural mechanisms mediating human visceral hypersensitivity

Area of Science:

• Neuroscience
• Gastroenterology
• Pain Research

Background:

• Visceral hypersensitivity is a key factor in functional gastrointestinal disorders.
• The precise neural mechanisms underlying visceral hypersensitivity remain unclear.
• Central sensitization, or hyperexcitability of spinal cord sensory neurons, is a potential contributor.

Purpose of the Study:

• To investigate the role of central sensitization in human visceral hypersensitivity.
• To provide electrophysiological evidence for central sensitization in the esophagus.

Main Methods:

• Healthy participants underwent a 30-minute infusion of hydrochloric acid (HCl) into the distal esophagus.
• Pain thresholds to electrical stimulation of the proximal esophagus were measured.
• Esophageal evoked potentials (EEP) were recorded from the proximal esophagus.

Main Results:

• Esophageal acid infusion reduced the pain threshold to electrical stimulation in the non-acid-exposed proximal esophagus.
• Latency of N1 and P2 components of esophageal evoked potentials (EEP) decreased.
• Reduced EEP latency suggests increased afferent pathway velocity and central hyperexcitability.

Conclusions:

• Findings provide the first electrophysiological evidence for central sensitization in human visceral hypersensitivity.
• Central sensitization contributes to hypersensitivity in non-exposed esophageal regions (secondary hyperalgesia/allodynia).
• This supports the role of central sensitization in the pathophysiology of functional gastrointestinal disorders.