Modulation of neuromuscular transmission using transcutaneous direct currents: An exploratory study

Area of Science:

• Neuroscience
• Neuromuscular Physiology
• Electrostimulation

Background:

• Neuromuscular transmission is crucial for motor control.
• Understanding factors that modulate neuromuscular function is important for therapeutic applications.
• Transcutaneous direct current stimulation (epDCS) is a non-invasive technique with potential to influence nerve function.

Purpose of the Study:

• To investigate the in vivo effects of anodal and cathodal transcutaneous direct currents applied over the end-plate region (epDCS) on neuromuscular transmission.
• To assess the long-lasting modulatory effects of epDCS on neuromuscular function.

Main Methods:

• Anodal or cathodal direct currents (2.5mA for 15min) were applied over the end-plate region of hand muscles (abductor pollicis brevis, first dorsal interosseous).
• Repetitive nerve stimulation (median and ulnar nerves) was performed before and after epDCS using different protocols (3Hz and 30Hz stimulation).
• Changes in compound muscle action potential (CMAP) amplitude and area were measured to assess neuromuscular transmission efficiency.

Main Results:

• Anodal epDCS showed no significant effects on neuromuscular transmission.
• Cathodal epDCS applied to the median nerve resulted in a significant increase in CMAP amplitude and a decrease in CMAP area during 30Hz stimulation.
• Cathodal epDCS showed a trend towards a smaller decrease in CMAP amplitude during 3Hz stimulation for the ulnar nerve.

Conclusions:

• Cathodal epDCS over the end-plate region may enhance neuromuscular transmission.
• These effects could be mediated by increased acetylcholine release or enhanced acetylcholine receptor availability.
• Further research is warranted to elucidate the precise mechanisms and clinical implications of cathodal epDCS on neuromuscular function.