Electrical Stimulation-Induced Muscle Damage Alters Hippocampal BDNF Signaling.

Area of Science:

• Neuroscience
• Exercise Physiology
• Muscle Biology

Background:

• Electrical stimulation (ES) is explored as an alternative to exercise for enhancing neuroplasticity.
• The fibronectin type III domain-containing protein 5 (FNDC5)/Irisin pathway is a potential mediator of muscle-brain communication.
• Brain-derived neurotrophic factor (BDNF) is crucial for neuroplasticity and synaptic function.

Purpose of the Study:

• To investigate if ES mimics exercise in promoting BDNF-dependent neuroplasticity via the FNDC5/Irisin pathway.
• To assess the impact of ES on muscle-brain communication and hippocampal function.
• To determine the effects of ES-induced muscle damage on neuroplasticity.

Main Methods:

• Male Wistar rats underwent daily transcutaneous ES of lumbar nerve roots for seven days.
• Muscle contractions were induced in the hindlimbs.
• Biochemical, histological, and molecular analyses were performed on blood and tissue samples.

Main Results:

• ES disrupted hippocampal BDNF signaling and reduced synaptic protein expression.
• ES caused significant soleus muscle damage and activated muscle satellite cells (MuSCs).
• Increased FNDC5 expression in muscles correlated with MuSC activation, not humoral signaling, and was linked to pro-inflammatory states and stress indicators in the hippocampus.

Conclusions:

• FNDC5 upregulation in damaged muscle reflects local repair, not beneficial muscle-brain dialogue.
• ES protocols causing muscle injury negatively impact BDNF-dependent plasticity through maladaptive muscle-brain interactions.
• Optimizing ES is vital to minimize muscle damage and prevent adverse effects on neuroplasticity, especially in vulnerable populations.