CB1 receptor affects cortical plasticity and response to physiotherapy in multiple sclerosis

Area of Science:

• Neuroscience
• Genetics
• Rehabilitation Medicine

Background:

• Physical therapy effectiveness in neurological disorders hinges on synaptic plasticity.
• The endocannabinoid system, particularly cannabinoid CB1 receptors (CB1Rs), plays a role in synaptic plasticity and is activated by physical exercise.

Purpose of the Study:

• To investigate if genetic variants of the CB1R impact patient response to exercise therapy.
• To explore the link between CB1R genetic variations, synaptic plasticity, and clinical outcomes in multiple sclerosis.

Main Methods:

• Assessed the effect of a specific CB1R genetic variant (long AAT trinucleotide repeats in the CNR1 gene) associated with reduced receptor expression.
• Evaluated long-term potentiation (LTP)-like cortical plasticity using transcranial magnetic theta burst stimulation (TBS) of the motor cortex.
• Correlated these findings with the clinical response to exercise therapy in multiple sclerosis patients.

Main Results:

• Patients with long AAT CNR1 repeats exhibited no TBS-induced LTP-like cortical plasticity.
• These patients also demonstrated a poor clinical benefit from exercise therapy.

Conclusions:

• Genetic variations in CB1R influence clinical responses to exercise therapy in multiple sclerosis.
• CB1Rs are implicated in regulating synaptic plasticity and spasticity in humans.
• Findings support patient stratification for personalized rehabilitation programs.