June 11, 2004
A potassium channel blocker called 3,4-diaminopyridine (3,4-DAP) has been shown to improve motor function and fatigue in patients with multiple sclerosis. Now, it appears that the agent works by increasing brain motor activity, probably by potentiating synaptic transmission.
In the June 8th issue of Neurology, Dr. Caterina Mainero and colleagues from the University of Rome "La Sapienza", report that they used functional MRI and transcranial magnetic stimulation (TMS) to assess cerebral activation in 12 women with multiple sclerosis who performed a simple motor task while being treated with 3,4-DAP or placebo.
The authors found that motor-evoked brain activation in the ipsilateral sensorimotor cortex and supplementary motor area was significantly greater when 3,4 DAP had been given rather than placebo (p < 0.05). Further analysis revealed that the drug decreased intracortical inhibition and increased intracortical facilitation, but had no effect on central motor conduction time or muscular fatigability.
The researchers conclude that "the complementary information we obtained by combining functional MRI and TMS provided new evidence that oral administration of 3,4-DAP induces distinct changes in cerebral motor activation and motor cortical excitability in patients with multiple sclerosis."
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