CARS imaging shows calcium ions may have role in multiple sclerosis

11 July 2007

Researchers at Purdue University have discovered that calcium ions could play a crucial role in multiple sclerosis by activating enzymes that degrade the fatty sheath that insulates nerve fibres.

The researchers employed an imaging technique called coherent anti-Stokes Raman scattering, or CARS, that uses interfering laser beams to vibrate and identify selected molecules. In this study they showed how the myelin sheath is degraded by a molecule called lysophosphatidylcholine (LPC).

The findings suggest that LPC causes sheath degradation by allowing an influx of calcium ions into the myelin. The increased concentration of calcium ions then activates two enzymes — calpain and cytosolic phospholipase A2 — which break down proteins and fatty molecules in the myelin called lipids.

Cytosolic phospholipase A2 cuts off one of the two tails of these lipid molecules and turns them into LPC, amplifying the effect and further degrading the myelin.

Learning exactly how the myelin sheath is degraded might enable scientists to determine how to halt disease progress and reverse damage by growing new myelin, said Ji-Xin Cheng, an assistant professor in Purdue University's Weldon School of Biomedical Engineering and Department of Chemistry.

LPC, does not cause multiple sclerosis, but it is used extensively in laboratory research to study the deterioration of myelin, which insulates nerve fibres and enables them to properly conduct impulses.

"Although multiple sclerosis has been studied for many years, nobody knows exactly how the disease initially begins. The pathway is not clear. It is possible that the same pathway causes myelin degradation in people suffering from multiple sclerosis and spinal cord injuries," Cheng said.

The research findings were published in the Journal of Neuroscience Research in June.

"The findings of this study will help us to identify key steps in the progression of the demyelination, which is a hallmark of multiple sclerosis," said Riyi Shi, a researcher at Purdue's Institute for Applied Neurology and Center for Paralysis Research. "This information will also facilitate the design of pharmaceutical interventions that slow down or even reverse the development of the debilitating disease."

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