Myelin Influences Signals Sent By Brain Cells

A recent study made by Ohio State University researchers have shown how myelin may act more than just insulation for neurons to enable normal communication between the central nervous system and the rest of the body. Myelin may also play a role in controlling nerve impulses traveling between the distant areas of the nervous system. The results of the study is published in the July 22 issue of the Journal of Biological Chemistry.

The Ohio State University researchers have developed a cell culture system that allows two types of cells to interact in a dish just as they would in nature. The cells used by the study are neurons from the hippocampus and oligodendrocytes, cells that play a role in developing myelin around the neural axons. Inn this system, the researchers are able to study how myelination is switched on and off for the hippocampal neurons. But it seems that the cell interaction does more than that.

The researchers have also shown that myelin regulates the placement and activity of a key protein known as a Kv1.2 voltage-gated potassium channel. This key protein is needed in order to maintain the ideal conditions that will make the sending and transmitting of electrical signals more effective along the hippocampal axons. According to Chen Gu, associate professor of neuroscience at OSU and the study’s lead author, “This channel is important because it is what leads to electrical activity and how neurons communicate with each other downstream. If that process is disrupted by demyelination, disease symptoms may occur.”

In order to make a cell culture system, the researchers made use of hippocampal neurons coming from a brain of a rodent. In the culture, these cells grow dendrites, other branch like projections from neurons, and axons which also generate electrical activity as well as develop synaptic connections, the same events that occur naturally in the brain. The researchers then add in oligodendrocytes along with some of their precursor cells on the same culture dish containing the neurons. As the oligodendrocytes mature, they start wrapping up myelin around the axons of the hippocampal neurons.

The researchers were also able to experimentally manipulate signal conditions in the cell culture system, allowing them to study and understand how myelin may affect electrical signals sent out by the neurons. The researchers traced a series of chemical reactions in the cell culture. They eventually found out that myelin on the hippocampal axons seem to be controlling the placement and activity of the Kv1.2 ion channel. This ion channel seems to play a role in putting a nerve cell into a resting state after a nerve impulse has passed through it, getting it ready to receive the next impulse.

When a disease such as multiple sclerosis damages the myelin in the axons, the affected nerve cells can’t seem to get into a resting state, not giving it adequate time to receive and transmit the next signal.

“This means a nerve impulse will have a hard time traveling through the demyelinated region,” Gu explains. “This shows that the ion channel is probably involved in the downstream disease progression of MS.”

Source: Ohio State University (2011, July 22). Multiple sclerosis research: Myelin influences how brain cells send signals. ScienceDaily. Retrieved August 2, 2011, from http://www.sciencedaily.com/releases/2011/07/110721163035.htm

 
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