Not just pancreas, brain too regulates glucose metabolism

What has brain to do with glucose metabolism? A lot, say researchers, suggesting that not just your pancreas, a group of neurons in the hypothalamus area also plays a vital role in maintaining blood glucose levels.

The team from Rockefeller University and Rensselaer Polytechnic Institute have used magnetic forces to remotely control the flow of ions into specifically targeted cells in mice.

Jeffrey Friedman, head of the laboratory of molecular genetics, and colleagues successfully employed this system to study the role of the central nervous system in glucose metabolism.

"These results are exciting because they provide a broader view of how blood glucose is regulated -- they emphasize how crucial the brain is in this process," Friedman said.

"Having a new means for controlling neural activity, one that doesn't require an implant and allows you to elicit rapid responses, fills a useful niche between the methods that are already available," added the scientist in a paper which appeared in the journal Nature.

The new study is the first to turn neurons on and off remotely with radio waves and magnetic fields.

Using this novel method, the researchers investigated the role these glucose sensing neurons play in blood glucose metabolism.

Hormones released by the pancreas, including insulin, maintain stable levels of glucose in the blood.

A region of the brain called the ventromedial hypothalamus was thought to play a role in regulating blood glucose.

Friedman and colleagues found that when they switched these neurons on with magnetic forces, blood glucose increased, insulin levels decreased, and behaviourally, the mice ate more.

When they inhibited the neurons, on the other hand, the opposite occurred, and blood glucose decreased.

"We tend to think about blood glucose being under the control of the pancreas, so it was surprising that the brain can affect blood glucose in either direction to the extent that it can," Friedman noted.

The system has several advantages that make it ideal for studies on other circuits in the brain or elsewhere.

It can be applied to any circuit, including dispersed cells like those involved in the immune system.

In addition to its utility as a research tool, the technique may also have clinical applications.

"Depending on the type of cell we target and the activity we enhance or decrease within that cell, this approach holds potential in development therapies for metabolic and neurologic diseases," explained Jonathan Dordick from Rensselaer.