Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


New mechanism explains glucose effect on wakefulness

One of the body’s basic survival mechanisms is the neural machinery that triggers the hungry brain to the alertness needed for seeking food. That same machinery swings the other way after a hearty meal, as exemplified by the long and honored custom of the siesta. However, scientists have understood little about how the basic energy molecule, glucose, regulates such wakefulness and other energy-related behaviors.

Now, in an article in the June 1, 2006, Neuron, Denis Burdakov of the University of Manchester and his colleagues have pinpointed how glucose inhibits neurons that are key to regulating wakefulness. In the process, they have discovered a role for a class of potassium ion channels whose role has remained largely unknown. Such ion channels are porelike proteins in the cell membrane that affect cellular responses by controlling the flow of potassium into the cell.

The researchers set out to discover how glucose inhibits a particular class of glucose-sensing neurons that produce tiny proteins called orexins, which are central regulators of states of consciousness.

Wrote Burdakov and colleagues, "These cells are critical for responding to the ever-changing body-energy state with finely orchestrated changes in arousal, food seeking, hormone release, and metabolic rate, to ensure that the brain always has adequate glucose."

Malfunction of orexin neurons can lead to narcolepsy and obesity, and researchers have also found evidence that orexin neurons play a role in learning, reward-seeking, and addiction, wrote the researchers.

"Considering these crucial roles of orexin neurons, their recently described inhibition by glucose is likely to have considerable implications for the regulation of states of consciousness and energy balance," wrote Burdakov and his colleagues. "However, as in other glucose-inhibited neurons, it is unknown how glucose suppresses the electrical activity of orexin cells." What’s more, they wrote, "Because the sensitivity of orexin cell firing to the small changes in extracellular glucose that occur between normal meals has never been tested, the daily physiological relevance of their glucose sensing is also unknown."

In their experiments, the researchers engineered mice to produce a fluorescent protein only in orexin neurons. Thus, the researchers could isolate the neurons in brain slices from the mice and perform precise biochemical and electrophysiological studies to explore how glucose acted on those neurons. In particular, the researchers performed experiments in which they exposed the neurons to the subtle changes in glucose levels known to occur in daily cycles of hunger and eating.

Their experiments showed that glucose inhibits orexin neurons by acting on a class of potassium ion channels known as "tandem pore" channels, about which little was known.

"Together, these results identify an unexpected physiological role for the recently characterized [tandem pore potassium] channels and shed light on the long-elusive mechanism of glucose inhibition, thus providing new insights into cellular pathways regulating vigilance states and energy balance," wrote Burdakov and colleagues.

"These results provide evidence that the firing rate of orexin cells is sensitive to changes in glucose that correspond to fluctuations occurring normally during the day and also show that the same electrical mechanism is involved in sensing both subtle and extreme changes in glucose," they wrote.

What’s more, they wrote, their finding that subtle changes in glucose levels affect firing of orexin "raises the possibility that, besides being important for adaptive responses to starvation, modulation of orexin cells by glucose has a much wider behavioral role, contributing to the continuous daily readjustments in the level of arousal and alertness."

The researchers concluded that their findings "provide important new insights into how the brain tunes arousal and metabolism according to body-energy levels."

Heidi Hardman | EurekAlert!
Further information:

More articles from Life Sciences:

nachricht Novel mechanisms of action discovered for the skin cancer medication Imiquimod
21.10.2016 | Technische Universität München

nachricht Second research flight into zero gravity
21.10.2016 | Universität Zürich

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

Im Focus: New Products - Highlights of COMPAMED 2016

COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.

In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...

Im Focus: Ultra-thin ferroelectric material for next-generation electronics

'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.

Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Resolving the mystery of preeclampsia

21.10.2016 | Health and Medicine

Stanford researchers create new special-purpose computer that may someday save us billions

21.10.2016 | Information Technology

From ancient fossils to future cars

21.10.2016 | Materials Sciences

More VideoLinks >>>