Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Spinal cord neurons that control pain and itch

19.03.2015

The spinal cord transmits pain signals to the brain, where they are consciously perceived. But not all the impulses arrive at their destination: Certain neurons act as checkpoints and determine whether a pain signal is relayed or not. Researchers from UZH identified these neurons and their connections. Moreover, they developed means to specifically activate these neurons, which reduces not only pain – but astonishingly also alleviates itch.

Sensing pain is extremely unpleasant and sometimes hard to bear – and pain can even become chronic. The perception of pain varies a lot depending on the context in which it is experienced. 50 years ago, neurobiologist Patrick Wall and psychologist Ronald Melzack formulated the so-called “Gate Control Theory” of pain.

The two researchers proposed that inhibitory nerve cells in the spinal cord determine whether a pain impulse coming from the periphery, such as the foot, is relayed to the brain or not. A team headed by Hanns Ulrich Zeilhofer from the Institute of Pharmacology and Toxicology at the University of Zurich did now reveal which inhibitory neurons in the spinal cord are responsible for this control function: As the study published in the science journal Neuron shows, the control cells are located in the spinal dorsal horn and use the amino acid glycine as an inhibitory messenger.

The pain gate can be manipulated with viruses

With the aid of genetically modified viruses, the research group from UZH managed to specifically interfere with the function of these neurons in mice. They discovered that disabling the glycine-releasing neurons leads to an increased sensitivity to pain and signs of spontaneous pain. Moreover, Zeilhofer‘s team developed viruses that enable these specific pain-control cells to be activated pharmacologically. Mice treated with these viruses were less sensitive to painful stimuli than their untreated counterparts. Activating these nerve cells also alleviated chronic pain. And the surprising additional result: “Evidently, the neurons don’t just control pain, but also various forms of itch,” explains Zeilhofer.

How light touch controls pain

One key aspect of the Gate Control Theory is that various influences can modulate the pain-controlling neurons’ activity. Based on our experience from everyday life, for instance, we know that gently rubbing or holding an injured extremity can alleviate pain in this area. According to the theory, non-painful contact with the skin is supposed to activate the inhibitory cells. Sure enough, the UZH researchers were able to verify this hypothesis and confirm that the inhibitory, glycine-releasing neurons are innervated by such touch-sensitive skin nerves.

Moreover, the pharmacologists were able to demonstrate that neurons on the superficial layers of the spinal cord, where the relay of the pain signals takes place, are primarily inhibited by glycine signals. “These three findings identify for the first the neurons and connections that underlie the Gate Control Theory of pain,” sums up Zeilhofer.

Targeted therapy in humans not yet possible

Can these findings be used to treat pain? “The targeted stimulation or inhibition of particular types of neurons in humans is still a long way off and might only be possible in a few decades’ time,” says Zeilhofer. Another way may well reach the target sooner – namely via the receptors that are activated by the inhibitory neurons: “As these receptors are located on the neurons that relay pain signals to the brain, their specific pharmacological activation should also block pain,” says Hanns Ulrich Zeilhofer. His group has already achieved promising initial results in this field, too.

Literature:

Edmund Foster, Hendrik Wildner, Laetitia Tudeau, Sabine Haueter, William T. Ralvenius, Monika Jegen, Helge Johannssen, Ladina Hösli, Karen Haenraets, Alexander Ghanem, Karl Klaus Conzelmann, Michael Bösl, Hanns Ulrich Zeilhofer (2015) Targeted ablation, silencing and activation establish glycinergic dorsal horn neurons as key components of a spinal gate for pain and itch. Neuron, in press. http://dx.doi.org/10.1016/j.neuron.2015.02.028


Contacts:

Hanns Ulrich Zeilhofer

Institute of Pharmacology and Toxicology

University of Zurich and ETH Zurich

Tel.: +41 44 63 55912

Email: zeilhofer@pharma.uzh.ch

Weitere Informationen:

http://www.mediadesk.uzh.ch

Nathalie Huber | Universität Zürich

Further reports about: Neuron Toxicology activation function inhibitory inhibitory neurons nerve cells neurons pain skin spinal spinal cord viruses

More articles from Life Sciences:

nachricht BigH1 -- The key histone for male fertility
14.12.2017 | Institute for Research in Biomedicine (IRB Barcelona)

nachricht Guardians of the Gate
14.12.2017 | Max-Planck-Institut für Biochemie

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Long-lived storage of a photonic qubit for worldwide teleportation

MPQ scientists achieve long storage times for photonic quantum bits which break the lower bound for direct teleportation in a global quantum network.

Concerning the development of quantum memories for the realization of global quantum networks, scientists of the Quantum Dynamics Division led by Professor...

Im Focus: Electromagnetic water cloak eliminates drag and wake

Detailed calculations show water cloaks are feasible with today's technology

Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while...

Im Focus: Scientists channel graphene to understand filtration and ion transport into cells

Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.

To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...

Im Focus: Towards data storage at the single molecule level

The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.

Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...

Im Focus: Successful Mechanical Testing of Nanowires

With innovative experiments, researchers at the Helmholtz-Zentrums Geesthacht and the Technical University Hamburg unravel why tiny metallic structures are extremely strong

Light-weight and simultaneously strong – porous metallic nanomaterials promise interesting applications as, for instance, for future aeroplanes with enhanced...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

AKL’18: The opportunities and challenges of digitalization in the laser industry

07.12.2017 | Event News

 
Latest News

Plasmonic biosensors enable development of new easy-to-use health tests

14.12.2017 | Health and Medicine

New type of smart windows use liquid to switch from clear to reflective

14.12.2017 | Physics and Astronomy

BigH1 -- The key histone for male fertility

14.12.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>