How stress alleviates pain

December 05, 2007

One way to alleviate the pain of banging your shin while on a hike is to encounter a grizzly bear--a well-known phenomenon called stress-induced analgesia. Now, researchers have elucidated a key mechanism by which the stress hormone noradrenaline--which floods the bloodstream during grizzly encounters and other stressful events--affects the brain's pain-processing pathway to produce such analgesia.

Pankaj Sah and colleagues published their findings in the December 6, 2007, issue of the journal Neuron, published by Cell Press.

In an accompanying perspective article on the research, Harvard Medical School researchers Keith Tully, Yan Li, and Vadim Bolshakov wrote that "The impressive new study... provides important mechanistic clues helping to explain this phenomenon."

In their experiments, Sah and colleagues studied a region of the amygdala, the brain's emotion-processing region known to mediate the emotional and stress-related aspects of pain. Researchers had long known that these amygdala-based processes were controlled by neurons that originated in the brainstem and that were regulated by noradrenaline.

Sah and colleagues sought in their studies to understand the mechanism by which noradrenaline influences neuronal transmission of pain inputs from the brainstem region known as the pontine parabrachial (PB).

In their experiments with rats, the researchers analyzed the effects of noradrenaline on electrical stimulation of the pathway between the PB and amygdala. They found that noradrenaline acted as a powerful suppressor of that stimulation. The researchers' studies also revealed that noradrenaline suppression acted on the "transmission" side of the connections between neurons, called synapses. Their analyses revealed how noradrenaline causes such suppression: by activating specific receptors, called adrenocreceptors, on the PB neurons.

The researchers' studies showed that noradrenaline's action appears to reduce the number of sites that launch the chemical signals called neurotransmitters by which one neuron triggers a nerve impulse in another, reported the researchers.

They concluded that "Our results show that an important mediator of stress-induced analgesia could be the potent modulation by noradrenaline of [pain] PB inputs in the central amygdala."
-end-
The researchers include Andrew J. Delaney, James W. Crane, and Pankaj Sah, of the Queensland Brain Institute, The University of Queensland, Australia.

Cell Press

Related Stress Articles from Brightsurf:

Stress-free gel
Researchers at The University of Tokyo studied a new mechanism of gelation using colloidal particles.

Early life stress is associated with youth-onset depression for some types of stress but not others
Examining the association between eight different types of early life stress (ELS) and youth-onset depression, a study in JAACAP, published by Elsevier, reports that individuals exposed to ELS were more likely to develop a major depressive disorder (MDD) in childhood or adolescence than individuals who had not been exposed to ELS.

Red light for stress
Researchers from the Institute of Industrial Science at The University of Tokyo have created a biphasic luminescent material that changes color when exposed to mechanical stress.

How do our cells respond to stress?
Molecular biologists reverse-engineer a complex cellular structure that is associated with neurodegenerative diseases such as ALS

How stress remodels the brain
Stress restructures the brain by halting the production of crucial ion channel proteins, according to research in mice recently published in JNeurosci.

Why stress doesn't always cause depression
Rats susceptible to anhedonia, a core symptom of depression, possess more serotonin neurons after being exposed to chronic stress, but the effect can be reversed through amygdala activation, according to new research in JNeurosci.

How plants handle stress
Plants get stressed too. Drought or too much salt disrupt their physiology.

Stress in the powerhouse of the cell
University of Freiburg researchers discover a new principle -- how cells protect themselves from mitochondrial defects.

Measuring stress around cells
Tissues and organs in the human body are shaped through forces generated by cells, that push and pull, to ''sculpt'' biological structures.

Cellular stress at the movies
For the first time, biological imaging experts have used a custom fluorescence microscope and a novel antibody tagging tool to watch living cells undergoing stress.

Read More: Stress News and Stress Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.