Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Chronic opiate use may raise vulnerability to stress

28.09.2004


Animal study sheds light on effects of hospital drugs

Chronic use of opiate drugs may alter brain neurons to make animal brains more sensitive to stress, according to a new study. If the research proves applicable to humans, the findings may help explain how hospital patients who have received morphine may be susceptible to stress disorder, attention problems and sleep disturbances. The effects on the brain may also contribute to better understanding of drug addiction.

The study, published in the September 22 issue of the Journal of Neuroscience, was the first to show that chronic opiate use disrupts the stress response of nerve cells in the noradrenergic system. This system, using a neurotransmitter called norepinephrine, influences the brain’s arousal and attention levels when a stressful event occurs.



The researchers observed that the norepinephrine neurons of rats that had received morphine infusions for a week discharged more frequently in response to a stressor, compared to neurons of rats that had not received morphine. "The increase in neuron firing indicated the neurons were more sensitive to stress, and we also found this sensitization translated into behavioral changes--as shown in the rats’ swimming behavior," said study leader Rita J. Valentino, Ph.D., a behavioral neuroscientist at The Children’s Hospital of Philadelphia.

The researchers used a swim stress test that involved placing rats into glass containers of water. The opiate-treated rats tried to climb the chamber walls, in contrast to untreated rats, which exerted only the effort needed to float. "The climbing behavior reflected a higher activity level in the rats whose brains had been sensitized by the opiates," added Dr. Valentino.

In both humans and rats, a stressful event, such as blood loss, causes one part of the brain to release a hormone called corticotropin-releasing factor (CRF). CRF in turn stimulates neurons in a portion of the brain called the locus ceruleus. Cells in the locus release the neurotransmitter norepinephrine, which activates the area of the brain governing arousal responses (part of the "fight or flight" response to an attack).

The current study found that chronic exposure to the opiate drug morphine made locus ceruleus neurons more sensitive to CRF than they had been previously. If this process occurs similarly in humans, it could have practical implications for hospital patients receiving morphine or similar opiate drugs. "Based on these findings, we would predict that patients will have an increased sensitivity to stress," said Dr. Valentino. Jittery patients might suffer disrupted sleep patterns, increased anxiety and other symptoms, many of them similar to those found in people with post-traumatic stress disorder (PTSD).

Researchers have previously noted sleep disturbances and a higher incidence of PTSD symptoms among opiate users, added Dr. Valentino. Her current study suggests that the opiate-induced sensitivity to stress may play a role in the cycle of addiction that causes drug abusers to continue seeking drugs. However, she added, the role of the norepinephrine system in opiate-seeking behavior remains controversial, and further studies are needed.

As a practical matter, physicians and family members of patients who are taking opiates should be aware of the potential for increased stress symptoms, explained Dr. Valentino. Both children and adults may receive opiates as painkillers in the hospital, and one concern is that young children are particularly vulnerable to the effects of stress because their brains are developing. "As research advances in this field, we may be able to find other opiate medications that do not sensitize neurons to the same degree," she added.

John Ascenzi | EurekAlert!
Further information:
http://www.chop.edu

More articles from Life Sciences:

nachricht A Map of the Cell’s Power Station
18.08.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau

nachricht On the way to developing a new active ingredient against chronic infections
18.08.2017 | Deutsches Zentrum für Infektionsforschung

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

A Map of the Cell’s Power Station

18.08.2017 | Life Sciences

Engineering team images tiny quasicrystals as they form

18.08.2017 | Physics and Astronomy

Researchers printed graphene-like materials with inkjet

18.08.2017 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>