Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Rats depleted of salt become sensitized to amphetamine, show unusual growth of brain cells

04.06.2002


Laboratory rats that have been repeatedly depleted of salt become sensitized to amphetamine, exhibiting an exaggerated hyperactive response to the drug and an unusual pattern of neuronal growth in a part of their brains, neuroscientists have found.



The researchers, headed by University of Washington psychologist Ilene Bernstein, discovered that nerve cells in the nucleus accumbens of sensitized rats have more branches and were 30 percent to 35 percent longer than normal. The nucleus accumbens, located in the forebrain, is involved in the reward and motivation system in rats and in humans. It is associated with regulating motivated behaviors of such natural drives as those for food and salt, and for artificial rewards provided by drugs.

The findings are published in the current issue of the Journal of Neuroscience.


"This number, 30 to 35 percent, is startling and implies an ability for neurons to make more connections," said Bernstein.

The research was triggered by several recent papers. One reported that rats sensitized to amphetamine showed this type of neuron growth. A second found that rats deprived of food seemed to be amphetamine sensitized. When an animal or person becomes sensitized their behavior changes. With amphetamine, animals and people become hyperactive. Rats that are salt sensitized drink and eat salt more rapidly and in greater quantities. Why they behave this way is unknown, Bernstein said.

"That research and ours seem to indicate that being hungry or sodium deprived enough can change an animal’s or a person’s response to a drug even if they have not been exposed to the drug previously," she said.

"We don’t know if this holds up in humans. But the same part of the brain and the response to drugs holds up across species. The same systems are involved in rats and humans when it comes to amphetamines and cocaine. This suggests evidence of a common natural substrate to natural and artificial rewards that is worth further investigation."

She added that the findings also point to questions that need to be explored. These include determining how long cross sensitization persists and whether physical challenges such as salt depletion alter people’s responses to drugs.

"There is differential response among people who are challenged or stressed based on their history. Some people may have a life-long susceptibility to these kinds of things. We also need to know why these drugs are so powerful and what systems they are taking advantage of that didn’t evolve naturally."

In the study, the researchers first gave a group of rats diuretics to deplete them of salt. Then they gave the animals a 3 percent saltwater solution, a mixture they ordinarily would not like or drink. This procedure was repeated two more times, with each treatment given a week apart.

Then the animals’ brains were examined under a microscope, revealing the 30 percent to 35 percent increase in neuron growth in the nucleus accumbens compared to the brains of normal rats. The ends of brain cells, or dendrites, are where neurons make connections with other neurons, implying an ability to make more connections, said Bernstein.

To check for cross sensitization to amphetamine, another group of rats was salt depleted twice. Then they were allowed to explore an open, dark plastic enclosure with the floor divided into a grid by white tape. A week after the second salt depletion, the rats and a control group of animals were injected with amphetamine and placed in the enclosure.

The psychostimulant effects of the drugs were measured by two behaviors – the number of taped lines each animal crossed over and how many times it reared up on its hind feet. The two groups didn’t differ in the number of lines each crossed, but the salt-depleted rats showed significantly more rearing behavior.

What was particularly striking about the findings is that they occurred relatively quickly, just two weeks after the first salt-depletion treatment, said Bernstein.


Other members of the research team included Mitchell Roitman, a UW graduate who is now a post-doctoral researcher at the University of North Carolina, and Theresa Jones, an assistant psychology professor at the University of Texas. The UW’s Royalty Research Fund supported the research.

For more information, contact Bernstein at (206) 543-4527 or ileneb@u.washington.edu


Joel Schwarz | EurekAlert

More articles from Life Sciences:

nachricht Cells migrate collectively by intermittent bursts of activity
30.09.2016 | Aalto University

nachricht The structure of the BinAB toxin revealed: one small step for Man, a major problem for mosquitoes!
30.09.2016 | CNRS (Délégation Paris Michel-Ange)

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: First-Ever 3D Printed Excavator Project Advances Large-Scale Additive Manufacturing R&D

Heavy construction machinery is the focus of Oak Ridge National Laboratory’s latest advance in additive manufacturing research. With industry partners and university students, ORNL researchers are designing and producing the world’s first 3D printed excavator, a prototype that will leverage large-scale AM technologies and explore the feasibility of printing with metal alloys.

Increasing the size and speed of metal-based 3D printing techniques, using low-cost alloys like steel and aluminum, could create new industrial applications...

Im Focus: New welding process joins dissimilar sheets better

Friction stir welding is a still-young and thus often unfamiliar pressure welding process for joining flat components and semi-finished components made of light metals.
Scientists at the University of Stuttgart have now developed two new process variants that will considerably expand the areas of application for friction stir welding.
Technologie-Lizenz-Büro (TLB) GmbH supports the University of Stuttgart in patenting and marketing its innovations.

Friction stir welding is a still-young and thus often unfamiliar pressure welding process for joining flat components and semi-finished components made of...

Im Focus: First quantum photonic circuit with electrically driven light source

Optical quantum computers can revolutionize computer technology. A team of researchers led by scientists from Münster University and KIT now succeeded in putting a quantum optical experimental set-up onto a chip. In doing so, they have met one of the requirements for making it possible to use photonic circuits for optical quantum computers.

Optical quantum computers are what people are pinning their hopes on for tomorrow’s computer technology – whether for tap-proof data encryption, ultrafast...

Im Focus: OLED microdisplays in data glasses for improved human-machine interaction

The Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP has been developing various applications for OLED microdisplays based on organic semiconductors. By integrating the capabilities of an image sensor directly into the microdisplay, eye movements can be recorded by the smart glasses and utilized for guidance and control functions, as one example. The new design will be debuted at Augmented World Expo Europe (AWE) in Berlin at Booth B25, October 18th – 19th.

“Augmented-reality” and “wearables” have become terms we encounter almost daily. Both can make daily life a little simpler and provide valuable assistance for...

Im Focus: Artificial Intelligence Helps in the Discovery of New Materials

With the help of artificial intelligence, chemists from the University of Basel in Switzerland have computed the characteristics of about two million crystals made up of four chemical elements. The researchers were able to identify 90 previously unknown thermodynamically stable crystals that can be regarded as new materials. They report on their findings in the scientific journal Physical Review Letters.

Elpasolite is a glassy, transparent, shiny and soft mineral with a cubic crystal structure. First discovered in El Paso County (Colorado, USA), it can also be...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Paper – Panacea Green Infrastructure?

30.09.2016 | Event News

HLF: From an experiment to an establishment

29.09.2016 | Event News

European Health Forum Gastein 2016 kicks off today

28.09.2016 | Event News

 
Latest News

First-Ever 3D Printed Excavator Project Advances Large-Scale Additive Manufacturing R&D

30.09.2016 | Materials Sciences

New Technique for Finding Weakness in Earth’s Crust

30.09.2016 | Earth Sciences

Cells migrate collectively by intermittent bursts of activity

30.09.2016 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>