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Entries in Rats (4)

Thursday
May312012

Paralyzed Rats Regain Ability to Walk

iStockphoto/Thinkstock(NEW YORK) — Paralyzed rats could walk again after scientists in Switzerland treated their injured spinal cords through a combination of chemical, electrical and physical stimulation.

Gregoire Courtine, the study’s lead author, said the technique would not completely cure a spinal cord injury, but the study gave scientists an idea of how they could combine therapies, each of which have been or are being tested in humans.

“This kind of approach will not make miracles,” Courtine said, “but it’s interesting because it offers new therapeutic avenues for these very traumatic injuries.”

First, the researchers injected the injured rats with chemicals designed to mimic the body’s own cocktail of signals that coordinate movement of the lower body. Five to 10 minutes after the injection, the researchers sent electrical impulses to tiny electrodes placed in the narrow space between the bones of the spine and the nerves of the spinal cord, stoking the spinal cord’s ability to come back after an injury, a quality scientists call neuroplasticity.

The findings were published Thursday in the journal Science.

After a few weeks of the combination of chemicals and electricity, 10 rats were trained to use their paralyzed hind legs with the help of a robotic device for 30 minutes each day, until they could move their legs voluntarily.

After a few weeks of treatment,  the rats sprinted, climbed stairs and avoided obstacles, the study found.

The improvement to the spinal cord was visible, too. The rats’ spinal cords regrew nerves to bridge the gap of their injuries.

The chemical, electrical and physical training therapies have each been individually studied in paralyzed humans. In 2011, electrical stimulation of the spine helped Rob Summers, a paralyzed 25-year-old, move his legs voluntarily.

Neurologists are cautiously encouraged by the results of the study, but many say much more research would be needed before the techniques can be tested in paralyzed humans.

Courtine said it is too early to know whether the approach will work in humans who have spinal cord injuries, and if it does, it is unlikely that a person would completely recover the ability to walk without help.

“But this condition is so traumatic that even a very small improvement would be a major step forward for these patients,” he said.

Copyright 2012 ABC News Radio

Monday
Aug222011

Does Parasite Cause Rats to Love Cats?

Hemera Technologies/Thinkstock(STANFORD, Calif.) -- While the smell of cat urine is normally a turn-off for rats, a group of Stanford University researchers found a certain group of rats was actually attracted to that same odor.

Cat urine is naturally a warning to rats to stay away from an area where their natural predators may be lurking. But study rats infected by the parasite Toxoplasma gondii ("toxo" for short) didn't show that fear and, instead, parts of their brains associated with sexual arousal were activated.

"Normally, we would expect toxoplasma to knock out the normal fear function in the brain, but in these rats the parasite also tapped into the sexual arousal pathway, which is strange," said Robert Sapolsky, a professor of neuroscience at Stanford University and a co-author of the study.

The belief is that the mind-manipulating parasite acts that way in order to ensure its reproduction. Toxo can only reproduce in the guts of cats, so if an infected rat wanders into cat territory, then there's a possibility the cat will eat the rat and toxo can multiply.

"The parasite does actually alter the brain of its host," said Patrick House, a doctoral student who is also a co-author of the study. "The fact that a parasite can get into an organism, target its brain, stay there without killing the host and alter the circuitry of the brain -- we've seen this is insects and fungi, but it's the first time we've seen it in a mammalian host."

Toxoplasma affects a rat's amygdala, the part of the brain associated with fear and anxiety.

"It atrophies some of the neurons along the pathway associated with fear," said Sapolsky. "What we don't understand is how it affects the fear response and then accesses the sexual arousal circuitry."

Toxo does infect humans. Humans contract the parasite by consuming contaminated food or water or by coming into contact with cat feces.

"It doesn't make people sick at all. It just infects them and the body holds it off, and it becomes a latent infection," said Dr. William Schaffner, chair of the Department of Preventive Medicine at Vanderbilt University Medical Center.

But occasionally, Schaffner added, people who are immunocompromised can become ill. Pregnant women who are infected can also pass toxo along in the womb, which can cause serious complications, including still birth and neurological problems.

Previous research has linked to the parasite to schizophrenia and depression, but little is known about how it causes changes in human behavior. Some experts, including Schaffner, are skeptical that toxoplasmosis has a link to mental illness at all.

But while Sapolsky believes there could be an association between human behavior and infection with toxoplasma, that relationship needs additional study before making any firm conclusions.

His future research, he said, will once again focus on rats. He hopes to learn more about how this mysterious parasite affects rats and whether it plays tricks on the human mind, as well.

"One of the more interesting questions," he said, "is: How many cases are there of parasites manipulating human behavior?"

Copyright 2011 ABC News Radio

Wednesday
Jul062011

Rat Study Finds that Fat Triggers the Munchies

Digital Vision/Thinkstock(IRVINE, Calif.) -- New research suggests that fatty foods give people a high that may contribute insatiable food cravings.

The study was conducted on rats by researchers at the University of California, Irvine School of Medicine. The rats were given various liquids containing fat, sugar, or protein. Scientists then found that the fatty liquid triggered endocannabinoids, naturally-produced substances which control the appetite.

Endocannabinoid research could lead to medication that helps regulate food cravings.

The study will be published in an upcoming issue of the Proceedings of the National Academy of Sciences.

Copyright 2011 ABC News Radio

Wednesday
Jun012011

Woman’s Pet Rat Senses Debilitating Spasms

One of Dani Moore's former service rats. (Courtesy of Dani Moore)(HESPERIA, Calif.) -- Dani Moore of Hesperia, Calif., owes much of what she can do in her life to a rat.

The rat, named Hiyo Silver, has the unique ability to feel when the 56-year-old Moore's body is just starting to shake because of muscle spasms. Because she suffered injuries to her spinal nerves, she can't feel those spasms until they become extremely bad. By then, it's sometimes too late to avoid a serious injury.

"Since I have osteporosis, if the spasms get too bad, they can fracture vertebrae, which has happened to me before."

When Hiyo licks her neck or face, Moore knows it's time to take action either by stretching her muscles or taking medication to stop the spasms. She keeps Hiyo on a leash atop her shoulder wherever she goes because she never knows when she'll get spasms.

"Before I got my service rat, I would sometimes spend weeks in bed because the spasms would not let up. I was so much more limited to where I could go or what I could do," Moore said.

Despite the freedom she's able to enjoy now, she wasn't always able to take Hiyo or her other rats with her anywhere. The Americans With Disabilities Act only recognizes dogs and miniature horses as service animals, meaning that businesses are only required to allow these animals onto premises. But back in March, Moore's home city of Hesperia voted to allow all species of service animals into local businesses provided they behave appropriately.

Hiyo isn't the only animal believed to be able to sense a human's physical ailments. Studies have shown that dogs may be able to sense when their diabetic owners are having trouble with their blood sugar. Other research has shown that dogs can sniff out cancer.

Experts say what animals sense is most likely a smell or some type of body language that alerts them that something is amiss.

"It can be as minute as a slight change in respiration, or the person just moves at a different pace, or he has a different look, or a smell -- it can be any of those things," said Dr. Marty Becker, a veterinarian in Idaho and author of The Healing Power of Pets.

In Hiyo's case, that signal is shaking from the very beginning of a muscle spasm. Moore said she first started using a service rat when her daughter was training them to provide therapy, meaning they're trained to assist with healing and rehabilitation.

"She noticed that one of her therapy rats was extremely sensitive to my spasms, so she trained him to tell me when I was starting to have them," Moore said.

"I never thought a rat would be this helpful," said Moore. "But I certainly can't say I would trade them for anything nowadays."

Copyright 2011 ABC News Radio







ABC News Radio