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Sunday, May 29, 2011

Gut Bacteria can affect Mental Health: Did you know that?

A gut feeling may help you make a quick decision, but one study credits the digestive system for possibly influencing our mental states and behavior as well. The results help scientists understand how inflammatory bowel diseases, irritable bowel syndrome and other digestive problems relate to the psychological issues that often accompany them. Anxiety and depression commonly occur alongside these bowel conditions.

Scientists want to know whether certain gut bacteria influence humans' behavior. If so, doctors may be able to battle the physical and psychological effects of disease-causing bacteria by developing treatments such as probiotics.In the experiment, researchers introduced antimicrobials to mice via drinking water in order to change the ratios of their gut bacteria. The control group received sterile water. Afterward, both groups of mice were placed between two boxes -- one in the dark, one with light, as scientists recorded their behaviors. Mice with altered digestive bacteria showed less apprehension and were less afraid to go into the well-lit box, a common sign the animals are under the influence of drugs or illness.

Scientists then euthanized the mice to study their intestines and brains. They also found out that the hippocampus of the rodents with altered gut bacteria produced more brain-derived neurotrophic factor, also called BDNF, which often increases with stress and mood disorders, according to the U.S. National Library of Medicine. Although more research is needed to extend the findings to humans, the team found that the effects of bacterial imbalance were reversible in mice, meaning there might be a way to do the same thing for humans in the future.

Source: U.S. National Library of Medicine


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Astrocytes now can be grown in lab

The most common brain cell, called the astrocyte, is often overlooked in the face of its cousin, the neuron. Researchers are finally realizing their importance and have, for the first time, been able to grow them in the lab.

"Not a lot of attention has been paid to these cells because human astrocytes have been hard to get," study researcher Su-Chun Zhang, at the University of Wisconsin-Madison. "But we can make billions or trillions of them from a single stem cell." Astrocytes are small, star-shaped cells in the brain that act like the neuron's bodyguards, and because of that they play an important role in diseases of the central nervous system, including dementia. They are more common than neurons but have been hard to grow in the lab. Being able to study them could help researchers understand their role in normal brain functioning, and help find new treatments for disease.

"Without the astrocyte, neurons can't function," Zhang said in a statement. "Astrocytes wrap around nerve cells to protect them and keep them healthy. They participate in virtually every function or disorder of the brain." They protect neurons by performing basic housekeeping functions, like regulating blood flow, cleaning up excess neurotransmitters (the communication molecules used by neurons), and playing a key role in controlling the blood-brain barrier, which keeps toxic substances out of the brain.

Zhang created the cells from both embryonic and adult stem cells by treating them with special proteins to get them to grow into astrocytes. These cells could also be useful as a transplant, to treat diseases like Lou Gehrig's disease (also called amyotrophic lateral sclerosis), in which the neurons are overworked. Transplanting healthy astrocytes could rescue the injured neurons.

Source: University of Wisconsin-Madison


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Anxiety may be in your gut rather than in your head

For the first time, researchers at McMaster University have conclusive evidence that bacteria residing in the gut influence brain chemistry and behaviour.The findings are important because several common types of gastrointestinal disease, including irritable bowel syndrome, are frequently associated with anxiety or depression. In addition there has been speculation that some psychiatric disorders, such as late onset autism, may be associated with an abnormal bacterial content in the gut.
"The exciting results provide stimulus for further investigating a microbial component to the causation of behavioural illnesses," said Stephen Collins, professor of medicine and associate dean research, Michael G. DeGroote School of Medicine. Collins and Premysl Bercik, assistant professor of medicine, undertook the research in the Farncombe Family Digestive Health Research Institute.The research appears in the online edition of the journal Gastroenterology.
For each person, the gut is home to about 1,000 trillium bacteria with which we live in harmony. These bacteria perform a number of functions vital to health: They harvest energy from the diet, protect against infections and provide nutrition to cells in the gut. Any disruption can result in life-threatening conditions, such as antibiotic-induced colitis from infection with the "superbug" Clostridium difficile.Working with healthy adult mice, the researchers showed that disrupting the normal bacterial content of the gut with antibiotics produced changes in behaviour; the mice became less cautious or anxious. This change was accompanied by an increase in brain derived neurotrophic factor (BDNF), which has been linked, to depression and anxiety.
When oral antibiotics were discontinued, bacteria in the gut returned to normal. "This was accompanied by restoration of normal behaviour and brain chemistry," Collins said.To confirm that bacteria can influence behaviour, the researchers colonized germ-free mice with bacteria taken from mice with a different behavioural pattern. They found that when germ-free mice with a genetic background associated with passive behaviour were colonized with bacteria from mice with higher exploratory behaviour, they became more active and daring. Similarly, normally active mice became more passive after receiving bacteria from mice whose genetic background is associated with passive behaviour.
While previous research has focused on the role bacteria play in brain development early in life, Collins said this latest research indicates that while many factors determine behaviour, the nature and stability of bacteria in the gut appear to influence behaviour and any disruption , from antibiotics or infection, might produce changes in behaviour. Bercik said that these results lay the foundation for investigating the therapeutic potential of probiotic bacteria and their products in the treatment of behavioural disorders, particularly those associated with gastrointestinal conditions such as irritable bowel syndrome.


Source: Mcmaster University
 


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Body can be re-educated to accept donor organ on its own

British-based researchers have discovered a way to reprogramme immune system cells so that they think the donated organ is a natural part of the recipient's body.Not only will the development avoid patients having to take three different types of costly drugs every day of their life, it will also mean the donated organs lasts indefinitely.
Dr Pervinder Sagoo, co-author at King's College London, said: "We hope this is the holy grail that means that the recipient is completely tolerant to the transplanted organ for the rest of their life."
Currently patients must take around three immunosuppressant drugs a day to prevent a new organ from being rejected after transplantation.However, these drugs suppress the entire immune system, leaving the patient susceptible to infections and tumours.
Transplanted organs are also put under pressure andoften do not last longer than 10 years.
The new approach involves re-educating the immune system so that the body sees the organ as a natural part of the body.The immune system carries on working in exactly the same way but because it does not see the new tissue as alien, leaves it alone.The technique works by mixing the immune cells of the donor and the recipient in the laboratory to produce a kind of hybrid which is then copied millions of times.These new cells of then injected into the recipient – spreading around the body and re-educating the immune system for life.Ultimately this approach could extend the life of a transplanted organ and in turn, could alleviate the organ shortage problem.
The technique has already been used in animals and clinical human trials start at the end of the year.
Scientists hope it could be used in earnest within a decade.Professor Robert Lechler, Vice-Principal for Health at King's, said: "This study is a promising step forward that could lead to dramatic advances in preventing organ rejection and improving the quality of life of transplant patients."
Dr Shannon Amoils, Research Advisor at the British Heart Foundation, which part-funded both studies, said: "If the techniques used in these studies can be transferred to the clinic it could signal a move to replace long term use of immune-suppressing drugs."This would be a huge step forward for transplantation, more than four decades since the revolutionary treatment began."

Source: King's College London
 


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Cross your Arm, Confuse your brain & relieve pain

Simply crossing your hands confuses your brain and distracts it from any pain being administered, a study suggests.The brain is used to your left hand carrying out tasks on your left hand side and the right hand carrying out tasks on the right.By crossing them, the brain is momentarily bamboozled and this makes it less susceptible to pain.
Researchers think the theory has most impact on pain felt in the hands, and have not yet tested it on other parts of the body."Perhaps when we get hurt, we should not only 'rub it better' but also cross our arms," said Dr Giandomenico Iannetti, the lead author of the study at the University College London.
In the study, scientists used a laser to generate a four millisecond pin prick of "pure pain" – which is pain without touch – on the hands of a small group of eight participants, which was repeated with the arms crossed.The hands were over the midline – an imaginary line running vertically down the centre of the body. Participants rated their perception of the intensity of the pain, and their electrical brain responses were also measured using electroencephalography (EEG) scanner.
The pain was rated from 0 to 100, with 100 being the most pain you could possibly imagine.
The results from both participants' reports and the EEG showed that the perception of pain was weaker when the arms were crossed.The effect is said to be "small but significant" and equivalent to a reduction in pain of around three per cent, the study claims.Dr Iannetti believes that the effect was caused by the brain being confused."In everyday life you mostly use your left hand to touch things on the left side of the world, and your right hand for the right side of the world – for example when picking up a glass of water on your right side you generally use your right hand," he said.
"Crossing your hands causes a mismatch and this makes the processing of pain more difficult.
"It works for other stimuli. The sensitivity of the brain is reduced. It is not a huge analgesic but we are testing it on people with chronic pain in their hands."

Source: University College London.
 


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Mahantesh.I.B
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