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Amino acids restore cognitive function in brain injured mice

Dietary amino acids offer hope for victims of traumatic brain injury
Dietary amino acids offer hope for victims of traumatic brain injury
AP Photo/Mel Evans

Neurology researchers have shown that feeding amino acids to brain-injured animals restores their cognitive abilities and may set the stage for the first effective treatment for cognitive impairments suffered by people with traumatic brain injuries (TBI). A Dec. 8 /PRNewswire by The Children's Hospital of Philadelphia made the announcement.

In this study, scientists first created brain injuries in mice, and one week later compared the animals' conditioned fear response to that of uninjured mice. A week after receiving a mild electric shock in a specific cage, normal mice tend to "freeze" when placed in the same cage, anticipating another shock. The brain-injured mice demonstrated fewer freezing responses -- a sign that they had partially lost that piece of learning.

The animals in the study received branched chain amino acids (BCAAs) leucine, isoleucine and valine in their drinking water. Brain-injured mice that received BCAAs showed the same normal response as the uninjured mice. The amino acids had restored their learning ability.
BCAAs are crucial precursors of two neurotransmitters -- glutamate and gamma-aminobutyric acid, or GABA, which function together to maintain an appropriate balance of brain activity. Glutamate excites neurons, stimulating them to fire, whilIe GABA inhibits the firing. Too much or too little of either and the brain doesn't work properly. A TBI upsets the balance.

In particular, a TBI frequently damages the hippocampus, a structure deep in the brain involved in higher learning and memory. In the current study, the researchers found that an injury to the hippocampus reduced levels of BCAAs. Although overall levels of glutamate and GABA were unchanged, the loss of BCAAs disturbed the critical balance of neurotransmitters in the hippocampus, making some localized regions more excitable and others less excitable. The research team found that providing dietary BCAAs would restore the balance in neural response.

The primary cause of death and disability in children and young adults, TBI accounts for permanent disabilities in more than 5 million Americans. The majority of those cases are from motor vehicle injuries, along with a rising incidence of battlefield casualties. Although physicians can relieve the dangerous swelling that occurs after a TBI, there are currently no treatments for the underlying brain damage characterized by cognitive losses in memory, learning and other functions.

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