University of North Carolina at Chapel Hill scientists have reported - for the first time - a burst in new brain cell development during abstinence from chronic alcohol consumption.
The UNC findings, from research at UNC's Bowles Center for Alcohol Studies, were based on an animal model of chronic alcohol dependence, in which adult rats were given alcohol over four days in amounts that produced alcohol dependency. The study is in the Nov. 3 issue of the Journal of Neuroscience.
In 2002, Dr. Fulton T. Crews, Bowles Center director, and Bowles Center research associate Dr. Kim Nixon were the first to report that alcohol, during intoxication, has a detrimental effect on the formation of new neurons in the adult rat hippocampus. This brain region is important for learning and memory - in animals and humans - and is linked to psychiatric disorders, particularly depression.
"When used in excess, alcohol damages brain structure and function. Alcoholics have impairments in the ability to reason, plan or remember," said Crews, also professor of pharmacology and psychiatry in UNC's School of Medicine. "A variety of psychological tests show alcoholics have a difficulty in ability to understand negative consequences."
In the new study, senior co-author Crews and co-author Nixon found inhibition of neurogenesis, or brain cell development, during alcohol dependency, followed by a pronounced increase in new neuron formation in the hippocampus within four-to-five weeks of abstinence. This included a twofold burst in brain cell proliferation at day seven of abstinence.
"We looked at dividing cells after our four-day binge model of alcohol dependency and confirmed what we previously observed: When the animals were intoxicated, the measure of dividing cells decreases," said Nixon. "And after abstinence for one week, we saw a huge burst in the number of new cells being born."
Nixon said the findings were confirmed by use of several biological markers, including bromodeoxyuridine, BrdU. Animals were injected with BrdU, which labels dividing cells. BrdU inserts itself into the DNA of a cell during cell division, so that it's found only in cells that have divided during the two hours that the substance is in the animals' system.
Imaging studies report shrinkage in brain ventricles - the fluid-filled spaces within the brain - indicating that the brain is growing as the spaces shrink as alcoholics recover from alcohol dependence.
"And when they stop drinking, you can show in a period of weeks, months, years, the brain grows back, there's a return of metabolic activity, and cognitive tests show a return of function," Crews said.
The findings may have significant implications for treatment of alcoholism during recovery. The discovery of regeneration of neurons in recovery opens up new avenues of therapies aimed at regeneration of brain cells. "When animals learn, they make more neurons. When animals exercise, they make more neurons and learn faster, as well," Crews said.
"Pharmacological agents such as antidepressants and behaviors such as running, increased physical activity and learning experiences apparently help regulate the process of neurogenesis," he added. "Our research suggests they could be considered in the treatment of chronic alcohol dependency."