Reports have shown that previous studies by the UIC researchers had first recognized a gene that controls anxiety and alcohol consumption. Dr. Subhash Pandey, the professor of psychiatry and anatomy and cell biology at UIC and Jesse Brown VA medical centre and lead author of the paper, said, "We knew that gene, called CREB, controls the expression of a number of important genes in the brain."
In their new study, they further showed that a protein that was made by one of those CREB-controlled genes also affects the anxiety and the drinking behaviour depending on its level in two areas of the brain.
Pandey and his colleagues injected DNA of complementary sequence to the gene of the protein, called brain-derived neurotrophic factor (BDNF), into the brains of rats to block the gene from expressing BDNF. The "anti-sense" DNA was injected into three areas of the amygdala, an area of the brain associated with emotion and fear.
The researchers found that when levels of BDNF in the central and medial areas of the amygdala were lowered, anxiety and alcohol consumption increased. Decreased levels of BDNF in the third area, called the basolateral amygdala, had no effect.
When levels of BDNF in the central and medial amygdala were restored to normal by injecting BDNF, anxiety, and alcohol consumption diminished.
The researchers measured anxiety by observing the rat's exploratory behaviour in a maze. Alcohol consumption was measured by offering the animal's one drinking bottle with water and one with alcohol, and noting the proportion of alcohol imbibed.
BDNF plays a vital role in the growth and maintenance of neurons. Many human studies have suggested that variations in the BDNF gene may be associated with alcoholism and anxiety disorders, Pandey said.
"In people, alcoholism is very frequently associated with anxiety disorders," he said. "And it is well established that high levels of anxiety promote alcohol consumption and also play a crucial role in relapse to alcohol drinking."
Pandey said the new research might suggest a target for drugs to treat or prevent anxiety and alcoholism.
"Our study suggests a molecular, neurochemical mechanism in the amygdala which may be responsible for the association of high levels of anxiety with excessive alcohol-drinking behaviour," he said.