Rat-faced No More: Israeli Scientists Get Rats Off Booze

Researchers manage to selectively delete memories related to and triggering alcohol consumption, while not harming other, unrelated memories.

Dan Even
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Dan Even

Israeli scientists have succeeded in deleting selected memories in rats, in what could be a useful tool in treating alcohol addiction. In a paper published in Nature Neuroscience, researchers say they have managed to selectively delete memories related to and triggering alcohol consumption, while not harming other, unrelated memories.

The research was headed by Prof. Dorit Ron of the Ernest Gallo Clinic and Research Center at UC San Francisco and Segev Barak, of the School of Psychological Sciences and the Sagol School of Neuroscience at Tel Aviv University.

At the first stage of the experiment, rats could choose between drinking water or a solution of 20 percent alcohol. Barak says that "we tried to mimic the experience of humans who could choose between alcohol and other beverages, who chose to drink alcohol without being forced to do so. In such experiments, usually 10-20 percent of the rats drink a small amount of alcohol and do not develop signs of addiction; these were not included in the current study."

The rats continued to receive alcohol and water for two months, with those consuming huge amounts of alcohol being used as a model of alcoholic addiction. The rats were later trained to self-administer drinks of alcohol by pressing a lever. After a 10-day abstention, researches awoke the "alcohol memory" of the rats by presenting the scent of alcohol and miniscule portions. At this stage the rats tried to self-administer shots of alcohol.

Scans of the rats' brains revealed that alcohol-related memories activate a protein complex named mTORC1, which is responsible for the creation of new proteins at the connection points between the brain's neurons, and has a substantial role in designing memories.

Researchers concluded that alcohol-related memories activated the protein in specific parts of the frontal lobe connected to memory processing, which is responsible for emotional memories and is involved in symptoms of alcohol withdrawal. Barak says that such a "focused and strong activation of a protein in a specific part of the brain is very rare. We immediately understood something important was happening there."

The researchers then tried to manipulate the process of reconsolidation, hoping to examine whether prevention of activation of the protein could damage the memories' stability and prevent the reoccurring search for alcohol. They neutralized the activity of the protein by injecting Rapamycin, a FDA-approved drug for humans who have rejected transplants. When administered, it moved towards the areas associated with alcoholism and prevented the activation of a process initiated by mTORC1.

Worked after 24 hours

The rats that were administered the drug demonstrated a notable decrease in their search for alcohol after 24 hours, 48 hours and 14 days. Researchers concluded that after 24 hours the drug effectively deleted the alcohol-related memories and caused the rats to stop seeking alcohol.

The researchers further revealed that memories unrelated to alcohol were not harmed, such as those involved in self-administering sugar solutions by using another lever.

The researchers believe that future studies will be held examining the use of Rapamycin to delete alcohol-related memories.

According to Barak: "Alcohol and drug addiction are a disease with a biological basis, causing severe financial and health damages. 70-80 percent of addicts are back on drugs or alcohol with a year of the rehabilitation. The major factors contributing to this high rate include those obstinate memories, associated objects and places with alcohol, such as pubs, bottles and, of course, scents and tastes characteristic to alcohol. The new finding might, in theory, delete these memories and constitute an innovative treatment strategy."

At present researchers from UC San Francisco and Tel Aviv University are discussing a deeper examination of cerebral and biological processes related to memories that renew dependence on alcohol. Barak is also developing behavioral treatments that might be carried out during the "window of opportunity" opened when the memory is being removed, and could cause similar results to the use of the Rapamycin to delete alcohol-related memories.

Lately, many research groups report studies using memory deletion to develop innovative treatments for diseases. Haaretz reported last week that researchers at Hebrew University developed a process that would temporarily delete traumatic memories from mice's brains by exposing certain areas of the brain to light waves, using a technique called optogenetics.

A two-year old male rat.Credit: AP