The use of animal models for substance use disorders (SUDs) has been criticized due to their limited translational value. Improvements in fundamental neuroscience have had little influence on treating addictive illnesses despite decades of study that resulted in considerable advancements in the neurobiology of drug and alcohol addiction.
It implies that widely used animal models may not adequately account for the complexity of SUDs but may have hampered the progress of finding treatments. To solve this dilemma, researchers developed exclusive choice-based models between drugs and food rewards, but a recent study explores the choice between drugs and social interaction.
Alcohol Vs. Alternative Rewards
In 2018, researchers conducted a study using a discrete-choice model of having rats choose between alcohol and alternative rewards, like a sweet solution of saccharin.
The study, titled "A Molecular Mechanism for Choosing Alcohol Over an Alternative Reward," published in Science, showed that alcohol addiction leads to an increased choice of alcohol over healthy rewards.
Researchers found that approximately 15% of outbred rats chose alcohol over a high-value reward. These rats have addiction-like traits, such as high motivation to obtain alcohol despite adverse consequences.
When translated to humans, it means that people confronted with opportunities to consume alcohol or healthy alternatives would choose alcohol despite high-value alternatives.
Researchers found this because of impaired GABA (γ-aminobutyric acid) clearance in the central amygdala. The expression of the GABA (γ-aminobutyric acid) transporter GAT-3 was preferentially reduced in the amygdalas of alcohol-choosing rats, but a reduction of this gene reversed the choice preference of rats that had previously chosen a sweet solution over alcohol. GAT-3 expression was reduced in the central amygdala of alcoholics compared to individuals who died from other causes.
Impaired GABA clearance inside the amygdala leads to alcohol addiction, appears species-specific, and may provide targets for novel pharmacotherapies to treat this illness. Postmortem analysis supports the possibility of a similar pathology in human alcoholism.
Alcohol Vs. Social Interaction
After conducting the study, the same researchers devised another discrete-choice model but this time; they observed rats choosing between alcohol and social interaction.
In the article "Wistar Rats Choose Alcohol Over Social Interaction in a Discrete-choice Model," published in Nature, researchers evaluated both female and male Wistar rats' choices.
They found that rats almost exclusively prefer alcohol over social interaction regardless of the nature of their social partner compared to their previous study between drugs and social reward.
Moreover, alcohol choice decreased every time the requirement for alcohol increased. But rats persisted in choosing alcohol even if it required them 10-16 times the effort to obtain it than simply choosing social interaction.
Overall, these findings suggest that the social choice model may not generalize to alcohol, implying that specific interactions between alcohol and social reward, which are not seen when a sweet solution is used as an alternative to the drug, may play an important role in alcohol vs. social choice experiments.
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