Like all good things, drinking should always be practiced in moderation – unless you happen to be a lab mouse, in which case you may be required to binge drink in the name of science. In doing so, a group of experimental rodents recently enabled a team of researchers from the University of North Carolina at Chapel Hill to study the neural activity controlling this type of uncontrolled boozing, providing new insights into what causes some people to go a little overboard when on the sauce.
Previous studies on animals have shown that binge drinking causes an increase in a type of hormone known as corticotropin-releasing factor (CRF) in a part of the brain called the ventral tegmental area (VTA). Since the VTA is involved in the brain’s reward system, processing pleasurable stimuli such as alcohol consumption, it would appear that CRF plays a role in activating this sense of satisfaction, triggering a desire to continue drinking.
At the same time, CRF levels have been found to increase in another brain region called the central amygdala after heavy drinking. As this part of the brain is involved in coordinating responses to stressful situations, it has been suggested that binge drinking may help to alleviate stress in some way.
This knowledge had enabled scientists to deduce that binge drinking is somehow modulated by CRF, and contributes to the interplay between the brain’s reward and stress centers. However, exactly how the hormone connects these two neuronal systems had until now remained poorly understood.
To investigate, the researchers trained mice to binge on an ethanol solution, before using a technique called chemogenetic manipulation to inhibit the CRF neurons in their VTAs. Reporting their findings in the journal Biological Psychiatry, they explain how, to their surprise, this did not reduce the animals’ tendency to gorge themselves on the boozy liquid.
CRF neurons that run from the BNST to the VTA appear to control binge drinking behavior. Andrii Vodolazhskyi/Shutterstock
However, when they inhibited the CRF neurons in a part of the amygdala known as the bed nucleus of the stria terminalis (BNST), they found that the mice suddenly overcame their unrestrained drinking behavior. As such, they were able to determine that binge drinking is actually modulated by the CRF neurons that run between the BNST and the VTA, identifying this neuronal circuit as the key to controlling excessive alcohol consumption.
Commenting on this finding, lead researcher Todd Thiele explained that “we now know that two brain regions that modulate stress and reward are part of a functional circuit that controls binge drinking and adds to the idea that manipulating the CRF system is an avenue for treating it.”
As such, the study authors suggest that focusing on this particular brain network may provide the key to developing new treatments for people with a tendency to lose their self-restraint when drinking. According to Thiele, “if you can stop somebody from binge drinking, you might prevent them from ultimately becoming alcoholics. We know that people who binge drink, especially in their teenage years, are much more likely to become alcoholic-dependent later in life.”
At present, these treatments remain a way off, which means those mice have a lot more drinking to do if we're to develop effective new therapies targeting this key pathway.