Peptides and their Effect on Alcohol Consumption Patterns

            The problem with alcohol is not its occasional use, but the excessive and chronic use that may result after the first drink. Alcohol consumption, depending on the individual’s drinking pattern, can often result in heart diseases and cirrhosis of the liver. Scientists advocate that evidence is showing these diseases are not only caused by consumption amount, but also by the patterns of consumption frequency and the duration of consumption. They have also found that the pattern of alcohol intake affects which medications effectively treat alcoholism and how they treat it. However, at this time, there are very few studies about how the neurochemicals in the brain have a role in mediating the characteristics of alcohol drinking patterns.

            The evidence that these patterns, and not just amount of consumption, do have an affect, involves the study of orexigenic peptides and their effects on patterns of eating behaviors.  For instance peptide orexin/hypocretin (OX) has been shown to increase the frequency of intake; where as, galanin (GAL) and encephalin (ENK) have been found to decrease meal size and meal duration. It has been discovered that these three peptides also stimulate ethanol consumption. These finding have raised the question of whether peptides could similarly affect the patterns of ethanol consumption.

            To test this, scientists used adult male rats and placed them in either hanging wire cages or in a plastic shoebox with wire netting as the floor. They were subjected to twelve-hour light and darkness durations. In preparation to the experiment, the rats were treated with ethanol for one week. The rats then underwent a surgery and were injected with metal plates. Next, the peptides were injected into the rats. The results showed that the peptide OX, over a three-hour period of time, increased the amount of ethanol intake but not the amount of water intake. During the first hour the amount of ethanol intake was significant, but in the second and third hour it was not. There results demonstrated that OX enhances ethanol consumption.

            These findings will no doubt stimulate the curiosity on how peptides could possibly lead to a medication to help mediate alcohol use disorders. Considering that humans are certainly more complex than rats, there are some limitations on this study. Still, these scientists may have found another piece of information that could help the medical model in finding a way to treat substance abuse.

Chen, Y., Barson, J. R., Chen, A., Hoebel, B. G., & Leibowitz, S. F. (2014). Hypothalamic peptides controlling alcohol intake: Differential effects on microstructure of drinking bouts. Alcohol. Advance online publication. doi:10.1016/j.alcohol.2014.08.005

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