A study published in Genome Biology journal states that humans and fruit flies respond to alcohol in very similar ways at the gene level. The researchers hope that it may help to explain why some people are genetically predisposed to alcohol abuse. Like humans, fruit flies get “drunk” when exposed to large amounts of alcohol.

Researchers Tatiana Morozova, Robert Anholt, and Trudy Mackay, of North Carolina State University in the United States show that in Drosophila, a specie of fruit fly, the expression of many genes is modified by exposure to alcohol, and that mutations in some of these genes affect the flies' sensitivity to alcohol. Many of these genes analyzed are also found in humans. The study conclude that further studies could shed light on the genetic basis of human response to alcohol, including the susceptibility to alcohol abuse.

According to the report, the researchers analyzed the activity of all Drosophila genes after exposure to alcohol. Using microarray analysis, a technique that enables to measure gene expression levels, they compared the gene expression levels in flies before they were exposed to ethanol, directly after exposure, and two hours after exposure.

The results of the study show that one single exposure to ethanol is enough to modify the expression of some genes in the fruit fly. The researchers identified a total of 582 genes whose expression is modified by exposure to ethanol. Some of these genes are down-regulated, while others are up-regulated, and a different set of genes is up-regulated as the flies become more tolerant to alcohol. Such genes include those involved in biosynthesis and regulation of fatty acid metabolism.

“Alcohol-induced fatty acid biosynthesis is well-documented in [human] heavy drinkers,” write the authors. “The identification of multiple enzymes associated with intermediary metabolism and fatty acid biosynthesis in the response to alcohol exposure in Drosophila is, therefore, of particular interest.”

The researchers then identified the genes that affect sensitivity or tolerance to alcohol by analyzing flies with mutated versions of the genes identified in the microarray experiment. They find that mutations in these genes can induce increased or reduces sensitivity to the effects of ethanol at first exposure, followed by increased or reduced tolerance. They find that the development of tolerance is only partly dependent on initial sensitivity to ethanol.