A team of researchers at Penn Sate has used an animal model to reveal, for the first time, a physiological basis for the effect of alcohol on male sexual behavior, including increased sexual arousal and decreased sexual inhibition.
The research, which will be published on 2 January 2008 in the scientific journal PLoS ONE, resulted in four novel findings with broad importance for further addiction research. It is the first study to characterize the effects of chronic alcohol exposure in fruit flies. "Physiological evidence supporting various theories about the effect of alcoholic drinks has been lacking, so our now having a suitable animal model makes it possible to conduct much-needed laboratory research on this issue," explains research-team-leader Kyung-An Han, associate professor of biology and a neuroscientist at Penn State. Information from this research can serve as a baseline for similar studies in other animals, including humans.
In contrast to previous studies in other labs, which subjected fruit flies to short-term doses of ethanol -- the intoxicating ingredient in alcoholic drinks -- Han's team administered to fruit flies a daily dose of ethanol to more closely mimic the drinking habits of alcoholics and chronic alcohol abusers. The team investigated several factors that influence the physiological effects of ethanol, including genetic and cellular components, age, and prior experience.
Among the team's discoveries is that male fruit flies, which typically court females, also actively court males when they are given a daily dose of ethanol. "We identified three molecules that are crucial for "ethanol-induced courtship disinhibition," Han said. In one of the team's experiments, Han and her students generated transgenic flies whose brain activities regulated by the neurotransmitter dopamine could be turned off temporarily by changing the temperature to 32-degrees C. "Without a temperature change, the transgenic males showed conspicuous inter-male courtship under the influence of ethanol; however, they exhibited negligible inter-male courtship when we changed the temperature to block the transmission of dopamine neurons in the brain," Han said. "This result suggests that dopamine is a key mediator of ethanol-induced inter-male courtship."