Following administration of 5 g/kg alcohol, adolescent and adult male and female rats were observed for loss of the righting reflex (the ability to right themselves onto all four paws). In addition, researchers used whole-cell recordings to measure the response of spontaneous, GABAA receptor-mediated IPSCs (an inhibitory process) in brain slices from drug-nave adult males and females. This combined approach allowed researchers to describe the behavioral difference between the effects of alcohol on males and females, and also to address a possible mechanism at the cellular level.
"The promotion of GABA-mediated neuronal inhibition is thought to be a primary mechanism of alcohol-induced sedation, and may also account for some of its anti-anxiety effects," explained Scott Swartzwelder, professor of psychiatry at Duke and senior author of the study. "This measurement is particularly significant in our study because it correlates with the result that the females are less sensitive to alcohol-induced sedation. Since these measurements are made in isolated brain sections, the effects cannot be due to sex differences in alcohol absorption or elimination in the body."
The female rodents' lesser sensitivity, compared with the adult males, to the behavioral sedative effects of alcohol was most pronounced in the proestrous (the first phase of the estrous cycle, which corresponds to the onset of mating behavior) and diestrous (the last phase of the estrous cycle) states.
"We know that females are affected by alcohol differently than males," said Swartzwelder, "but unlike many studies, this one shows a way in which females are less sensitive than males. People generally think that alcohol is more potent in females, but that is because women are smaller than men and it genera
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3-Jan-2006