Estrogen May Combat Marijuana's Effect on Cognition

MONDAY, April 20 (HealthDay News) -- Ovaries and the estrogen hormone they produce might help protect women from some of the learning and memory issues caused by the active ingredient in marijuana, Louisiana State University researchers predict, based on their study on rats.

The protection did not seem to apply, however, if the female rats were exposed to the drug during the time period equivalent to human adolescence.

The findings led the researchers to hypothesize that exposure to tetrahydrocannabinol, better known as THC, the main ingredient in marijuana, during the critical puberty and teenage development period of humans could have lifelong ramifications.

The study, though, involved only female rats so any implication for adolescent males remains untested.

The findings were to be presented April 19 in New Orleans at the Experimental Biology meeting sponsored by the Federation of American Societies for Experimental Biology.

In earlier experiments on adult rats, the researchers had found that estrogen, or having ovaries, somewhat countered THC's effects of slowing response time and increasing mistakes on tests of memory and learning.

In the latest tests, the researchers removed the ovaries from six female rats and then exposed them and six female rats with ovaries intact to THC during the rodent equivalent of adolescence. They trained the rats to perform sequential tasks to obtain rewards of food. When the rats became adults, they were again exposed to THC and given a learning test. For comparison, another group of 12 rats, half with ovaries removed, were given the same learning and memory skills training but were not exposed to THC as adolescents.

The rats exposed to THC during adolescence all performed more poorly on the tests than a similar group of female rats exposed to THC only as adults, regardless of whether they did or did not have ovaries.

-- Kevin McKeever

SOURCE: Federation of American Societies for Experimental Biology, news release, April 19, 2009

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