Female vulnerability to drugs tied to estrogen, U-M research...( persist for some time Becker says po...)

persist for some time," Becker says, pointing to recent work by U-M colleagues Kent Berridge and Terry Robinson. (See http://www.umich.edu/~newsinfo/Releases/2001/Sep01/r092501b.html). "Our results suggest that estrogen not only affects the acute response to cocaine, but also intensifies the long-term changes that occur in the brain. These results are important for our understanding of the basic neural processes that lead to drug addiction, and for our understanding of why some individuals may be more at risk than others."

For many years, Becker explains, scientists have tried to determine how estrogen can produce all of the effects attributed to it, including mood swings, improvement in verbal abilities, decreases in spatial abilities, and enhanced sensory and motor functions, including lower thresholds for visual, olfactory and tactile stimuli and more rapid complex motor sequence abilities.

Recently, Becker and others have been examining the hormone's impact on neurotransmitters such as dopamine in two specific areas of the brain, the nucleus accumbens and the striatum. These brain areas are known to be important in behaviors such as eating, sex, and compulsive drug use.

"My lab has demonstrated that estrogen has rapid effects that boost the amount of dopamine released," says Becker. "These effects are evident in sexual behavior, as well as compulsive drug-seeking. Dopamine levels increase when a female rat is engaging in sexual behavior that she finds rewarding, and for female rats, not all sex is rewarding." Male rats apparently prefer intromission every 30 seconds, followed by rapid ejaculation, she reports, while females prefer a slower pace, with one or two minutes between intromissions. This pace activates a series of synaptic pathways in the female's brain that triggers the release of prolactins necessary for successful pregnancy.

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Contact: Diane Swanbrow
swanbrow@umich.edu
734-647-4416
University of Michigan
14-Nov-2001

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