Does motherhood dampen cocaine’s effects?
Mother rats respond much differently to cocaine than female rats that have never given birth, according to new University of Michigan research that looks at both behavior and brain chemistry.
The findings may help lay the groundwork for more tailored human addiction treatment, based on scientific understanding of how gender, hormones and life experience impact drug use.
In an oral presentation at the Society for Neuroscience meeting, U-M researcher Jennifer Cummings, Ph.D., summarized findings from experiments with rats at the Molecular and Behavioral Neuroscience Institute, part of the U-M Medical School. She worked with Jill Becker, Ph.D., of the U-M Department of Psychology.
They identified clear differences in how intensely the “pleasure centers” in the mother rats’ brains reacted to the drug, compared with non-mothers. Mother rats’ brains released less of a chemical called dopamine, which helps cause the “high” from cocaine.
They also found an interaction with stress: mother rats that were exposed to periods of increased stress weren’t willing to work as hard to get a dose of cocaine, compared with rats that had never given birth or mother rats that weren’t exposed to the stress – even though the stressed mother rats showed an increased tendency to use cocaine when it was easy to get.
Taken together, the findings suggest that the experience of becoming a mother alters a female’s overall response to cocaine – adding complexity to the issue of how best to treat addiction.
“While we have not yet identified a mechanism to explain these differences, they do suggest that the reward system and brain circuitry affected by cocaine is changed with maternal experience,” says Cummings, a research investigator at MBNI and former postdoctoral fellow in Becker’s laboratory. “The next step is to determine how factors such as hormone changes in pregnancy and early motherhood, and the experience of caring for offspring, might be differentially contributing to this response.”
