Doctors warn that marijuana use during pregnancy may have harmful effects on the development of a fetus, in part because the cannabinoid receptors activated by the drug are known be critical for enabling a developing brain to wire up properly. Now, scientists at MIT’s McGovern Institute have learned that cannabinoid receptors’ critical role in brain development does not end at birth.
In today’s online issue of the journal eNeuro, scientists led by McGovern investigator Ann Graybiel report that mice need the cannabinoid receptor CB1R to establish connections within the brain’s dopamine system that take shape soon after birth. The finding raises concern that marijuana use by nursing moms, who pass the CB1R-activating compound THC to their infants when they breastfeed, might interfere with brain development by disrupting cannabinoid signaling.
“This is a real change to one of the truly important systems in the brain—a major controller of our dopamine,” Graybiel says. Dopamine exerts a powerful influence over our motivations and behavior, and changes to the dopamine system contribute to disorders from Parkinson’s disease to addiction. Thus, the researchers say, it is vital to understand whether postnatal drug exposure might put developing dopamine circuits at risk.
