A new study found that prenatal exposure of THC changes the behavior and brain chemistry of male rats. The main psychoactive compound found in cannabis has also been linked to hyperactive dopamine neurons and increased sensitivity to the effects of THC in pre-adolescent rodents.
Miriam Melis, a neuroscientist at the University of Cagliari Cittadella Universitaria in Monserrato, Italy, administered THC to pregnant rats and then carefully studied the behaviors of the offspring.
Melis and colleagues found that male, but not female, offspring had a heightened susceptibility to THC. They also found that the rats' dopamine neurons found in a brain region called the ventral tegmental area -- which is involved in reward motivation -- were hyperactive.
Previous research had linked prenatal cannabis exposure to psychiatric disorders like schizophrenia and forms of psychosis later in adolescence, and the authors believe that these latest findings may explain why.
The researchers were able to correct the dopamine hyperactivity and behavioral changes by treating the adolescent rats with pregnenolone, an FDA-approved drug meant to treat schizophrenia, autism, and bipolar disorder.
“This is an exciting finding that suggests a therapeutic approach for children born to mothers who used cannabis during pregnancy,” said Joseph Cheer, PhD, a Professor of Anatomy & Neurobiology and Psychiatry at the University of Maryland School of Medicine. “It also raises important questions that need to be addressed such as how does pregnenolone exert its effects and how can we improve its efficacy? Do these detrimental effects persist into adulthood, and if so, could they also be treated in a similar way?”
The findings, which were published in the journal Nature Neuroscience, come on the backdrop of growing cannabis legalization in the United States. Some pregnant women use cannabis to treat symptoms of morning sickness and anxiety but this new evidence suggests that there may be long-term consequences for the babies' brain development. More research is required to clarify this association.