JUL 05, 2021 9:01 AM PDT

Prenatal Cannabis Exposure Lessens Effects of Antidepressants

WRITTEN BY: Annie Lennon

Researchers at Indiana University have found that mice exposed to cannabinoids while in the womb are less responsive to fluoxetine, a commonly-used antidepressant drug, as adults. They published their study in Cannabis and Cannabinoid Research.

Numerous studies have found that tetrahydrocannabinol (THC) has detrimental effects on the developing central nervous system of unborn fetuses. However, little to no research has been conducted on perinatal exposure to cannabidiol (CBD). As such, in this study, researchers set out to find how perinatal exposure to THC and CBD affects adult behaviors.

Prenatal cannabis exposure is also thought to increase one’s risk for anxiety and depression. The researchers thus also sought to investigate the response of adult mice exposed to cannabinoids both in the womb and just after birth when given popular antidepressant, fluoxetine, often sold as Prozac. Fluoxetine is a selective serotonin reuptake inhibitor (SSRI) that works by increasing serotonin levels in between neurons.

For the study, the researchers injected pregnant mice with 3mg/kg THC, 3 mg/kg CBD or both from day 5 of pregnancy to 10 days after giving birth. They used mass spectroscopic analyses to measure levels of THC and CBD in the brains of both the mothers and their offspring throughout the period. The researchers also monitored a control group in which mothers received a placebo.

Upon reaching adulthood, all of the mice then underwent several behavioral tests, both on and off fluoxetine, to see how they responded to the drug.

Using mass spectrometry tests, the researchers found that both CBD and THC can make it past the placenta and into the embryonic brain. From behavioral tests, they further found that both prenatal THC and CBD impair adult mice’s response to fluoxetine.

During a stress test, mice born to mothers given a placebo treatment became more resilient to stress after receiving fluoxetine. Meanwhile, the drug was ineffective for mice exposed to cannabinoids in the womb. The researchers thus say that prenatal exposure to both CBD and THC prevented fluoxetine from improving coping behavior in these mice, perhaps having implications for people exposed to cannabis while in the womb

Curiously, the researchers also found that, in another test, female mice exposed to THC or CBD tended to bury significantly more marbles than mice in the control group. Male mice exposed to cannabinoids also tended to prefer sugar water over normal water more than control mice.

The researchers say that their findings mark the beginning of efforts to understand how THC and CBD affect the endogenous cannabinoid system in the developing brain and body. Furthermore, their results suggest a cautious approach to taking CBD during pregnancy, especially as the compound is often considered a safe and harmless ‘natural’ therapy for morning sickness.


Sources: Cannabis and Cannabinoid Research, Drugs.com, Indiana University

About the Author
Annie Lennon is a writer whose work also appears in Medical News Today, Psych Central, Psychology Today, and other outlets. When she's not writing, she is COO of Xeurix, an HR startup that assesses jobfit from gamified workplace simulations.
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