OXFORD – A new study by two scientists at the University of Mississippi aims to shed light on the possible effects of cannabis use during pregnancy.
The National Institutes of Health has awarded toxicologist Kristine Willett and neuroscientist Nicole Ashpole more than $2.2 million to study the effects of cannabinoids – synthetic compounds or naturally occurring chemicals in cannabis – on zebrafish. Zebrafish are a type of small fish that share 70% of human genes and have a nervous system very similar to that of humans.
“People have been using cannabis for centuries to treat nausea and vomiting,” said Ashpole, associate professor of pharmacology. “I think a lot of people who want to use natural remedies during pregnancy think, ‘Cannabis is safe.’
“We don’t know if that’s true, but there is still a misconception among the public.”
Cannabinoid use among pregnant women is increasing, despite evidence that it may affect child development. According to one study, the proportion of American women who report using cannabis during pregnancy has more than doubled from 3.4% in 2002 to 7% in 2017.
Women report using it to treat their morning sickness, although there is a possibility that cannabis use may lead to impaired neurological development, a higher risk of stillbirth, and an increased likelihood of low birth weight.
“The biggest misconception is that we actually know what (cannabinoids) do,” said Willett, professor of pharmacology and environmental toxicology and chair of the Department of Biomolecular Sciences. “We don’t understand what they do. The field is way behind.”
“A lot of that is due to limitations (in cannabis research), but we’re particularly far behind in understanding cannabinoids in early life. They’re so widespread, and yet we still don’t understand them.”
Zebrafish eggs develop in about 96 hours, just as humans do in nine months. By treating zebrafish eggs with cannabinoids, researchers can study how this affects the embryo during development in just a few days.
“We have also been using zebrafish as models in neuroscience for a long time, for example in developmental toxicology, because we can observe the entire early development,” said Ashpole. “From the single-cell stage onwards. If there is a defect, we could potentially see it.”
“We will examine individual embryos under the microscope and see what is happening in their brains in vivo.”
Because zebrafish go through the same early developmental stages as humans, Ashpole and Willett hope to determine not only the effects of cannabinoid consumption, but also when they are most powerful.
“We can’t break it down as easily as the first trimester versus the third trimester, but we might learn, for example, that the risk is lower when the spinal cord has developed or the eye is fully developed,” Ashpole said.
“This allows us to look more closely at these windows of vulnerability and determine whether there is a safe time for exposure or whether there is a point in development where the greatest harm occurs.”
Regardless of whether researchers find that cannabinoids have a negative impact on pregnancy, the ultimate goal is to better understand an area of research that has proven difficult to study in the past, they said.
“For us, this has been about persistence,” Willett said. “We submitted this proposal six times at different stages. We have been so persistent because we believe it is really important to understand the toxicity of cannabinoids or the risks of cannabinoid exposure in early development.”
“With this funding, we can now shed light on this matter.”
This work is based on material supported by grant 1R01DA057317-01A1 from the National Institutes of Health.
