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Fish eggs develop weirdly when given cannabis

Expectant mothers might want to think twice before taking a drag on a joint.
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Expectant mothers might want to think twice before taking a drag on a joint.

A University of Alberta study discovered that fish embryos exposed to cannabis took longer to hatch, had a lower survival rate, a reduced heart rate and developed weirdly shaped motor neurons.

“We think this is a starting point, a place where we can say, ‘look, exposure to these compounds may impact a developing organism’,” said Declan Ali, biological studies professor at the university and researcher behind the study.

Ali said zebrafish embryos, which have been used in the past to study the impact of alcohol on fetuses, have paved a path towards understanding drug use while pregnant.

Along with some notable developmental issues, once the fish were born it was easy to see other differences.

“The fish also looked a little bit different themselves, there were some morphological differences. They looked a little bit smaller and their tails were a little bit thinner,” he said.

Fish eggs v.s. human eggs

In comparing the two species, there are notable differences between zebrafish and human embryos, Ali noted.

The fish embryos were exposed to cannabis compounds during gastrulation – a critical developmental stage for the fetus.

In fish, this phase starts five hours after conception and lasts for about another five. For humans, the stage starts three weeks after conception and lasts for up to six days.

This could have an impact on how the fetus develops with exposure to cannabis, although the results shouldn’t be completely discounted, Ali said.

Zebrafish embryos have been used for almost a decade in completing studies, so a considerable amount is known about the species and how it develops.

Additionally, fish have a very similar system – called the endocannabinoid system – as humans in how they break down cannabis.

“The systems are more or less the same,” he said. “Because the systems are the same, just to be on the safe side, if these compounds are affecting the development of an embryo in one organism, then it’s potentially capable of doing that in humans as well.”

The study

Over the course of a year, various zebrafish embryos were exposed to two cannabis compounds, THC and CBD. While there were minor differences in how the compounds affected the fish, the results were virtually the same.

The findings also suggest that some of the affects are long lasting. For example, the cannabis compounds caused the fish’s motor neurons – which are used to send messages between the brain and muscles – to develop weirdly.

“They were not of the correct shape and they didn’t send out the proper processes to the muscles,” he said.

This caused the fish’s muscles to not move as well as fish with properly formed neurons.

When it comes to why the study was done, Ali said he felt it was important to do ahead of the cannabis legalization deadline of Oct. 17.

Next, researchers will examine exposure rates to determine how much cannabis it takes before an embryo is affected. Ali also hopes future research will examine how the different strains impact the body and how different ways of consuming cannabis impact the body.

When cannabis is heated, such as in smoking it or baking it, the chemical composition of the drug changes.

“We need to do a lot more work to determine what’s really going on here, because there are a lot of questions with this,” he said. “If it were my kids, I would certainly say if you’re thinking of getting pregnant, stay away from this until we know much more about how everything is working and what’s going on.”





Dayla Lahring

About the Author: Dayla Lahring

Dayla Lahring joined the St. Albert Gazette in 2017. She writes about business, health, general news and features. She also contributes photographs.
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