Neurons get all the spotlight, but the microglia play an important role in the brain’s resiliency and aging process. Sophia’s study looked at the effects of vaporized cannabis on this understudied cell.
Graduate student in neurobiology at the University of Victoria
B.Sc. Biology, ’22, University of Victoria
Undergraduate grant in 2022
Everyone is familiar with the neuron: the key player in our central nervous system that act as information messengers. But have you heard of the microglia? Less is known about this important cell, which serves as the brain’s resident immune cell.
Sophia Loewen was an undergraduate student studying biology at the University of Victoria when she first heard about the microglia. She was reading about the research being done at the Tremblay Lab in the Division of Medical Sciences. Led by Dr. Marie-Ève Tremblay, the lab is attempting to determine how the microglia can be targeted to promote brain resilience and healthy cognitive functions along the aging trajectory, thereby treating or preventing neurological conditions such as Parkinson’s and Alzheimer’s disease, or mental illnesses such as major depressive disorder and schizophrenia.
Inspired, Loewen reached out and was offered a directed studies with the lab, where she completed both an honours thesis and a research co-op in the summer of 2022, for the latter of which she received funding from the Branch Out Neurological Foundation.
“The summer research co-op I was involved with studied the effects of vaporized cannabis on the microglia in mice,” Loewen said. “Microglia are very important cells in the brain and are active from the very start of the brain’s development. They are always changing and reacting. They can change shape if we’re experiencing stress or a lack of sleep, or even perform synaptic pruning if they are not being used.”
Microglia have reactors that cannabis can act on (called CB1 and CB2). Most previous studies involving cannabis have used an injected form, but Loewen used vaporized cannabis in part because it is more translationally relevent. It also helps that since legalization in Canada, people are more interested in the drug and funding for research has become more readily available.
Mice made an excellent candidate for the study, not only because the use of mice models in research is well established, but vaporized cannabis affects them in ways similar to humans.
During the experiment, healthy adult male mice were placed in a vapour chamber at the University of Guelph where they were exposed to the vaporized cannabis. The strands used were a high THC, a high CBD, and a balanced THC & CBD. After 15 minutes of exposure, the mice were then removed, euthanized, and the brain perfused. The frozen brain would then be shipped to Victoria, where the Tremblay Lab used specialized equipment to image it.
“We were looking at the number and distribution of the microglia in the brain after being exposed to the vaporized cannabis, specifically in the prefrontal cortex, a brain region important for learning and memory,” Loewen explains. “As immune cells, the microglia perform a wide variety of tasks that ensure the proper formation and function of the brain. Understanding how cannabis exposure affects a healthy brain is the first step before we can begin investigating how it may potentially be used to impact microglia in injured and diseased states.”
Early findings from the study show that the vaporized cannabis does affect the microglia, but the effects differ depending on the region of the brain and the strain of cannabis used. The next phases of the project include investigating the effects in female mice and the impacts of chronic exposure to vaporized cannabis on both sexes. Once this baseline information is established, then further investigation can look at different mouse models such as diseased, ageing, and stress models.
“One of the early lessons I’m learning as a researcher is that every answer you find leads to more questions,” Loewen said. “Can the difference between acute and chronic exposure be seen in the microglia? How about microglia in other areas of the brain? It’s very exciting to be involved but I’ve discovered that it often takes much longer to reach a conclusion then you first imagine.”
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