Determining the Causation of Microphthalmia in Cannabidiol Treated Zebrafish Embryos

Cannabidiol (CBD) is a cannabinoid derived from the plant cannabis sativa. Multiple studies on CBD show that it is used as an anti-psychotic, an anti-inflammatory for pain relief, and an antinausea agent. The Agriculture Improvement Act (2018) played a role in removing hemp and hemp derivatives like CBD from being categorized as a Schedule I substance, which led to recreational usage in America. In 2003, there was an increase in cannabinoid consumption during pregnancy to alleviate morning sickness along with distress. Prior studies on CBD-treated zebrafish embryos have demonstrated phenotypes of microphthalmia, scoliosis, fewer neuronal connections, and less motor neuron activity. While previous research identified effects of CBD exposure like microphthalmia, the mechanism behind the reduction in eye size remains unclear. Are there fewer cells, or are the cells smaller? Zebrafish are utilized as a model organism for early human development. Human and zebrafish have 70% gene similarity for cannabinoid receptors, along with similar cellular signaling and tissue locations of cannabinoid receptors. Using a previous experimental design that observed microphthalmia, we aimed to determine how CBD affects early eye development. [High] CBD-treated embryos had a significant decrease in survival rate when compared to wild-type survival (p < 0.05). To determine if a decrease in cell count was associated with microphthalmia, we counted cells using DAPI and measured cell size using phalloidin in [high] CBD-treated versus untreated embryos via confocal microscopy. Confocal images were cropped to equal sizes and adjusted equally for brightness and contrast. Channels were split to show each stain individually for 1 optical micron section. [High] CBD had fewer cells without a decreased cell size, particularly at 4mg/L. It is unclear if this reduction in cell count is due to a lack of migration, increased cell death, or decreased mitosis.