Effects of cannabis tea on the development of zebrafish embryo and larval behaviour

Cannabis is a known illicit substance that is often used by pregnant women, however its potential impact on the developing embryo is unknown. Thus, this experiment used a zebrafish model to investigate how chronic exposure to cannabis tea affected zebrafish development and behaviour. Zebrafish embryos were exposed to cannabis tea prepared at concentrations of 5, 10 and 15 mg/L for 96 hours. The resulting mortality, hatching duration, morphological abnormalities, startle response, light-dark preference and optokinetic response were then assessed. The cannabis tea had a significant impact on the mortality, hatching duration, startle response and optokinetic response. The tea had a LC50 of 11.20 mg/L with mortality increasing with the tea concentration. The hatching duration increased with cannabis exposure (p = 0.046). For the startle response, the effect of the cannabis tea was concentration dependent, with higher concentrations reducing the startle response (p < 0.001). The optokinetic response initially increased at the lowest cannabis dose, but subsequent increase caused reductions in the response (p < 0.001). As for the morphological abnormalities, deformities were only observed in larvae exposed to cannabis. The cannabis tea also showed both anxiolytic and anxiogenic effects on the larvae in the light-dark preference assay. These results were comparable to studies investigating THC and CBD separately. Although more comprehensive research is required to offer a better understanding, these findings aid in our knowledge of how a cannabis whole extract influences development.