A general tendency in modern scientific research has been to replace the use of vertebrates by invertebrate model systems as a mean to resolve ethical dilemma. The purpose of this research was to evaluate the potential of the crustacean Daphnia Magna as a model system for further heart- based research as it possesses a myogenic heart with ion channels similar to ones found in vertebrates. The effects on the heart rate of two different neurotransmitters, dopamine and serotonin, were analyzed. After being stabilized in a petri dish, the Daphnia Magna were exposed to different concentrations of the neurotransmitters for 5 minutes. A video of the crustacean under an inverted microscope was then recorded to count the heart rate. The effect of the isolation time without any neurotransmitters was also analyzed for a period of 150 minutes. It was observed that the heart rate significantly decreases after 45 minutes of isolation. Additionally, dopamine did not affect the heart rate significantly, but serotonin caused a significant decrease at high concentration. These results indicate that Daphnia Magna might be a potentially good model system, but further research involving other neurotransmitters need to be conducted. This project was funded by the M.J. Murdock Charitable Trust.

The Effect of Monoamine Neurotransmitters, Serotonin and Dopamine, on Daphnia Magna Heart Rate