Meeting Abstract
The heart is the first organ to develop in vertebrate embryos and is necessary for subsequent development. Disruption of cardiac morphogenesis can result in reduced cardiac function. Serotonin (5-HT), while not usually thought of as a developmental signal, plays an important role in cardiac development. To explore this further, we treated Japanese quail embryos with different concentrations of 5-HT. We chose to study quail because bird eggs are accessible to experimentation and quail embryos are small, can be imaged as whole mounts in a confocal microscope, and they are similar to mammals in cardiac development. After incubation for 52-64 hours (stage 17) ventricular septation is just beginning. We removed eggs from the incubator at this stage and injected them with a dose of 5-HT (2 mM in Tyrode’s solution). We replaced a small volume of the albumen with the serotonin solution to achieve concentrations of serotonin ranging from 0-100 µM. After a total of six days of incubation, we dissected the hearts out of the embryos, fixed them in 4% formaldehyde, cleared them in BABB, and imaged them under a confocal microscope. We selected image slices from the middle depth of the heart and measured the length and width of the heart, the right and left ventricular wall thicknesses, and the septum thickness. Analysis of the data revealed interesting trends. A 5-HT concentration of 1 µM increased the length to width ratio, indicating a more elongated heart. The thickness of the septum increased at 10 µM but decreased below the control thickness at 100 µM. The ventricular wall thickness displayed a trend similar to septum thickness but to a lesser degree. Overall, stimulation of growth occurred at low doses while higher doses inhibited growth.
