A Simple Analysis and Scoring of Zebrafish Larvae Cardiac Performance in Teratogenicity Study using Light Microscopy and ImageJ Software

Background: Zebrafish is one of the suitable model organisms for teratogenicity study. One of the organs assessed during the study is the heart. There has been an established scoring system for the cardiac morphology, but not cardiac performance. Furthermore, the assessment of cardiac function in zebrafish often use expensive instruments and complicated methods.

Materials and Methods: Cardiac performance scoring method and system was proposed for zebrafish larvae aged 5 dpf. Observation was done using light microscope and the video of the observation was taken using smartphone or camera. The videos were then converted and rendered to be compatible with the ImageJ program using the measure function and time series analyzer plugin. The assessed parameters were the heart rate and rhythm, strength of heart contraction, and synchronicity between atrium and ventricle.

Results: The scoring system was formulated based on the assessments towards healthy control 5 dpf zebrafish larvae and references. The score for cardiac performance ranged from 3 – 6, with score 3 representing arrhythmic, weak, and asynchronous contractions, while score 6 representing rhythmic, strong, and synchronous contraction. The scoring system was also valid to point out the difference in cardiac performance between healthy control zebrafish larvae and larvae that previously exposed to lithium as teratogenic agent (p = 0.000).

Conclusions: The scoring methods and system developed in this study allowed for a non – expensive and simple assessment of cardiac performance in zebrafish larvae aged 5 dpf, especially for a teratogenicity study.