Abstract

Background: Zebrafish (Danio rerio) is the new model for human diseases. About 70% of its genome matches with that of human and 84% of diseases can be modeled in zebrafish. Zebrafish has been established as a complimentary model to the classic rodent models in the modern day’s animal studies. Learning, memory, and intelligence are the most vulnerable functions due to hypoxia of brain. This study aims to model a hypoxic state in adult zebrafish and delineating its impact on cognitive functions of the brain with regard to learning and memory using a visual discrimination test. Aim and
Objective: The objectives of this study are to create a zebrafish model for learning and memory and to study the effects of acute and chronic hypoxia on the same.
Materials and Methods: Eighteen adult zebrafish were randomly divided into three groups (six in each): Group 1: Acute hypoxia exposed group (AHEG); Group 2: Chronic hypoxia exposed group (CHEG); and Group 3: SHAM (control group with no hypoxia exposure). All were subjected to color-cued plus maze test for 6 days for establishing memory to find the food in the red arm. Then, they were subjected to acute and chronic hypoxia and then the test is repeated again on days 9, 10, and 13 to check for short-term memory (STM) and longterm memory (LTM). The data were pooled and analyzed using SPSS by repeated measures of ANOVA.
Results: AHEG group fishes showed significant prolongation in STM after exposure to hypoxia (P = 0.031), whereas LTM seems to be unaffected. CHEG group fishes showed significant changes in LTM but not in STM. STM and LTM unaffected in SHAM group. Conclusion: STM was affected due to acute hypoxia, whereas LTM did not have any profound effects due to acute or chronic hypoxia. Thus, this zebrafish model worked out to study the learning and memory, the results of which can be applied to humans.