Declínio cognitivo decorrente do envelhecimento em zebrafish (Danio rerio)

Abstract

Aging is a natural process that involves physical and psychological changes resulting from the passage of time, including alterations in the ability to perform certain activities. Biological aging, which encompasses physical changes throughout life, leads to functional losses in various tissues, including the brain. In this study, we assessed cognitive performance in adult zebrafish (Danio rerio) at different ages: 6 and 18 months (n=10). We evaluated the process of formation and retrieval of long-term memory in these animals through the object discrimination test. Initially, the fish explored the environment by accessing two identical 3D objects (same size, color, and shape), and after 24 hours, the ability to discriminate between the objects based on the memory formed in the previous event was assessed. In the second phase, one of the objects was replaced by another of a different color. Our data showed that the 6- month-old animals increased the exploration time of the new object in the discriminative phase, while the 18-month-old animals explored one of the objects more during the memorization phase, without showing subsequent discriminative capacity. The results demonstrate cognitive differences between animals of different ages, indicating aging processes related to memory formation in 18-month-old animals. Older individuals did not discriminate the new object, which may indicate a decline in processing new information or the need for longer time of exploration. We emphasize the use of zebrafish as an animal model for studies on aging processes and for testing therapies to improve mnemonic responses.