Efeitos do estresse agudo de contenção sobre parâmetros comportamentais tipo-ansiedade em zebrafish (Danio rerio)

Abstract

Acute restraint stress (ARS) has been used as an important inducer of behavioural responses in pharmacological, pathological and physiological studies in animals. In vertebrates, stress responses are related to anxiety responses, but the neurobiology of these complex mechanisms is still unclear. Therefore, animal models have been used experimentally to investigate the pathophysiology of these mechanisms. The zebrafish (Danio rerio) has emerged as an essential model organism for these investigations, due to its homologous genetic characteristics and its potential in behavioural tests. Thus, the aim of this study was to evaluate the effects of ARS on anxiety-like behavioural parameters in zebrafish. To this end, 12 animals were exposed to 90 min of restraint in 1.5 ml microtubes, positioned on a plastic shelf inside an aquarium, and a control group with 12 animals was maintained under the same circumstances, but without the restraint in the microtubes. After 90 min, all the animals were subjected to the novelty elicited vertical distribution test and the light/dark preference test. The data obtained was statistically analysed using Student's t-test, with a significance level of p < 0.05. The results indicate that there were no statistically significant differences between the control and ARS-exposed groups in the variables observed in both tests, with the exception of the animal's increased freezing in the clear part of the preference test (t (22) = -1.82; p = 0.041). When compared with previous research, these findings are both concordant and discordant in relation to the variables studied. In the literature analysed, there is inconsistency between the protocols adopted in research with ARS, with important differences in the procedures for carrying out the stressor and the behavioural tests, which could explain the differences between the findings of this research and those of other studies involving exposure to ARS. Furthermore, the literature shows some differences between the behavioural tests used in this study which may have influenced the increase in the animal's freezing only in the light/dark preference test. Finally, we note the need for better standardisation of the procedures for carrying out the ARS and the behavioural tests mentioned above. Further research in this area is also crucial to understanding the phenomena observed in this study and the complexity of stress, anxiety and animal behaviour.