Individual differences and psychoactive substances: alcohol and caffeine effects on zebrafish behavior (Danio rerio)
personality, zebrafish, alcohol, caffeine, animal behavior
Individuals have different behavioral traits that make up their personalities. Traits are considered characteristics that both have a genetic basis and are shaped by experiences throughout life, and guide the way individuals behave in different situations and environmental contexts experienced. The wide behavioral variability in a population is important for species maintenance and individual survival. These characteristics may also be related to risk behavior and influence the consumption, effects, and sensitivity of individuals to psychoactive substances. Among them, alcohol and caffeine seem to be the most consumed worldwide. Alcohol is the licit drug responsible for numerous diseases and accidents in human beings, while caffeine, despite not having such serious effects, can also be harmful if consumed in large quantities. Thus, the objective of this thesis was to evaluate the response of behavioral profiles related to one of the personality traits, the bold-shy profile, under the influence of alcohol and caffeine in zebrafish. In the first chapter, we assess the differences between the profiles of a zebrafish population, to determine the risk-taking and exploration behaviors that determine the two extremes of the bold-shy continuum. Then, we tested the extreme profiles in two different contexts, an affiliative context (social group) and an aversive context (presence of a predator), and under the effect of chronic and acute treatments with alcohol (chapter 2) and caffeine (chapter 3). Our results show that bold and shy profiles show differences in risk-taking, bold individuals are more prone to risk than shy ones, and in exploratory response, bold individuals are more exploitative than shy ones. Furthermore, the profiles respond differently to drug concentrations and analyzed contexts, with differences in drug sensitivity, which makes bold individuals more sociable in some situations and shy individuals less risk-averse in others. Our data show that there is a difference in responsiveness between bold and shy, corroborating studies that relate personality to the effects of psychoactive substances. We hope these results will help advance further research on the effects and treatments for substance abuse and its consequences. Finally, we reinforce the use of zebrafish as an adequate and reliable tool for translational studies related to psychotropic drugs