Caracterização do comportamento defensivo de Ratas Submetidos ao Protocolo de Condicionamento Aversivo Olfatório: efeito da fluoxetina

Abstract

Physiological and anatomical differences between male and female rats affect the expression of defensive behavior. Based on the fact that female rats are more active than male rats, and their social role in a colony, there is great importance in including female rats in preclinical studies. Pavlovian or classical conditioning is an animal model widely used to clarify the processes and mechanisms involved in the neurobiology of defensive responses. In olfactory aversive conditioning a neutral stimulus or context is paired with an aversive unconditioned stimulus. After associations, the neutral stimulus acquires the ability to generate defensive responses that would supposedly occur in the presence of danger, becoming a conditioned stimulus. Animal models allow neurochemical, neuroanatomical and behavioral investigations which would not always be possible to be carried out in humans. Thus, the present project was designed with the purpose of studying the behavioral differences presented in the defensive behavior in female Wistar rats, treated with the drug used in the treatment of mood disorders. Initially, the characterization of the behavioral pattern presented by the rats in the olfactory aversive conditioning model was carried out. Next, the effect of chronic treatment with the drug fluoxetine was evaluated. The main results of this study revealed that the shock intensities are capable of modifying the defensive behavioral pattern of the rats and related to this, the behavior parameter with greater emphasis presented by the rats was the risk assessment, which confirms that the rats exhibit active defensive responses, in addition, the olfactory stimulus used in this study was able to generate reduced responses in the time spent in the space close to the CS. And related to the effect of the pharmacological treatment used in this study, fluoxetine 10 mg/kg increased the risk assessment response and reduced the non-defensive behavior response, it was also found that there was an increase in the time spent in the closed space for both the doses of fluoxetine used before conditioning in this study, and in addition, there was a reduction in the time spent in the open space only in rats previously treated with 5 mg/kg fluoxetine