Ativação celular e expressão de redes perineuronais no hipocampo dorsal de ratos pré-púberes expostos ao condicionamento de medo ao contexto

Abstract

The experiences that occur during the period of sexual maturation in animals are considered critical, as processes such as neurogenesis, axonal growth and synaptogenesis occur at this stage. Rats are altricial animals; undergo important biological events in the postnatal period, such as considerable structural changes in gray matter and increased dendritic density and complexity. There is also the influence of hormonal factors in adolescence, which generate changes in the physiology and brain structure of animals. The development of memory for fear-aversive information is essential for survival, which is linked to the emotion of fear in the animal. Understanding this, we can use the association learning mechanism, which configures Pavlovian fear conditioning, to study aversive memory. Using this method, our study verified defensive responses, focusing on the behaviors of self-cleaning (self-cleaning), elevation (supporting the hind legs) and freezing (immobility), in addition to investigating the dorsal hippocampus, through the expression of C -fos, which is an immediate gene, and PNNs, which are proteins that act in neural plasticity, in the different phases of aversive memory processing in 24-day-old rats, which are at the beginning of adolescence, a period that does not yet understand puberty. The results indicated that the rats responded with freezing during the acquisition and recall of the fear memory to the context, and we observed that females are more willing to express freezing compared to males in the memory retrieval phase. Furthermore, we recorded C-fos and WFA immunoreactive cells (indicative of the presence of perineuronal networks) throughout the dorsal hippocampus, in all experimental groups and in both sexes. In the field of memory ontogenesis, these results will be even more useful when compared with future studies, which aim to investigate the neurobiology of rats during puberty.