Enriquecimento ambiental na puberdade: o efeito no cuidado materno e na metilação de genes em fêmeas murinas

Abstract

Environmental enrichment (EE) is a procedure used to improve the living conditions of confined animals. It can impact the welfare of these animals by reducing stress, anxiety, and depressive-like behaviors, increasing the quality of life due to the sensory changes. EE administration at different stages of the life could result in behavioral changes that may impact in changes in the expression of several genes, that is, epigenetic changes. The present project aimed to verify the effect that EE at puberty has on the emotionality and maternal care of LG/J females’ mice. For this purpose, 40 LG/J females were used (Control Group-CG; n=20, and Experimental Group exposed to AE at puberty-EG; n=20). The EE was performed by exposing the females to the cardboard roll. The result of emotionality, investigated by the Open Field, Elevated Cross Maze, and Forced Swimming tests, in the Pubertal, Adult and Maternal and Post-Weaning (PW) phases, suggest that LG/J females have anxious and depressive behaviors intrinsically to them, and that the life stage can change behavior, and in the PD stage these females are more anxious and show depressive-like behavior, regardless of the evaluated groups. There was no significant difference for emotionality between CG and EG. Some aspects of maternal care had a significant difference (p<0.05) between the studied groups. Placentophagy was less performed by the EG, but their offspring were heavier in the first week of life and had less fat deposited in the mesenteric region, in adulthood. EG also had more interaction with their pups performing licking, which is an important posture for the initial development of pups. The positive effect verified in some maternal postures indicates the potential effect of EE, even in the early stages of the animal's life. To verify the epigenetic changes in the hypothalamic region, a search for candidate genes was carried out, selecting the Bdnf gene. In the promoter IV region of this gene, primers were designed to detect methylation, or not, in this region, by performing Methylation-Specific PCR. These primers should be standardized and used in the genotyping of females to investigate methylation differences between them, with the potential of this gene to be an epigenetic marker for animal welfare.