Early life stress does not alter global DNA methylation in the striatum of an animal model of mania

  • BBiomedSc Gabriel Fries, Federal University of Rio Grande do Sul and National Institute of Science and Technology in Translational Medicine, CNPq, Brazil
  • Camila Lersch, Federal University of Rio Grande do Sul and National Institute of Science and Technology in Translational Medicine, CNPq, Brazil
  • PhD Maria de Lima, Pontifical Catholic University, Porto Alegre and National Institute of Science and Technology in Translational Medicine, CNPq, Brazil
  • BBiomedSc Laura Stertz, Federal University of Rio Grande do Sul and National Institute of Science and Technology in Translational Medicine, CNPq, Brazil
  • MD Brisa Fernandes, Federal University of Rio Grande do Sul and National Institute of Science and Technology in Translational Medicine, CNPq, Brazil
  • MD/PhD Flávio Kapczinski, Federal University of Rio Grande do Sul and National Institute of Science and Technology in Translational Medicine, CNPq, Brazil
  • PhD Maria Saraiva-Pereira, Genetics Identification Laboratory, Research Center, Hospital de Clínicas de Porto Alegre, Porto Alegre, RS, Brazil
  • PhD Nadja Schröder, Pontifical Catholic University, Porto Alegre and National Institute of Science and Technology in Translational Medicine, CNPq, Brazil

Epigenetic mechanisms such as DNA methylation lead to genome plasticity and short-term adaptations to environment effects associated with mood disorders.
Objective: To evaluate the effects of an environmental risk factor (maternal deprivation) on a previously developed animal model of mania based on D-amphetamine (AMPH) administration, on global DNA methylation levels in the striatum of rats.
Methods: Rats were exposed to one of the following conditions from postnatal days 1-14: handled (H) or maternal deprived (MD, daily 180min period of separation of the dam). In the adulthood, both groups received injections of saline or AMPH (2.0mg/Kg/ip) for 7 days (7 animals/group). The striatum was dissected from each rat and submitted to a DNA extraction protocol. The global methylation levels were assessed by a colorimetric kit. The data were analysed by Kruskal-Wallis test, and p values lower than 0.05 were considered statistically significant. The values are presented as median and minimum and maximum.
Results: No statistically significant differences among groups were observed (median MD-Sal 20.7, range from 12.63 to 40.86; median MD-AMPH 12.16, range from 8.2 to 46.00; median H-Sal 11.09, range from 5.98 to 29.58; median H-AMPH 11.32, range from 6.69 to 24.85; p=0.31).
Conclusions: Exposure to an environment risk factor such as maternal deprivation does not alter global DNA methylation in the striatum of rats. Nonetheless, methylation in specific genes can be present and require further investigation. This mechanism might be taking place in other areas rather than the striatum, including some associated with the pathophysiology of bipolar disorder.