Methylation of the Glial Derived Neurotrophic Factor Gene Promoter in the Mesolimbic Pathway

Open Access
Author:
Witowski, Rachel L
Area of Honors:
Biology
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
  • David John Vandenbergh, Thesis Supervisor
  • Stephen Wade Schaeffer, Honors Advisor
  • Sonia Angele Cavigelli, Faculty Reader
Keywords:
  • methylation
  • epigenetics
  • LINE elements
  • Gdnf
  • glial derived neurotrophic factor
  • nicotine
  • drug addiction
Abstract:
Drug addiction and substance abuse is a major problem in the US, and it imposes major costs on society due to factors like increased mortality, loss of productive years, health costs, and criminal costs. Nicotine, a highly addictive drug, represents the single biggest preventable cause of death in adults in the US and accounts for much of the costs of drug addiction to society. There is evidence that nicotine may exert its addictive effects by altering epigenetic marks in dopamine neurons that play a role in reward and addiction. This study investigated how methylation of DNA, one type of epigenetic modification, may be measured in two regions of the mesolimbic circuit in the brain to test its role in reward and addiction in future studies. Methylation was tested in two ways. First, attempts were made to measure global methylation by using methylation of Long Interspersed Nuclear Elements (LINE) that proved unsuccessful. Second, levels of methylation were tested in the promoter of a specific gene, Glial-derived neurotrophic factor (Gdnf) in mice.). This gene is crucial to the maintenance and survival of dopamine neurons of the mesolimbic pathway, which has been implicated in the rewarding functions of drugs like nicotine. The current study investigated levels of methylation in the Gdnf promoter in two important brain regions in the mesolimbic system, the Ventral Midbrain, containing the Ventral Tegmental Area (VTA), and the Nucleus Accumbens using a qMethyl assay. Results showed that there was no significant difference in methylation of the Gdnf promoter between these two brain regions. Finally, methylation in the Ventral Midbrain and Nucleus Accumbens did not vary with the level of nicotine consumed by mice.