The DRD4 gene, a specific G protein-coupled receptor, is responsible for encoding the D4 subtype of the dopamine receptor and is a common target for drugs treating mental illnesses, such as schizophrenia. When dopamine, a neurotransmitter in the synapse, binds to the D4 subtype of the receptor, the receptor becomes activated and a structural change occurs within the receptor, making it easier for a methyl group to attach to the phospholipid membrane surrounding the receptor. Phospholipid methylation affects the packaging and function of the proteins surrounding the dopamine receptor D4 on the postsynaptic neuron, resulting in a more rapid firing of neurons and gamma waves. Increased expression of the DRD4 gene could increase gamma synchronization as a result of increased chances of phospholipid methylation. Past research has identified that there is significant increased DRD4 promoter methylation in Alzheimer’s versus controls and concluded that increased DRD4 promoter methylation is associated with an increased risk for Alzheimer’s Disease (AD) in males. This research investigated the difference in expression of the DRD4 gene between AD and older controls using RT-qPCR to see if factors other than age contributed to any differences. We found that in the majority of our AD samples there was undetectable expression of the DRD4 gene, whereas the majority of our controls had detectable expression. In the future, I would like to investigate the different methylation levels of the promoter regions in the DRD4 gene to confirm that increased promoter methylation is associated with decreased expression of the DRD4 gene.
