The long-term interaction of diet and dopamine D2 gene expression on brain microglial activation

Dopamine D2 receptors are expressed on microglial in the central nervous system and promote anti-inflammatory responses. Little work has been done on the interaction between the dopamine D2 receptors and diet on activated microglial expression in the brain. To assess this, the current study uses in vitro autoradiography to look at microglial activation in the brain as a marker for neuroinflammation. Mice with different levels of expression of the DA D2 gene were given a chronic diet of either normal diet chow or high fat diet chow for 30 weeks. Mice were then euthanized and their brains were processed for [³H]PK11195 autoradiography. Mice with reductions or lack of the D2 gene showed higher [³H]PK11195 binding in a diet-specific manner within somatosensory and striatal regions, as well as the piriform, frontal, insular, and entorhinal regions compared to mice with normal D2 gene levels. These brain regions are important for sensory processing, habit formation, as well as cognitive function tasks related to learning, motivation, and memory. These results suggest that decreased D2R levels may increase vulnerability to specific inflammatory markers. Future studies will need to examine the implications of these inflammatory changes on brain function and behavior.