The effects of obesity on microglial activation are poorly understood particularly in neurodegenerative diseases. In this study, we examined microglial function in obese and healthy mice. 

Microglia were isolated from brains of adult mice fed either high fat or low fat diet. Percoll gradient centrifugation was used to isolate the microglia. The cells were then activated in culture using lipopolysaccharides (LPS) and imaged at 2, 6, 10 minutes post treatment. The soma area, process length, and number of processes were compared between groups using ImageJ. 

High fat diet microglia exhibit a delayed response to LPS compared to low fat diet cells. The soma area of low fat diet microglia is significantly bigger after 2 minutes of activation (p< 0.05). The same increase was not observed in high fat diet microglia. Similarly process retraction was slower in high fat diet mice. 

The data suggest that microglia isolated from high fat diet mice display an altered state of responsiveness compared to low fat diet mice likely due to chronic inflammation as a result of obesity. The inflammatory triggers due to obesity could hinder the microglial ability to efficiently respond to insults from the surrounding microenvironment e.g. Amyloid.