Long-term obesity is associated with depression and neuroinflammation.

Objective: Obesity is characterized by a state of chronic, low-intensity systemic inflammation frequently associated with insulin resistance and dyslipidemia.

Methods: Given that chronic inflammation has been implicated in the pathogenesis of mood disorders, we investigated if chronic obesity that was initiated early in life - lasting through adulthood - could be more harmful to memory impairment and mood fluctuations such as depression.

Results: Here we show that pre-pubertal male rats (30 days old) treated with a high-fat diet (40%) for 8-months gained ~50% more weight when compared to controls, exhibited depression and anxiety-like behaviors but no memory impairment. The prefrontal cortex of the obese rats exhibited an increase in the expression of genes related to inflammatory response, such as NFKb, MMP9, CCl2, PPARb, and PPARg. There were no alterations in genes known to be related to depression.

Conclusion: Long-lasting obesity with onset in prepuberal age led to depression and neuroinflammation but not to memory impairment.