TLR4 and metabolic dysfunction-associated steatohepatitis: Supporting these results, other studies have found that NASH animals displayed behavioral abnormalities that have been linked to an increased protein expression of Toll-like receptor 4 (TLR4), a major regulator of pro-inflammatory response and microglial activation, in the prefrontal cortex but not elsewhere.55,56 Moreover, in NASH animals, signs of microglial activation and oxidative stress in the prefrontal cortex have been found57 together with increased protein oxidation and lipid peroxidation in the frontal cortex.58A.