TLR4 and obesity due to melanocortin 4 receptor deficiency: In Toll-Like Receptor 4 (TLR4) mice, HFD-induced obesity activates phosphorylated Akt (pAkt) in the liver, with TLR4 signaling—via NF-κB activation—leading to palmitic acid-induced vascular inflammation and insulin resistance, disrupting endothelial NO signaling [78].