INS and obesity due to melanocortin 4 receptor deficiency: Docking: styrene > ethylene/propylene in macrophage binding ↑ fPS-MP binding to microglia (dose-dependent) In vivo: fPS-MP in blood + immune cells, ↑ insulin resistance, ↑ systemic inflammation Brain accumulation, ↑ hypothalamic microglia activation MPs exacerbate inflammation and metabolism in obesity