P2RX7 and metabolic syndrome: Imaging tracers targeting neuroinflammatory markers (eg, TSPO [translocator protein], COX-2 [cyclooxygenase-2], CB2 [cannabinoid receptor 2], MAO-B [monoamine oxidase-B], and P2X7 [purinergic receptor P2X 7]) have been used to study brain inflammation, with mixed results in MetS models.