NOS1 and metabolic syndrome: Particularly, the levels of NOS (iNOS, eNOS, and nNOS) and transcription factors (HIF-1α and NRF2) in the MetS + L-arginine group and the MetS + OVX + L-arginine group were markedly increased compared to the MetS + L-NAME group and the MetS + OVX + L-NAME group.