This document discusses the roles of nitric oxide (NO) and reactive oxygen/nitrogen species (ROS/RNS) in neurons and astrocytes. It describes how nitric oxide synthases (NOS1-3) in neurons and astrocytes produce NO to regulate processes like vasodilation, neurotransmission, and inflammation. NO and ROS/RNS are balanced by antioxidant defenses like glutathione (GSH) and superoxide dismutase (SOD). Astrocytes help neurons maintain GSH levels through the cysteine-glycine pathway and coupling glucose metabolism to NADPH and GSH production. This maintains redox homeostasis and protects against oxidative stress in the brain.