FIG. 3. Mechanism of gp120-induced neurotoxicity. gp120, the HIV-1 coat protein, may elicit neurotoxicity by interacting with macrophage/microglia and astrocytes to release cytokines and/or arachidonic acid metabolites. Glutamate then interacts with the cytokines and/or arachidonic acid metabolites to activate NMDA receptors, which increases intracellular calcium levels. NOS is subsequently activated, and excessive formation of NO kills adjacent neurons. (From ref. 16.)