17β-, not 17α-E
, protects human fetal neurons against the synergistically toxic of incubation with Tat [40 nM] plus gp120 [32.5 pM] (HIV Proteins) plus cocaine (Coc) [1.6 μM]. Control conditions of incubation with Locke's Buffer vehicle or the HIV proteins or Coc only produced similar neuronal death. (Left Panel) Significant interaction of the HIV proteins with Coc, as illustrated by the lines diverging from parallel, produced toxic synergism (*p < 0.0008). (Right Panel) Significant neuroprotection by 17β-E2 against HIV proteins w/ Coc toxic synergism (#p < 0.0001).