MDM release excitotoxins during productive HIV-1 infection. HIV-1 infection of MDM (indicated by supernatant p24 antigen content; y-axis) was blocked with the non-nucleoside reverse transcriptase inhibitor efavirenz (A), and supernatants were added to DIV 21 hippocampal neurons (B). Control hippocampal cultures received mock-infected supernatants with or without efavirenz. The number of surviving neurons was determined as in Figure 1B. The NMDA receptor antagonist MK801 (10 μm) was added to hippocampal cultures 1 h before addition of macrophage supernatants (**p < 0.01 vs HIV-Jago/efavirenz; ^#p < 0.01 vs HIV-Jago plus MK801).