Different effects of selective dopamine uptake inhibitors, GBR 12909 and WIN 35428, on HIV-1 Tat toxicity in rat fetal midbrain neurons

Drug abuse is a risk factor for neurological complications in HIV infection. Cocaine has been shown to exacerbate HIV-associated brain pathology and enhance neurotoxicity of HIV-1 Tat and gp120 proteins. In this study, we found that the selective inhibitor of dopamine transporter (DAT) function, 1-[2-[bis(4-fluorophenyl) methoxy]ethyl]-4-(3-phenylpropyl) piperazine (GBR 12909, vanoxerine), but not the selective inhibitors of serotonin and norepinephrine (SERT and NET) transporters, sertraline and nizoxetine, emulated cocaine-mediated enhancement of Tat neurotoxicity in rat fetal midbrain primary cell cultures. Similar to cocaine, the significant increase of Tat toxicity in midbrain cell cultures was observed at micromolar dose (5 μM) of GBR 12909. However, different doses of another selective dopamine uptake inhibitor, WIN 35428 did not affect Tat neurotoxicity. The study supports the hypothesis that changes in control of dopamine (DA) homeostasis are important for the cocaine-mediated enhancement of HIV-1 Tat neurotoxicity. Our results also demonstrate that inhibitors of DA uptake, which can bind to different domains of DAT, differ in their ability to mimic synergistic toxicity of cocaine and HIV-1 Tat in the midbrain cell culture.