Human immunodeficiency virus-1 Tat activates calpain proteases via the ryanodine receptor to enhance surface dopamine transporter levels and increase transporter-specific uptake and Vmax.

Human immunodeficiency virus-associated neurological disease (HAND) still causes significant morbidity, despite success reducing viral loads with combination antiretroviral therapy. The dopamine (DA) system is particularly vulnerable in HAND. We hypothesize that early, "reversible" DAergic synaptic dysfunction occurs long before DAergic neuron loss.