TAT and HIV-1 infection: Given the beneficial outcomes of nicotine on HIV-1 infection-induced neurological deficits (Cao et al., 2013), we speculate that acute nicotine may be beneficial to Tat-induced neuron loss due to Tat-induced transient increase in the neuronal activity; however, long-term exposure of nicotine is unlikely to be beneficial in Tat-induced dysfunction of neuronal activity, such as morphological changes in the VTA neuron.